W3C

Web Services Description Language (WSDL) Version 2.0 Part 1: Core Language

W3C Candidate Recommendation 27 March 2006

This version:
    http://www.w3.org/TR/2006/CR-wsdl20-20060327
Latest version:
    http://www.w3.org/TR/wsdl20
Previous versions:
    http://www.w3.org/TR/2006/CR-wsdl20-20060106
Editors:
    Roberto Chinnici, Sun Microsystems
    Jean-Jacques Moreau, Canon
    Arthur Ryman, IBM
    Sanjiva Weerawarana, WSO2

This document is also available in these non-normative formats: XHTML with Z
Notation, PDF, PDF with Z Notation, PostScript, XML, and plain text.

Copyright © 2006 W3C^® (MIT, ERCIM, Keio), All Rights Reserved. W3C liability,
trademark and document use rules apply.

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Abstract

This document describes the Web Services Description Language Version 2.0 (WSDL
2.0), an XML language for describing Web services. This specification defines
the core language which can be used to describe Web services based on an
abstract model of what the service offers. It also defines the conformance
criteria for documents in this language.

Status of this Document

This section describes the status of this document at the time of its
publication. Other documents may supersede this document. A list of current W3C
publications and the latest revision of this technical report can be found in
the W3C technical reports index at http://www.w3.org/TR/.

This is an updated version of the W3C Candidate Recommendation of Web Services
Description Language (WSDL) Version 2.0 Part 1: Core Language for review by W3C
Members and other interested parties. It has been produced by the Web Services
Description Working Group, which is part of the W3C Web Services Activity. The
publication of this document signifies a call for implementations of this
specification. The Candidate Recommendation period specified in the previous
draft (15 March 2006) has passed. The Working Group does not anticipate
garnering enough implementation experience to fulfill its Candidate
Recommendation exit criteria until at least 1 July 2006.

This version addresses the modest number of comments received to date on the
Candidate Recommendation of Web Services Description Language (WSDL) Version
2.0 Part 1: Core Language, and primarily differs from the previous version in
the inclusion of marked test assertions to help implementers. The detailed
disposition of the comments received can be found in the Candidate
Recommendation issues list. A diff-marked version against the previous version
of this document is available. For a detailed list of changes since the last
publication of this document, please refer to appendix E. Part 1 Change Log.

The Working Group plans to submit this specification for consideration as a W3C
Proposed Recommendation if the following exit criteria have been met:

  • Two interoperable implementations of all the features, both mandatory and
    optional, of the specifications have been produced.

  • The Working Group releases a test suite along with an implementation report
    .

The sections 2.7 Feature and 2.8 Property in this specification, defining the
feature and property components, are considered at risk. The Working Group may
recommend to remove the components from the specification, depending on their
use and the implementations.

Implementers are invited to send feedback on this document to the public
public-ws-desc-comments@w3.org mailing list (public archive).

Issues about this document are recorded in the Candidate Recommendation issues
list maintained by the Working Group. A list of formal objections against the
set of WSDL 2.0 Working Drafts is also available.

Publication as a Candidate Recommendation does not imply endorsement by the W3C
Membership. This is a draft document and may be updated, replaced or obsoleted
by other documents at any time. It is inappropriate to cite this document as
other than work in progress.

This document was produced by a group operating under the 24 January 2002 CPP
as amended by the W3C Patent Policy Transition Procedure. W3C maintains a
public list of any patent disclosures made in connection with the deliverables
of the group; that page also includes instructions for disclosing a patent. An
individual who has actual knowledge of a patent which the individual believes
contains Essential Claim(s) must disclose the information in accordance with
section 6 of the W3C Patent Policy.

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Short Table of Contents

1. Introduction
2. Component Model
3. Types
4. Modularizing WSDL 2.0 descriptions
5. Documentation
6. Language Extensibility
7. Locating WSDL 2.0 Documents
8. Conformance
9. XML Syntax Summary (Non-Normative)
10. References
A. The application/wsdl+xml Media Type
B. Acknowledgements (Non-Normative)
C. IRI-References for WSDL 2.0 Components (Non-Normative)
D. Component Summary (Non-Normative)
E. Part 1 Change Log (Non-Normative)
F. Assertion Summary (Non-Normative)

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Table of Contents

1. Introduction
    1.1 Web Service
    1.2 Document Conformance
    1.3 The Meaning of a Service Description
    1.4 Notational Conventions
        1.4.1 RFC 2119 Keywords
        1.4.2 RFC 3986 Namespaces
        1.4.3 XML Schema anyURI
        1.4.4 Prefixes and Namespaces Used in This Specification
        1.4.5 Terms Used in This Specification
        1.4.6 XML Information Set Properties
        1.4.7 WSDL 2.0 Component Model Properties
        1.4.8 Z Notation
        1.4.9 BNF Pseudo-Schemas
        1.4.10 Assertions
2. Component Model
    2.1 Description
        2.1.1 The Description Component
        2.1.2 XML Representation of Description Component
            2.1.2.1 targetNamespace attribute information item
        2.1.3 Mapping Description's XML Representation to Component Properties
    2.2 Interface
        2.2.1 The Interface Component
        2.2.2 XML Representation of Interface Component
            2.2.2.1 name attribute information item with interface [owner
element]
            2.2.2.2 extends attribute information item
            2.2.2.3 styleDefault attribute information item
        2.2.3 Mapping Interface's XML Representation to Component Properties
    2.3 Interface Fault
        2.3.1 The Interface Fault Component
        2.3.2 XML Representation of Interface Fault Component
            2.3.2.1 name attribute information item with fault [owner element]
            2.3.2.2 element attribute information item with fault [owner
element]
        2.3.3 Mapping Interface Fault's XML Representation to Component
Properties
    2.4 Interface Operation
        2.4.1 The Interface Operation Component
            2.4.1.1 Message Exchange Pattern
            2.4.1.2 Operation Style
        2.4.2 XML Representation of Interface Operation Component
            2.4.2.1 name attribute information item with operation [owner
element]
            2.4.2.2 pattern attribute information item with operation [owner
element]
            2.4.2.3 style attribute information item with operation [owner
element]
        2.4.3 Mapping Interface Operation's XML Representation to Component
Properties
    2.5 Interface Message Reference
        2.5.1 The Interface Message Reference Component
        2.5.2 XML Representation of Interface Message Reference Component
            2.5.2.1 messageLabel attribute information item with input or
output [owner element]
            2.5.2.2 element attribute information item with input or output
[owner element]
        2.5.3 Mapping Interface Message Reference's XML Representation to
Component Properties
    2.6 Interface Fault Reference
        2.6.1 The Interface Fault Reference Component
        2.6.2 XML Representation of Interface Fault Reference
            2.6.2.1 ref attribute information item with infault, or outfault
[owner element]
            2.6.2.2 messageLabel attribute information item with infault, or
outfault [owner element]
        2.6.3 Mapping Interface Fault Reference's XML Representation to
Component Properties
    2.7 Feature
        2.7.1 The Feature Component
            2.7.1.1 Feature Composition Model
                2.7.1.1.1 Example of Feature Composition Model
        2.7.2 XML Representation of Feature Component
            2.7.2.1 ref attribute information item with feature [owner element]
            2.7.2.2 required attribute information item with feature [owner
element]
        2.7.3 Mapping Feature's XML Representation to Component Properties
    2.8 Property
        2.8.1 The Property Component
            2.8.1.1 Property Composition Model
        2.8.2 XML Representation of Property Component
            2.8.2.1 ref attribute information item with property [owner
element]
            2.8.2.2 value element information item with property [parent]
            2.8.2.3 constraint element information item with property [parent]
        2.8.3 Mapping Property's XML Representation to Component Properties
    2.9 Binding
        2.9.1 The Binding Component
        2.9.2 XML Representation of Binding Component
            2.9.2.1 name attribute information item with binding [owner
element]
            2.9.2.2 interface attribute information item with binding [owner
element]
            2.9.2.3 type attribute information item with binding [owner
element]
            2.9.2.4 Binding extension elements
        2.9.3 Mapping Binding's XML Representation to Component Properties
    2.10 Binding Fault
        2.10.1 The Binding Fault Component
        2.10.2 XML Representation of Binding Fault Component
            2.10.2.1 ref attribute information item with fault [owner element]
            2.10.2.2 Binding Fault extension elements
        2.10.3 Mapping Binding Fault's XML Representation to Component
Properties
    2.11 Binding Operation
        2.11.1 The Binding Operation Component
        2.11.2 XML Representation of Binding Operation Component
            2.11.2.1 ref attribute information item with operation [owner
element]
            2.11.2.2 Binding Operation extension elements
        2.11.3 Mapping Binding Operation's XML Representation to Component
Properties
    2.12 Binding Message Reference
        2.12.1 The Binding Message Reference Component
        2.12.2 XML Representation of Binding Message Reference Component
            2.12.2.1 messageLabel attribute information item with input or
output [owner element]
            2.12.2.2 Binding Message Reference extension elements
        2.12.3 Mapping Binding Message Reference's XML Representation to
Component Properties
    2.13 Binding Fault Reference
        2.13.1 The Binding Fault Reference Component
        2.13.2 XML Representation of Binding Fault Reference Component
            2.13.2.1 ref attribute information item with infault or outfault
[owner element]
            2.13.2.2 messageLabel attribute information item with infault or
outfault [owner element]
            2.13.2.3 Binding Fault Reference extension elements
        2.13.3 Mapping Binding Fault Reference's XML Representation to
Component Properties
    2.14 Service
        2.14.1 The Service Component
        2.14.2 XML Representation of Service Component
            2.14.2.1 name attribute information item with service [owner
element]
            2.14.2.2 interface attribute information item with service [owner
element]
        2.14.3 Mapping Service's XML Representation to Component Properties
    2.15 Endpoint
        2.15.1 The Endpoint Component
        2.15.2 XML Representation of Endpoint Component
            2.15.2.1 name attribute information item with endpoint [owner
element]
            2.15.2.2 binding attribute information item with endpoint [owner
element]
            2.15.2.3 address attribute information item with endpoint [owner
element]
            2.15.2.4 Endpoint extension elements
        2.15.3 Mapping Endpoint's XML Representation to Component Properties
    2.16 XML Schema 1.0 Simple Types Used in the Component Model
    2.17 Equivalence of Components
    2.18 Symbol Spaces
    2.19 QName resolution
    2.20 Comparing URIs and IRIs
3. Types
    3.1 Using W3C XML Schema Description Language
        3.1.1 Importing XML Schema
            3.1.1.1 namespace attribute information item
            3.1.1.2 schemaLocation attribute information item
        3.1.2 Inlining XML Schema
            3.1.2.1 targetNamespace attribute information item
        3.1.3 References to Element Declarations and Type Definitions
    3.2 Using Other Schema Languages
    3.3 Describing Messages that Refer to Services and Endpoints
        3.3.1 wsdlx:interface attribute information item
        3.3.2 wsdlx:binding attribute information item
        3.3.3 wsdlx:interface and wsdlx:binding Consistency
        3.3.4 Use of wsdlx:interface and wsdlx:binding with xs:anyURI
4. Modularizing WSDL 2.0 descriptions
    4.1 Including Descriptions
        4.1.1 location attribute information item with include [owner element]
    4.2 Importing Descriptions
        4.2.1 namespace attribute information item
        4.2.2 location attribute information item with import [owner element]
5. Documentation
6. Language Extensibility
    6.1 Element based Extensibility
        6.1.1 Mandatory extensions
        6.1.2 required attribute information item
    6.2 Attribute-based Extensibility
    6.3 Extensibility Semantics
7. Locating WSDL 2.0 Documents
    7.1 wsdli:wsdlLocation attribute information item
8. Conformance
    8.1 XML Information Set Conformance
9. XML Syntax Summary (Non-Normative)
10. References
    10.1 Normative References
    10.2 Informative References

Appendices

A. The application/wsdl+xml Media Type
    A.1 Registration
    A.2 Fragment Identifiers
        A.2.1 The Description Component
        A.2.2 The Element Declaration Component
        A.2.3 The Type Definition Component
        A.2.4 The Interface Component
        A.2.5 The Interface Fault Component
        A.2.6 The Interface Operation Component
        A.2.7 The Interface Message Reference Component
        A.2.8 The Interface Fault Reference Component
        A.2.9 The Binding Component
        A.2.10 The Binding Fault Component
        A.2.11 The Binding Operation Component
        A.2.12 The Binding Message Reference Component
        A.2.13 The Binding Fault Reference Component
        A.2.14 The Service Component
        A.2.15 The Endpoint Component
        A.2.16 The Feature Component
        A.2.17 The Property Component
        A.2.18 Extension Components
    A.3 Security considerations
B. Acknowledgements (Non-Normative)
C. IRI-References for WSDL 2.0 Components (Non-Normative)
    C.1 WSDL 2.0 IRIs
    C.2 Example
D. Component Summary (Non-Normative)
E. Part 1 Change Log (Non-Normative)
    E.1 WSDL 2.0 Specification Changes
F. Assertion Summary (Non-Normative)

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1. Introduction

Web Services Description Language Version 2.0 (WSDL 2.0) provides a model and
an XML format for describing Web services. WSDL 2.0 enables one to separate the
description of the abstract functionality offered by a service from concrete
details of a service description such as “how” and “where” that functionality
is offered.

This specification defines a language for describing the abstract functionality
of a service as well as a framework for describing the concrete details of a
service description. It also defines the conformance criteria for documents in
this language. The WSDL Version 2.0 Part 2: Adjuncts specification [WSDL 2.0
Adjuncts] describes extensions for Message Exchange Patterns, SOAP modules, and
a language for describing such concrete details for SOAP 1.2 [SOAP 1.2 Part 1:
Messaging Framework] and HTTP [IETF RFC 2616].

1.1 Web Service

WSDL 2.0 describes a Web service in two fundamental stages: one abstract and
one concrete. Within each stage, the description uses a number of constructs to
promote reusability of the description and to separate independent design
concerns.

At an abstract level, WSDL 2.0 describes a Web service in terms of the messages
it sends and receives; messages are described independent of a specific wire
format using a type system, typically XML Schema.

An operation associates a message exchange pattern with one or more messages. A
message exchange pattern identifies the sequence and cardinality of messages
sent and/or received as well as who they are logically sent to and/or received
from. An interface groups together operations without any commitment to
transport or wire format.

At a concrete level, a binding specifies transport and wire format details for
one or more interfaces. An endpoint associates a network address with a
binding. And finally, a service groups together endpoints that implement a
common interface.

1.2 Document Conformance

An element information item (as defined in [XML Information Set]) whose
namespace name is "http://www.w3.org/2006/01/wsdl" and whose local part is
description conforms to this specification if it is valid according to the XML
Schema for that element as defined by this specification (http://www.w3.org/
2006/01/wsdl/wsdl20.xsd) and additionally adheres to all the constraints
contained in this specification family and conforms to the specifications of
any extensions contained in it. Such a conformant element information item
constitutes a WSDL 2.0 document.

The definition of the WSDL 2.0 language is based on the XML Information Set [
XML Information Set] but also imposes many semantic constraints over and above
structural conformance to this XML Infoset. In order to precisely describe
these constraints, and as an aid in precisely defining the meaning of each WSDL
2.0 document, the WSDL 2.0 specification defines a component model 2. Component
Model as an additional layer of abstraction above the XML Infoset. Constraints
and meaning are defined in terms of this component model, and the definition of
each component includes a mapping that specifies how values in the component
model are derived from corresponding items in the XML Infoset.

An XML 1.0 document that is valid with respect to the WSDL 2.0 XML Schema and
that maps to a valid WSDL 2.0 Component Model is conformant to the WSDL 2.0
specification.

1.3 The Meaning of a Service Description

A WSDL 2.0 service description indicates how potential clients are intended to
interact with the described service. It represents an assertion that the
described service fully implements and conforms to what the WSDL 2.0 document
describes. For example, as further explained in section 6.1.1 Mandatory
extensions, if the WSDL 2.0 document specifies a particular optional extension,
the functionality implied by that extension is only optional to the client. It
must be supported by the Web service.

A WSDL 2.0 interface describes potential interaction with a service--not
required interaction. The declaration of an operation in a WSDL 2.0 interface
is not an assertion that the interaction described by the operation must occur.
Rather it is an assertion that if such an interaction is (somehow) initiated,
then the declared operation describes how that interaction is intended to
occur.

1.4 Notational Conventions

All parts of this specification are normative, with the EXCEPTION of notes,
pseudo-schemas, examples, and sections explicitly marked as “Non-Normative”.

1.4.1 RFC 2119 Keywords

The keywords “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”,
“SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in this document are to be
interpreted as described in RFC 2119 [IETF RFC 2119].

1.4.2 RFC 3986 Namespaces

Namespace names of the general form:

  • "http://example.org/..." and

  • "http://example.com/..."

represent application or context-dependent URIs [IETF RFC 3986].

1.4.3 XML Schema anyURI

This specification uses the XML Schema type xs:anyURI (see [XML Schema:
Datatypes]). It is defined so that xs:anyURI values are essentially IRIs (see [
IETF RFC 3987]). The conversion from xs:anyURI values to an actual URI is via
an escaping procedure defined by (see [XML Linking Language (XLink) 1.0]),
which is identical in most respects to IRI Section 3.1.

For interoperability, WSDL authors are advised to avoid the US-ASCII
characters: "<", ">", '"', space, "{", "}", "|", "\", "^", and "`", which are
allowed by the xs:anyURI type, but disallowed in IRIs.

1.4.4 Prefixes and Namespaces Used in This Specification

This specification uses predefined namespace prefixes throughout; they are
given in the following list. Note that the choice of any namespace prefix is
arbitrary and not semantically significant (see [XML Namespaces]).

wsdl

    "http://www.w3.org/2006/01/wsdl"

    Defined by this specification.

wsdli

    "http://www.w3.org/2006/01/wsdl-instance"

    Defined by this specification 7.1 wsdli:wsdlLocation attribute information
    item.

wsdlx

    "http://www.w3.org/2006/01/wsdl-extensions"

    Defined by this specification 3.3 Describing Messages that Refer to
    Services and Endpoints.

wrpc

    "http://www.w3.org/2006/01/wsdl/rpc"

    Defined by WSDL 2.0: Adjuncts [WSDL 2.0 Adjuncts].

wsoap

    "http://www.w3.org/2006/01/wsdl/soap"

    Defined by WSDL 2.0: Adjuncts [WSDL 2.0 Adjuncts].

whttp

    "http://www.w3.org/2006/01/wsdl/http"

    Defined by WSDL 2.0: Adjuncts [WSDL 2.0 Adjuncts].

xs

    "http://www.w3.org/2001/XMLSchema"

    Defined in the W3C XML Schema specification [XML Schema: Structures], [XML
    Schema: Datatypes].

xsi

    "http://www.w3.org/2001/XMLSchema-instance"

    Defined in the W3C XML Schema specification [XML Schema: Structures], [XML
    Schema: Datatypes].

1.4.5 Terms Used in This Specification

This section describes the terms and concepts introduced in Part 1 of the WSDL
Version 2.0 specification (this document).

Actual Value

    As in [XML Schema: Structures], the phrase actual value is used to refer to
    the member of the value space of the simple type definition associated with
    an attribute information item which corresponds to its normalized value.
    This will often be a string, but may also be an integer, a boolean, an
    IRI-reference, etc.

Inlined Schema

    An XML schema that is defined in the xs:types element information item of a
    WSDL 2.0 description. For example, an XML Schema defined in an xs:schema
    element information item 3.1.2 Inlining XML Schema.

1.4.6 XML Information Set Properties

This specification refers to properties in the XML Information Set [XML
Information Set]. Such properties are denoted by square brackets, e.g.
[children], [attributes].

1.4.7 WSDL 2.0 Component Model Properties

This specification defines and refers to properties in the WSDL 2.0 Component
Model 2. Component Model. Such properties are denoted by curly brackets, e.g. {
name}, {interfaces}.

This specification uses a consistent naming convention for component model
properties that refer to components. If a property refers to a required or
optional component, then the property name is the same as the component name.
If a property refers to a set of components, then the property name is the
pluralized form of the component name.

1.4.8 Z Notation

Z Notation [Z Notation Reference Manual] was used in the development of this
specification. Z Notation is a formal specification language that is based on
standard mathematical notation. The Z Notation for this specification has been
verified using the Fuzz 2000 type-checker [Fuzz 2000].

Since Z Notation is not widely known, it is not included the normative version
of this specification. However, it is included in a non-normative version which
allows to dynamically hide and show the Z Notation. Browsers correctly display
the mathematical Unicode characters, provided that the required fonts are
installed. Mathematical fonts for Mozilla Firefox can be downloaded from the
Mozilla Web site.

The Z Notation was used to improve the quality of the normative text that
defines the Component Model, and to help ensure that the test suite covered all
important rules implied by the Component Model. However, the Z Notation is
non-normative, so any conflict between it and the normative text is an error in
the Z Notation. Readers and implementors may nevertheless find the Z Notation
useful in cases where the normative text is unclear.

There are two elements of Z Notation syntax that conflict with the notational
conventions described in the preceding sections. In Z Notation, square brackets
are used to introduce basic sets, e.g. [ID], which conflicts with the use of
square brackets to denote XML Information Set properties 1.4.6 XML Information
Set Properties. Also, in Z Notation, curly brackets are used to denote set
display and set comprehension, e.g. {1, 2, 3}, which conflicts with the use of
curly brackets to denote WSDL 2.0 Component Model properties 1.4.7 WSDL 2.0
Component Model Properties. However, the intended meaning of square and curly
brackets should be clear from their context and this minor notational conflict
should not cause any confusion.

1.4.9 BNF Pseudo-Schemas

Pseudo-schemas are provided for each component, before the description of the
component. They use BNF-style conventions for attributes and elements: "?"
denotes optionality (i.e. zero or one occurrences), "*" denotes zero or more
occurrences, "+" one or more occurrences, "[" and "]" are used to form groups,
and "|" represents choice. Attributes are conventionally assigned a value which
corresponds to their type, as defined in the normative schema. Elements with
simple content are conventionally assigned a value which corresponds to the
type of their content, as defined in the normative schema. Pseudo schemas do
not include extensibility points for brevity.

<!-- sample pseudo-schema -->
<defined_element
      required_attribute_of_type_string="xs:string"
      optional_attribute_of_type_int="xs:int"? >
  <required_element />
  <optional_element />?
  <one_or_more_of_these_elements />+
  [ <choice_1 /> | <choice_2 /> ]*
</defined_element>

1.4.10 Assertions

Assertions about WSDL 2.0 documents and components that are not enforced by the
normative XML schema for WSDL 2.0 are marked by a dagger symbol (†) at the end
of a sentence. Each assertion has been assigned a unique identifier that
consists of a descriptive textual prefix and a unique numeric suffix. The
numeric suffixes are assigned sequentially and never reused so there may be
gaps in the sequence. The assertion identifiers MAY be used by implementations
of this specification for any purpose, e.g. error reporting.

The assertions and their identifiers are summarized in section F. Assertion
Summary.

2. Component Model

This section describes the conceptual model of WSDL 2.0 as a set of components
with attached properties, which collectively describe a Web service. This model
is called the Component Model of WSDL 2.0. A valid WSDL 2.0 component model is
a set of WSDL 2.0 components and properties that satisfy all the requirements
given in this specification as indicated by keywords whose interpretation is
defined by RFC 2119 [IETF RFC 2119].

Components are typed collections of properties that correspond to different
aspects of Web services. Each subsection herein describes a different type of
component, its defined properties, and its representation as an XML Infoset [
XML Information Set].

Properties are unordered and unique with respect to the component they are
associated with. Individual properties' definitions may constrain their content
(e.g., to a typed value, another component, or a set of typed values or
components), and components may require the presence of a property to be
considered conformant. Such properties are marked as REQUIRED, whereas those
that are not required to be present are marked as OPTIONAL. By convention, when
specifying the mapping rules from the XML Infoset representation of a component
to the component itself, an optional property that is absent in the component
in question is described as being “empty”. Unless otherwise specified, when a
property is identified as being a collection (a set or a list), its value may
be a 0-element (empty) collection. In order to simplify the presentation of the
rules that deal with sets of components, for all OPTIONAL properties whose type
is a set, the absence of such a property from a component MUST be treated as
semantically equivalent to the presence of a property with the same name and
whose value is the empty set. In other words, every OPTIONAL set-valued
property MUST be assumed to have the empty set as its default value, to be used
in case the property is absent.

Component definitions are serializable in XML 1.0 format but are independent of
any particular serialization of the component model. Component definitions use
a subset (see 2.16 XML Schema 1.0 Simple Types Used in the Component Model) of
the simple types defined by the XML Schema 1.0 specification [XML Schema:
Datatypes].

In addition to the direct XML Infoset representation described here, the
component model allows components external to the Infoset through the
mechanisms described in 4. Modularizing WSDL 2.0 descriptions.

A component model can be extracted from a given XML Infoset which conforms to
the XML Schema for WSDL 2.0 by recursively mapping Information Items to their
identified components, starting with the wsdl:description element information
item. This includes the application of the mechanisms described in 4.
Modularizing WSDL 2.0 descriptions.

This document does not specify a means of producing an XML Infoset
representation from a component model instance. In particular, there are in
general many valid ways to modularize a given component model instance into one
or more XML Infosets.

2.1 Description

2.1.1 The Description Component

At the abstract level, the Description component is just a container for two
categories of components: WSDL 2.0 components and type system components.

WSDL 2.0 components are interfaces, bindings and services. Type system
components are element declarations and type definitions.

Type system components describe the constraints on a message's content. By
default, these constraints are expressed in terms of the [XML Information Set],
i.e. they define the [local name], [namespace name], [children] and
[attributes] properties of an element information item. Type systems based upon
other data models are generally accommodated by extensions to WSDL 2.0; see 6.
Language Extensibility. In the case where they define information equivalent to
that of a XML Schema global element declaration, they can be treated as if they
were such a declaration.

This specification does not define the behavior of a WSDL 2.0 document that
uses multiple schema languages for describing type system components
simultaneously.

An Element Declaration component defines the name and content model of an
element information item such as that defined by an XML Schema global element
declaration. It has a {name} property that is the QName of the element
information item and a {system} property that is the namespace IRI of the
extension element information items for the type system, e.g. the namespace of
XML Schema.

A Type Definition component defines the content model of an element information
item such as that defined by an XML Schema global type definition. It has a {
name} property that is the QName of the type and a {system} property that is
the namespace IRI of the extension element information items for the type
system, e.g. the namespace of XML Schema.

Interface, Binding, Service, Element Declaration, and Type Definition
components are directly contained in the Description component and are referred
to as top-level components. The top-level WSDL 2.0 components contain other
components, e.g. Interface Operation and Endpoint, which are referred to as
nested components. Nested components may contain other nested components. The
component that contains a nested component is referred to as the parent of the
nested components. Nested components have a {parent} property that is a
reference to their parent component.

The properties of the Description component are as follows:

  • {interfaces} OPTIONAL. A set of Interface components.

  • {bindings} OPTIONAL. A set of Binding components.

  • {services} OPTIONAL. A set of Service components.

  • {element declarations} OPTIONAL. A set of Element Declaration components.

  • {type definitions} OPTIONAL. A set of Type Definition components.

The {type definitions} property of the Description component contains all of
the built-in datatypes defined by XML Schema Part 2: Datatypes Second Edition [
XML Schema: Datatypes], namely the nineteen primitive datatypes xs:string ,
xs:boolean , xs:decimal , xs:float , xs:double , xs:duration , xs:dateTime ,
xs:time , xs:date , xs:gYearMonth , xs:gYear , xs:gMonthDay , xs:gDay ,
xs:gMonth , xs:hexBinary , xs:base64 , xs:Binary , xs:anyURI , xs:QName ,
xs:NOTATION , and the twenty-five derived datatypes xs:normalizedString ,
xs:token , xs:language , xs:NMTOKEN , xs:NMTOKENS , xs:Name , xs:NCName , xs:ID
, xs:IDREF , xs:IDREFS , xs:ENTITY , xs:ENTITIES , xs:integer ,
xs:nonPositiveInteger , xs:negativeInteger , xs:long , xs:int , xs:short ,
xs:byte , xs:nonNegativeInteger , xs:unsignedLong , xs:unsignedInt ,
xs:unsignedShort , xs:unsignedByte , xs:positiveInteger .

The set of top-level components contained in the Description component
associated with an initial WSDL 2.0 document consists of the components defined
in the initial document and the components associated with the documents that
the initial document includes and the namespaces that the initial document
imports. The component model makes no distinction between the components that
are defined in the initial document versus those that are defined in the
included documents or imported namespaces. However, any WSDL 2.0 document that
contains component definitions that refer by QName to WSDL 2.0 components that
belong to a different namespace MUST contain a wsdl:import element information
item for that namespace (see 4.2 Importing Descriptions ).^† Furthermore, all
QName references, whether to the same or to different namespaces MUST resolve
to components (see 2.19 QName resolution ).^†

In addition to WSDL 2.0 components and type system components, additional
extension components MAY be added via extensibility 6. Language Extensibility.
Further, additional properties to WSDL 2.0 and type system components MAY also
be added via extensibility.

2.1.2 XML Representation of Description Component

<description
      targetNamespace="xs:anyURI" >
  <documentation />*
  [ <import /> | <include /> ]*
  <types />?
  [ <interface /> | <binding /> | <service /> ]*
</description>

WSDL 2.0 definitions are represented in XML by one or more WSDL 2.0 Information
Sets (Infosets), that is one or more description element information items.^† A
WSDL 2.0 Infoset contains representations for a collection of WSDL 2.0
components that share a common target namespace. A WSDL 2.0 Infoset that
contains one or more wsdl:import element information items 4.2 Importing
Descriptions corresponds to a collection with components drawn from multiple
target namespaces.

The components directly defined or included within a Description component are
said to belong to the same target namespace. The target namespace therefore
groups a set of related component definitions and represents an unambiguous
name for the intended semantics of the collection of components. The value of
the targetNamespace attribute information item SHOULD be dereferenceable.^† It
SHOULD resolve to a human or machine processable document that directly or
indirectly defines the intended semantics of those components.^† It MAY resolve
to a WSDL 2.0 document that provides service description information for that
namespace.^†

If a WSDL 2.0 document is split into multiple WSDL 2.0 documents (which may be
combined as needed via 4.1 Including Descriptions), then the targetNamespace
attribute information item SHOULD resolve to a master WSDL 2.0 document that
includes all the WSDL 2.0 documents needed for that service description.^† This
approach enables the WSDL 2.0 component designator fragment identifiers to be
properly resolved.

Imported components have different target namespace values from the WSDL 2.0
document that is importing them.^† Thus importing is the mechanism to use
components from one namespace in definition of components from another
namespace.

Each WSDL 2.0 or type system component of the same kind MUST be uniquely
identified by its qualified name. ^† That is, if two distinct components of the
same kind ( Interface, Binding, etc.) are in the same target namespace, then
their QNames MUST be unique. However, different kinds of components (e.g., an
Interface component and a Binding component) MAY have the same QName. Thus,
QNames of components must be unique within the space of those components in a
given target namespace.

The description element information item has the following Infoset properties:

  • A [local name] of description .

  • A [namespace name] of "http://www.w3.org/2006/01/wsdl".

  • One or more attribute information items amongst its [attributes] as
    follows:

      □ A REQUIRED targetNamespace attribute information item as described
        below in 2.1.2.1 targetNamespace attribute information item.

      □ Zero or more namespace qualified attribute information items whose
        [namespace name] is NOT "http://www.w3.org/2006/01/wsdl".

  • Zero or more element information items amongst its [children], in order as
    follows:^†

     1. Zero or more documentation element information items (see 5.
        Documentation).

     2. Zero or more element information items from among the following, in any
        order:

          ☆ Zero or more include element information items (see 4.1 Including
            Descriptions)

          ☆ Zero or more import element information items (see 4.2 Importing
            Descriptions)

          ☆ Zero or more namespace-qualified element information items whose
            [namespace name] is NOT "http://www.w3.org/2006/01/wsdl".

     3. An OPTIONAL types element information item (see 3. Types).

     4. Zero or more element information items from among the following, in any
        order:

          ☆ interface element information items (see 2.2.2 XML Representation
            of Interface Component).

          ☆ binding element information items (see 2.9.2 XML Representation of
            Binding Component).

          ☆ service element information items (see 2.14.2 XML Representation of
            Service Component).

          ☆ Zero or more namespace-qualified element information items whose
            [namespace name] is NOT "http://www.w3.org/2006/01/wsdl".

2.1.2.1 targetNamespace attribute information item

The targetNamespace attribute information item defines the namespace
affiliation of top-level components defined in this description element
information item. Interface, Binding and Service are top-level components.

The targetNamespace attribute information item has the following Infoset
properties:

  • A [local name] of targetNamespace

  • A [namespace name] which has no value

The type of the targetNamespace attribute information item is xs:anyURI. Its
value MUST be an absolute IRI (see [IETF RFC 3987]) and should be
dereferenceable.^†

2.1.3 Mapping Description's XML Representation to Component Properties

The mapping from the XML Representation of the description element information
item (see 2.1.2 XML Representation of Description Component) to the properties
of the Description component is described in Table 2-1.


Table 2-1. Mapping from XML Representation to Description Component Properties
┌─────────────┬───────────────────────────────────────────────────────────────┐
│  Property   │                             Value                             │
├─────────────┼───────────────────────────────────────────────────────────────┤
│             │The set of Interface components corresponding to all the       │
│             │interface element information items in the [children] of the   │
│{interfaces} │description element information item, if any, plus any included│
│             │(via wsdl:include ) or imported (via wsdl:import ) Interface   │
│             │components (see 4. Modularizing WSDL 2.0 descriptions).        │
├─────────────┼───────────────────────────────────────────────────────────────┤
│             │The set of Binding components corresponding to all the binding │
│             │element information items in the [children] of the description │
│{bindings}   │element information item, if any, plus any included (via       │
│             │wsdl:include ) or imported (via wsdl:import ) Binding          │
│             │components (see 4. Modularizing WSDL 2.0 descriptions).        │
├─────────────┼───────────────────────────────────────────────────────────────┤
│             │The set of Service components corresponding to all the service │
│             │element information items in the [children] of the description │
│{services}   │element information item, if any, plus any included (via       │
│             │wsdl:include ) or imported (via wsdl:import ) Service          │
│             │components (see 4. Modularizing WSDL 2.0 descriptions).        │
├─────────────┼───────────────────────────────────────────────────────────────┤
│             │The set of Element Declaration components corresponding to all │
│             │the element declarations defined as descendants of the types   │
│             │element information item, if any, plus any included (via       │
│             │xs:include ) or imported (via xs:import ) Element Declaration  │
│{element     │components. At a minimum this will include all the global      │
│declarations}│element declarations defined by XML Schema element element     │
│             │information items. It MAY also include any declarations from   │
│             │some other type system which describes the [local name],       │
│             │[namespace name], [attributes] and [children] properties of an │
│             │element information item. Each XML Schema element declaration  │
│             │MUST have a unique QName.^†                                    │
├─────────────┼───────────────────────────────────────────────────────────────┤
│             │The set of Type Definition components corresponding to all the │
│             │type definitions defined as descendants of the types element   │
│             │information item, if any, plus any (via xs:include ) or        │
│             │imported (via xs:import ) Type Definition components. At a     │
│{type        │minimum this will include all the global type definitions      │
│definitions} │defined by XML Schema simpleType and complexType element       │
│             │information items. It MAY also include any definitions from    │
│             │some other type system which describes the [attributes] and    │
│             │[children] properties of an element information item. Each XML │
│             │Schema type definition MUST have a unique QName.^†             │
└─────────────┴───────────────────────────────────────────────────────────────┘


2.2 Interface

2.2.1 The Interface Component

An Interface component describes sequences of messages that a service sends and
/or receives. It does this by grouping related messages into operations. An
operation is a sequence of input and output messages, and an interface is a set
of operations.

An interface can optionally extend one or more other interfaces. To avoid
circular definitions, an interface MUST NOT appear as an element of the set of
interfaces it extends, either directly or indirectly. ^† The set of operations
available in an interface includes all the operations defined by the interfaces
it extends, along with any operations it directly defines. The operations
directly defined on an interface are referred to as the declared operations of
the interface. In the process, operation components that are equivalent per
2.17 Equivalence of Components are treated as one. The interface extension
mechanism behaves in a similar way for all other components that can be defined
inside an interface, namely Interface Fault, Feature and Property components.

Interfaces are named constructs and can be referred to by QName (see 2.19 QName
resolution). For instance, Binding components refer to interfaces in this way.

The properties of the Interface component are as follows:

  • {name} REQUIRED. An xs:QName.

  • {extended interfaces} OPTIONAL. A set of declared Interface components
    which this interface extends.

  • {interface faults} OPTIONAL. The set of declared Interface Fault
    components. The namespace name of the {name} property of each Interface
    Fault in this set MUST be the same as the namespace name of the {name}
    property of this Interface component.^†

  • {interface operations} OPTIONAL. A set of declared Interface Operation
    components. The namespace name of the {name} property of each Interface
    Operation in this set MUST be the same as the namespace name of the {name}
    property of this Interface component.^†

  • {features} OPTIONAL. A set of declared Feature components.

  • {properties} OPTIONAL. A set of declared Property components.

For each Interface component in the {interfaces} property of a Description
component, the {name} property MUST be unique.^†

2.2.2 XML Representation of Interface Component

<description>
  <interface
        name="xs:NCName"
        extends="list of xs:QName"?
        styleDefault="list of xs:anyURI"? >
    <documentation />*
    [ <fault /> | <operation /> | <feature /> | <property /> ]*
  </interface>
</description>

The XML representation for an Interface component is an element information
item with the following Infoset properties:

  • A [local name] of interface

  • A [namespace name] of "http://www.w3.org/2006/01/wsdl"

  • One or more attribute information items amongst its [attributes] as
    follows:

      □ A REQUIRED name attribute information item as described below in
        2.2.2.1 name attribute information item with interface [owner element].

      □ An OPTIONAL extends attribute information item as described below in
        2.2.2.2 extends attribute information item.

      □ An OPTIONAL styleDefault attribute information item as described below
        in 2.2.2.3 styleDefault attribute information item.

      □ Zero or more namespace qualified attribute information items whose
        [namespace name] is NOT "http://www.w3.org/2006/01/wsdl".

  • Zero or more element information items amongst its [children], in order, as
    follows:

     1. Zero or more documentation element information items (see 5.
        Documentation).

     2. Zero or more element information items from among the following, in any
        order:

          ☆ Zero or more fault element information items 2.3.2 XML
            Representation of Interface Fault Component.

          ☆ Zero or more operation element information items 2.4.2 XML
            Representation of Interface Operation Component.

          ☆ Zero or more feature element information items 2.7.2 XML
            Representation of Feature Component.

          ☆ Zero or more property element information items 2.8.2 XML
            Representation of Property Component.

          ☆ Zero or more namespace-qualified element information items whose
            [namespace name] is NOT "http://www.w3.org/2006/01/wsdl".

2.2.2.1 name attribute information item with interface [owner element]

The name attribute information item together with the targetNamespace attribute
information item of the [parent] description element information item forms the
QName of the interface.

The name attribute information item has the following Infoset properties:

  • A [local name] of name

  • A [namespace name] which has no value

The type of the name attribute information item is xs:NCName.

2.2.2.2 extends attribute information item

The extends attribute information item lists the interfaces that this interface
derives from.

The extends attribute information item has the following Infoset properties:

  • A [local name] of extends

  • A [namespace name] which has no value

The type of the extends attribute information item is a list of xs:QName.

2.2.2.3 styleDefault attribute information item

The styleDefault attribute information item indicates the default style (see
2.4.1.2 Operation Style) used to construct the {element declaration} properties
of {interface message references} of all operations contained within the [owner
element] interface .

The styleDefault attribute information item has the following Infoset
properties:

  • A [local name] of styleDefault.

  • A [namespace name] which has no value.

The type of the styleDefault attribute information item is list of xs:anyURI.
Its value, if present, MUST contain absolute IRIs (see [IETF RFC 3987]).^†

2.2.3 Mapping Interface's XML Representation to Component Properties

The mapping from the XML Representation of the interface element information
item (see 2.2.2 XML Representation of Interface Component) to the properties of
the Interface component is as described in Table 2-2.


 Table 2-2. Mapping from XML Representation to Interface Component Properties
┌────────────┬────────────────────────────────────────────────────────────────┐
│  Property  │                             Value                              │
├────────────┼────────────────────────────────────────────────────────────────┤
│            │The QName whose local name is actual value of the name attribute│
│{name}      │information item and whose namespace name is the actual value of│
│            │the targetNamespace attribute information item of the [parent]  │
│            │description element information item                            │
├────────────┼────────────────────────────────────────────────────────────────┤
│{extended   │The set of Interface components resolved to by the values in the│
│interfaces} │extends attribute information item, if any (see 2.19 QName      │
│            │resolution).                                                    │
├────────────┼────────────────────────────────────────────────────────────────┤
│{interface  │The set of Interface Fault components corresponding to the fault│
│faults}     │element information items in [children], if any.                │
├────────────┼────────────────────────────────────────────────────────────────┤
│{interface  │The set of Interface Operation components corresponding to the  │
│operations} │operation element information items in [children], if any.      │
├────────────┼────────────────────────────────────────────────────────────────┤
│{features}  │The set of Feature components corresponding to the feature      │
│            │element information items in [children], if any.                │
├────────────┼────────────────────────────────────────────────────────────────┤
│{properties}│The set of Property components corresponding to the property    │
│            │element information items in [children], if any.                │
└────────────┴────────────────────────────────────────────────────────────────┘


Recall that, per 2.2.1 The Interface Component, the Interface components in the
{extended interfaces} property of a given Interface component MUST NOT contain
that Interface component in any of their {extended interfaces} properties, that
is to say, recursive extension of interfaces is disallowed.

2.3 Interface Fault

2.3.1 The Interface Fault Component

A fault is an event that occurs during the execution of a message exchange that
disrupts the normal flow of messages.

A fault is typically raised when a party is unable to communicate an error
condition inside the normal message flow, or a party wishes to terminate a
message exchange. A fault message may be used to communicate out of band
information such as the reason for the error, the origin of the fault, as well
as other informal diagnostics such as a program stack trace.

An Interface Fault component describes a fault that MAY occur during invocation
of an operation of the interface. The Interface Fault component declares an
abstract fault by naming it and indicating the contents of the fault message.
When and how the fault message flows is indicated by the Interface Operation
component.

The Interface Fault component provides a clear mechanism to name and describe
the set of faults an interface may generate. This allows operations to easily
identify the individual faults they may generate by name. This mechanism allows
the ready identification of the same fault occurring across multiple operations
and referenced in multiple bindings as well as reducing duplication of
description for an individual fault.

Faults other than the ones described in the Interface component may also be
generated at run-time, i.e. faults are an open set. The Interface component
describes faults that have application level semantics, i.e. that the client or
service is expected to handle, and potentially recover from, as part of the
application processing logic. For example, an Interface component that accepts
a credit card number may describe faults that indicate the credit card number
is invalid, has been reported stolen, or has expired. The Interface component
does not describe general system faults such as network failures, out of memory
conditions, out of disk space conditions, invalid message formats, etc.,
although these faults may be generated as part of the message exchange. Such
general system faults can reasonably be expected to occur in any message
exchange and explicitly describing them in an Interface component is therefore
uninformative.

The properties of the Interface Fault component are as follows:

  • {name} REQUIRED. An xs:QName.

  • {element declaration} OPTIONAL. A reference to a Element Declaration
    component in the {element declarations} property of the Description
    component. This element represents the content or “payload” of the fault.

  • {features} OPTIONAL. A set of Feature components.

  • {properties} OPTIONAL. A set of Property components.

  • {parent} REQUIRED. The Interface component that contains this component in
    its {interface faults} property.

For each Interface Fault component in the {interface faults} property of an
Interface component, the {name} property must be unique. ^†

Interface Fault components are uniquely identified by the the QName of the
enclosing Interface component and QName of the Interface Fault component
itself.

Note:

Despite having a {name} property, Interface Fault components cannot be
identified solely by their QName. Indeed, two Interface components whose {name}
property value has the same namespace name, but different local names, can
contain Interface Fault components with the same {name} property value. Thus,
the {name} property of Interface Fault component is not sufficient to form the
unique identity of an Interface Fault component. A method for uniquely
identifying components is defined in A.2 Fragment Identifiers . See A.2.5 The
Interface Fault Component for the definition of the fragment identifier for the
Interface Fault component.

In cases where, due to an interface extending one or more other interfaces, two
or more Interface Fault components have the same value for their {name}
property, then the component models of those Interface Fault components MUST be
equivalent (see 2.17 Equivalence of Components ). ^† If the Interface Fault
components are equivalent then they are considered to collapse into a single
component. It is an error if two Interface Fault components that are available
in the same Interface component have the same value for their {name} properties
but are not equivalent.

Note that, due to the above rules, if two interfaces that have the same value
for the namespace name of their {name} property also have one or more faults
that have the same value for their {name} property then those two interfaces
cannot both form part of the derivation chain of a derived interface unless
those faults are the same fault.

Note:

For the above reason, it is considered good practice to ensure, where
necessary, that the local name of the {name} property of Interface Fault
components within a namespace are unique, thus allowing such derivation to
occur without inadvertent error.

If a type system NOT based on the XML Infoset [XML Information Set] is in use
(as considered in 3.2 Using Other Schema Languages) then additional properties
would need to be added to the Interface Fault component (along with
extensibility attributes to its XML representation) to allow associating such
message types with the message reference.

2.3.2 XML Representation of Interface Fault Component

<description>
  <interface>
    <fault
          name="xs:NCName"
          element="xs:QName"? >
      <documentation />*
      [ <feature /> | <property /> ]*
    </fault>
  </interface>
</description>

The XML representation for an Interface Fault component is an element
information item with the following Infoset properties:

  • A [local name] of fault

  • A [namespace name] of "http://www.w3.org/2006/01/wsdl"

  • One or more attribute information items amongst its [attributes] as
    follows:

      □ A REQUIRED name attribute information item as described below in
        2.3.2.1 name attribute information item with fault [owner element].

      □ An OPTIONAL element attribute information item as described below in
        2.3.2.2 element attribute information item with fault [owner element].

      □ Zero or more namespace qualified attribute information items whose
        [namespace name] is NOT "http://www.w3.org/2006/01/wsdl".

  • Zero or more element information item amongst its [children], in order, as
    follows:

     1. Zero or more documentation element information items (see 5.
        Documentation).

     2. Zero or more element information items from among the following, in any
        order:

          ☆ Zero or more feature element information items 2.7.2 XML
            Representation of Feature Component

          ☆ Zero or more property element information items 2.8.2 XML
            Representation of Property Component

          ☆ Zero or more namespace-qualified element information items whose
            [namespace name] is NOT "http://www.w3.org/2006/01/wsdl".

2.3.2.1 name attribute information item with fault [owner element]

The name attribute information item identifies a given fault element
information item inside a given interface element information item.

The name attribute information item has the following Infoset properties:

  • A [local name] of name

  • A [namespace name] which has no value

The type of the name attribute information item is xs:NCName.

2.3.2.2 element attribute information item with fault [owner element]

The element attribute information item refers, by QName, to an Element
Declaration component.

The element attribute information item has the following Infoset properties:

  • A [local name] of element .

  • A [namespace name] which has no value.

The type of the element attribute information item is xs:QName.

2.3.3 Mapping Interface Fault's XML Representation to Component Properties

The mapping from the XML Representation of the fault element information item
(see 2.3.2 XML Representation of Interface Fault Component) to the properties
of the Interface Fault component is as described in Table 2-3.


    Table 2-3. Mapping from XML Representation to Interface Fault Component
                                  Properties
┌────────────┬────────────────────────────────────────────────────────────────┐
│  Property  │                             Value                              │
├────────────┼────────────────────────────────────────────────────────────────┤
│            │The QName whose local name is the actual value of the name      │
│            │attribute information item. and whose namespace name is the     │
│{name}      │actual value of the targetNamespace attribute information item  │
│            │of the [parent] description element information item of the     │
│            │[parent] interface element information item.                    │
├────────────┼────────────────────────────────────────────────────────────────┤
│            │The Element Declaration component from the {element declarations│
│            │} property of the Description component resolved to by the value│
│{element    │of the element attribute information item if present (see 2.19  │
│declaration}│QName resolution), otherwise empty. It is an error for the      │
│            │element attribute information item to have a value and for it to│
│            │not resolve to an Element Declaration component from the {      │
│            │element declarations} property of the Description component.^†  │
├────────────┼────────────────────────────────────────────────────────────────┤
│{features}  │The set of Feature components corresponding to the feature      │
│            │element information items in [children], if any.                │
├────────────┼────────────────────────────────────────────────────────────────┤
│{properties}│The set of Property components corresponding to the property    │
│            │element information items in [children], if any.                │
├────────────┼────────────────────────────────────────────────────────────────┤
│{parent}    │The Interface component corresponding to the interface element  │
│            │information item in [parent].                                   │
└────────────┴────────────────────────────────────────────────────────────────┘


2.4 Interface Operation

2.4.1 The Interface Operation Component

An Interface Operation component describes an operation that a given interface
supports. An operation is an interaction with the service consisting of a set
of (ordinary and fault) messages exchanged between the service and the other
parties involved in the interaction. The sequencing and cardinality of the
messages involved in a particular interaction is governed by the message
exchange pattern used by the operation (see {message exchange pattern}
property).

A message exchange pattern defines placeholders for messages, the participants
in the pattern (i.e., the sources and sinks of the messages), and the
cardinality and sequencing of messages exchanged by the participants. The
message placeholders are associated with specific message types by the
operation that uses the pattern by means of message and fault references (see {
interface message references} and {interface fault references} properties). The
service whose operation is using the pattern becomes one of the participants of
the pattern. This specification does not define a machine understandable
language for defining message exchange patterns, nor does it define any
specific patterns. The companion specification, [WSDL 2.0 Adjuncts] defines a
set of such patterns and defines identifying IRIs any of which MAY be used as
the value of the {message exchange pattern} property.

The properties of the Interface Operation component are as follows:

  • {name} REQUIRED. An xs:QName.

  • {message exchange pattern} REQUIRED. An xs:anyURI identifying the message
    exchange pattern used by the operation. This xs:anyURI MUST be an absolute
    IRI (see [IETF RFC 3987]).^†

  • {interface message references} OPTIONAL. A set of Interface Message
    Reference components for the ordinary messages the operation accepts or
    sends.

  • {interface fault references} OPTIONAL. A set of Interface Fault Reference
    components for the fault messages the operation accepts or sends.

  • {style} OPTIONAL. A set of xs:anyURIs identifying the rules that were used
    to construct the {element declaration} properties of {interface message
    references}. (See 2.4.1.2 Operation Style.) These xs:anyURIs MUST be
    absolute IRIs (see [IETF RFC 3986]).^†

  • {features} OPTIONAL. A set of Feature components.

  • {properties} OPTIONAL. A set of Property components.

  • {parent} REQUIRED. The Interface component that contains this component in
    its {interface operations} property.

For each Interface Operation component in the {interface operations} property
of an Interface component, the {name} property MUST be unique. ^†

Interface Operation components are uniquely identified by the the QName of the
enclosing Interface component and QName of the Interface Operation component
itself.

Note:

Despite having a {name} property, Interface Operation components cannot be
identified solely by their QName. Indeed, two Interface components whose {name}
property value has the same namespace name, but different local names, can
contain Interface Operation components with the same {name} property value.
Thus, the {name} property of Interface Operation components is not sufficient
to form the unique identity of an Interface Operation component. A method for
uniquely identifying components is defined in A.2 Fragment Identifiers . See
A.2.6 The Interface Operation Component for the definition of the fragment
identifier for the Interface Operation component.

In cases where, due to an interface extending one or more other interfaces, two
or more Interface Operation components have the same value for their {name}
property, then the component models of those Interface Operation components
MUST be equivalent (see 2.17 Equivalence of Components).^† If the Interface
Operation components are equivalent then they are considered to collapse into a
single component. It is an error if two Interface Operation components have the
same value for their {name} property but are not equivalent.

Note that, due to the above rules, if two interfaces that have the same value
for the namespace name of their {name} property also have one or more
operations that have the same value for their {name} property then those two
interfaces cannot both form part of the derivation chain of a derived interface
unless those operations are the same operation.

Note:

For the above reason, it is considered good practice to ensure, where
necessary, that the {name} property of Interface Operation components within a
namespace are unique, thus allowing such derivation to occur without
inadvertent error.

More than one Interface Fault Reference component in the {interface fault
references} property of an Interface Operation component may refer to the same
message label. In that case, the listed fault types define alternative fault
messages. This allows one to indicate that there is more than one type of fault
that is related to that message.

2.4.1.1 Message Exchange Pattern

This section describes some aspects of message exchange patterns in more
detail. Refer to the WSDL Version 2.0 Part 2: Adjuncts specification [WSDL 2.0
Adjuncts] for a complete discussion of the semantics of message exchange
patterns in general as well as the definitions of the message exchange patterns
that are predefined by WSDL 2.0.

A placeholder message is a template for an actual message as described by an
Interface Message Reference component. Although a placeholder message is not
itself a component, it is useful to regard it as having both a {message label}
and a {direction} property which define the values of the actual Interface
Message Reference component that corresponds to it. A placeholder message is
also associated with some node that exchanges the message with the service.
Furthermore, a placeholder message may be designated as optional in the
exchange.

A fault propagation ruleset specifies the relation between the Interface Fault
Reference and Interface Message Reference components of an Interface Operation
component. The WSDL Version 2.0 Part 2: Adjuncts specification [WSDL 2.0
Adjuncts] defines three fault propagation rulesets which we'll refer to as
fault-replaces-message , message-triggers-fault , and no-faults . These fault
propagation rulesets are used by the predefined message exchange patterns.
Other message exchange patterns may define additional fault propagation
rulesets.

A message exchange pattern is a template for the exchange of one or more
messages, and their associated faults, between the service and one or more
other nodes as described by an Interface Operation component. The service and
the other nodes are referred to as the participants in the exchange. A message
exchange pattern consists of a sequence of one or more placeholder messages.
Each placeholder message within this sequence is uniquely identified by its {
message label} property. A message exchange pattern is uniquely identified by
an absolute IRI which is used as the value of the {message exchange pattern}
property of the Interface Operation component, and it specifies the fault
propagation ruleset that its faults obey.^†

2.4.1.2 Operation Style

An operation style specifies additional information about an operation. For
example, an operation style may define structural constraints on the element
declarations of the interface message reference or interface fault components
used by the operation. This additional information in no way affects the
messages and faults exchanged with the service and it may therefore be safely
ignored in that context. However, the additional information may be used for
other purposes, for example, improved code generation. The {style} property of
the Interface Operation component contains a set of zero or more IRIs that
identify operation styles. An Interface Operation component MUST satisfy the
specification defined by each operation style identified by its {style}
property. ^† If no Interface Operation component can simultaneously satisfy all
of the styles, the document is invalid.

If the {style} property of an Interface Operation component does have a value,
then that value (a set of IRIs) specifies the rules that were used to define
the element declarations (or other properties that define the message and fault
contents; see 3.2 Using Other Schema Languages) of the Interface Message
Reference or Interface Fault components used by the operation. Although a given
operation style has the ability to constrain all input and output messages and
faults of an operation, it MAY choose to constrain any combination thereof,
e.g. only the messages, or only the inputs.

Please refer to the WSDL Version 2.0 Part 2: Adjuncts specification [WSDL 2.0
Adjuncts] for particular operation style definitions.

2.4.2 XML Representation of Interface Operation Component

<description>
  <interface>
    <operation
          name="xs:NCName"
          pattern="xs:anyURI"
          style="list of xs:anyURI"? >
      <documentation />*
      [ <feature /> | <property /> |
        [ <input /> | <output /> | <infault /> | <outfault /> ]+
      ]*
    </operation>
  </interface>
</description>

The XML representation for an Interface Operation component is an element
information item with the following Infoset properties:

  • A [local name] of operation

  • A [namespace name] of "http://www.w3.org/2006/01/wsdl"

  • Two or more attribute information items amongst its [attributes] as
    follows:

      □ A REQUIRED name attribute information item as described below in
        2.4.2.1 name attribute information item with operation [owner element].

      □ A REQUIRED pattern attribute information item as described below in
        2.4.2.2 pattern attribute information item with operation [owner
        element].

      □ An OPTIONAL style attribute information item as described below in
        2.4.2.3 style attribute information item with operation [owner element]
        .

      □ Zero or more namespace qualified attribute information items whose
        [namespace name] is NOT "http://www.w3.org/2006/01/wsdl".

  • One or more element information item amongst its [children], in order, as
    follows:

     1. Zero or more documentation element information items (see 5.
        Documentation).

     2. One or more element information items from among the following, in any
        order:

          ☆ One or more element information items from among the following, in
            any order:

              ○ Zero or more input element information items (see 2.5.2 XML
                Representation of Interface Message Reference Component).

              ○ Zero or more output element information items (see 2.5.2 XML
                Representation of Interface Message Reference Component).

              ○ Zero or more infault element information items (see 2.6.2 XML
                Representation of Interface Fault Reference).

              ○ Zero or more outfault element information items (see 2.6.2 XML
                Representation of Interface Fault Reference).

          ☆ Zero or more element information items from among the following, in
            any order:

              ○ A feature element information item (see 2.7.2 XML
                Representation of Feature Component).

              ○ A property element information item (see 2.8.2 XML
                Representation of Property Component).

              ○ Zero or more namespace-qualified element information items
                whose [namespace name] is NOT "http://www.w3.org/2006/01/wsdl".

2.4.2.1 name attribute information item with operation [owner element]

The name attribute information item identifies a given operation element
information item inside a given interface element information item.

The name attribute information item has the following Infoset properties:

  • A [local name] of name

  • A [namespace name] which has no value

The type of the name attribute information item is xs:NCName.

2.4.2.2 pattern attribute information item with operation [owner element]

The pattern attribute information item identifies the message exchange pattern
a given operation uses.

The pattern attribute information item has the following Infoset properties:

  • A [local name] of pattern

  • A [namespace name] which has no value

The type of the pattern attribute information item is xs:anyURI. Its value MUST
be an absolute IRI (see [IETF RFC 3987]).^†

2.4.2.3 style attribute information item with operation [owner element]

The style attribute information item indicates the rules that were used to
construct the {element declaration} properties of the Interface Message
Reference components which are members of the {interface message references}
property of the [owner element] operation.

The style attribute information item has the following Infoset properties:

  • A [local name] of style

  • A [namespace name] which has no value

The type of the style attribute information item is list of xs:anyURI. Its
value MUST be an absolute IRI (see [IETF RFC 3987]).^†

2.4.3 Mapping Interface Operation's XML Representation to Component Properties

The mapping from the XML Representation of the operation element information
item (see 2.4.2 XML Representation of Interface Operation Component) to the
properties of the Interface Operation component (see 2.4.1 The Interface
Operation Component) is as described in Table 2-4.


  Table 2-4. Mapping from XML Representation to Interface Operation Component
                                  Properties
┌────────────┬────────────────────────────────────────────────────────────────┐
│  Property  │                             Value                              │
├────────────┼────────────────────────────────────────────────────────────────┤
│            │The QName whose local name is the actual value of the name      │
│            │attribute information item and whose namespace name is the      │
│{name}      │actual value of the targetNamespace attribute information item  │
│            │of the [parent] description element information item of the     │
│            │[parent] interface element information item.                    │
├────────────┼────────────────────────────────────────────────────────────────┤
│{message    │The actual value of the pattern attribute information item;     │
│exchange    │otherwise 'http://www.w3.org/2006/01/wsdl/in-out'.              │
│pattern}    │                                                                │
├────────────┼────────────────────────────────────────────────────────────────┤
│{interface  │The set of message references corresponding to the input and    │
│message     │output element information items in [children], if any.         │
│references} │                                                                │
├────────────┼────────────────────────────────────────────────────────────────┤
│{interface  │The set of interface fault references corresponding to the      │
│fault       │infault and outfault element information items in [children], if│
│references} │any.                                                            │
├────────────┼────────────────────────────────────────────────────────────────┤
│            │The set containing the IRIs in the actual value of the style    │
│            │attribute information item, if present; otherwise the set       │
│{style}     │containing the IRIs in the actual value of the styleDefault     │
│            │attribute information item of the [parent] interface element    │
│            │information item, if present; otherwise empty.                  │
├────────────┼────────────────────────────────────────────────────────────────┤
│{features}  │The set of Feature components corresponding to the feature      │
│            │element information items in [children], if any.                │
├────────────┼────────────────────────────────────────────────────────────────┤
│{properties}│The set of Property components corresponding to the property    │
│            │element information items in [children], if any.                │
├────────────┼────────────────────────────────────────────────────────────────┤
│{parent}    │The Interface component corresponding to the interface element  │
│            │information item in [parent].                                   │
└────────────┴────────────────────────────────────────────────────────────────┘


2.5 Interface Message Reference

2.5.1 The Interface Message Reference Component

An Interface Message Reference component associates a defined element with a
message exchanged in an operation. By default, the element is defined in the
XML Infoset [XML Information Set].

A message exchange pattern defines a set of placeholder messages that
participate in the pattern and assigns them unique message labels within the
pattern (e.g. 'In', 'Out'). The purpose of an Interface Message Reference
component is to associate an actual message element (XML element declaration or
some other declaration (see 3.2 Using Other Schema Languages)) with a message
in the pattern, as identified by its message label. Later, when the message
exchange pattern is instantiated, messages corresponding to that particular
label will follow the element assignment made by the Interface Message
Reference component.

The properties of the Interface Message Reference component are as follows:

  • {message label} REQUIRED. An xs:NCName. This property identifies the role
    this message plays in the {message exchange pattern} of the Interface
    Operation component this message is contained within. The value of this
    property MUST match the name of a placeholder message defined by the
    message exchange pattern.^†

  • {direction} REQUIRED. An xs:token with one of the values in or out,
    indicating whether the message is coming to the service or going from the
    service, respectively.^† The direction MUST be the same as the direction of
    the message identified by the {message label} property in the {message
    exchange pattern} of the Interface Operation component this is contained
    within.^†

  • {message content model} REQUIRED. An xs:token with one of the values #any,
    #none, #other, or #element.^† A value of #any indicates that the message
    content is any single element. A value of #none indicates there is no
    message content. A value of #other indicates that the message content is
    described by some other extension property that references a declaration in
    a non-XML extension type system. A value of #element indicates that the
    message consists of a single element described by the global element
    declaration referenced by the {element declaration} property. This property
    is used only when the message is described using an XML based data model.

  • {element declaration} OPTIONAL. A reference to an XML element declaration
    in the {element declarations} property of the Description component. This
    element represents the content or “payload” of the message. When the {
    message content model} property has the value #any or #none the {element
    declaration} property MUST be empty.^†

  • {features} OPTIONAL. A set of Feature components.

  • {properties} OPTIONAL. A set of Property components.

  • {parent} REQUIRED. The Interface Operation component that contains this
    component in its {interface message references} property.

For each Interface Message Reference component in the {interface message
references} property of an Interface Operation component, its {message label}
property MUST be unique.^†

If a type system not based upon the XML Infoset is in use (as considered in 3.2
Using Other Schema Languages) then additional properties would need to be added
to the Interface Message Reference component (along with extensibility
attributes to its XML representation) to allow associating such message types
with the message reference.

2.5.2 XML Representation of Interface Message Reference Component

<description>
  <interface>
    <operation>
      <input
            messageLabel="xs:NCName"?
            element="union of xs:QName, xs:token"? >
        <documentation />*
        [ <feature /> | <property /> ]*
      </input>
      <output
            messageLabel="xs:NCName"?
            element="union of xs:QName, xs:token"? >
        <documentation />*
        [ <feature /> | <property /> ]*
      </output>
    </operation>
  </interface>
</description>

The XML representation for an Interface Message Reference component is an
element information item with the following Infoset properties:

  • A [local name] of input or output

  • A [namespace name] of "http://www.w3.org/2006/01/wsdl"

  • Zero or more attribute information items amongst its [attributes] as
    follows:

      □ An OPTIONAL messageLabel attribute information item as described below
        in 2.5.2.1 messageLabel attribute information item with input or output
        [owner element].

      □ An OPTIONAL element attribute information item as described below in
        2.5.2.2 element attribute information item with input or output [owner
        element].

      □ Zero or more namespace qualified attribute information items whose
        [namespace name] is NOT "http://www.w3.org/2006/01/wsdl".

  • Zero or more element information item amongst its [children], in order, as
    follows:

     1. Zero or more documentation element information items (see 5.
        Documentation).

     2. Zero or more element information items from among the following, in any
        order:

          ☆ Zero or more feature element information items 2.7.2 XML
            Representation of Feature Component

          ☆ Zero or more property element information items 2.8.2 XML
            Representation of Property Component

          ☆ Zero or more namespace-qualified element information items whose
            [namespace name] is NOT "http://www.w3.org/2006/01/wsdl".

2.5.2.1 messageLabel attribute information item with input or output [owner
element]

The messageLabel attribute information item identifies the role of this message
in the message exchange pattern of the given operation element information item
.

The messageLabel attribute information item has the following Infoset
properties:

  • A [local name] of messageLabel

  • A [namespace name] which has no value

The type of the messageLabel attribute information item is xs:NCName.

2.5.2.2 element attribute information item with input or output [owner element]

The element attribute information item has the following Infoset properties:

  • A [local name] of element .

  • A [namespace name] which has no value.

The type of the element attribute information item is a union of xs:QName and
xs:token where the allowed token values are #any, #none, or #other.^†

2.5.3 Mapping Interface Message Reference's XML Representation to Component
Properties

The mapping from the XML Representation of the interface message reference
element information item (see 2.5.2 XML Representation of Interface Message
Reference Component) to the properties of the Interface Message Reference
component (see 2.5.1 The Interface Message Reference Component) is as described
in Table 2-5.

Define the message exchange pattern of the element information item to be the {
message exchange pattern} of the parent Interface Operation component.

Define the message direction of the element information item to be in if its
local name is input and out if its local name is output .

The messageLabel attribute information item of an interface message reference
element information item MUST be present if the message exchange pattern has
more than one placeholder message with {direction} equal to the message
direction. ^†

If the messageLabel attribute information item of an interface message
reference element information item is present then its actual value MUST match
the {message label} of some placeholder message with {direction} equal to the
message direction. ^†

If the messageLabel attribute information item of an interface message
reference element information item is absent then there MUST be a unique
placeholder message with {direction} equal to the message direction. ^†

Define the effective message label of an interface message reference element
information item to be either the actual value of the messageLabel attribute
information item if it is present, or the {message label} of the unique
placeholder message with {direction} equal to the message direction if the
attribute information item is absent.


   Table 2-5. Mapping from XML Representation to Interface Message Reference
                             Component Properties
┌────────────┬────────────────────────────────────────────────────────────────┐
│  Property  │                             Value                              │
├────────────┼────────────────────────────────────────────────────────────────┤
│{message    │The effective message label.                                    │
│label}      │                                                                │
├────────────┼────────────────────────────────────────────────────────────────┤
│{direction} │The message direction.                                          │
├────────────┼────────────────────────────────────────────────────────────────┤
│{message    │If the element attribute information item is present and its    │
│content     │value is a QName, then #element: otherwise the actual value of  │
│model}      │the element attribute information item, if any; otherwise #other│
│            │.                                                               │
├────────────┼────────────────────────────────────────────────────────────────┤
│            │If the element attribute information item is present and its    │
│            │value is a QName, then the Element Declaration component from   │
│            │the {element declarations} property of the Description component│
│{element    │resolved to by the value of the element attribute information   │
│declaration}│item (see 2.19 QName resolution); otherwise empty. It is an     │
│            │error for the element attribute information item to have a value│
│            │and for it to NOT resolve to an Element Declaration from the {  │
│            │element declarations} property of the Description.^†            │
├────────────┼────────────────────────────────────────────────────────────────┤
│{features}  │The set of Feature components corresponding to the feature      │
│            │element information items in [children], if any.                │
├────────────┼────────────────────────────────────────────────────────────────┤
│{properties}│The set of Property components corresponding to the property    │
│            │element information items in [children], if any.                │
├────────────┼────────────────────────────────────────────────────────────────┤
│{parent}    │The Interface Operation component corresponding to the interface│
│            │element information item in [parent].                           │
└────────────┴────────────────────────────────────────────────────────────────┘


2.6 Interface Fault Reference

2.6.1 The Interface Fault Reference Component

An Interface Fault Reference component associates a defined type, specified by
an Interface Fault component, to a fault message exchanged in an operation.

A message exchange pattern defines a set of placeholder messages that
participate in the pattern and assigns them unique message labels within the
pattern (e.g. 'In', 'Out'). The purpose of an Interface Fault Reference
component is to associate an actual message type (XML element declaration or
some other declaration (see 3.2 Using Other Schema Languages) for message
content, as specified by an Interface Fault component) with a fault message
occurring in the pattern. In order to identify the fault message it describes,
the Interface Fault Reference component uses the message label of the message
the fault is associated with as a key.

The companion specification [WSDL 2.0 Adjuncts] defines several fault
propagation rulesets that a given message exchange pattern may use. For the
ruleset fault-replaces-message, the message that the fault relates to
identifies the message in place of which the declared fault message will occur.
Thus, the fault message will travel in the same direction as the message it
replaces in the pattern. For the ruleset message-triggers-fault, the message
that the fault relates to identifies the message after which the indicated
fault may occur, in the opposite direction of the referred to message. That is,
the fault message will travel in the opposite direction of the message it comes
after in the message exchange pattern.

The properties of the Interface Fault Reference component are as follows:

  • {interface fault} REQUIRED. An Interface Fault component in the {interface
    faults} property of the [parent] Interface Operation component's [parent]
    Interface component, or an Interface component that it directly or
    indirectly extends. Identifying the Interface Fault component therefore
    indirectly defines the actual content or payload of the fault message.

  • {message label} REQUIRED. An xs:NCName. This property identifies the
    message this fault relates to among those defined in the {message exchange
    pattern} property of the Interface Operation component it is contained
    within. The value of this property MUST match the name of a placeholder
    message defined by the message exchange pattern.^†

  • {direction} REQUIRED. A xs:token with one of the values in or out,
    indicating whether the fault is coming to the service or going from the
    service, respectively. The direction MUST be consistent with the direction
    implied by the fault propagation ruleset used in the message exchange
    pattern of the operation.^† For example, if the ruleset
    fault-replaces-message is used, then a fault that refers to an outgoing
    message would have a {direction} property value of out. On the other hand,
    if the ruleset message-triggers-fault is used, then a fault that refers to
    an outgoing message would have a {direction} property value of in as the
    fault travels in the opposite direction of the message.

  • {features} OPTIONAL. A set of Feature components.

  • {properties} OPTIONAL. A set of Property components.

  • {parent} REQUIRED. The Interface Operation component that contains this
    component in its {interface fault references} property.

For each Interface Fault Reference component in the {interface fault references
} property of an Interface Operation component, the combination of its {
interface fault} and {message label} properties MUST be unique.^†

2.6.2 XML Representation of Interface Fault Reference

<description>
  <interface>
    <operation>
      <infault
            ref="xs:QName"
            messageLabel="xs:NCName"? >
        <documentation />*
        [ <feature /> | <property /> ]*
      </infault>*
      <outfault
            ref="xs:QName"
            messageLabel="xs:NCName"? >
        <documentation />*
        [ <feature /> | <property /> ]*
      </outfault>*
    </operation>
  </interface>
</description>

The XML representation for a Interface Fault Reference component is an element
information item with the following Infoset properties:

  • A [local name] of infault or outfault

  • A [namespace name] of "http://www.w3.org/2006/01/wsdl"

  • One or more attribute information items amongst its [attributes] as
    follows:

      □ A REQUIRED ref attribute information item as described below in 2.6.2.1
        ref attribute information item with infault, or outfault [owner
        element].

      □ An OPTIONAL messageLabel attribute information item as described below
        in 2.6.2.2 messageLabel attribute information item with infault, or
        outfault [owner element].

      □ Zero or more namespace qualified attribute information items whose
        [namespace name] is NOT "http://www.w3.org/2006/01/wsdl".

  • Zero or more element information item amongst its [children], in order, as
    follows:

     1. Zero or more documentation element information items (see 5.
        Documentation).

     2. Zero or more element information items from among the following, in any
        order:

          ☆ Zero or more feature element information items 2.7.2 XML
            Representation of Feature Component

          ☆ Zero or more property element information items 2.8.2 XML
            Representation of Property Component

          ☆ Zero or more namespace-qualified element information items whose
            [namespace name] is NOT "http://www.w3.org/2006/01/wsdl".

2.6.2.1 ref attribute information item with infault , or outfault [owner
element]

The ref attribute information item refers to a fault component.

The ref attribute information item has the following Infoset properties:

  • A [local name] of ref

  • A [namespace name] which has no value

The type of the ref attribute information item is xs:QName.

2.6.2.2 messageLabel attribute information item with infault , or outfault
[owner element]

The messageLabel attribute information item identifies the message in the
message exchange pattern of the given operation element information item that
is associated with this fault.

The messageLabel attribute information item has the following Infoset
properties:

  • A [local name] of messageLabel

  • A [namespace name] which has no value

The type of the messageLabel attribute information item is xs:NCName.

The messageLabel attribute information item MUST be present in the XML
representation of an Interface Fault Reference component with a given {
direction} if the {message exchange pattern} of the parent Interface Operation
component has more than one fault with that direction.^† Recall that the fault
propagation ruleset of the {message exchange pattern} specifies the relation
between faults and messages. For example, the fault-replaces-message ruleset
specifies that the faults have the same direction as the messages, while the
message-triggers-fault ruleset specifies that the faults have the opposite
direction from the messages.

2.6.3 Mapping Interface Fault Reference's XML Representation to Component
Properties

The mapping from the XML Representation of the message reference element
information item (see 2.6.2 XML Representation of Interface Fault Reference) to
the properties of the Interface Fault Reference component (see 2.6.1 The
Interface Fault Reference Component) is as described in Table 2-6.

Define the message exchange pattern of the element information item to be the {
message exchange pattern} of the parent Interface Operation component.

Define the fault direction of the element information item to be in if its
local name is infault and out if its local name is outfault .

Define the message direction of the element information item to be the
{direction} of the placeholder message associated with the fault as specifed by
the fault propagation ruleset of the message exchange pattern.

The messageLabel attribute information item of an interface fault reference
element information item MUST be present if the message exchange pattern has
more than one placeholder message with {direction} equal to the message
direction. ^†

If the messageLabel attribute information item of an interface fault reference
element information item is present then its actual value MUST match the
{message label} of some placeholder message with {direction} equal to the
message direction. ^†

If the messageLabel attribute information item of an interface fault reference
element information item is absent then there MUST be a unique placeholder
message with {direction} equal to the message direction. ^†

Define the effective message label of an interface fault reference element
information item to be either the actual value of the messageLabel attribute
information item if it is present, or the {message label} of the unique
placeholder message whose {direction} is equal to the message direction if the
attribute information item is absent.


    Table 2-6. Mapping from XML Representation to Interface Fault Reference
                             Component Properties
┌────────────┬────────────────────────────────────────────────────────────────┐
│  Property  │                             Value                              │
├────────────┼────────────────────────────────────────────────────────────────┤
│            │The Interface Fault component from {interface faults} property  │
│{interface  │of the parent Interface component, or an Interface component    │
│fault}      │that it directly or indirectly extends, with {name} equal to the│
│            │actual value of the ref attribute information item.             │
├────────────┼────────────────────────────────────────────────────────────────┤
│{message    │The effective message label.                                    │
│label}      │                                                                │
├────────────┼────────────────────────────────────────────────────────────────┤
│{direction} │The fault direction.                                            │
├────────────┼────────────────────────────────────────────────────────────────┤
│{features}  │The set of Feature components corresponding to the feature      │
│            │element information items in [children], if any.                │
├────────────┼────────────────────────────────────────────────────────────────┤
│{properties}│The set of Property components corresponding to the property    │
│            │element information items in [children], if any.                │
├────────────┼────────────────────────────────────────────────────────────────┤
│{parent}    │The Interface Operation component corresponding to the interface│
│            │element information item in [parent].                           │
└────────────┴────────────────────────────────────────────────────────────────┘


2.7 Feature

2.7.1 The Feature Component

A Feature component describes an abstract piece of functionality typically
associated with the exchange of messages between communicating parties.
Although WSDL 2.0 imposes no constraints on the potential scope of such
features, examples might include “reliability”, “security”, “correlation”, and
“routing”. The presence of a Feature component in a WSDL 2.0 description
indicates that the service supports the feature and may require that a client
that interacts with the service use that feature. Each Feature is identified by
its IRI.

WSDL 2.0's Feature concept is derived from SOAP 1.2's abstract feature concept
([SOAP 1.2 Part 1: Messaging Framework]). Every SOAP 1.2 abstract feature is
therefore also a WSDL 2.0 Feature. There is no need to define a separate WSDL
2.0 Feature in order to use a particular SOAP 1.2 feature. The SOAP 1.2 feature
can be used directly.

The properties of the Feature component are as follows:

  • {ref} REQUIRED. An xs:anyURI. This xs:anyURI MUST be an absolute IRI as
    defined by [IETF RFC 3987]. ^† This IRI SHOULD be dereferenceable to a
    document that directly or indirectly defines the meaning and use of the
    Feature that it identifies.

  • {required} REQUIRED. An xs:boolean. If the value of this property is true,
    then the client MUST use the Feature that is identified by the {ref} IRI.
    Otherwise, the client MAY use the Feature that is identified by the {ref}
    IRI. In either case, if the client does use the Feature that is identified
    by the {ref} IRI, then the client MUST obey all semantics implied by the
    definition of that Feature.

  • {parent} REQUIRED. The component that contains this component in its {
    features} property.

The {ref} property of a Feature component MUST be unique within the {features}
property of an Interface, Interface Fault, Interface Operation, Interface
Message Reference, Interface Fault Reference, Binding, Binding Fault, Binding
Operation, Binding Message Reference, Binding Fault Reference, Service, or
Endpoint component.^†

2.7.1.1 Feature Composition Model

The set of features which are required or available for a given component
consists of the combined set of ALL feature declarations applicable to that
component. A feature is applicable to a component if:

  • it is asserted directly within that component, or

  • it is asserted in a containing component, or

  • it is asserted in a component referred to by the current component.

Many of the component types in the component model contain a {features}
property, which is a set of Feature components. We refer to these as the
declared features of the component. Furthermore, the {features} property is
itself a subset of Feature components that are required or available for the
given component as determined by the Feature Composition Model. We refer to
these as the in-scope features of the component.

Following these rules, the set of features applicable at each component are as
follows:

  • Interface component: all features asserted within the Interface component
    and those with any extended Interface components.

  • Interface Fault component: all features asserted within the Interface Fault
    component and those within the parent Interface component.

  • Interface Operation component: all features asserted within the Interface
    Operation component and those within the parent Interface component.

  • Interface Message Reference component: all features asserted within the
    Interface Message Reference component, those within the parent Interface
    Operation component and those within its parent Interface component.

  • Interface Fault Reference component: all features asserted within the
    Interface Fault Reference component, those within the parent Interface
    Operation component and those within its parent Interface component.

  • Binding component: all features asserted within the Binding component and
    those within the Interface component referred to by the Binding component
    (if any).

  • Binding Fault component: all features asserted within the Binding Fault
    component, those within the parent Binding component, those within the
    corresponding Interface Fault component, and those within the Interface
    component referred to by the Binding component.

  • Binding Operation component: all features asserted within the Binding
    Operation component, those within the parent Binding component, those
    within the corresponding Interface Operation component, and those within
    the Interface component referred to by the Binding component.

  • Binding Message Reference component: all features asserted within the
    Binding Message Reference component, those within the parent Binding
    operation component, those within its parent Binding component, those
    within the corresponding Interface Message Reference component, and those
    within the Interface component referred to by the Binding component.

  • Binding Fault Reference component: all features asserted within the Binding
    Fault Reference component, those within the parent Binding Operation
    component, those within its parent Binding component, those within the
    corresponding Interface Fault Reference component, and those within the
    Interface component referred to by the Binding component.

  • Service component: all features asserted within the Service component and
    those within the Interface implemented by the Service component.

  • Endpoint component: all features asserted within the Endpoint component,
    whose within the Binding component implemented by the Endpoint component,
    and those within the parent Service component.

If a given feature is asserted at multiple locations, then the value of that
feature at a particular component is determined by the conjunction of all the
constraints implied by its asserted values. If a feature is not required then
it may or may not be engaged, but if a feature is required then it must be
engaged. Therefore, the conjunction of a required value and a non-required
value is a required value. A composed feature is required if and only if at
least one of its asserted values is required. This rule may be summarized as
"true trumps".

2.7.1.1.1 Example of Feature Composition Model

In the following example, the depositFunds operation on the BankService has to
be used with the ISO9001 , the notarization and the secure-channel features;
they are all in scope. The fact that the notarization feature is declared both
in the operation and in the binding has no effect.

<description targetNamespace="http://example.com/bank"
     xmlns="http://www.w3.org/2006/01/wsdl"
     xmlns:ns1="http://example.com/bank">
  <interface name="ns1:Bank">
    <!-- All implementations of this interface must be secure -->
    <feature ref="http://example.com/secure-channel"
             required="true"/>
    <operation name="withdrawFunds">
      <!-- This operation must have ACID properties -->
      <feature ref="http://example.com/transaction"
               required="true"/>
      ...
    </operation>
    <operation name="depositFunds">
      <!-- This operation requires notarization -->
      <feature ref="http://example.com/notarization"
               required="true"/>
      ...
    </operation>
  </interface>

  <binding name="ns1:BankSOAPBinding">
    <!-- This particular binding requires ISO9001
         compliance to be verifiable -->
    <feature ref="http://example.com/ISO9001"
             required="true"/>
    <!-- This binding also requires notarization -->
    <feature ref="http://example.com/notarization"
             required="true"/>
  </binding>

  <service name="ns1:BankService"
           interface="tns:Bank">
    <endpoint binding="ns1:BankSOAPBinding">
      ...
    </endpoint>
  </service>
</description>

2.7.2 XML Representation of Feature Component

<feature
      ref="xs:anyURI"
      required="xs:boolean"? >
  <documentation />*
</feature>

The XML representation for a Feature component is an element information item
with the following Infoset properties:

  • A [local name] of feature

  • A [namespace name] of "http://www.w3.org/2006/01/wsdl"

  • One or more attribute information items amongst its [attributes] as
    follows:

      □ A REQUIRED ref attribute information item as described below in 2.7.2.1
        ref attribute information item with feature [owner element].

      □ An OPTIONAL required attribute information item as described below in
        2.7.2.2 required attribute information item with feature [owner
        element].

      □ Zero or more namespace qualified attribute information items whose
        [namespace name] is NOT "http://www.w3.org/2006/01/wsdl".

  • Zero or more element information items amongst its [children], in order as
    follows:

     1. Zero or more documentation element information items (see 5.
        Documentation).

     2. Zero or more namespace-qualified element information items whose
        [namespace name] is NOT "http://www.w3.org/2006/01/wsdl".

2.7.2.1 ref attribute information item with feature [owner element]

The ref attribute information item specifies the IRI of the feature.

The ref attribute information item has the following Infoset properties:

  • A [local name] of ref

  • A [namespace name] which has no value

The type of the ref attribute information item is xs:anyURI .

2.7.2.2 required attribute information item with feature [owner element]

The required attribute information item specifies whether the use of the
feature is mandatory or optional.

The required attribute information item has the following Infoset properties:

  • A [local name] of required

  • A [namespace name] which has no value

The type of the required attribute information item is xs:boolean .

2.7.3 Mapping Feature's XML Representation to Component Properties

The mapping from the XML Representation of the feature element information item
(see 2.7.2 XML Representation of Feature Component) to the properties of the
Feature component (see 2.7.1 The Feature Component) is as described in Table
2-7.


  Table 2-7. Mapping from XML Representation to Feature Component Properties
┌──────────┬──────────────────────────────────────────────────────────────────┐
│ Property │                              Value                               │
├──────────┼──────────────────────────────────────────────────────────────────┤
│{ref}     │The actual value of the ref attribute information item.           │
├──────────┼──────────────────────────────────────────────────────────────────┤
│{required}│The actual value of the required attribute information item, if   │
│          │present, otherwise "false".                                       │
├──────────┼──────────────────────────────────────────────────────────────────┤
│{parent}  │The component corresponding to the element information item in    │
│          │[parent].                                                         │
└──────────┴──────────────────────────────────────────────────────────────────┘


2.8 Property

2.8.1 The Property Component

A “property” in the Features and Properties architecture represents a named
runtime value which affects the behavior of some aspect of a Web service
interaction, much like an environment variable. For example, a reliable
messaging SOAP module may specify a property to control the number of retries
in the case of network failure. WSDL 2.0 documents may specify the value
constraints for these properties by referring to a Schema type, or by
specifying a particular value. Properties, and hence property values, can be
shared amongst features/bindings/modules, and are named with IRIs precisely to
allow this type of sharing.

The properties of the Property component are as follows:

  • {ref} REQUIRED. An xs:anyURI. This xs:anyURI MUST be an absolute IRI as
    defined by [IETF RFC 3987].^† This IRI SHOULD be dereferenceable to a
    document that directly or indirectly defines the meaning and use of the
    Property that it identifies.

  • {value constraint} OPTIONAL. A reference to a Type Definition component in
    the {type definitions} property of the Description component constraining
    the value of the Property, or the token #value if the {value} property is
    not empty.^†

  • {value} OPTIONAL. The value of the Property, an ordered list of child
    information items, as specified by the [children] property of element
    information items in [XML Information Set].

  • {parent} REQUIRED. The component that contains this component in its {
    properties} property.

The {ref} property of a Property component MUST be unique within the {
properties} property of an Interface, Interface Fault, Interface Operation,
Interface Message Reference, Interface Fault Reference, Binding, Binding Fault,
Binding Operation, Binding Message Reference, Binding Fault Reference, Service,
or Endpoint component.^†

If a type system not based upon the XML Infoset is in use (as considered in 3.2
Using Other Schema Languages) then additional properties would need to be added
to the Property component (along with extensibility attributes to its XML
representation) to allow using such a type system to describe values and
constraints for properties.

2.8.1.1 Property Composition Model

At runtime, the behavior of features, (SOAP) modules and bindings may be
affected by the values of in-scope properties. Properties combine into a
virtual “execution context” which maps property names (IRIs) to constraints.
Each property IRI MAY therefore be associated with AT MOST one property
constraint for a given interaction.

The set of properties which are required or available for a given component
consists of the combined set of ALL property declarations applicable to that
component. A property is applicable to a component if:

  • it is asserted directly within that component, or

  • it is asserted in a containing component, or

  • it is asserted in a component referred to by the current component.

Many of the component types in the component model contain a {properties}
property, which is a set of Property components. We refer to these as the
declared properties of the component. Furthermore, the {properties} property is
itself a subset of Property components that are required or available for the
given component as determined by the Property Composition Model. We refer to
these as the in-scope properties of the component.

Following these rules, the set of properties applicable at each component are
as follows:

  • Interface component: all properties asserted within the Interface component
    and those with any extended Interface components.

  • Interface Fault component: all properties asserted within the Interface
    Fault component and those within the parent Interface component.

  • Interface Operation component: all properties asserted within the Interface
    Operation component and those within the parent Interface component.

  • Interface Message Reference component: all properties asserted within the
    Interface Message Reference component, those within the parent Interface
    Operation component and those within its parent Interface component.

  • Binding component: all properties asserted within the Binding component and
    those within the Interface component referred to by the Binding component
    (if any).

  • Binding Fault component: all properties asserted within the Binding Fault
    component, those within the parent Binding component, those within the
    corresponding Interface Fault component, and those within the Interface
    component referred to by the Binding component.

  • Binding Operation component: all properties asserted within the Binding
    Operation component, those within the parent Binding component, those
    within the corresponding Interface Operation component, and those within
    the Interface component referred to by the Binding component.

  • Binding Message Reference component: all properties asserted within the
    Binding Message Reference component, those within the parent Binding
    Operation component, those within its parent Binding component, those
    within the corresponding Interface Message Reference component, and those
    within the Interface component referred to by the Binding component.

  • Binding Fault Reference component: all properties asserted within the
    Binding Fault Reference component, those within the parent Binding
    Operation component, those within its parent Binding component, those
    within the corresponding Interface Fault Reference component, and those
    within the Interface component referred to by the Binding component.

  • Service component: all properties asserted within the Service component and
    those within the Interface implemented by the Service component.

  • Endpoint component: all properties asserted within the Endpoint component,
    whose within the Binding component implemented by the Endpoint component,
    and those within the parent Service component.

Note that, in the text above, “property constraint” (or, simply, “constraint”)
is used to mean EITHER a constraint inside a Property component OR a value ,
since value may be considered a special case of constraint .

If a given Property is asserted at multiple locations, then the value of that
Property at a particular component is determined by the conjunction of all the
constraints of its in-scope Property components. A Property constraint asserts
that, for a given interaction, the value of a Property is either a specified
value or belongs to a specified set of values. A specified value may be
regarded as a singleton set, so in both cases a Property constraint corresponds
to an assertion that the Property value belongs to some set. The conjunction of
all the constraints associated with the in-scope properties is an assertion
that the property value belongs to each of the associated sets, or
equivalently, that the value belongs to the intersection of all the associated
sets. If the intersection of the associated sets is empty, then the property
constraints are mutually incompatible, and the composition is invalid.
Therefore, the intersection of the associated sets SHOULD NOT be empty.

Note:

The reason that we phrase the requirement for a non-empty intersection as
SHOULD rather than MUST, is that in general, it may be computationally
difficult to determine by inspection of the type definitions that the
intersection of two or more value sets is empty. Therefore, it is not a strict
validity requirement that the intersection of the value sets be non-empty. An
empty intersection will always result in failure of the service at run-time.

However, it is in general feasible to test specified values for either equality
or membership in value sets. All specified values MUST be equal and belong to
each specified value set.^†

2.8.2 XML Representation of Property Component

<property
      ref="xs:anyURI" >
  <documentation />*
  [ <value /> | <constraint /> ]?
</property>

The XML representation for a Property component is an element information item
with the following Infoset properties:

  • A [local name] of property

  • A [namespace name] of "http://www.w3.org/2006/01/wsdl"

  • One or more attribute information items amongst its [attributes] as
    follows:

      □ A REQUIRED ref attribute information item as described below in 2.8.2.1
        ref attribute information item with property [owner element].

      □ Zero or more namespace qualified attribute information items whose
        [namespace name] is NOT "http://www.w3.org/2006/01/wsdl".

  • Zero or more element information items amongst its [children], in order as
    follo