SOAP Version 1.2 Part 1: Messaging Framework

W3C Working Draft 17 December 2001

This version:
Latest version:
Previous version:
Martin Gudgin, DevelopMentor
Marc Hadley, Sun Microsystems
Jean-Jacques Moreau, Canon
Henrik Frystyk Nielsen, Microsoft


SOAP version 1.2 is a lightweight protocol for exchange of information in a decentralized, distributed environment. It is an XML based protocol at the core of which is an envelope that defines a framework for describing what is in a message and how to process it and a transport binding framework for exchanging messages using an underlying protocol. Adjuncts to the envelope and binding framework include a set of encoding rules for expressing instances of application-defined data types and a convention for representing remote procedure calls and responses. Part 1 (this document) describes the SOAP envelope and SOAP transport binding framework; Part 2[1]describes adjuncts to the envelope and binding framework.

Status of this Document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. The latest status of this document series is maintained at the W3C.

This is the third W3C Working Draft of the SOAP Version 1.2 specification for review by W3C members and other interested parties. It has been produced by the XML Protocol Working Group (WG), which is part of the XML Protocol Activity.

For a detailed list of changes since the last publication of this document, refer to appendix C Part 1 Change Log. A list of open issues against this document can be found at http://www.w3.org/2000/xp/Group/xmlp-issues.

Comments on this document should be sent to xmlp-comments@w3.org (public archive[13]). It is inappropriate to send discussion emails to this address.

Discussion of this document takes place on the public xml-dist-app@w3.org mailing list[14] per the email communication rules in the XML Protocol Working Group Charter[15].

This is a public W3C Working Draft. It is a draft document and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use W3C Working Drafts as reference material or to cite them as other than "work in progress". A list of all W3C technical reports can be found at http://www.w3.org/TR/.

Table of Contents

1 Introduction
    1.1 Design Goals
    1.2 Notational Conventions
    1.3 Example of SOAP Message
    1.4 SOAP Terminology
        1.4.1 Protocol Concepts
        1.4.2 Data Encapsulation Concepts
        1.4.3 Message Sender and Receiver Concepts
2 SOAP Message Exchange Model
    2.1 SOAP Nodes
    2.2 SOAP Actors and SOAP Nodes
    2.3 Targeting SOAP Header Blocks
    2.4 Understanding SOAP Headers
    2.5 Structure and Interpretation of SOAP Bodies
    2.6 Processing SOAP Messages
3 Relation to XML
4 SOAP Envelope
    4.1 Envelope Encoding and Versioning
        4.1.1 SOAP encodingStyle Attribute
        4.1.2 Envelope Versioning Model
    4.2 SOAP Header
        4.2.1 Use of Header Attributes
        4.2.2 SOAP actor Attribute
        4.2.3 SOAP mustUnderstand Attribute
    4.3 SOAP Body
    4.4 SOAP Fault
        4.4.1 SOAP faultcode Element
        4.4.2 SOAP faultstring Element
        4.4.3 SOAP faultactor Element
        4.4.4 SOAP detail Element
        4.4.5 SOAP Fault Codes
        4.4.6 MustUnderstand Faults
5 SOAP Protocol Binding Framework
    5.1 Introduction
    5.2 Goals of the Binding Framework
    5.3 Binding Framework
    5.4 Binding to Application-Specific Protocols
    5.5 Security Considerations
6 Use of URIs in SOAP
7 References
    7.1 Normative References
    7.2 Informative References


A Version Transition From SOAP/1.1 to SOAP Version 1.2
B Acknowledgements (Non-Normative)
C Part 1 Change Log (Non-Normative)
    C.1 SOAP Specification Changes
    C.2 XML Schema Changes

1 Introduction

SOAP version 1.2 provides a simple and lightweight mechanism for exchanging structured and typed information between peers in a decentralized, distributed environment using XML. SOAP does not itself define any application semantics such as a programming model or implementation specific semantics; rather it defines a simple mechanism for expressing application semantics by providing a modular packaging model and mechanisms for encoding application defined data. This allows SOAP to be used for a large variety of purposes ranging from messaging systems to remote procedure call (RPC) invocations. In previous versions of this specification the SOAP name was an acronym. This is no longer the case.

Part 1 of the SOAP specification (this document) describes:

  1. The SOAP envelope (4 SOAP Envelope). This construct defines an overall framework for expressing what is in a message, who should deal with it, and whether it is optional or mandatory.

  2. The SOAP binding framework (5 SOAP Protocol Binding Framework). This defines an abstract framework for exchanging SOAP envelopes between peers using an underlying protocol for transport. The SOAP HTTP binding [1](SOAP in HTTP) defines a concrete instance of a binding to the HTTP protocol[2].

Part 2[1] describes adjuncts to the envelope and binding framework including the SOAP encoding rules [1](SOAP Encoding) that define a serialization mechanism that can be used to exchange instances of application-defined datatypes and the SOAP RPC representation [1]( SOAP for RPC) that defines a convention that can be used to represent remote procedure calls and responses.

1.1 Design Goals

Two major design goals for SOAP are simplicity and extensibility. SOAP attempts to meet these goals by omitting features often found in messaging systems and distributed object systems such as:

  • distributed garbage collection;

  • boxcarring or batching of messages;

  • objects-by-reference (which requires distributed garbage collection);

  • activation (which requires objects-by-reference).

Note that it is possible to implement such features using SOAP but they are out of scope for this specification.

1.2 Notational Conventions

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 [3].

The namespace prefixes "env" and "enc" used in the prose sections of this document are associated with the SOAP namespace names "http://www.w3.org/2001/12/soap-envelope" and "http://www.w3.org/2001/12/soap-encoding" respectively.

The namespace prefixes "xs" and "xsi" used in the prose sections of this document are associated with the namespace names "http://www.w3.org/2001/XMLSchema" and "http://www.w3.org/2001/XMLSchema-instance" respectively, both of which are defined in the XML Schemas specification[4],[5].

Note that the choice of any namespace prefix is arbitrary and not semantically significant.

Namespace URIs of the general form "http://example.org/..." and "http://example.com/..." represent an application-dependent or context-dependent URI[6].

1.3 Example of SOAP Message

The following example shows a simple notification message expressed in SOAP. The message contains a header block alertcontrol and the body alert both of which are application defined and not defined by SOAP. The header contains information which may be of use to intermediaries as well as the ultimate destination of the message. The body contains the actual notification message to be delivered.

Example: SOAP message containing a header block and a body
<?xml version="1.0" ?>
<env:Envelope xmlns:env="http://www.w3.org/2001/12/soap-envelope">
  <n:alertcontrol xmlns:n="http://example.org/alertcontrol">
  <m:alert xmlns:m="http://example.org/alert">
   <m:msg>Pick up Mary at school at 2pm</m:msg>

1.4 SOAP Terminology

1.4.1 Protocol Concepts


The formal set of conventions governing the format and processing rules of a SOAP message and basic control of interaction between SOAP nodes generating and accepting SOAP messages for the purpose of exchanging information along a SOAP message path.

SOAP binding

The formal set of rules for carrying a SOAP message within or on top of another protocol (underlying protocol) for the purpose of transmission. Example SOAP bindings include carrying a SOAP message within an HTTP entity-body, or over a TCP stream.

SOAP node

A SOAP node processes a SOAP message according to the formal set of conventions defined by SOAP. The SOAP node is responsible for enforcing the rules that govern the exchange of SOAP messages and accesses the services provided by the underlying protocols through SOAP bindings. Non-compliance with SOAP conventions can cause a SOAP node to generate a SOAP fault (see also SOAP receiver and SOAP sender).

1.4.2 Data Encapsulation Concepts

SOAP message

A SOAP message is the basic unit of communication between peer SOAP nodes.

SOAP envelope

The outermost syntactic construct or structure of a SOAP message defined by SOAP within which all other syntactic elements of the message are enclosed.

SOAP header block

A syntactic construct or structure used to delimit data that logically constitutes a single computational unit within the SOAP header. SOAP header blocks are direct children of the SOAP Header (4.2 SOAP Header) element information item. The type of a SOAP header block is identified by the fully qualified name of the outer element information item of the block, which consists of its namespace URI and local name.

SOAP header

A collection of zero or more SOAP header blocks each of which may be targeted at any SOAP receiver within the SOAP message path.

SOAP body

A collection of zero or more element information items targeted at the ultimate SOAP receiver in the SOAP message path.

SOAP fault

A special SOAP element information item which contains fault information generated by a SOAP node.

The following diagram illustrates how a SOAP message is composed.

Encapsulation model illustrating the parts of a SOAP message.

1.4.3 Message Sender and Receiver Concepts

SOAP sender

A SOAP sender is a SOAP node that transmits a SOAP message.

SOAP receiver

A SOAP receiver is a SOAP node that accepts a SOAP message.

SOAP message path

The set of SOAP senders and SOAP receivers through which a single SOAP message passes. This includes the initial SOAP sender, zero or more SOAP intermediaries, and the ultimate SOAP receiver.

Initial SOAP sender

The SOAP sender that originates a SOAP message as the starting point of a SOAP message path.

SOAP intermediary

A SOAP intermediary is both a SOAP receiver and a SOAP sender and is target-able from within a SOAP message. It processes a defined set of blocks in a SOAP message along a SOAP message path. It acts in order to forward the SOAP message towards the ultimate SOAP receiver.

Ultimate SOAP receiver

The SOAP receiver that the initial sender specifies as the final destination of the SOAP message within a SOAP message path. A SOAP message may not reach the ultimate recipient because of a SOAP fault generated by a SOAP node along the SOAP message path.

SOAP Application

A software entity that produces, consumes or otherwise acts upon SOAP messages in a manner conforming to the SOAP processing model

2 SOAP Message Exchange Model

SOAP messages are fundamentally one-way transmissions from a SOAP sender to a SOAP receiver; however, SOAP messages are often combined to implement patterns such as request/response.

SOAP implementations can be optimized to exploit the unique characteristics of particular network systems. For example, the HTTP binding described in [1](SOAP in HTTP) provides for SOAP response messages to be delivered as HTTP responses, using the same connection as the inbound request.

2.1 SOAP Nodes

A SOAP node can be the initial SOAP sender, the ultimate SOAP receiver, or a SOAP intermediary, in which case it is both a SOAP sender and a SOAP receiver. SOAP does not provide a routing mechanism, however SOAP does recognise that a SOAP sender originates a SOAP message which is sent to an ultimate SOAP receiver, via zero or more SOAP intermediaries.

A SOAP node receiving a SOAP message MUST perform processing according to the SOAP processing model as described in this section and, if appropriate, generate SOAP faults, SOAP responses and send additional SOAP messages, as provided by the remainder of this specification.

2.2 SOAP Actors and SOAP Nodes

In processing a SOAP message, a SOAP node is said to act in the role of one or more SOAP actors, each of which is identified by a URI known as the SOAP actor name. Each SOAP node MUST act in the role of the special SOAP actor named "http://www.w3.org/2001/12/soap-envelope/actor/next", and can additionally assume the roles of zero or more other SOAP actors. A SOAP node can establish itself as the ultimate SOAP receiver by acting in the (additional) role of the anonymous SOAP actor. The roles assumed MUST be invariant during the processing of an individual SOAP message; because this specification deals only with the processing of individual SOAP messages, no statement is made regarding the possibility that a given piece of software might or might not act in varying roles when processing more than one SOAP message.

SOAP nodes MUST NOT act in the role of the special SOAP actor named "http://www.w3.org/2001/12/soap-envelope/actor/none". Header blocks targeted to this special actor are carried with the message to the ultimate receiver, but are never formally "processed". Such blocks MAY carry data that is required for processing of other blocks.

While the purpose of a SOAP actor name is to identify a SOAP node, there are no routing or message exchange semantics associated with the SOAP actor name. For example, SOAP Actors MAY be named with a URI useable to route SOAP messages to an appropriate SOAP node. Conversely, it is also appropriate to use SOAP actor roles with names that are related more indirectly to message routing (e.g. "http://example.org/banking/anyAccountMgr") or which are unrelated to routing (e.g. a URI meant to identify "all cache management software"; such a header might be used, for example, to carry an indication to any concerned software that the containing SOAP message is idempotent, and can safely be cached and replayed.)

Except for "http://www.w3.org/2001/12/soap-envelope/actor/next", "http://www.w3.org/2001/12/soap-envelope/actor/none" and the anonymous actor this specification does not prescribe the criteria by which a given node determines the (possible empty) set of roles in which it acts on a given message. For example, implementations can base this determination on factors including, but not limited to: hardcoded choices in the implementation, information provided by the transport binding (e.g. the URI to which the message was physically delivered), configuration information made by users during system installation, etc.

2.3 Targeting SOAP Header Blocks

SOAP header blocks carry optional actor attribute information items (see 4.2.2 SOAP actor Attribute) that are used to target them to the appropriate SOAP node(s). SOAP header blocks with no such attribute information item are implicitly targeted at the anonymous SOAP actor, implying that they are to be processed by the ultimate SOAP receiver. This specification refers to the (implicit or explicit) value of the SOAP actor attribute as the SOAP actor for the corresponding SOAP header block.

A SOAP header block is said to be targeted to a SOAP node if the SOAP actor (if present) on the block matches (see [7]) a role played by the SOAP node, or in the case of a SOAP header block with no actor attribute information item, if the SOAP node is acting in the role of the ultimate SOAP receiver.

A SOAP Node that acts in the role of the anonymous actor with respect to a particular SOAP message becomes the ultimate recipient of that SOAP message. Such a SOAP node is responsible for processing all parts of the message intended for the anonymous actor, including the body, according to the rules described in this section. The SOAP message path for that message ends at the ultimate recipient. However, the ultimate recipient may delegate all or part of its responsibility to other entities. The ultimate recipient may happen to use distinct SOAP message exchanges to interact with such entities. Nevertheless, responsibility for the processing of parts of a SOAP message targetted at the anonymous actor rests with the ultimate recipient of that message

2.4 Understanding SOAP Headers

It is likely that specifications for a wide variety of header functions will be developed over time, and that some SOAP nodes MAY include the software necessary to implement one or more such extensions. A SOAP header block is said to be understood by a SOAP node if the software at that SOAP node has been written to fully conform to and implement the semantics conveyed by the combination of local name and namespace name of the outer-most element information item of that block.

SOAP header blocks carry optional mustUnderstand attribute information items (see 4.2.3 SOAP mustUnderstand Attribute). When the value of such an attribute information item is "true" or "1", the SOAP block is said to be mandatory.

For every mandatory SOAP header block targeted to a node, that node MUST either process the block according to the semantics conveyed by the combination of local name and namespace name of the outer-most element information item of that block; or not process the SOAP message at all, and instead generate a fault (see 2.6 Processing SOAP Messages and 4.4 SOAP Fault).

Mandatory blocks MUST be presumed to somehow modify the semantics of other headers or body elements. Tagging SOAP blocks as mandatory thus assures that such changes in semantics will not be silently (and, presumably, erroneously) ignored.

The mustUnderstand attribute information item is not intended as a mechanism for detecting errors in routing, misidentification of nodes, failure of a node to serve in its intended role(s), etc., any of which may result in a failure to even attempt processing, and the subsequent removal, of a given SOAP header block from a SOAP envelope. This specification therefore does not require any fault to be generated based on the presence or value of this attribute on a SOAP header block not targeted at the current processing node, for example when it is suspected that such a block has survived erronously due to a routing or targeting error at a preceeding intermediairy. In particular, it is not an error for a mandatory header block targeted to a role other than the ones assumed by the ultimate SOAP receiver to reach that node without having been processed.

2.5 Structure and Interpretation of SOAP Bodies

A SOAP body consists of zero or more namespace qualified element information items, which are the immediate children of the Body element information item. The ultimate SOAP receiver MUST correctly process such body elements. However, Part 1 of this specification (this document) mandates no particular structure or interpretation of such elements, and provides no standard means for specifying the processing to be done.

When multiple body elements are present, such elements MAY represent a single unit of work to be performed, MAY represent multiple separate processing steps, possibly but not necessarily in order, MAY represent data or metadata, MAY convey a mixture of work units and data, etc. The ultimate SOAP recipient MAY use the local name(s) and namespace name(s), on any or all body elements, to determine the processing to be performed. Indeed, the SOAP RPC convention (see [1]Using SOAP for RPC) uses just such a method. Conversely, other information in the body and/or headers MAY be used to make such a determination.

2.6 Processing SOAP Messages

This section sets out the rules by which SOAP messages are processed. Unless otherwise stated, processing must be semantically equivalent to performing the following steps separately, and in the order given. Note however that nothing in this specification should be taken to prevent the use of optimistic concurrency, roll back, or other techniques that might provide increased flexibility in processing order as long as all SOAP messages, SOAP faults and application-level side effects are equivalent to those that would be obtained by direct implementation of the following rules in the order shown below.

  1. Determine the set of roles in which the node is to act. The contents of the SOAP envelope, including header blocks and the body, MAY be inspected in making such determination.

  2. Identify all header blocks targeted at the node that are mandatory.

  3. If one or more of the header blocks identified in the preceding step are not understood by the node then generate a single SOAP MustUnderstand fault (see 4.4.6 MustUnderstand Faults). If such a fault is generated, any further processing MUST NOT be done. Faults relating to the existence or contents of the body MUST NOT be generated in this step.

  4. Process all header blocks targeted at the node and, in the case of the ultimate SOAP recipient, the SOAP body. A SOAP node MUST process all SOAP header blocks targeted at it. A SOAP node MAY choose to ignore the processing implied by non-mandatory SOAP header blocks targeted at it.

  5. In the case of a SOAP intermediary, and where the message is to be forwarded further along the message path, remove all SOAP header blocks targeted at the node, and possibly insert new SOAP header blocks.

In all cases where a SOAP header block is processed, the SOAP node must understand the SOAP block and must do such processing in a manner fully conformant with the specification for that block. The ultimate recipient MUST process the SOAP body, in a manner consistent with 2.5 Structure and Interpretation of SOAP Bodies.

If processing is unsuccessful, exactly one fault MUST be generated by the node. Header-related faults other than mustUnderstand faults (see 4.4 SOAP Fault) MUST be SOAP Sender or DataEncodingUnknown faults (see 4.4.5 SOAP Fault Codes) and MUST conform to the specification for the corresponding SOAP header block. Faults relating to the body MUST be SOAP Sender or DataEncodingUnknown faults (see 4.4.5 SOAP Fault Codes).

SOAP nodes can make reference to any information in the SOAP envelope when processing a SOAP block. For example, a caching function can cache the entire SOAP message, if desired.

The processing of particular SOAP header block MAY control or determine the order of processing for other SOAP header blocks and/or the SOAP body. For example, one could create a SOAP header block to force processing of other SOAP header blocks in lexical order. In the absence of such a controlling block, the order of header and body processing is at the discretion of the SOAP node; header blocks MAY be processed in arbitrary order, and such processing MAY precede, be interleaved with, or MAY follow processing of the body. For example, a "begin transaction" header block would typically precede, a "commit transaction" would likely follow, and a "logging" function might run concurrently with body processing.

If the SOAP node is a SOAP intermediary, the SOAP message pattern and results of processing (e.g. no fault generated) MAY require that the SOAP message be sent further along the SOAP message path. Such relayed SOAP messages MUST contain all SOAP header blocks and the SOAP body from the original SOAP message, in the original order, except that SOAP header blocks targeted at the SOAP intermediary MUST be removed (such SOAP blocks are removed regardless of whether they were processed or ignored). Additional SOAP header blocks MAY be inserted at any point in the SOAP message, and such inserted SOAP header blocks MAY be indistinguishable from one or more just removed (effectively leaving them in place, but emphasizing the need to reinterpret at each SOAP node along the SOAP message path.)


The above rules apply to processing at a single node. SOAP extensions MAY be designed to ensure that mandatory (and other) headers are processed in an appropriate order, as the message moves along the message path towards the ultimate recipient. Specifically, such extensions might specify that a (Sender) fault is generated if some SOAP header blocks have inadvertently survied past some intended point in the message path. Such extensions MAY depend on the presence or value of the mustUnderstand attribute information item in the surviving headers when determining whether an error has occurred.

3 Relation to XML

All SOAP messages have an XML Information Set[10]

A SOAP node MUST ensure that all element information items and attribute information items in messages that it generates are correctly namespace qualified. A SOAP node MUST be able to process SOAP namespace information in messages that it receives. It MUST treat messages with incorrect namespace information as described in 4.1.2 Envelope Versioning Model.

This document defines the following namespaces[7]:

Schema documents for these namespaces can be found by dereferencing the namespace identifiers. These schemas are normative.

A SOAP message MUST NOT contain a Document Type Declaration. On receipt of a SOAP message containing a Document Type Declaration, a SOAP receiver MUST generate a fault (see 4.4 SOAP Fault) with a faultcode of "DTDNotSupported". A SOAP message SHOULD NOT contain processing instruction information items. A SOAP receiver MUST ignore processing instruction information items in SOAP messages it receives.

A SOAP message MUST NOT impose any XML schema processing (assessment and validation) requirement on the part of any receiving SOAP node. Therefore, SOAP REQUIRES that all attribute information items, whether specified in this specification or whether they belong to a foreign namespace be caried in the serialized SOAP envelope.

4 SOAP Envelope

A SOAP message has an XML Infoset that consists of a document information item with exactly one child, which is an element information item as described below.

The document element information item has:

4.1 Envelope Encoding and Versioning

4.1.1 SOAP encodingStyle Attribute

SOAP defines an encodingStyle attribute information item which can be used to indicate the encoding rules used to serialize a SOAP message.

The encodingStyle attribute information item has:

  • A local name of encodingStyle

  • A namespace name of http://www.w3.org/2001/12/soap-envelope

Editorial note: MJG20010802
The following sentence conflicts with the definition of the Body

It may appear on any element information item in the SOAP message. Its scope is that of its owner element information item and that element information item's descendants, unless a descendant itself owns such an attribute information item.

The encodingStyle attribute information item is of type anyURI in the namespace http://www.w3.org/2001/XMLSchema. Its value identifies a set of serialization rules that can be used to deserialize the SOAP message.

Example: Example values for the encodingStyle attribute

The serialization rules defined by SOAP (see [1]SOAP Encoding) are identified by the URI "http://www.w3.org/2001/12/soap-encoding". SOAP messages using this particular serialization SHOULD indicate this using the SOAP encodingStyle attribute information item. In addition, all URIs syntactically beginning with "http://www.w3.org/2001/12/soap-encoding" indicate conformance with the SOAP encoding rules defined in [1](SOAP Encoding), though with potentially tighter rules added.

A value of the zero-length URI ("") explicitly indicates that no claims are made for the encoding style of contained elements. This can be used to turn off any claims from containing elements.

4.1.2 Envelope Versioning Model

SOAP does not define a traditional versioning model based on major and minor version numbers. If a SOAP message is received by a SOAP 1.2 node in which the document element information item does NOT have a namespace name of http://www.w3.org/2001/12/soap-envelope the SOAP node MUST treat this as a version error and generate a VersionMismatch SOAP fault (see 4.4 SOAP Fault). See A Version Transition From SOAP/1.1 to SOAP Version 1.2 for further details.

Any other malformation of the message structure MUST be treated as a Sender SOAP fault.

4.2 SOAP Header

SOAP provides a flexible mechanism for extending a SOAP message in a decentralized and modular way without prior knowledge between the communicating parties. Typical examples of extensions that can be implemented as SOAP header blocks are authentication, transaction management, payment, etc.

The Header element information item has:

  • A local name of Header

  • A namespace name of http://www.w3.org/2001/12/soap-envelope

  • Zero or more namespace qualified attribute information item children.

  • Zero or more namespace qualified element information item children.

All child element information items of the SOAP Header are called SOAP header blocks.

Each SOAP header block element information item:

  • MUST be namespace qualified;

  • MAY have an encodingStyle attribute information item

  • MAY have an actor attribute information item

  • MAY have a mustUnderstand attribute information item

4.2.1 Use of Header Attributes

The SOAP header block attribute information items defined in this section determine how a SOAP receiver should process an incoming SOAP message, as described in 2 SOAP Message Exchange Model.

A SOAP sender generating a SOAP message SHOULD only use the SOAP header block attribute information items on child element information items of the SOAP Header element information item.

A SOAP receiver MUST ignore all SOAP header block attribute information items that are applied to other descendant element information items of the SOAP Header element information item.

Example: Example header with a single header block
<env:Header xmlns:env="http://www.w3.org/2001/12/soap-envelope" >
  <t:Transaction xmlns:t="http://example.org/2001/06/tx" env:mustUnderstand="1" >

SOAP header block attribute information items MUST appear in the SOAP message itself in order to be effective; default values which may be specified in an XML Schema or other description language do not affect SOAP processing (see 3 Relation to XML).

4.2.2 SOAP actor Attribute

As described in 2 SOAP Message Exchange Model, not all parts of a SOAP message may be intended for the ultimate SOAP receiver. The actor attribute information item is to be used to indicate the SOAP node at which a particular SOAP header block is targeted.

The actor attribute information item has the following Infoset properties:

  • A local name of actor;

  • A namespace name of http://www.w3.org/2001/12/soap-envelope ;

  • A specified property with a value of true.

The type of the actor attribute information item is anyURI in the namespace http://www.w3.org/2001/XMLSchema . The value of the actor attribute information item is a URI that names a role that a SOAP node may assume.

Omitting the SOAP actor attribute information item implicitly targets the SOAP header block at the ultimate SOAP receiver. An empty value for this attribute is equivalent to omitting the attribute completely, i.e. targeting the block at the ultimate SOAP recipient.

4.2.3 SOAP mustUnderstand Attribute

As described in 2.4 Understanding SOAP Headers, the SOAP mustUnderstand attribute information item is used to indicate whether the processing of a SOAP header block is mandatory or optional at the target SOAP node.

The mustUnderstand attribute information item has the following Infoset properties:

  • A local name of mustUnderstand;

  • A namespace name of http://www.w3.org/2001/12/soap-envelope;

  • A specified property with a value of true.

The type of the mustUnderstand attribute information item is boolean in the namespace http://www.w3.org/2001/XMLSchema. Omitting this attribute information item is defined as being semantically equivalent to including it with a value of "false".

4.3 SOAP Body

The SOAP Body element information item provides a simple mechanism for exchanging mandatory information intended for the ultimate SOAP receiver of a SOAP message. Example uses of SOAP Body include marshalling RPC calls and error reporting.

The Body element information item has:

  • A local name of Body

  • A namespace name of http://www.w3.org/2001/12/soap-envelope

  • Zero or more element information item children.

Editorial note: MJG20010802
The description of Body does not allow additional attributes.

All child element information items of the SOAP Body element information item:

Editorial note: MJG20011025
The requirement that direct children of the SOAP body be namespace qualified is a change from previous drafts. The XML Protocol Working Group solicits feedback from implementors on this change.
  • MUST be namespace qualified.

  • MAY have an encodingStyle attribute information item

SOAP defines one particular direct child of the SOAP body, the SOAP fault, which is used for reporting errors (see 4.4 SOAP Fault).

4.4 SOAP Fault

The SOAP Fault element information item is used to carry error and/or status information within a SOAP message. If present, the SOAP Fault MUST appear as a direct child of the SOAP body and MUST NOT appear more than once within a SOAP Body.

The Fault element information item has:

4.4.1 SOAP faultcode Element

The faultcode element information item has:

  • A local name of faultcode

  • A namespace name which is empty

The type of the faultcode element information item is QName in the http://www.w3.org/2001/XMLSchema namespace. It is intended for use by software to provide an algorithmic mechanism for identifying the fault. SOAP defines a small set of SOAP fault codes covering basic SOAP faults (see 4.4.5 SOAP Fault Codes)

4.4.2 SOAP faultstring Element

The faultstring element information item has:

  • A local name of faultstring ;

  • A namespace name which is empty.

The type of the faultstring element information item is string in the http://www.w3.org/2001/XMLSchema namespace. It is intended to provide a human readable explanation of the fault and is not intended for algorithmic processing. This element information item is similar to the 'Reason-Phrase' defined by HTTP[2] and SHOULD provide at least some information explaining the nature of the fault.

4.4.3 SOAP faultactor Element

The faultactor element information item has:

  • A local name of faultactor

  • A namespace name which is empty

The type of the faultactor element information item is anyURI in the http://www.w3.org/2001/XMLSchema namespace. It is intended to provide information about which SOAP node on the SOAP message path caused the fault to happen (see 2 SOAP Message Exchange Model). It is similar to the SOAP actor attribute information item (see 4.2.2 SOAP actor Attribute) but instead of indicating the target of a SOAP header block, it indicates the source of the fault. The value of the faultactor element information item identifies the source of the fault. SOAP nodes that do not act as the ultimate SOAP receiver MUST include this element information item The ultimate SOAP receiver MAY include this element information item to indicate explicitly that it generated the fault.

4.4.4 SOAP detail Element

The detail element information item has:

  • A local name of detail ;

  • A namespace name which is empty;

  • Zero or more attribute information items;

  • Zero or more child element information items.

The detail element information item is intended for carrying application specific error information related to the SOAP Body . It MUST be present when the contents of the SOAP Body could not be processed successfully . It MUST NOT be used to carry error information about any SOAP header blocks. Detailed error information for SOAP header blocks MUST be carried within the SOAP header blocks themselves.

The absence of the detail element information item indicates that a SOAP Fault is not related to the processing of the SOAP Body . This can be used to find out whether the SOAP Body was at least partially processed by the ultimate SOAP receiver before the fault occurred, or not.

All child element information items of the detail element Information Item are called detail entries.

Each such element information item:

  • MAY be namespace qualified;

  • MAY have an encodingStyle attribute information item.

The SOAP encodingStyle attribute information item is used to indicate the encoding style used for the detail entries (see 4.1.1 SOAP encodingStyle Attribute).

4.4.5 SOAP Fault Codes

Editorial note: MJG20011130
Previous versions of this specification supported a hierarchical notation for fault codes using a 'dot' notation. This support has been removed in this draft and will also be omitted from the next version of this specification unless significant evidence for the contrary is provided.

SOAP faultcode values are XML qualified names [7]. The faultcodes defined in this section MUST be used as values for the SOAP faultcode element information item when describing faults defined by SOAP 1.2 Part 1 (this document). The namespace identifier for these SOAP faultcode values is "http://www.w3.org/2001/12/soap-envelope". Other specifications may define their own fault codes. Use of this namespace is recommended (but not required) in the specification of such faultcodes

The faultcode values defined by this specification are listed in the following table.

Name Meaning
VersionMismatch The processing party found an invalid namespace for the SOAP Envelope element information item (see 4.1.2 Envelope Versioning Model)
MustUnderstand An immediate child element information item of the SOAP Header element information item that was either not understood or not obeyed by the processing party contained a SOAP mustUnderstand attribute information item with a value of "true" (see 4.2.3 SOAP mustUnderstand Attribute)
DTDNotSupported The SOAP message contained a Document Type Definition ( see 3 Relation to XML ).
DataEncodingUnknown A header or body targetted at the current SOAP node is scoped ( See 4.1.1 SOAP encodingStyle Attribute) with a data encoding that the current node does not support.
Sender A Sender faultcode indicates that the message was incorrectly formed or did not contain the appropriate information in order to succeed. For example, the message could lack the proper authentication or payment information. It is generally an indication that the message should not be resent without change. See also 4.4 SOAP Fault for a description of the SOAP fault detail sub-element.
Receiver The Receiver faultcode indicates that the message could not be processed for reasons not directly attributable to the contents of the message itself but rather to the processing of the message. For example, processing could include communicating with an upstream SOAP node, which did not respond. The message may succeed at a later point in time. See also 4.4 SOAP Fault for a description of the SOAP fault detail sub-element.

4.4.6 MustUnderstand Faults

When a SOAP node generates a MustUnderstand fault, it SHOULD provide, in the generated fault message, header blocks as described below which detail the qualified names (QNames, per the XML Schema Datatypes specification[5]) of the particular header block(s) which were not understood.

Each such header block element information item has:

  • A local name of Misunderstood ;

  • A namespace name of http://www.w3.org/2001/12/soap-faults;

  • A qname attribute information item as desribed below.

The qname attribute information item has the following Infoset properties:

  • A local name of qname;

  • A namespace name which is empty;

  • A specified property with a value of true.

The type of the qname attribute information item is QName in the http://www.w3.org/2001/XMLSchema namespace. Its value is the QName of a header block which the faulting node failed to understand.

Consider the following message:

Example: SOAP envelope that will cause a SOAP MustUnderstand fault if Extension1 or Extension2 are not understood
<?xml version="1.0" ?>
<env:Envelope xmlns:env='http://www.w3.org/2001/12/soap-envelope'>
    <abc:Extension1 xmlns:abc='http://example.org/2001/06/ext'
                       env:mustUnderstand='1' />
    <def:Extension2 xmlns:def='http://example.com/stuff'
                       env:mustUnderstand='1' />
  . . .

The above message would result in the fault message shown below if the recipient of the initial message does not understand the two header elements abc:Extension1 and def:Extension2 .

Example: SOAP fault generated as a result of not understanding Extension1 and Extension2
<?xml version="1.0" ?>
<env:Envelope xmlns:env='http://www.w3.org/2001/12/soap-envelope'
                      xmlns:f='http://www.w3.org/2001/12/soap-faults' >
    <f:Misunderstood qname='abc:Extension1'
                                xmlns:abc='http://example.org/2001/06/ext' />
    <f:Misunderstood qname='def:Extension2'
                                xmlns:def='http://example.com/stuff' />
      <faultstring>One or more mandatory headers not understood</faultstring>

Note that when serializing the qname attribute information item there must be an in-scope namespace declaration for the namespace name of the misunderstood header and the value of the attribute information item must use the prefix of such a namespace declaration

Note also that there is no guarantee that each MustUnderstand error contains ALL misunderstood header QNames. SOAP nodes MAY generate a fault after the first header block that causes an error containing details about that single header block only, alternatively SOAP nodes MAY generate a combined fault detailing all of the MustUnderstand problems at once.

5 SOAP Protocol Binding Framework

5.1 Introduction

SOAP provides a simple messaging framework with a core set of functionality which is primarily concerned with providing extensibility. The SOAP processing model (2 SOAP Message Exchange Model) describes the behavior of a single SOAP node with respect to the processing of an individual message.

The sending and receiving of SOAP messages by a SOAP node is mediated by a binding to an underlying protocol. A SOAP underlying protocol binding operates between adjacent SOAP nodes along a SOAP message path. A binding does not provide a separate processing model and does not constitute a SOAP node by itself. Rather a SOAP binding is an integral part of a SOAP node. There is no requirement that the same underlying protocol is used for all hops along a SOAP message path.

As part of communicating between SOAP nodes it may be necessary to introduce a variety of abstract features generally associated with the exchange of messages in a protocol environment. Although SOAP poses no constraints on the potential scope of such features, typical examples include "reliability", "security", "correlation", and "routing". In addition, the communication may require message exchange patterns (MEPs) beyond the one-way MEP that SOAP provides. MEPs are considered to be a type of feature; unless otherwise stated, references to the term "feature" apply also to MEPs.

In some cases, underlying protocols are equipped, either directly or through extension, with mechanisms for providing certain features, in whole or in part. Features are the modular components from which the contract between SOAP nodes and the bindings they support are formed. The SOAP binding framework provides a framework for describing these features and how they relate to SOAP nodes. A SOAP binding specification declares the features provided by a binding and describes how the services of the underlying protocol are used to honor the contract formed by the declaration of features supported by that binding. In addition, a binding specification defines the requirements for building a conformant implementation of the binding being specified.

The combination of the SOAP extensibility model and the SOAP binding framework provides some flexibility in the way that particular features can be expressed: they can be expressed entirely within the SOAP envelope (as blocks), outside the envelope (typically in a manner that is specific to the underlying protocol), or as a combination of such expressions. It is up to the communicating nodes to decide how best to express particular features; often when a binding-level implementation for a particular feature is available, utilizing it when appropriate will provide for optimized processing.

Editorial note: HFN20011201
Some discussion continues on how best to represent the balance of responsibility between binding specifications in particular, vs. other software at the SOAP node, when dealing with features that are represented entirely within the SOAP envelope. The paragraph above may need some additional work to clarify

5.2 Goals of the Binding Framework

As described above, SOAP messages can be transported using a variety of underlying protocols. SOAP Part 2: Adjuncts[1] includes the specification for a binding to HTTP. Additional bindings can be created by specifications that conform to the binding framework introduced in this chapter. The goals of the binding framework are:

  1. To set out the requirements and concepts that are common to all binding specifications.

  2. To facilitate homogenous description of bindings that support common features.

  3. To facilitate homogenous description of bindings that support common features.

Note, that the second and third goals above are related: two or more bindings may offer a given optional feature, such as reliable delivery, with one operating using an underlying protocol that directly facilitates the feature (the protocol is reliable), and the other providing the logic (logging and retransmission) in the binding. The feature can be made available to applications in a consistent manner, regardless of which binding is used.

5.3 Binding Framework

The creation, transmission, and processing of a SOAP message, possibly through one or more intermediaries, is specified in terms of a distributed state machine. The state consists of information known to a SOAP node at a given point in time, including but not limited to the contents of messages being assembled for transmission or received for processing. The state at each node can be updated either by local processing, or by information received from an adjacent node.

Section 2 SOAP Message Exchange Model of this specification describes the processing that is common to all SOAP nodes when receiving a message. The purpose of a binding specification is to augment those core SOAP rules with any additional processing that may be particular to the binding, and to specify the manner in which the underlying protocol is used to transmit information between adjacent nodes in the message path.

Thus, the distributed state machine that manages the transmission of a given SOAP message through its message path is the combination of the core SOAP processing (see 2 SOAP Message Exchange Model) operating at each node, in conjunction with the binding specifications connecting each pair of nodes.

As described above, SOAP can be augmented with optional features, (such as reliable message delivery, request/response MEPs, multicast MEPs, etc.). The specification of each such feature MUST include the following:

  1. The information (state) required at each node to implement the feature.

  2. The processing required at each node in order to fulfill the obligations of the feature.

  3. The information transmitted from node to node, and in the case of MEPs, any requirements to generate additional messages (such as responses to requests in a request/response MEP).

Every binding specification MUST support the transmission and processing of one-way messages as described in this specification. A binding specification MAY state that it supports additional features, in which case the binding specification MUST provide for maintaining state, performing processing, and transmitting information in a manner consistent with the specification for those features.

In cases where multiple features are supported by a binding specification the specifications for those features must provide any information necessary for their successful use in combination; this binding framework does not provide any explicit mechanism for ensuring such compatibility of multiple features.

The binding framework provides no fixed means of naming or typing the information comprising the state at a given node. Individual feature and binding specifications are free to adopt their own conventions for specifying state. Note, however, that consistency across bindings and features is likely to be enhanced in situations where multiple feature specifications adopt consistent conventions for representing state. For example, multiple features may benefit from a consistent specification for an authentication credential, the transaction ID, etc. The HTTP binding in SOAP Part 2[1] illustrates one such convention.

As described in 4 SOAP Envelope, each SOAP message is modeled as an XML Infoset that consists of a document information item with exactly one child: the envelope element information item. Therefore, the minimum responsibility of a binding in transmitting a message is to specify the means by which the SOAP XML Infoset is transferred to and reconstituted by the binding at the receiving SOAP node and to specify the manner in which the transmission of the envelope is effected using the facilities of the underlying protocol. The binding framework does NOT require that every binding use the XML 1.0[8] serialization as the "on the wire" representation of the Infoset; compressed, encrypted, fragmented representations and so on can be used if appropriate.

Bindings MAY depend on state that is modeled as being outside of the SOAP XML Infoset (e.g. retry counts), and MAY transmit such information to adjacent nodes. For example, some bindings take a message delivery address (typically URI) that is not within the envelope; the HTTP binding in Part 2[1] (see Using SOAP in HTTP) transmits an HTTP field named SOAPAction that is not contained within the SOAP XML Infoset.

5.4 Binding to Application-Specific Protocols

Some underlying protocols may be designed for a particular purpose or application profile. SOAP bindings to such protocols MAY use the same endpoint identification (e.g., TCP port number) as the underlying protocol, in order to reuse the existing infrastructure associated that protocol.

However, the use of well-known ports by SOAP may incur additional, unintended handling by intermediaries and underlying implementations. For example, HTTP is commonly thought of as a "Web browsing" protocol, and network administrators may place certain restrictions upon its use, or may interpose services such as filtering, content modification, routing, etc. Often, these services are interposed using port number as a heuristic.

As a result, binding definitions for underlying protocols with well-known default ports or application profiles SHOULD document potential (harmful?) interactions with commonly deployed infrastructure at those default ports or in-conformance with default application profiles. Binding definitions SHOULD also illustrate the use of the binding on a non-default port as a means of avoiding unintended interaction with such services.

5.5 Security Considerations

Editorial note: MJG20010926
This section will in a future revision provide some guidelines for the security considerations that should be taken into account when using the binding framework defined in this document.

6 Use of URIs in SOAP

SOAP uses URIs for some identifiers including, but not limited to, values of the encodingStyle (see 4.1.1 SOAP encodingStyle Attribute) and actor (see 4.2.2 SOAP actor Attribute) attribute information items. To SOAP, a URI is simply a formatted string that identifies a web resource via its name, location, or via any other characteristics.

Although this section only applies to URIs directly used by information items defined by this specification, it is RECOMMENDED but NOT REQUIRED that application-defined data carried within a SOAP envelope use the same mechanisms and guidelines defined here for handling URIs.

URIs used as values in information items identified by the "http://www.w3.org/2001/12/soap-envelope" and "http://www.w3.org/2001/12/soap-encoding" XML namespaces can be either relative or absolute. In addition, URIs used as values of the local, unqualified href attribute information item can be relative or absolute.

SOAP does not define a base URI but relies on the mechanisms defined in XML Base[11] and RFC 2396[6] for establishing a base URI against which relative URIs can be made absolute.

The underlying protocol binding MAY define a base URI which can act as the base URI for the SOAP envelope (see 5 SOAP Protocol Binding Framework and the HTTP binding[1]).

SOAP does not define any equivalence rules for URIs in general as these are defined by the individual URI schemes and by RFC 2396[6]. However, because of inconsistencies with respect to URI equivalence rules in many current URI parsers, it is RECOMMENDED that SOAP senders do NOT rely on any special equivalence rules in SOAP receivers in order to determine equivalence between URI values used in a SOAP message.

The use of IP addresses in URIs SHOULD be avoided whenever possible (see RFC 1900[16]). However, when used, the literal format for IPv6 addresses in URI's as described by RFC 2732[12] SHOULD be supported.

SOAP does not place any a priori limit on the length of a URI. Any SOAP node MUST be able to handle the length of any URI that it publishes and both SOAP senders and SOAP receivers SHOULD be able to deal with URIs of at least 8k in length.

7 References

7.1 Normative References

W3C Working Draft "SOAP Version 1.2 Part 2: Adjuncts", Martin Gudgin, Marc Hadley, Jean-Jacques Moreau, Henrik Frystyk Nielsen, 2 10 2001 (See http://www.w3.org/TR/2001/WD-soap12-part2-20011217/.)
IETF "RFC 2616: Hypertext Transfer Protocol -- HTTP/1.1", R. Fielding, J. Gettys, J. C. Mogul, H. Frystyk, T. Berners-Lee, January 1997. (See http://www.ietf.org/rfc/rfc2616.txt.)
IETF "RFC 2119: Key words for use in RFCs to Indicate Requirement Levels", S. Bradner, March 1997. (See http://www.ietf.org/rfc/rfc2119.txt.)
W3C Recommendation "XML Schema Part 1: Structures", Henry S. Thompson, David Beech, Murray Maloney, Noah Mendelsohn, 2 May 2001. (See http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/.)
W3C Recommendation "XML Schema Part 2: Datatypes", Paul V. Biron, Ashok Malhotra, 2 May 2001. (See http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/.)
IETF "RFC 2396: Uniform Resource Identifiers (URI): Generic Syntax", T. Berners-Lee, R. Fielding, L. Masinter, August 1998. (See http://www.ietf.org/rfc/rfc2396.txt.)
W3C Recommendation "Namespaces in XML", Tim Bray, Dave Hollander, Andrew Layman, 14 January 1999. (See http://www.w3.org/TR/1999/REC-xml-names-19990114/.)
W3C Recommendation "Extensible Markup Language (XML) 1.0 (Second Edition)", Tim Bray, Jean Paoli, C. M. Sperberg-McQueen, Eve Maler, 6 October 2000. (See http://www.w3.org/TR/2000/REC-xml-20001006.)
W3C Recommendation "XML Linking Language (XLink) Version 1.0", Steve DeRose, Eve Maler, David Orchard, 27 June 2001. (See http://www.w3.org/TR/2001/REC-xlink-20010627/.)
W3C Recommendation "XML Information Set", John Cowan, Richard Tobin, 24 October 2001. (See http://www.w3.org/TR/2001/REC-xml-infoset-20011024/.)
W3C Recommendation "XML Base", Johnathan Marsh, 27 June 2001. (See http://www.w3.org/TR/2001/REC-xmlbase-20010627/.)
IETF "RFC 2732: Format for Literal IPv6 Addresses in URL's", R. Hinden, B. Carpenter, L. Masinter, December 1999. (See http://www.ietf.org/rfc/rfc2732.txt.)

7.2 Informative References

XML Protocol Comments Archive (See http://lists.w3.org/Archives/Public/xmlp-comments/.)
XML Protocol Discussion Archive (See http://lists.w3.org/Archives/Public/xml-dist-app/.)
XML Protocol Charter (See http://www.w3.org/2000/09/XML-Protocol-Charter.)
W3C Note "Simple Object Access Protocol (SOAP) 1.1", Don Box, David Ehnebuske, Gopal Kakivaya, Andrew Layman, Noah Mendelsohn, Henrik Nielsen, Satish Thatte, Dave Winer, 8 May 2000. (See http://www.w3.org/TR/SOAP/.)
IETF "RFC 1900: Renumbering Needs Work", B. Carpenter, Y. Rekhter, February 1996. (See http://www.ietf.org/rfc/rfc1900.txt.)

A Version Transition From SOAP/1.1 to SOAP Version 1.2

The SOAP/1.1 specification[15] says the following on versioning in section 4.1.2:

"SOAP does not define a traditional versioning model based on major and minor version numbers. A SOAP message MUST have an Envelope element associated with the "http://schemas.xmlsoap.org/soap/envelope/" namespace. If a message is received by a SOAP application in which the SOAP Envelope element is associated with a different namespace, the application MUST treat this as a version error and discard the message. If the message is received through a request/response protocol such as HTTP, the application MUST respond with a SOAP VersionMismatch faultcode message (see section 4.4) using the SOAP "http://schemas.xmlsoap.org/soap/envelope/" namespace."

That is, rather than a versioning model based on shortnames (typically version numbers), SOAP uses a declarative extension model which allows a sender to include the desired features within the SOAP envelope construct. SOAP says nothing about the granularity of extensions nor how extensions may or may not affect the basic SOAP processing model. It is entirely up to extension designers be it either in a central or a decentralized manner to determine which features become SOAP extensions.

The SOAP extensibility model is based on the following three basic assumptions:

  1. SOAP versioning is directed only at the SOAP envelope. It explicitly does not address versioning of blocks, encodings, protocol bindings, or otherwise.

  2. A SOAP node must determine whether it supports the version of a SOAP message on a per message basis. In the following, "support" means understanding the semantics of the envelope version identified by the QName of the Envelope element information item:

    • A SOAP node receiving an envelope that it doesn't support must not attempt to process the message according to any other processing rules regardless of other up- or downstream SOAP nodes.

    • A SOAP node may provide support for multiple envelope versions. However, when processing a message a SOAP node must use the semantics defined by the version of that message.

  3. It is essential that the envelope remains stable over time and that new features are added using the SOAP extensibility mechanism. Changing the envelope inherently affects interoperability, adds complexity, and requires central control of extensions -- all of which directly conflicts with the SOAP requirements.

The rules for dealing with the possible SOAP/1.1 and SOAP Version 1.2 interactions are as follows:

  1. Because of the SOAP/1.1 rules, a compliant SOAP/1.1 node receiving a SOAP Version 1.2 message will generate a VersionMismatch SOAP fault using an envelope qualified by the "http://schemas.xmlsoap.org/soap/envelope/" namespace identifier.

  2. A SOAP Version 1.2 node receiving a SOAP/1.1 message may either process the message as SOAP/1.1 or generate a SOAP VersionMismatch fault using the "http://schemas.xmlsoap.org/soap/envelope/" namespace identifier. As part of the SOAP VersionMismatch fault, a SOAP Version 1.2 node should include the list of envelope versions that it supports using the SOAP upgrade extension identified by the "http://www.w3.org/2001/12/soap-upgrade" identifier.

The upgrade extension consists of an Upgrade element information item.

The Upgrade element information item contains an ordered list of namespace identifiers of SOAP envelopes that the SOAP node supports in the order most to least preferred

The Upgrade element information item has:

The envelope element information item has:

The value of the qname attribute information item specifies the qualified name of an element that the SOAP node accepts as the top-level element of a SOAP message

Following is an example of a VersionMismatch fault generated by a SOAP Version 1.2 node including the SOAP upgrade extension:

Example: VersionMismatch fault generated by a SOAP Version 1.2 node, and including a SOAP upgrade extension
<?xml version="1.0" ?>
<env:Envelope xmlns:env="http://schemas.xmlsoap.org/soap/envelope/">
    <V:Upgrade xmlns:V="http://www.w3.org/2001/12/soap-upgrade">
      <envelope qname="ns1:Envelope" xmlns:ns1="http://www.w3.org/2001/12/soap-envelope"/>
      <faultstring>Version Mismatch</faultstring>

The following is an example of some future SOAP node which returns multiple envelope elements in the Upgrade element. This SOAP node prefers the Envelope element in the "http://www.example.org/2002/10/soap-envelope" namespace but will also accept the Envelope element in the "http://www.w3.org/2001/12/soap-envelope" namespace

Example: VersionMismatch fault generated by some future SOAP node, and including a SOAP upgrade extension with multiple envelope elements
<?xml version="1.0" ?>
<env:Envelope xmlns:env="http://schemas.xmlsoap.org/soap/envelope/">
    <V:Upgrade xmlns:V="http://www.w3.org/2001/12/soap-upgrade">
      <envelope qname="ns1:Envelope" xmlns:ns1="http://www.example.org/2002/10/soap-envelope"/>
      <envelope qname="ns2:Envelope" xmlns:ns2="http://www.w3.org/2001/12/soap-envelope"/>
      <faultstring>Version Mismatch</faultstring>

Note that existing SOAP/1.1 nodes are not likely to indicate which envelope versions they support. If nothing is indicated then this means that SOAP/1.1 is the only supported envelope.

B Acknowledgements (Non-Normative)

This document is the work of the W3C XML Protocol Working Group.

Members of the Working Group are (at the time of writing, and by alphabetical order): Yasser al Safadi (Philips Research), Vidur Apparao (Netscape), Don Box (DevelopMentor), Charles Campbell (Informix Software), Michael Champion (Software AG), Dave Cleary (webMethods), Ugo Corda (Xerox), Paul Cotton (Microsoft Corporation), Ron Daniel (Interwoven), Glen Daniels (Allaire), Doug Davis (IBM), Ray Denenberg (Library of Congress), Paul Denning (MITRE Corporation), Frank DeRose (TIBCO Software, Inc.), James Falek (TIBCO Software, Inc.), David Fallside (IBM), Chris Ferris (Sun Microsystems), Daniela Florescu (Propel), Dietmar Gaertner (Software AG), Rich Greenfield (Library of Congress), Martin Gudgin (DevelopMentor), Hugo Haas (W3C), Marc Hadley (Sun Microsystems), Mark Hale (Interwoven), Randy Hall (Intel), Gerd Hoelzing (SAP AG), Oisin Hurley (IONA Technologies), Yin-Leng Husband (Compaq), John Ibbotson (IBM), Ryuji Inoue (Matsushita Electric Industrial Co., Ltd.), Scott Isaacson (Novell, Inc.), Kazunori Iwasa (Fujitsu Software Corporation), Murali Janakiraman (Rogue Wave), Mario Jeckle (Daimler-Chrysler Research and Technology), Eric Jenkins (Engenia Software), Mark Jones (AT&T), Anish Karmarkar (Oracle), Jeffrey Kay (Engenia Software), Richard Koo (Vitria Technology Inc.), Jacek Kopecky (IDOOX s.r.o.), Yves Lafon (W3C), Tony Lee (Vitria Technology Inc.), Michah Lerner (AT&T), Henry Lowe (OMG), Richard Martin (Active Data Exchange), Noah Mendelsohn (Lotus Development), Jeff Mischkinsky (Oracle), Nilo Mitra (Ericsson Research Canada), Jean-Jacques Moreau (Canon), Highland Mary Mountain (Intel), Masahiko Narita (Fujitsu Software Corporation), Mark Needleman (Data Research Associates), Eric Newcomer (IONA Technologies), Henrik Frystyk Nielsen (Microsoft Corporation), Mark Nottingham (Akamai Technologies), David Orchard (BEA Systems), Kevin Perkins (Compaq), Jags Ramnaryan (BEA Systems), Andreas Riegg (Daimler-Chrysler Research and Technology), Herve Ruellan (Canon), Marwan Sabbouh (MITRE Corporation), Shane Sesta (Active Data Exchange), Miroslav Simek (IDOOX s.r.o.), Simeon Simeonov (Allaire), Nick Smilonich (Unisys), Soumitro Tagore (Informix Software), Lynne Thompson (Unisys), Patrick Thompson (Rogue Wave), Asir Vedamuthu (webMethods) Ray Whitmer (Netscape), Volker Wiechers (SAP AG), Stuart Williams (Hewlett-Packard), Amr Yassin (Philips Research) and Jin Yu (Martsoft Corp.).

Previous members were: Eric Fedok (Active Data Exchange), Susan Yee (Active Data Exchange), Dan Frantz (BEA Systems), Alex Ceponkus (Bowstreet), James Tauber (Bowstreet), Rekha Nagarajan (Calico Commerce), Mary Holstege (Calico Commerce), Krishna Sankar (Cisco Systems), David Burdett (Commerce One), Murray Maloney (Commerce One), Jay Kasi (Commerce One), Yan Xu (DataChannel), Brian Eisenberg (DataChannel), Mike Dierken (DataChannel), Michael Freeman (Engenia Software), Bjoern Heckel (Epicentric), Dean Moses (Epicentric), Julian Kumar (Epicentric), Miles Chaston (Epicentric), Alan Kropp (Epicentric), Scott Golubock (Epicentric), Michael Freeman (Engenia Software), Jim Hughes (Fujitsu Limited), Dick Brooks (Group 8760), David Ezell (Hewlett Packard), Fransisco Cubera (IBM), David Orchard (Jamcracker), Alex Milowski (Lexica), Steve Hole (MessagingDirect Ltd.), John-Paul Sicotte (MessagingDirect Ltd.), Vilhelm Rosenqvist (NCR), Lew Shannon (NCR), Art Nevarez (Novell, Inc.), David Clay (Oracle), Jim Trezzo (Oracle), David Cleary (Progress Software), Andrew Eisenberg (Progress Software), Peter Lecuyer (Progress Software), Ed Mooney (Sun Microsystems), Mark Baker (Sun Microsystems), Anne Thomas Manes (Sun Microsystems), George Scott (Tradia Inc.), Erin Hoffmann (Tradia Inc.), Conleth O'Connell (Vignette), Waqar Sadiq (Vitria Technology Inc.), Randy Waldrop (WebMethods), Bill Anderson (Xerox), Tom Breuel (Xerox), Matthew MacKenzie (XMLGlobal Technologies), David Webber (XMLGlobal Technologies), John Evdemon (XMLSolutions) and Kevin Mitchell (XMLSolutions).

The people who have contributed to discussions on xml-dist-app@w3.org are also gratefully acknowledged.

C Part 1 Change Log (Non-Normative)

C.1 SOAP Specification Changes

Date Author Description
20011213MJHUpdated namespace URIs, fixed spelling error.
20011211MJHAdded section headings for faultcode, faultstring, faultactor and detail elements.
20011211MJHFixed a number of spelling errors and grammatical problems throughout the document. Applied some limited rewording to improve readability.
20011211MJHRemoved duplicate description of "must happen" extension from section 2.
20011206MJHRemoved more mentions of body blocks.
20011206MJHLimited rewording and removal of duplication from section 2. In particular, removed namespace definition for mU and actor (this is in section 4) and massaged text in processing model to remove duplication and improve readability.
20011206MJHIncorporated Chris Ferris suggested changes to glossary and section 2.
20011206MJHGeneral editorial work on new sections. Added references and other tagging as required.
20011206MJHIncorporated agreed changes to URIs in SOAP section (remove duplication with XML base and cite XML base more strongly).
20011206MJHIncorporated issue 155 resolution.
20011205JJMElevated the header removal step to a processing model step.
20011204MJHAdded bibref to Use of URIs section and tidied up the language in that section.
20011204MJHModified soapEncoding descriptive text - Issues 159 and 166.
20011204JJMAdded text to section 2.2, second paragraph, to indicate none blocks may carry data for processing of other blocks.
20011204JJMSection 2.2, four paragraph, added "anonymous actor" to the list.
20011204JJMSection 2.3, remove text for SOAP body blocks.
20011204JJMSection 2.3, replace "has assumed the role of the anonymous actor" by "is the ultimate receiver".
20011204JJMSection 2.4, incorporated 2 paragraph previously in section 2.
20011204JJMAdded section 2.5 (text from Noah).
20011204JJMAdded an extra step to the processing model (now section 2.6).
20011204JJMSimplified step 3, and moved the previous text further below in the same section (2.6).
20011204JJMSection 2.6, incorporated text from section 4.
20011204JJMSection 4.2.2, removed explanation of next and none roles.
20011204JJMSection 4.2.2, added text to indicate the meaning of an empty actor attribute.
20011204JJMTrimmed section 4.2.3, as the text is now in section 2.
20011204JJMRemoved section 4.3.1, since body processing is now in section 2.6.
20011204JJMAdded ednote to flag the definition for SOAP block is out of date.
20011204JJMReformated section 5 (Binding Framework).
20011204JJMReformated section 6 (Use of URIs in SOAP). Removed non ASCII characters.
20011204JJMAdded missing "att" and "attval" around elements and attributes in section 6.
20011204JJMFixed a number of lax references in section 6.
20011201HFNAdded SOAP Protocol Binding Framework
20011201HFNAdded section on URIs and XML Base
2001129MJGIncorporated resolution text for Issue 146 into Section 2.3
2001129MJGChanged "Client" and "Server" fault codes to be "Sender" and "Receiver" respectively as resolution of Issue 143
2001129MJGRemoved dot notation from spec. Added "DTDNotSupported" fault code to fault code table.
20011122MJHIncorporated resolution to issue 172 (criteria for generating version mismatch fault into 4.1.2 Envelope Versioning Model. Removed duplication of versioning error text and associated ednote from 3 Relation to XML
20011029MJHChanged "default actor" to "anonymous actor".
20011029MJHAmended relation to XML section (Issue 135).
20011029MJHAmended section 2.5 (Issue 157).
20011029MJHRemoved citation of ABNF - not used in part 1.
20011029MJHAmended section 1.3 (Issue 150)
20011029MJHAmended section 1.1 (Issue 149)
20011029MJHAmended introductory text (Issue 148)
20011029MJHAmended introductory text (Issue 147)
20011029MJHAmended abstract (Issue 147)
20011026 MJG Amended text in Section 2.5 bullet 2 ( Issue 158 )
20011026 MJG Amended text in Section 2.4 para 2 ( Issue 156 )
20011026 MJG Amended text in Section 2.1 para 2 ( Issue 152 )
20011026 MJG Amended prose related to DTDs and PIs ( Issue 4 )
20011026 MJG Added text to state that SOAP is no longer an acronym ( Issue 125 )
20011026 MJG Amended description of Upgrade extension in Appendix A to be Infoset based.
20011026 MJG Added an example of returning multiple versions in the VersionMismatch header to Appendix A ( Issue 119 )
20011026 MJG Added definition of SOAP Application to glossary ( Issue 139 )
20011026 MJG Added xml declaration to all XML examples with a root of env:Envelope or xs:schema ( Issue 10 )
20011025 MJG Changed MAY to MUST regarding namespace qualification of SOAP body blocks ( Issue 141 )
20011011 MJG Added para to section 2.2 on criteria ( or lack thereof ) for determining whether a SOAP node acts as a particular actor
20010926 MJG Updated member list
20010926 MJG Removed extra double quotes around certain URLs
20010921 MJG Changed targetNamespace attribute of faults schema to http://www.w3.org/2001/09/soap-faults
20010921 MJG Changed targetNamespace attribute of upgrade schema to http://www.w3.org/2001/09/soap-upgrade
20010921 MJG Changed targetNamespace attribute of envelope schema to http://www.w3.org/2001/09/soap-envelope
20010921 MJG Modified content model of Envelope complex type in envelope schema to disallow content after the Body element.
20010920 JJM Included MarkN's text regarding issue 11 and 13 as amended by Stuart in the specification and expand the ednote appropriately.
20010920 JJM Change the namespace of the envelope to http://www.w3.org/2001/09/...
20010918 JJM Incorporated several editorial comments from Stuart Williams.
20010918 JJM Removed reference to trailer from the "SOAP Envelope" section.
20010914 JJM Fixed issues 124, 126, 127, 128 and 132.
20010914 JJM Used the rewrite from Mark Nottingham for section "SOAPAction attribute".
20010914 JJM Incoporated text from Mark Nottingham clarifying the role of none blocks.
20010914 JJM Reference the XML InfoSet Proposed Recommandation instead of the Candidate Recommandation.
20010911 JJM Changed XML Information Set into a normative reference. Changed XML Protocol Comments Archive, Discussion Archive and Charter into non-normative references. Removed "as illustrated above" from section 2. Added missing parantheses in sections 2.5 and 4.1.1.
20010905 MJH Wordsmithed abstract and introduction to better reflect split into parts 1 and 2. Rationalised list of references so only cited works appear. Removed encoding schema changes. Added bibref entries for cross references to Part 2, fixed links so they target the HTML instead of XML version of the doc.
20010831 JJM Added a close paragraph tag before starting a new olist or ulist.
20010831 JJM Properly declared the language for the spec, so that we can generate valid HTML.
20010830 MJG Added an element declaration for a Fault element of type Fault to the envelope schema
20010830 JJM Removed terminology not relevant for part1.
20010830 JJM Moved some introductory examples to part2.
20010830 JJM Moved SOAP example appendix to part2.
20010830 JJM Added a paragraph to section 1 pointing to part2 for encoding, rpc and http binding.
20010829 JJM Added a placeholder for the forthcoming Transport Binding Framework section.
20010829 JJM Updated the spec's title.
20010829 JJM Replaced specref with xspecref for references to Part2 items.
20010829 JJM Added bibliography entry for SOAP 1.2 Part 2.
20010829 JJM Removed former sections 5, 6, 7 and 8.
20010829 JJM Did split the spec into two parts.
20010829 JJM Refered to the proper DTD and stylesheet.
20010829 JJM Updated the list of WG members: one person per line in the XML file, for easier updating.
20010816 MJH Replaced a mustUnderstand="1" with mustUnderstand="true". Slight rewording in mu description.
20010810 MJH Merged in RPC fault rules text from Jacek. Added new DataEncodingUnknown fault code to SOAP Fault Codes section. Added editorial notes about introduction of new fault code namespace for RPC.
20010809 MJH Merged in "mustHappen" descriptive text from Glen and Noah.
20010809 MJH Fixed language around "default" values of attributes.
20010809 MJH Removed HTTP extension framework, added editorial note to describe why.
20010808 MJH Added Infoset "specified" property text from Chris.
20010808 MJH Removed assumption 4 from version transition appendix.
20010808 MJH Added reference to SOAP 1.1 specification to references section, removed SOAP 1.1 author list from acknowledgments section.
20010807 MJH Converted specification from HTML to XML conforming to W3C XMLSpec DTD. Numerous resulting formatting changes.
20010720 MJG Applied Infoset terminology to sections 1, 2, 3 and 4.
20010629 MJG Amended description of routing and intermediaries in Section 2.1
20010629 JJM Changed "latest version" URI to end with soap12 
20010629 JJM Remove "previous version" URI
20010629 JJM Removed "Editor copy" in <title>
20010629 JJM Removed "Editor copy" in the title.
20010629 JJM Added "Previous version" to either point to SOAP/1.1, or explicitly mention there was no prior draft.
20010629 JJM Pre-filed publication URIs.
20010629 JJM Incorporated David's suggested changes for the examples in section 4.1.1 to 4.4.2
20010629 JJM Fixed some remaining typos.
20010629 MJH Fixed a couple of typos.
20010628 MJG Made various formatting, spelling and grammatical fixes.
20010628 MJG Moved soap:encodingStyle from soap:Envelope to children of soap:Header/soap:Body in examples 1, 2, 47, 48, 49 and 50
20010628 MJG Changed text in Section 2.1 from 'it is both a SOAP sender or a SOAP receiver' to 'it is both a SOAP sender and a SOAP receiver'
20010628 MJG Fixed caption on Example 24
20010628 MJH Fixed a couple of capitalisation errors where the letter A appeared as a capital in the middle of a sentence.
20010628 MJH Updated figure 1, removed ednote to do so.
20010622 HFN Removed the introductory text in terminology section 1.4.3 as it talks about model stuff that is covered in section 2. It was left over from original glossary which also explained the SOAP model.
20010622 HFN Moved the definition of block to encapsulation section in terminology
20010622 HFN Removed introductory section in 1.4.1 as this overlaps with the model description in section 2 and doesn't belong in a terminology section
20010622 HFN Removed reference to "Web Characterization Terminology & Definitions Sheet" in terminology section as this is not an active WD
20010622 HFN Added revised glossary
20010622 HFN Added example 0 to section 1.3 and slightly modified text for example 1 and 2 to make it clear that HTTP is used as a protocol binding
20010622 MJG Added http://example.com/... to list of application/context specific URIs in section 1.2
20010622 MJG Updated examples in section 4.1.1 to be encodingStyle attributes rather than just the values of attributes
20010622 MJG Added table.norm, td.normitem and td.normtext styles to stylesheet. Used said styles for table of fault code values in section 4.4.1
20010622 MJG In Appendix C, changed upgrade element to Upgrade and env to envelope. Made envelope unqualified. Updated schema document to match.
20010622 MJG Moved MisunderstoodHeader from envelope schema into seperate faults schema. Removed entry in envelope schema change table in Appendix D.2 that refered to additon of said element. Modified example in section 4.4.2 to match. Added reference to schema document to section 4.4.2
20010622 MJH Added binding as a component of SOAP in introduction. Fixed a couple of typos and updated a couple of example captions.
20010622 MJG Made BNF in section 6.1.1 into a table.
20010622 MJG Made BNFs in section 5.1 clause 8 into tables. Added associated 'bnf' style for table and td elements to stylesheet
20010622 MJG Amended text regarding namespace prefix mappings in section 1.2
20010622 MJG Added link to schema for the http://www.w3.org/2001/06/soap-upgrade namespace to Appendix C. Updated associated ednote.
20010622 MJG Added reference numbers for XML Schema Recommendation to text prior to schema change tables in Appendix D.2 and linked said numbers to local references in this document
20010622 MJG Reordered entries in schema change classification table in Appendix D.2
20010622 MJG Changed type of mustUnderstand and root attributes to standard boolean and updated schema change tables in Appendix D.2 accordingly
20010622 JJM Manually numbered all the examples (53 in total!)
20010622 JJM Added caption text to all the examples
20010622 JJM Replaced remaining occurrences of SOAP/1.2 with SOAP Version 1.2 (including <title>)
20010621 HFN Added ednote to section 4.2.2 and 4.2.3 that we know they have to be incorporated with section 2
20010621 HFN Added version transition appendix C
20010621 HFN Applied new styles to examples
20010621 HFN Changed term "transport" to "underlying protocol
20010621 HFN Changed example URNs to URLs of the style http://example.org/...
20010621 MJH Updated the Acknowledgements section.
20010621 JJM Added new style sheet definitions (from XML Schema) for examples, and used them for example 1 and 2.
20010621 JJM Incorporated David Fallside's comments on section Status and Intro sections.
20010620 HFN Changed the status section
20010620 HFN Changed title to SOAP Version 1.2 and used that first time in abstract and in body
20010620 HFN Removed question from section 2.4 as this is an issue and is to be listed in the issues list
20010620 HFN Moved change log to appendix
20010615 JJM Renamed default actor to anonymous actor for now (to be consistent)
20010615 JJM Fixed typos in section 2
20010614 JJM Updated section 2 to adopt the terminology used elsewhere in the spec.
20010613 MJH Updated mustUnderstand fault text with additions from Martin Gudgin.
20010613 MJH Added schema changes appendix from Martin Gudgin.
20010613 MJH Added mustUnderstand fault text from Glen Daniels.
20010612 MJH Fixed document <title>.
20010612 MJH Moved terminology subsection from message exchange model section to introduction section.
20010612 MJH Fixed capitalisation errors by replacing "... A SOAP ..." with "... a SOAP ..." where appropriate.
20010612 MJH Removed trailing "/" from encoding namespace URI.
20010612 MJH Fixed links under namespace URIs to point to W3C space instead of schemas.xmlsoap.org.
20010612 MJH Removed some odd additional links with text of "/" pointing to the encoding schema following the text of the encoding namespace URI in several places.
20010611 MJH Incorporated new text for section 2.
20010611 JJM Changed remaining namespaces, in particular next.
20010609 JJM Changed the spec name from XMLP/SOAP to SOAP.
20010609 JJM Changed the version number from 1.1 to 1.2.
20010609 JJM Changed the namespaces from http://schemas.xmlsoap.org/soap/ to http://www.w3.org/2001/06/soap-.
20010609 JJM Replaced the remaining XS and XE prefixes to env and enc, respectively.
20010601 MJH Updated the examples in section 1, 6 and appendix A with text suggested by Martin Gudgin to comply with XML Schema Recommendation.
20010601 JJM Updated the examples in section 4 and 5 with text suggested by Martin Gudgin, to comply with XML Schema Recommendation.
20010531 HFN Removed appendices C and D and added links to live issues list and separate schema files.
20010531 MJH Added this change log and updated schemas in appendix C to comply with XML Schema Recommendation.

C.2 XML Schema Changes

The envelope schema has been updated to be compliant with the XML Schema Recomendation[4][5]. The table below shows the categories of change.

Class Meaning
Addition New constructs have been added to the schema
Clarification The meaning of the schema has been changed to more accurately match the specification
Deletion Constructs have been removed from the schema
Name The schema has been changed due to a datatype name change in the XML Schema specification
Namespace A namespace name has been changed
Semantic The meaning of the schema has been changed
Style Style changes have been made to the schema
Syntax The syntax of the schema has been updated due to changes in the XML Schema specification

The table below lists the changes to the envelope schema.

Class Description
Namespace Updated to use the http://www.w3.org/2001/XMLSchema namespace
Namespace Value of targetNamespace attribute changed to http://www.w3.org/2001/06/soap-envelope
Clarification Changed element and attribute wildcards in Envelope complex type to namespace="##other"
Clarification Changed element and attribute wildcards in Header complex type to namespace="##other"
Clarification Added explicit namespace="##any" to element and attribute wildcards in Body complex type
Clarification Added explicit namespace="##any" to element and attribute wildcards in detail complex type
Clarification Added an element wildcard with namespace="##other" to the Fault complex type
Name Changed item type of encodingStyle from uri-reference to anyURI
Name Changed type of actor attribute from uri-reference to anyURI
Name Changed type of faultactor attribute from uri-reference to anyURI
Semantic Added processContents="lax" to all element and attribute wildcards
Semantic Changed type of the mustUnderstand attribute from restriction of boolean that only allowed 0 or 1 as lexical values to the standard boolean in the http://www.w3.org/2001/XMLSchema namespace. The lexical forms 0, 1, false, true are now allowed.
Style Where possible comments have been changed into annotations
Syntax Changed all occurences of maxOccurs="*" to maxOccurs="unbounded"
Syntax Added <xs:sequence> to all complex type definitions derived implicitly from the ur-type
Syntax Added <xs:sequence> to all named model group definitions

In addition several changes occured in the names of datatypes in the XML Schema specification and some datatypes were removed. The following table lists those changes.

Datatype Class Description
timeDuration Renamed New name is duration
timeInstant Renamed New name is dateTime
recurringDuration Removed The recurringDuration datatype no longer exists.
recurringInstant Removed The recurringInstant datatype no longer exists.
binary Removed The binary datatype has been replaced by the hexBinary and base64Binary datatypes.
month Renamed New name is gYearMonth
timePeriod Removed The timePeriod datatype no longer exists
year Renamed New name is gYear
century Removed The century datatype no longer exists
recurringDate Renamed New name is gMonthDay
recurringDay Renamed New name is gDay