SOAP Version 1.2 Part 1: Messaging Framework

Editors copy Mar 23 2002

This version:
soap12-part1.html
Latest version:
http://www.w3.org/TR/soap12-part1/
Previous versions:
http://www.w3.org/TR/2001/WD-soap12-part1-20011002/
Editors:
Martin Gudgin, DevelopMentor
Marc Hadley, Sun Microsystems
Jean-Jacques Moreau, Canon
Henrik Frystyk Nielsen, Microsoft

Abstract

SOAP Version 1.2 is a lightweight protocol intended for exchange of structured information in a decentralized, distributed environment. It defines an extensible messaging framework that contains a message construct based on XML technologies that can be exchanged over a variety of underlying protocols. The SOAP specification is split into two parts: Part 1 (this document) defines the SOAP messaging framework consisting of the SOAP message construct, the SOAP processing model, and the SOAP underlying protocol binding framework. Part 2 [1] defines a set of adjuncts that may be used with the SOAP messaging framework. Adjuncts include a set of encoding rules for expressing instances of application-defined data types and a convention for representing remote procedure calls and responses.

Status of this Document

This document is an editors' copy that has no official standing.

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 fourth 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 Web Services 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] under 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 "works 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 Notational Conventions
1.2 Relation to other XML Specifications
1.3 Processing Requirements
1.4 Robustness Principle
1.5 Example of SOAP Message
1.6 SOAP Terminology
1.6.1 Protocol Concepts
1.6.2 Data Encapsulation Concepts
1.6.3 Message Sender and Receiver Concepts
2 SOAP Processing Model
2.1 SOAP Nodes
2.2 SOAP Roles 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
2.7 Relaying SOAP Messages
2.7.1 SOAP Intermediaries
2.7.2 Forwarding Intermediaries
2.7.3 Active Intermediaries
2.8 SOAP Versioning Model
3 SOAP Extensibility Model
4 SOAP Protocol Binding Framework
4.1 Goals of the Binding Framework
4.2 Binding Framework
5 SOAP Message Construct
5.1 SOAP Envelope
5.1.1 SOAP encodingStyle Attribute
5.2 SOAP Header
5.2.1 Use of Header Attributes
5.2.2 SOAP role Attribute
5.2.3 SOAP mustUnderstand Attribute
5.3 SOAP Body
5.4 SOAP Fault
5.4.1 SOAP faultcode Element
5.4.2 SOAP faultstring Element
5.4.3 SOAP faultactor Element
5.4.4 SOAP faultrole Element
5.4.5 SOAP detail Element
5.4.6 SOAP Fault Codes
5.4.7 VersionMismatch Faults
5.4.8 Must Understand Faults
6 Use of URIs in SOAP
7 Security Considerations
7.1 SOAP Nodes
7.2 SOAP Intermediaries
7.3 Underlying Protocol Bindings
7.3.1 Binding to Application-Specific Protocols
8 References
8.1 Normative References
8.2 Informative References

Appendices

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 (SOAP) is a lightweight protocol intended for exchange of structured information between peers in a decentralized, distributed environment. It defines an extensible messaging framework that contains a message construct based on XML technologies that can be exchanged over a variety of underlying protocols. The framework has been designed to be independent of any particular programming model and other implementation specific semantics.

Note:

In previous versions of this specification the SOAP name was an acronym. This is no longer the case.

Two major design goals for SOAP are simplicity and extensibility (see XMLP Requirements [16]). SOAP attempts to meet these goals by omitting features often found in distributed systems from the messaging framework and rather leave them to be defined as extensions. Such features include but are not limited to "reliability", "security", "correlation", "routing", and the concept of message exchange patterns. While it is anticipated that many such features will be defined, it is beyond the scope of this specification to do so.

The SOAP specification is divided into two parts. Part 1 of the SOAP specification (this document) defines the SOAP messaging framework consisting of:

  1. The SOAP processing model defining the rules for processing a SOAP message (see 2 SOAP Processing Model).

  2. The SOAP message construct defining the structure of a SOAP message (see 5 SOAP Message Construct).

  3. The SOAP underlying protocol binding framework describing the rules for defining a binding to an underlying protocol that can be used for exchanging SOAP messages between SOAP nodes (see 4 SOAP Protocol Binding Framework).

Part 2 [1] describes a set of adjuncts that may be used in connection with the SOAP messaging framework: a graph-based data model (SOAP Data Model) and corresponding encoding rules (SOAP Encoding) for exchanging instances of application-defined data; a convention for representing remote procedure calls and responses (SOAP RPC Representation); and a binding to HTTP (SOAP HTTP Binding) using the protocol binding framework.

1.1 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 RFC 2119 [3].

As a convention, the namespace prefix "env" used in the prose sections of this document is associated with the SOAP namespace name "http://www.w3.org/2001/12/soap-envelope". Note that the choice of any namespace prefix is arbitrary and not semantically significant (see [10]).

A normative XML Schema [4], [5] document for the "http://www.w3.org/2001/12/soap-envelope" namespace can be found at http://www.w3.org/2001/12/soap-envelope.

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

With the exception of examples and sections explicitly marked as "Non-Normative", all parts of this specification are normative.

1.2 Relation to other XML Specifications

A SOAP message is specified as an XML Information Set [10]. While all SOAP message examples in this document are shown using XML 1.0 [8] this is not a requirement of SOAP (see 4 SOAP Protocol Binding Framework).

All information items defined by this document are identified using XML namespace names [7] (see 5 SOAP Message Construct). In particular, this document defines the following namespace names:

Normative XML Schema [4], [5] documents for these namespace names can be found by dereferencing the namespace names above.

SOAP does not require any XML schema processing (assessment or validation) in order to establish the values or correctness of element and attribute information items defined by this specification. These information items must, unless stated otherwise, be carried explicitly in the transmitted SOAP message (see 5 SOAP Message Construct).

SOAP attribute information items have types described by XML Schema: Datatypes [5]. E.g. the mustUnderstandattribute information item is a boolean. Unless otherwise stated, all lexical forms are supported for each such attribute, and lexical forms representing the same value in the XML Schema value space are considered equivalent for purposes of SOAP processing. E.g. the boolean lexical forms "1" and "true" are interchangeable (see 1.4 Robustness Principle). For brevity, text in this specification refers only to one lexical form for each value, e.g. "if the value of the mustUnderstandattribute information item is "true"".

Specifications for the processing of application-defined data carried in a SOAP message but not defined by this specification may but NEED NOT call for additional validation of the SOAP message in conjunction with application-level processing. In such cases, the choice of schema language and/or validation technology is at the discretion of the application.

SOAP uses XML Base [11] for determining a base URI for relative URI references used as values in information items defined by this specification (see 6 Use of URIs in SOAP).

1.3 Processing Requirements

The ability to use SOAP in a particular environment will vary by the actual constraints, choice of tools, processing model, and nature of the messages being exchanged.

The XML encoding of SOAP has dependencies on a relatively small number of other specifications, none of which has prohibitive processing requirements. Also, limiting use of SOAP to small messages instead of arbitrarily-sized messages and using a few specific message types instead of implementing generalized SOAP encoding could significantly lower processing requirements.

1.4 Robustness Principle

The use of XML technologies leaves in some cases flexibility for expressing semantically equivalent statements in a variety of different ways. In order to obtain robust and interoperable implementations it is essential that SOAP implementations take into account the Robustness Principle as expressed by RFC 1123 [19] and RFC 793 [20]: "Be liberal in what you accept, and conservative in what you send".

Throughout this specification, guidelines will be provided as to what constitutes "conservative". However, it is important that implementers realize that this often represents only a subset of the set of acceptable values.

1.5 Example of SOAP Message

The following example shows a sample notification message expressed in SOAP. The message contains two pieces of application-defined data not defined by this specification: a header block with a local name of alertcontrol and a body element with a local name of alert . In general, header blocks contain information which may be of use to intermediaries as well as the ultimate destination of the message. In this example an intermediary might prioritise the delivery of the message based on the priority and expiry information in the header block. The body contains the actual message payload, in this case the alert message.

Example: SOAP message containing a header block and a body
<env:Envelope xmlns:env="http://www.w3.org/2001/12/soap-envelope">
 <env:Header>
  <n:alertcontrol xmlns:n="http://example.org/alertcontrol">
   <n:priority>1</n:priority>
   <n:expires>2001-06-22T14:00:00-05:00</n:expires>
  </n:alertcontrol>
 </env:Header>
 <env:Body>
  <m:alert xmlns:m="http://example.org/alert">
   <m:msg>Pick up Mary at school at 2pm</m:msg>
  </m:alert>
 </env:Body>
</env:Envelope>

1.6 SOAP Terminology

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

1.6.1 Protocol Concepts

SOAP

The formal set of conventions governing the format and processing rules of a SOAP message. These conventions include the interactions among SOAP nodes generating and accepting SOAP messages for the purpose of exchanging information along a SOAP message path.

SOAP node

The embodiment of the processing logic necessary to transmit, receive, process and/or relay a SOAP message, according to the set of conventions defined by this recommendation. A SOAP node is responsible for enforcing the rules that govern the exchange of SOAP messages (see 2 SOAP Processing Model). It accesses the services provided by the underlying protocols through one or more SOAP bindings.

SOAP role

A SOAP node's expected function in processing a message. A SOAP node may act in multiple roles.

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 exchange (see 4 SOAP Protocol Binding Framework). Examples of SOAP bindings include carrying a SOAP message within an HTTP entity-body, or over a TCP stream.

SOAP feature

An abstract piece of functionality typically associated with the exchange of messages between communicating SOAP nodes (see 3 SOAP Extensibility Model). Examples of features include "reliability", "security", "correlation", "routing", and the concept of message exchange patterns.

SOAP application

A software entity that produces, consumes or otherwise acts upon SOAP messages in a manner conforming to the SOAP processing model (see 2 SOAP Processing Model).

1.6.2 Data Encapsulation Concepts

SOAP message

The basic unit of communication between SOAP nodes.

SOAP envelope

The outermost element information item of a SOAP message.

SOAP header block

An element information item 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 element information item (see 5.2 SOAP Header) . 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 name 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 and which are direct children of the SOAP Body information item (see 5.3 SOAP Body).

SOAP fault

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

1.6.3 Message Sender and Receiver Concepts

SOAP sender

A SOAP node that transmits a SOAP message.

SOAP receiver

A SOAP node that accepts a SOAP message.

SOAP message path

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

Initial SOAP sender

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

SOAP intermediary

A SOAP intermediary is both a SOAP receiver and a SOAP sender and is targetable from within a SOAP message. It processes a defined set of SOAP header blocks in a SOAP message. It acts to forward a SOAP message towards the ultimate SOAP receiver.

Ultimate SOAP receiver

The SOAP receiver that is a final destination of a SOAP message. It is responsible for processing the contents of the SOAP body and any SOAP header blocks targeted at it. In some circumstances, a SOAP message may not reach an ultimate SOAP receiver, for example because of a problem at a SOAP intermediary. An ultimate SOAP receiver cannot also be a SOAP intermediary for the same SOAP message (see 2 SOAP Processing Model).

2 SOAP Processing Model

SOAP provides a distributed processing model that assumes that a SOAP message originates at an initial SOAP sender and is sent to an ultimate SOAP receiver via zero or more SOAP intermediaries. Note that the SOAP distributed processing model can support many message exchange patterns including but not limited to one-way messages, request/response interactions, and peer-to-peer conversations.

This section defines the SOAP distributed processing model. Section 4 SOAP Protocol Binding Framework defines a framework for describing the rules for how SOAP messages can be exchanged over a variety of underlying protocols. Section 3 SOAP Extensibility Model describes how SOAP can be extended and how SOAP extensions may interact with the SOAP processing model and the SOAP protocol binding framework.

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.

A SOAP node receiving a SOAP message MUST perform processing according to the SOAP processing model as described in this section and in the remainder of this specification.

A SOAP node MUST be identified by a URI

2.2 SOAP Roles and SOAP Nodes

In processing a SOAP message, a SOAP node is said to act in one or more SOAP roles, each of which is identified by a URI known as the SOAP role name. The roles assumed by a node MUST be invariant during the processing of an individual SOAP message. This specification deals only with the processing of individual SOAP messages, no statement is made regarding the possibility that a given SOAP node might or might not act in varying roles when processing more than one SOAP message.

The following SOAP roles are defined by this specification:

"http://www.w3.org/2001/12/soap-envelope/role/next"

Each SOAP intermediary and ultimate SOAP receiver MUST act in this role and MAY additionally assume zero or more other SOAP roles.

"http://www.w3.org/2001/12/soap-envelope/role/none"

SOAP nodes MUST NOT act in this role.

"http://www.w3.org/2001/12/soap-envelope/role/ultimateReceiver"

To establish itself as an ultimate SOAP receiver a SOAP node MUST act in this role. SOAP intermediaries MUST NOT act in this role.

In addition to those described above, other roles MAY be defined as necessary to meet the needs of SOAP applications.

While the purpose of a SOAP role name is to identify a SOAP node or nodes, there are no routing or message exchange semantics associated with the SOAP role name. For example, SOAP roles MAY be named with a URI useable to route SOAP messages to an appropriate SOAP node. Conversely, it is also appropriate to use SOAP 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/role/next", "http://www.w3.org/2001/12/soap-envelope/role/none" and "http://www.w3.org/2001/12/soap-envelope/role/ultimateReceiver" this specification does not prescribe the criteria by which a given node determines the (possibly 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 underlying protocol binding (e.g. the URI to which the message was physically delivered), configuration information made by users during system installation.

2.3 Targeting SOAP Header Blocks

SOAP header blocks carry optional roleattribute information items (see 5.2.2 SOAP role Attribute) that are used to target the blocks to the appropriate SOAP node(s). This specification refers to the (implicit or explicit) value of the SOAP role attribute as the SOAP role for the corresponding SOAP header block.

A SOAP header block is said to be targeted to a SOAP node if the SOAP role for the header block is the name of a role played by the SOAP node.

Header blocks targeted to the special role "http://www.w3.org/2001/12/soap-envelope/role/none" are carried with the message to the ultimate SOAP receiver, but are never formally processed. Such blocks MAY carry data that is required for processing of other blocks.

The ultimate SOAP receiver MUST process the message body. The SOAP message path for that message ends at its ultimate SOAP receiver.

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 mustUnderstandattribute information items (see 5.2.3 SOAP mustUnderstand Attribute). When the value of such an attribute information item is "true", the SOAP block is said to be mandatory.

Mandatory blocks MUST be presumed to somehow modify the semantics of other headers or body elements. Therefore, for every mandatory SOAP header block targeted to a node, that node MUST either process the block or not process the SOAP message at all, and instead generate a fault (see 2.6 Processing SOAP Messages and 5.4 SOAP Fault).

Tagging SOAP blocks as mandatory thus assures that such modifications will not be silently (and, presumably, erroneously) ignored by a SOAP node to which the header block is targeted.

The mustUnderstandattribute 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 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 the ultimate SOAP receiver to receive a message containing a mandatory header block that is targeted to a role other than the ones assumed by the ultimate SOAP receiver.

2.5 Structure and Interpretation of SOAP Bodies

An ultimate SOAP receiver MUST correctly process the immediate children of the SOAP body (see 5.3 SOAP Body). However, Part 1 of this specification (this document) mandates no particular structure or interpretation of these elements, and provides no standard means for specifying the processing to be done.

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 prevents 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 any 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 fault with a value of "env:MustUnderstand" for faultcode (see 5.4.8 Must Understand Faults). If such a fault is generated, any further processing MUST NOT be done. Faults relating to the 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 receiver, 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. An ultimate SOAP receiver MUST process the SOAP body, in a manner consistent with 2.5 Structure and Interpretation of SOAP Bodies.

Failure is indicated by the generation of a fault (see 5.4 SOAP Fault). SOAP message processing MAY result in the generation of at-most one fault. Header-related faults other than than those related to understanding header blocks (see 2.4 Understanding SOAP Headers) MUST conform to the specification for the corresponding SOAP header block.

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

The processing of a 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, MAY be interleaved with, or MAY follow processing of the body. For example, a "begin transaction" header block would typically precede, a "commit transaction" header block would likely follow, and a "logging" function might run concurrently with body processing.

Note:

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 SOAP receiver. Specifically, such extensions might specify that a fault with a value of "env:Sender" for faultcode 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 mustUnderstandattribute information item in the surviving headers when determining whether an error has occurred.

2.7 Relaying SOAP Messages

As mentioned earlier in this section, SOAP provides a distributed processing model that assumes that a SOAP message originates at an initial SOAP sender and is sent to an ultimate SOAP receiver via zero or more SOAP intermediaries. While SOAP does not itself define any routing or forwarding semantics, it is anticipated that such functionality can be described as one or more features and expressed as SOAP extensions or as part of the underlying protocol binding (see 3 SOAP Extensibility Model and 4 SOAP Protocol Binding Framework). The purpose of this section is to describe how message forwarding interacts with the SOAP distributed processing model.

2.7.1 SOAP Intermediaries

The semantics of one or more SOAP blocks in a SOAP message, or the SOAP message exchange pattern used MAY request that the SOAP message be forwarded to another SOAP node on behalf of the initiator of the inbound SOAP message. In this case, the processing SOAP node acts in the role of a SOAP intermediary.

SOAP defines two different types of intermediaries: forwarding intermediaries and active intermediaries. These two type of intermediary are described below.

2.7.2 Forwarding Intermediaries

Forwarding intermediaries process the message according to the SOAP processing model defined in 2.6 Processing SOAP Messages. SOAP header blocks targeted at the SOAP intermediary MUST be removed from the SOAP message prior to forwarding (such SOAP blocks are removed regardless of whether they were processed or ignored).

It is the responsibility of the feature defining the SOAP forwarding to describe the required semantics including rules describing how the forwarded message is constructed. Such rules MAY describe placement of inserted or reinserted blocks. Inserted SOAP header blocks may be indistinguishable from one or more of the header blocks removed above. Re-inserting processed SOAP header blocks in this manner effectively leaves them in place, but emphasizes the need to process them at each SOAP node along the SOAP message path.

2.7.3 Active Intermediaries

In addition to the processing performed by forwarding intermediaries, active intermediaries undertake additional processing that may modify the outbound message in ways not described in the inbound message. That is, they may undertake processing not described by header blocks in the incoming message. The potential set of services provided by an active intermediary includes, but is not limited to: security services, annotation services, and content manipulation services.

The collective effect of such additional processing may affect the correct processing of features expressed in the inbound message by downstream SOAP nodes. For example, as part of generating an outbound message, an active intermediary may have removed and encryped some or all of the blocks found in the inbound message. It is strongly recommended that features provided by active intermediaries be described in a manner that allows such modifications to be detected by affected SOAP nodes in the message path.

One mechanism by which an active intermediary can describe the modifications performed on a message is by inserting header blocks into the outbound SOAP message. These header blocks can inform downstream SOAP nodes acting in roles whose correct operation depends on receiving such notification. In this case, the semantics of such inserted header blocks should also call for either the same or other headers to be (re)inserted at subsequent intermediaries as necessary to ensure that the message can be safely processed by nodes yet further downstream. For example, if a message with header blocks removed for encryption passes through a second intermediary (without the original headers being decrypted and reconstructed), then indication that the encryption has occurred must be retained in the second relayed message.

2.8 SOAP Versioning Model

SOAP does not define a traditional versioning model based on major and minor version numbers. Rather, the SOAP processing model enables extensiblity of SOAP through the concept of features (see 2.6 Processing SOAP Messages).

A SOAP node determines whether it supports the version of a SOAP message on a per message basis. In this context "support" means understanding the semantics of the envelope identified by the qualified name of the Envelope element information item (see 5.1 SOAP Envelope). The envelope versioning model is directed only at the Envelope element information item. It does NOT address versioning of blocks, encodings, protocol bindings, or otherwise.

If the child element information item of the document information item does NOT have a local name of Envelope and a namespace name of "http://www.w3.org/2001/12/soap-envelope" then the receiving SOAP node MUST generate a fault (see 5.4 SOAP Fault) with a value of "env:VersionMismatch" for faultcode . Any other malformation of the message construct MUST result in the generation of a fault with a value of "env:Sender" for faultcode .

A SOAP node MAY provide support for multiple envelopes. However, when processing a message a SOAP node MUST use the semantics defined by the version of that message.

Appendix A Version Transition From SOAP/1.1 to SOAP Version 1.2 defines a mechanism for transitioning from SOAP/1.1 to SOAP Version 1.2 using the Upgrade element information item (see 5.4.7 VersionMismatch Faults).

3 SOAP Extensibility Model

As part of communicating in a distributed environment, it may be necessary to deploy a variety of features generally associated with the exchange of messages. For the purpose of this specification, the term "feature" is used to identify an abstract piece of functionality typically associated with the exchange of messages between communicating SOAP nodes. Although SOAP poses no constraints on the potential scope of such features, examples include "reliability", "security", "correlation", and "routing". In addition, the communication may require a varity of message exchange patterns (MEPs) like for example one-way messages, request/response interactions, and peer-to-peer conversations. MEPs are considered to be a type of feature; unless otherwise stated, references to the term "feature" apply also to MEPs.

SOAP provides a simple messaging framework whose core functionality is concerned with providing extensibility. As a result, most features often found in distributed systems have been left out of the messaging framework. While it is anticipated that many such features will be defined for SOAP, it is beyond the scope of this specification to do so. Instead, they are expected to be defined as extensions to SOAP.

The SOAP extensibility model provides two mechanisms through which features may be expressed: the SOAP Processing Model and the SOAP Protocol Binding Framework (see 2 SOAP Processing Model and 4 SOAP Protocol Binding Framework). The former describes the behavior of a single SOAP node with respect to the processing of an individual message. The latter mediates the act of sending and receiving SOAP messages by a SOAP node via an underlying protocol.

The SOAP Processing Model enables SOAP nodes that include the mechanisms necessary to implement one or more features to express such features within the SOAP envelope as header blocks (see 2.4 Understanding SOAP Headers). Such header blocks can be intended for any SOAP node or nodes along a SOAP message path (see 2.3 Targeting SOAP Header Blocks).

In contrast, a SOAP protocol binding operates between two adjacent SOAP nodes along a SOAP message path. There is no requirement that the same underlying protocol is used for all hops along a SOAP message path. In some cases, underlying protocols are equipped, either directly or through extension, with mechanisms for providing certain features. The SOAP Protocol Binding Framework provides a scheme for describing these features and how they relate to SOAP nodes through a binding specification (see 4 SOAP Protocol Binding Framework).

The combination of the SOAP Processing Model and the SOAP Protocol Binding Framework provides some flexibility in the way that particular features can be expressed: they can be expressed entirely within the SOAP envelope (as header blocks), outside the envelope (typically in a manner that is specific to the underlying protocol), or as a combination of such expressions.

Certain features may require end-to-end as opposed to hop-to-hop processing semantics. While the SOAP Protocol Binding Framework provides for the possibility that such features may be expressed outside the SOAP envelope, it does not define a specific architecture for the processing or error handling of these externally expressed features by a SOAP intermediary. A binding specification that expresses such features external to the SOAP envelope should define its own processing rules to which a SOAP node is expected to conform (for example, describing what information must be passed along with the SOAP message as it leaves the intermediary). It is recommended that, where practical, end-to-end features be expressed as SOAP header blocks, so that the rules defined by the SOAP Processing Model can be employed.

4 SOAP Protocol Binding Framework

SOAP enables exchange of SOAP messages using a variety of underlying protocols. The formal set of rules for carrying a SOAP message within or on top of another protocol (underlying protocol) for the purpose of exchange is called a binding. The SOAP Protocol Binding Framework provides a scheme for describing bindings and how they relate to SOAP nodes through a binding specification. As an example of a binding specification, SOAP Part 2 [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.

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.

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 (see 2 SOAP Processing Model).

4.1 Goals of the Binding Framework

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 optional 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 binding exploiting an underlying protocol that directly facilitates the feature (the protocol is reliable), and the other providing the logic (logging and retransmission) in the binding. In such case, the feature can be made available to applications in a consistent manner, regardless of which binding is used.

4.2 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 Processing 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 additional processing that is 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 Processing 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 to be 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) and rules for the delivery or other disposition of SOAP faults generated during the operation of the MEP.

A binding specification MUST enable one or more MEPs. 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, a transaction ID, etc. The HTTP binding in SOAP Part 2 [1] illustrates one such convention.

As described in 5 SOAP Message Construct, 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. A binding, if using XML 1.0 serialization of the infoset, MAY mandate that a particular character encoding or set of encodings be used.

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], section Using SOAP in HTTP, transmits an HTTP field named SOAPAction that is not contained within the SOAP XML Infoset.

5 SOAP Message Construct

A SOAP message is specified as an XML Infoset that consists of a document information item with exactly one child, which MUST be the SOAP Envelope element information item (see 5 SOAP Message Construct).

The XML infoset of a SOAP message MUST NOT contain a document type declaration information item. On receipt of a SOAP message containing a document type declaration information item, a SOAP receiver MUST generate a fault (see 5.4 SOAP Fault) with a value of "DTDNotSupported" for faultcode .

A SOAP message SHOULD NOT contain processing instruction information items. A SOAP receiver MUST ignore processing instruction information items in SOAP messages that it receives.

Element information items defined by this specification may have zero or more character information item children whose character code is amongst the whitespace characters as defined by [8]. Such character information items are not considered significant. A SOAP receiver MUST ignore such character information items. A SOAP intermediary MAY ignore such character information items if forwarding ( see 2.7 Relaying SOAP Messages ).

5.1 SOAP Envelope

The Envelope element information item has:

  • A local name of Envelope .

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

  • Zero or more namespace qualified attribute information items.

  • One or two element information item children in order as follows:

    1. An optional Header element information item (see 5.2 SOAP Header).

    2. A mandatory Body element information item (see 5.3 SOAP Body).

5.1.1 SOAP encodingStyle Attribute

SOAP defines an optional encodingStyleattribute information item which indicates the encoding rules used to serialize a SOAP message.

The encodingStyleattribute information item has:

  • A local name of encodingStyle.

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

It may appear on any element information item in the SOAP message except the Envelope element information item. Its scope is that of its owner element information item and that element information item's descendants, unless a descendant itself carries such an attribute information item. If no encodingStyleattribute information item is in scope for a particular element information item or the value of such an attribute information item is the zero-length URI ( "" ) then no claims are made regarding the encoding style of that element infomation item.

The encodingStyleattribute information item is of type anyURI in the namespace named "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 encodingStyleattribute information item.
"http://www.w3.org/2001/12/soap-encoding"
"http://example.org/encoding/"
""

5.2 SOAP Header

A SOAP header provides a mechanism for extending a SOAP message in a decentralized and modular way (see 2.4 Understanding SOAP Headers).

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 items.

  • Zero or more namespace qualified element information item children.

Each child element information item of the SOAP Header is called a SOAP header block.

Each SOAP header block element information item:

  • MUST be namespace qualified.

  • MAY have an encodingStyleattribute information item.

  • MAY have an roleattribute information item.

  • MAY have a mustUnderstandattribute information item.

5.2.1 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 Processing 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="true" >
   5
 </t:Transaction>
</env:Header>

Except as specified below, SOAP header block attribute information items whose value differs from their default value as defined in sections 5.2.2 SOAP role Attribute and 5.2.3 SOAP mustUnderstand Attribute MUST appear in the SOAP message itself in order to be effective; any other value that does not appear directly in the SOAP message MUST NOT affect the SOAP processing as defined by section 2 SOAP Processing Model.

5.2.2 SOAP role Attribute

A SOAP role is used to indicate the SOAP node to which a particular SOAP header block is targeted (see 2.2 SOAP Roles and SOAP Nodes).

The roleattribute information item has the following Infoset properties:

  • A local name of role.

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

  • A specified property with a value of "true".

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

Omitting the SOAP role attribute information item is equivalent to supplying that attribute with a value of "http://www.w3.org/2001/12/soap-envelope/role/ultimatereceiver". An empty value for this attribute is equivalent to omitting the attribute completely, i.e. targeting the block at the ultimate SOAP receiver.

SOAP senders SHOULD NOT generate, but SOAP receivers MUST accept the SOAP role attribute information item for SOAP header blocks targeted at the ultimate SOAP receiver (see section 1.4 Robustness Principle). If relaying a SOAP message, a SOAP intermediary MAY discard the SOAP role attribute information item for SOAP header blocks targeted at the ultimate SOAP receiver (see 2.7 Relaying SOAP Messages).

5.2.3 SOAP mustUnderstand Attribute

The SOAP mustUnderstand attribute information item is used to indicate whether the processing of a SOAP header block is mandatory or optional (see 2.4 Understanding SOAP Headers)

The mustUnderstandattribute 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 mustUnderstandattribute 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" or "0".

SOAP senders SHOULD NOT generate, but SOAP receivers MUST accept the SOAP mustUnderstand attribute information item with a value of "false" or "0" (see section 1.4 Robustness Principle). If generating a SOAP mustUnderstand attribute information item, a SOAP sender SHOULD use the canonical representation "true" of the attribute value (see [5]). A SOAP receiver MUST accept any valid lexical representation of the attribute value.

If relaying the message, a SOAP intermediary MAY substitute a non-canonical value with the canonical value "true" and MAY omit the SOAP mustUnderstand attribute information item if the value is "false" or "0".

5.3 SOAP Body

A SOAP body provides a mechanism for transmitting information to an ultimate SOAP receiver (see 2.5 Structure and Interpretation of SOAP Bodies).

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 namespace qualified attribute information items. These MAY include an encodingStyleattribute information item.

  • Zero or more namespace qualified element information item children.

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

  • MUST be namespace qualified.

  • MAY have an encodingStyleattribute information item.

SOAP defines one particular direct child of the SOAP body, the SOAP fault, which is used for reporting errors (see 5.4 SOAP Fault).

5.4 SOAP Fault

A SOAP fault is used to carry error information within a SOAP message.

If present, a 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:

5.4.1 SOAP faultcode Element

The faultcode element information item has:

  • A local name of faultcode .

  • A namespace name which is empty.

  • One or two child element information items as follows:

    1. A mandatory value element information item of type faultCodeEnum in the "http://www.w3.org/2001/12/soap-envelope" namespace. This 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 high level SOAP faults (see 5.4.6 SOAP Fault Codes).

    2. An optional subcode element information item.

The subcode element information item has:

  • A local name of subcode .

  • A namespace name which is empty.

  • One or two child element information items as follows:

    1. A mandatory value element information item of type QName in the "http://www.w3.org/2001/XMLSchema" namespace. The value of this element is an application defined subcategory of the value of the value child element information item of the subcode 's parent element information item.

    2. An optional subcode element information item.

5.4.2 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.

5.4.3 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 Processing Model). The value of the faultactor element information item is the URI that identifies the SOAP node that generated the fault (see 2.1 SOAP Nodes). 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.

5.4.4 SOAP faultrole Element

The faultrole element information item has:

  • A local name of faultrole .

  • A namespace name which is empty.

The type of the faultrole element information item isanyURI in the "http://www.w3.org/2001/XMLSchema" namespace. It is similar to the SOAP roleattribute information item (see 5.2.2 SOAP role Attribute) except that the value of the faultrole element information item identifies the role the node was playing at the point the fault occured.

5.4.5 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 encodingStyleattribute information item.

The SOAP encodingStyleattribute information item is used to indicate the encoding style used for the detail entries (see 5.1.1 SOAP encodingStyle Attribute).

5.4.6 SOAP Fault Codes

SOAP fault code (see 5.4.1 SOAP faultcode Element) values are XML qualified names (see XML Namespaces [7]) from the table below. The namespace name for these SOAP fault code values is "http://www.w3.org/2001/12/soap-envelope".

The values of the value child element information item of the faultcode element are restricted to those in the table below. Specifications that wish to implement their own fault codes MUST do so by sub-categorizing an existing fault code via the subcode element.

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

Name Meaning
VersionMismatch The processing party found an invalid element information item instead of the expected Envelope element information item. The namespace, localname or both did not match the Envelope element information item (see 2.8 SOAP Versioning Model and 5.4.7 VersionMismatch Faults)
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 mustUnderstandattribute information item with a value of "true" (see 5.2.3 SOAP mustUnderstand Attribute and 5.4.8 Must Understand Faults)
DTDNotSupported The SOAP message contained a Document Type Definition (see 1.2 Relation to other XML Specifications).
DataEncodingUnknown A header or body targetted at the current SOAP node is scoped (see 5.1.1 SOAP encodingStyle Attribute) with a data encoding that the current node does not support.
Sender A value of "env:Sender" for 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 5.4 SOAP Fault for a description of the SOAP fault detail sub-element).
Receiver A value of "env:Receiver" for 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 5.4 SOAP Fault for a description of the SOAP fault detail sub-element).

5.4.7 VersionMismatch Faults

When a SOAP node generates a fault with a value of "env:VersionMismatch" for faultcode , it SHOULD provide, in the generated fault message, an Upgrade header block as described below which detail the qualified names (QNames, per XML Schema: Datatypes [5]) of the supported SOAP envelopes that the SOAP node supports (see 2.8 SOAP Versioning Model).

The Upgrade header block consists of an Upgrade element information item containing an ordered list of qualified names of SOAP envelopes that the SOAP node supports in the order most to least preferred.

The Upgrade element information item has:

  • A local name of Upgrade .

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

  • One or more envelope child element information items as described below:

The envelope element information item has:

  • A local name of envelope .

  • A namespace name which is empty.

  • An unqualified attribute information item with a local name of qname and a type of QName in the "http://www.w3.org/2001/XMLSchema" namespace.

Following is an example of a SOAP node that supports both SOAP Version 1.2 and SOAP/1.1 but which prefers SOAP Version 1.2 (see appendix A Version Transition From SOAP/1.1 to SOAP Version 1.2 for a mechanism for transitioning from SOAP/1.1 to SOAP Version 1.2). This is indicated by including an Upgrade header block with two envelope element information items, the first containing the local name and namespace name of the SOAP Version 1.2 Envelope element information item, the latter the local name and namespace name of the SOAP/1.1 Envelope element.

Example: Version mismatch fault generated by a SOAP node. The message includes a SOAP Upgrade header block indicating support for both SOAP Version 1.2 and SOAP/1.1 but with a preference for SOAP Version 1.2.
<?xml version="1.0" ?>
<env:Envelope xmlns:env="http://www.w3.org/2002/10/soap-envelope">
 <env:Header>
  <V:Upgrade xmlns:V="http://www.w3.org/2001/12/soap-upgrade">
   <envelope qname="ns1:Envelope" 
             xmlns:ns1="http://www.w3.org/2002/10/soap-envelope"/>
   <envelope qname="ns2:Envelope" 
             xmlns:ns2="http://schemas.xmlsoap.org/soap/envelope/"/>
  </V:Upgrade>
 </env:Header>
 <env:Body>
  <env:Fault>
   <faultcode><value>env:VersionMismatch</value></faultcode>
    <faultstring>Version Mismatch</faultstring>
   </env:Fault>
 </env:Body>
</env:Envelope>

5.4.8 Must Understand Faults

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

It is NOT a requirement that the fault contain the qualified names of ALL header blocks that were not understood in a SOAP message. A SOAP node MAY generate a fault immediately upon encountering a header block that is not understood containing information about that single header block only. Alternatively SOAP nodes MAY generate a combined fault containing information about all the header blocks that were not understood at once.

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 qnameattribute information item as desribed below.

The qnameattribute 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 qnameattribute 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 fault if Extension1 or Extension2 are not understood
<?xml version="1.0" ?>
<env:Envelope xmlns:env='http://www.w3.org/2001/12/soap-envelope'>
  <env:Header>
    <abc:Extension1 xmlns:abc='http://example.org/2001/06/ext'
       env:mustUnderstand='true'/>
    <def:Extension2 xmlns:def='http://example.com/stuff'
       env:mustUnderstand='true' />
  </env:Header>
  <env:Body>
    . . .
  </env:Body>
</env:Envelope>

The above message would result in the fault message shown below if the receiver 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' >
 <env:Header>
  <f:Misunderstood qname='abc:Extension1'
                   xmlns:abc='http://example.org/2001/06/ext' />
  <f:Misunderstood qname='def:Extension2'
                   xmlns:def='http://example.com/stuff' />
 </env:Header>
 <env:Body>
  <env:Fault>
   <faultcode><value>env:MustUnderstand</value></faultcode>
   <faultstring>One or more mandatory 
                headers not understood</faultstring>
  </env:Fault>
 </env:Body>
</env:Envelope>

Note:

When serializing the qnameattribute 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. The prefix used need not be the same as the one used in the message that was misunderstood.

6 Use of URIs in SOAP

SOAP uses URIs for some identifiers including, but not limited to, values of the encodingStyle (see 5.1.1 SOAP encodingStyle Attribute) and role (see 5.2.2 SOAP role 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.

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 4 SOAP Protocol Binding Framework and Part 2 [1] section HTTP binding).

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 [18]). 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 2048 characters in length.

7 Security Considerations

The SOAP Framework does not directly provide any mechanisms for dealing with access control, confidentiality, integrity and non-repudiation. Such mechanisms can either be provided as SOAP extensions using the SOAP extensibility model (see 3 SOAP Extensibility Model) or through features expressed within the underlying protocol and made available to SOAP applications through the SOAP binding framework (see 4 SOAP Protocol Binding Framework). This section describes the security considerations that designers and implementers should take into consideration when designing and using such mechanisms.

SOAP implementers should anticipate rogue SOAP applications sending intentionally malicious data to a SOAP node (see 2 SOAP Processing Model). Similarly, SOAP nodes should be aware of the implications of sending data to other SOAP nodes in case those nodes are malicious. It is strongly recommended that a SOAP node receiving a SOAP message is capable of evaluating to what level it can trust the sender of that SOAP message and its contents. Likewise, any SOAP node sending a SOAP message to another SOAP node should be capable of evaluating to what level it can trust the receiving SOAP node to process the message responsibly. This applies not only to ultimate SOAP receivers but also SOAP intermediaries.

7.1 SOAP Nodes

SOAP can carry application-defined data as SOAP header blocks or as SOAP body contents. Processing a SOAP header block may include dealing with side effects such as state changes, logging of information, or the generation of additional messages. It is strongly recommended that only well-defined header blocks with known security implications of any side effects be processed by a SOAP node.

As for SOAP header blocks, processing a SOAP body may imply the occurrence of side affects that may, if not properly understood, have severe consequences for the receiving SOAP node. As for SOAP header blocks, it is strongly recommended that only well-defined body contents with known security implications be processed.

Security considerations, however, are not just limited to recognizing the immediate child elements of the SOAP header and the SOAP body. Implementers should pay special attention to the security implications of all data carried within a SOAP message that can cause the remote execution of any actions in the receiver's environment. This includes not only data expressed in XML infoset but data that may be encoded as binary data or carried as parameters like for example URI query strings. Before accepting data of any type, an application should be aware of the particular security implications associated with that data within the context it is being used.

SOAP implementers should be careful to ensure that if processing of the various parts of a SOAP message is provided through modular software architecture, that each module is aware of the overall SOAP security context. For example, a SOAP body should not be processed without knowing the SOAP context in which it was received.

7.2 SOAP Intermediaries

SOAP inherently provides a distributed processing model that may involve a SOAP message passing through multiple SOAP nodes (see 2 SOAP Processing Model). SOAP intermediaries are by definition men-in-the-middle, and represent an opportunity for man-in-the-middle attacks. Security breaches on systems that run SOAP intermediaries can result in serious security and privacy problems. A compromised SOAP intermediary, or an intermediary implemented or configured without regard to security and privacy considerations, might be used in the commission of a wide range of potential attacks.

In analyzing the security implications of potential SOAP related security problems, it is important to realize that the scope of security mechanisms provided by the underlying protocol may not be the same scope as the whole message path of the SOAP message. There is no requirement in SOAP that all hops between participating SOAP nodes use the same underlying protocol and even if this was the case, the very use of SOAP intermediaries is likely to reach beyond the scope of transport-level security.

7.3 Underlying Protocol Bindings

The effects on security of not implementing a MUST or SHOULD, or doing something the specification says MUST NOT or SHOULD NOT be done may be very subtle. Binding specification authors should describe, in detail, the security implications of not following recommendations or requirements as most implementors will not have had the benefit of the experience and discussion that produced the specification (see 4 SOAP Protocol Binding Framework).

In addition, a binding specification may not address or provide countermeasures for all aspects of the inherent security risks. The binding specification authors should identify any such risks as might remain and indicate where further countermeasures would be needed above and beyond those provided for in the binding specification.

Binding specification authors should be aware that SOAP extension modules expressed as SOAP header blocks may affect the underlying protocol in unforeseen ways. It is strongly recommended that a binding specification should describe any such interactions. For example, a SOAP message carried over a particular protocol binding may result in seemingly conflicting features such as might be the case with HTTP basic auth combined with a SOAP based authentication mechanism.

7.3.1 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.

8 References

8.1 Normative References

1
W3C Working Draft "SOAP Version 1.2 Part 2: Adjuncts", Martin Gudgin, Marc Hadley, Jean-Jacques Moreau, Henrik Frystyk Nielsen, @@@@2002 (See soap12-part2.html.)
2
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.)
3
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.)
4
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/.)
5
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/.)
6
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.)
7
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/.)
8
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.)
9
W3C Recommendation "XML Linking Language (XLink) Version 1.0", Steve DeRose, Eve Maler, David Orchard, 27 June 2001. (See http://www.w3.org/TR/2000/REC-xlink-20010627/.)
10
W3C Recommendation "XML Information Set", John Cowan, Richard Tobin, 24 October 2001. (See http://www.w3.org/TR/2001/REC-xml-infoset-20011024/.)
11
W3C Recommendation "XML Base", Johnathan Marsh, 27 June 2001. (See http://www.w3.org/TR/2001/REC-xmlbase-20010627/.)
12
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.)

8.2 Informative References

13
XML Protocol Comments Archive (See http://lists.w3.org/Archives/Public/xmlp-comments/.)
14
XML Protocol Discussion Archive (See http://lists.w3.org/Archives/Public/xml-dist-app/.)
15
XML Protocol Charter (See http://www.w3.org/2000/09/XML-Protocol-Charter.)
16
W3C Working Draft "XML Protocol (XMLP) Requirements", Vidur Apparao, Alex Ceponkus, Paul Cotton, David Ezell, David Fallside, Martin Gudgin, Oisin Hurley, John Ibbotson, R. Alexander Milowski, Kevin Mitchell, Jean-Jacques Moreau, Eric Newcomer, Henrik Frystyk Nielsen, Mark Nottingham, Waqar Sadiq, Stuart Williams, Amr Yassin, @@@@2002. This is work in progress. (See xmlp-reqs.html.)
17
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/.)
18
IETF "RFC 1900: Renumbering Needs Work", B. Carpenter, Y. Rekhter, February 1996. (See http://www.ietf.org/rfc/rfc1900.txt.)
19
IETF "RFC 1123: Requirements for Internet Hosts -- Application and Support", R. Braden, October 1989. (See http://www.ietf.org/rfc/rfc1123.txt.)
20
IETF "RFC 793: Transmission Control Protocol", DARPA, September 1981. (See http://www.ietf.org/rfc/rfc793.txt.)

A Version Transition From SOAP/1.1 to SOAP Version 1.2

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

  1. A SOAP/1.1 node receiving a SOAP Version 1.2 message will according to SOAP/1.1 generate a version mismatch SOAP fault based on a SOAP/1.1 message construct. That is, the envelope will have a local name of Envelope and a namespace name of "http://schemas.xmlsoap.org/soap/envelope/".

  2. A SOAP Version 1.2 node receiving a SOAP/1.1 message either:

    • MAY process the message as a SOAP/1.1 message (if supported), or

    • MUST generate a version mismatch SOAP fault based on a SOAP/1.1 message construct following SOAP/1.1 semantics. The SOAP fault SHOULD include an Upgrade header block as defined in this specification (see 5.4.7 VersionMismatch Faults) indicating support for SOAP Version 1.2. This allows a receiving SOAP/1.1 node to correctly interpret the SOAP fault generated by the SOAP Version 1.2 node.

Below is an example of a version mismatch SOAP fault generated by a SOAP Version 1.2 node as a result of receiving a SOAP/1.1 message. The fault message is a SOAP/1.1 message with an Upgrade header block indicating support for SOAP Version 1.2.

Example: SOAP Version 1.2 node generating a SOAP/1.1 version mismatch fault message including an Upgrade header block indicating support for SOAP Version 1.2.
<?xml version="1.0" ?>
<env:Envelope xmlns:env="http://schemas.xmlsoap.org/soap/envelope/">
 <env:Header>
  <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"/>
   </V:Upgrade>
  </env:Header>
  <env:Body>
   <env:Fault>
    <faultcode><value>env:VersionMismatch</value></faultcode>
    <faultstring>Version Mismatch</faultstring>
   </env:Fault>
 </env:Body>
</env:Envelope>

Note:

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

B Acknowledgements (Non-Normative)

This specification 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
20020322 HFN Changed mU='1' with mu='true' in examples.
20020322 HFN Fixed section names in cross references to part 2
20020322 HFN Changed all occurrences of 'receipient' to 'receiver' and 'ultimate' receiver' to 'ultimate SOAP receiver'
20020322 HFN Reordered spec as follows:
  • introduction

  • processing model

  • extensibility model

  • binding framework

  • envelope construct

  • URI

  • Security

20020322 HFN Added resolution for issue 176
20020322 MJG Added clause regarding whitespace characters to infoset decsription of Envelope, Header and Body.
20020322 MJH changed all namespace identifiers, URIs to names.
20020322 MJH removed links in NS URIs.
20020322 MJH Added in David F review changes.
20020322 JJM Incorporated Henrik's comments on 1.3 and 1.4.
20020321 MJH Issue 174 changes.
20020321 MJH Made styling of URIs consistent throughout.
20020321 MJH Made styling of references to infoset terms consistent throughout.
20020321 MJH Made references to faults and fault codes consistent throughout.
20020311 HFN Say that versioning is determined based on the namespace name AND local name of the document information item. If the namespace name AND local name doesn't match then generate a VersionMismatch fault.
20020311 HFN Say that ALL VersionMismatch faults SHOULD use the Upgrade header block for describing which revision they support. Editorially, this means moving the description of the Upgrade header block into section 3.4 rather than having it in appendix
20020311 HFN Make it clear that SOAP/1.1 is ONLY used it VersionMismatch fault IF the sender is a SOAP/1.1 node. Otherwise, use SOAP 1.2 envelope.
20020311 HFN Turned into a note: "Note that when serializing the qnameattribute 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"
20020311 HFN In section 5.4.8 Must Understand Faults moved last paragraph to beginning and made the requirements to a SOAP node clear (was written as a note)
20020311 HFN Moved section on Upgrade fault element from appendix to section 3.4 in a manner similar to the MustUnderstand fault subsection in the same section.
20020314 HFN Added reference to 5.4 SOAP Fault for issue 182 resolution.
20020320 JJM Incorporated resolution to issue 40.
20020320 JJM Incoporated resolution for issue 183, including amendements from Noah (and taking into account later comments from Noah on Part 1).
20020320 JJM Updated cross-references from saying "bibref" "xspecref" to "bibref" section "xspecref". Otherwise the generated HTML looked funny (the links were back to back) [Ednote issue #33]
20020320 JJM More generally, made all "bibrefs" more uniform.
20020318 HFN The section on SOAP Extensibility (see 3 SOAP Extensibility Model) showed signs of originally being the introduction to the Protocol Binding Framework (see 4 SOAP Protocol Binding Framework) and needed some editorial work in order to stand on its own. This section was "promoted" to a top-level section by simply moving it out of section 4 SOAP Protocol Binding Framework. The text is now rebalanced. There should be no semantic changes, merely a rewrite to make it more clear what we mean by features. The involved sections are section 3 SOAP Extensibility Model, the introduction of 4 SOAP Protocol Binding Framework, and section 4.1 Goals of the Binding Framework.
20020318 JJM Removed duplication between section "2.5 Structure and Interpretation of SOAP Bodies" and section "3.3 SOAP Body".
20020318 JJM Trimmed down the introductions to the sub-sections of section 3, in a way Henrik and I both feel comfortable with.
20020318 JJM Finsihed incorporating Noah's comments on Part1, albeit two issues raised separately.
20020315 HFN Lower-cased MAY in the last paragraph in section 2.6 Processing SOAP Messages as these are not requirements on anything in our spec and the paragraph is a note in the first place.
20020316 HFN In the introduction, changed the word "transmit" to "exchange" in places where transmit and receive is implied.
20020316 HFN In the introduction, removed reference to header block and body before these are introduced.
20020314 HFN Added reference to 5.4 SOAP Fault for issue 182 resolution.
20020312 HFN In section 5.1 SOAP Envelope, changed: "The document element information item has:..." with "The Envelope element information item has:..."
20020314 JJM Added back comments from Noah
20020314 JJM Added revised definition for ultimate receiver, after Henrik and Noah's approval.
20020312 MJH Added issue 182 resolution.
20020311 HFN Glossary: added "feature": "An abstract piece of functionality typically associated with the exchange of messages between communicating SOAP nodes (see 3 SOAP Extensibility Model). Examples of features include "reliability", "security", "correlation", "routing", and the concept of message exchange patterns."
20020311 HFN Glossary: moved "soap application" under "protocol concepts" (was in "Message Sender and Receiver Concepts") as it belongs better there.
20020310 HFN Clarified example in section 1.3
20020310 HFN Made cross references consistent of the form (see X)
20020310 HFN Made editorial changes to section Envelope Versioning Model and moved to section 2 as it is a part of the processing model
20020310 HFN Added XML Protocol requirements document as a non-normative reference
20020310 HFN Removed paragraph as it is no longer used: "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 Schema specifications [4], [5]."
20020310 HFN Removed paragraph as it is no longer used: "The namespace prefixes "env" 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."
20020310 HFN Updated example in section 3.1.2: the description of the encodingStyle attribute: it was written as if it is part of the encoding schema, it is not
20020310 HFN Updated introduction to read better and removed section 1.1 Design Goals as this is now part of the general introduction
20020310 HFN Changed "SOAP Message Structure" to "SOAP Message Construct" as a) I think it is more appropriate and b) It doesn't confuse the use of structure used elsewhere in the document.
20020310 HFN Updated abstract to read better
20020308 HFN Incorporated resolution to issue 137
20020305 JJM Started incorporating Noah's comments on the latest ed's copy.
20020304 HFN Changed "It is based on XML..." to "It is based on XML Infoset..."
20020304 HFN Restructured section 3 and moved to section 1 as 1.3 "Relation to other XML Specifications"
20020304 HFN Removed the following paragraph from (new) 1.3 as it is duplicated in section 4: "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 2.8 SOAP Versioning Model."
20020304 HFN Moved the following paragraph to section 4 as it enables us to gather all strict requirements in one place. "People get confused if there are requirements spread out all over the place. 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 5.4 SOAP Fault) with a fault code 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."
20020304 HFN Added text to (new) 1.3 to clarify relationship with XML namespaces, XML base, and XML schema.
20020304 HFN Clarified relationship to schema based on Noah's formulation
20020324 HFN Renamed "4 SOAP Envelope" to "4 SOAP Message Structure" and introduced a new section called 4.1 "SOAP Envelope"
20020324 HFN Removed the heading in section 4.1 "Envelope Encoding and Versioning" and promoted section 4.1.1 and 4.1.2 to 4.1 and 4.2 respectively (I reordered them as I think the versioning model is more important).
20020324 HFN In section "SOAP encodingStyle Attribute" modified the paragraph to say that encodingStyle can't appear on the Envelope information item
20020324 HFN As per Gudge's suggestion, moved SOAP Extensibility Model to section 3 just after the processing model.
20020228 HFN Updated abstract slightly
20020228 HFN Incorporated resolution to issue 178
20020228 HFN Insert resolution to issue 179, replacing 'support' with 'enable'
20020228 HFN Insert resolution of issue 103 with the following modifications; a) "Normally" with "in the absence of faults" b) "recipient" with "receiver" c) "the ultimate" with "an ultimate"
20020228 HFN Move section 6.3 into 6.4 and add security considerations text.
20020228 HFN Added first part of resolution of issue 59: "It is the responsibility of transport bindings to specify how the infoset is being transfered to and reconstituted by the binding at the receiving node. Such a binding, if using XML 1.0 serialization of the infoset, may mandate that a particular character encoding or set of encodings be used."
20020221 MJG Edited examples so that no line is longer than 66 characters
20020219 HFN Updated section 7: removed reference to href and clarified suggestion for length of URIs.
20020219 MJG Qualified encoding attributes in examples.
20020218 HFN Added resolution text for issue 102: "and rules for the delivery or other disposition of SOAP faults generated during the operation of the MEP"
20020216 MJG Added text to Section 3 explaining where schema documents are located
20020216 MJG Added hierarchical fault types to soap-envelope schema
20020215 MJH Inserted section 2 rewrite and associated changes to section 4.
20020215 HFN Promoted section 5.1 to top-level section 5 and moved the rest of the old section 5 to top-level section 6
20020131 MJH Removed the sentence that said that an encodingStyle value that was prefixed with the SOAP encoding style URI indicated a restricted version of the SOAP encoding. This change was agreed on the conf call of 20020130, but no issue existed for it.
20020131 MJH Removed old ednote asking for feedback on the new requirement that direct children of the body be namespace qualified.
20020131 MJH Fixed text on Body element to match schema. This change was agreed on the conf call of 20020130 but no issue existed for it. Body element allows zero or more unspecified attribute information items including encodingStyle. Removed ednotes that previously highlighted the removed contradiction.
20020129 MJH Removed duplication in list of goals of binding framework (Sect 5.2).
20020121 MJH Rolled in most of the suggested editorial changes from John Ibbotson. Section 2 not changed.
20020117 MJH Added hierarchical fault codes (issue 173).
20011213 MJH Updated namespace URIs, fixed spelling error.
20011211 MJH Added section headings for faultcode, faultstring, faultactor and detail elements.
20011211 MJH Fixed a number of spelling errors and grammatical problems throughout the document. Applied some limited rewording to improve readability.
20011211 MJH Removed duplicate description of "must happen" extension from section 2.
20011206 MJH Removed more mentions of body blocks.
20011206 MJH Limited 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.
20011206 MJH Incorporated Chris Ferris suggested changes to glossary and section 2.
20011206 MJH General editorial work on new sections. Added references and other tagging as required.
20011206 MJH Incorporated agreed changes to URIs in SOAP section (remove duplication with XML base and cite XML base more strongly).
20011206 MJH Incorporated issue 155 resolution.
20011205 JJM Elevated the header removal step to a processing model step.
20011204 MJH Added bibref to Use of URIs section and tidied up the language in that section.
20011204 MJH Modified soapEncoding descriptive text - Issues 159 and 166.
20011204 JJM Added text to section 2.2, second paragraph, to indicate none blocks may carry data for processing of other blocks.
20011204 JJM Section 2.2, four paragraph, added "anonymous actor" to the list.
20011204 JJM Section 2.3, remove text for SOAP body blocks.
20011204 JJM Section 2.3, replace "has assumed the role of the anonymous actor" by "is the ultimate receiver".
20011204 JJM Section 2.4, incorporated 2 paragraph previously in section 2.
20011204 JJM Added section 2.5 (text from Noah).
20011204 JJM Added an extra step to the processing model (now section 2.6).
20011204 JJM Simplified step 3, and moved the previous text further below in the same section (2.6).
20011204 JJM Section 2.6, incorporated text from section 4.
20011204 JJM Section 4.2.2, removed explanation of next and none roles.
20011204 JJM Section 4.2.2, added text to indicate the meaning of an empty actor attribute.
20011204 JJM Trimmed section 4.2.3, as the text is now in section 2.
20011204 JJM Removed section 4.3.1, since body processing is now in section 2.6.
20011204 JJM Added ednote to flag the definition for SOAP block is out of date.
20011204 JJM Reformated section 5 (Binding Framework).
20011204 JJM Reformated section 6 (Use of URIs in SOAP). Removed non ASCII characters.
20011204 JJM Added missing "att" and "attval" around elements and attributes in section 6.
20011204 JJM Fixed a number of lax references in section 6.
20011201 HFN Added SOAP Protocol Binding Framework
20011201 HFN Added section on URIs and XML Base
2001129 MJG Incorporated resolution text for Issue 146 into Section 2.3
2001129 MJG Changed "Client" and "Server" fault codes to be "Sender" and "Receiver" respectively as resolution of Issue 143
2001129 MJG Removed dot notation from spec. Added "DTDNotSupported" fault code to fault code table.
20011122 MJH Incorporated resolution to issue 172 (criteria for generating version mismatch fault into 2.8 SOAP Versioning Model. Removed duplication of versioning error text and associated ednote from 1.2 Relation to other XML Specifications
20011029 MJH Changed "default actor" to "anonymous actor".
20011029 MJH Amended relation to XML section (Issue 135).
20011029 MJH Amended section 2.5 (Issue 157).
20011029 MJH Removed citation of ABNF - not used in part 1.
20011029 MJH Amended section 1.3 (Issue 150)
20011029 MJH Amended section 1.1 (Issue 149)
20011029 MJH Amended introductory text (Issue 148)
20011029 MJH Amended introductory text (Issue 147)
20011029 MJH Amended 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