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SOAP Version 1.2 provides a request-response MEP and a request-response bindings. This provides a one way + optional Fault MEP and a binding to HTTP request/response that supports SOAP request-response and the Robust-request way MEP over a single http connection or 2 http connections. This specification depends on SOAP Version 1.2 Part 2: Adjuntcts [SOAP-PART2].
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1 Introduction
1.1 Notational Conventions
2 SOAP Robust Request Message Exchange Pattern
2.1 SOAP Feature Name
2.2 Description
2.3 State Machine Description
3 One-way + optional additional connection SOAP HTTP binding
3.1 Introduction
3.1.1 Description
3.1.2 Optionality
3.1.3 Use of HTTP
3.1.4 Interoperability with non-SOAP HTTP Implementations
3.1.5 HTTP Media-Type
3.2 Binding Name
3.3 Supported Message Exchange Patterns
3.4 Supported Features
3.5 Supported Properties
3.6 MEP Operation
3.6.1 Behavior of Requesting SOAP Node
3.6.1.1 Init
3.6.1.2 Requesting
3.6.1.3 Sending+Receiving
3.6.1.4 Success and Fail
3.6.2 Behavior of Responding SOAP Node
3.6.2.1 Init
3.6.2.2 Receiving
3.6.2.3 Receiving+Sending
3.6.2.4 Success and Fail
3.7 Security Considerations
4 References
4.1 Normative References
4.2 Informative References
A Change Log (Non-Normative)
SOAP Version 1.2 (SOAP) provides a request-response MEP and a request-response Bindins. This specification provides a 1 way + fault MEP and a 1 or 2 connection binding.
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 [RFC 2119].
This specification uses a number of namespace prefixes throughout; they are listed in ???. Note that the choice of any namespace prefix is arbitrary and not semantically significant (see XML Infoset [XML InfoSet]).
| Prefix | Namespace | Notes |
|---|---|---|
| env | "http://www.w3.org/2003/05/soap-envelope" | Defined by SOAP 1.2 Part 1 [SOAP Part 1]. |
| xs | "http://www.w3.org/2001/XMLSchema" | Defined in the W3C XML Schema specification [XML Schema Part 1], [XML Schema Part 2]. |
Namespace names of the general form "http://example.org/..." and "http://example.com/..." represent application or context-dependent URIs (see RFC 2396 [RFC 2396]).
This specification uses the Extended Backus-Naur Form (EBNF) as described in XML 1.0 [XML 1.0].
With the exception of examples and sections explicitly marked as "Non-Normative", all parts of this specification are normative.
This section defines the message exchange pattern (MEP) called "Robust Request". The description is an abstract presentation of the operation of this MEP. It is not intended to describe a real implementation or to suggest how a real implementation should be structured.
This message exchange pattern is identified by the URI (see SOAP 1.2 Part 1 [SOAP Part 1]SOAP Features):
"http://www.w3.org/2005/6/ws-addr/mep/robustrequest/"
The SOAP Robust Request MEP defines a pattern for the exchange of a SOAP message acting as a request optionally followed by a SOAP Fault. In the absence of failure in the underlying protocol, this MEP consists of one SOAP message and one optional SOAP Fault
A request message which contains a SOAP envelope.
An optional response message which contains SOAP Fault.
Abnormal operation during a Request message exchange might be caused by a failure to transfer the request message, a failure at the responding SOAP node to process the request message, or failure to transfer the optional binding-specific response message. Such failures might be silent at either or both of the requesting and recieving SOAP nodes involved, or might result in the generation of a SOAP or binding-specific fault (see ???). Also, during abnormal operation each SOAP node involved in the message exchange might differ in its determination of the successful completion of the message exchange.
The scope of a Robust Request MEP is limited to the exchange of a request message between one requesting and one responding SOAP node and the exchange of an optional binding specific response message. Implementations MAY choose to support multiple ongoing requests (and associated response processing) at the same time.
The One-way + Optional Additional Connection SOAP HTTP binding provides a binding of SOAP to HTTP. The binding conforms to the SOAP Protocol Binding Framework (see SOAP 1.2 Part 1 [SOAP Part 1]SOAP Protocol Binding Framework) and supports the message exchange patterns and features described in ???.
This binding is intended for one-way with optional fault message exchanges, request response exchanges using two different HTTP Connections (async two-way HTTP), as the request binding in request response exchange using HTTP for the request and a different protocol for the response, and as the response binding in a request response exchange using a non HTTP protocol for the request and HTTP for the response.
The algorithm is:
If (MEP==Robust in-only) then
Message is transmitted using HTTP
Optional Fault is transmitted
If (MEP==Request-Response) then
Request Message is transmitted using HTTP
If No response address specified then
Set Fault to no response address, exit
MEP is set to Robust in-only
If response binding is empty then
set response binding to HTTP One-way + Optional Additional Connection binding
Response Message is transmitted by specified binding
There are a few design points worth noting. Firstly, the state machine for the receiving node when responding remains as sending+receiving. The receiving node could commence the use of the second binding at any time after it has started receiving the request message. This parallelism is difficult to model in single threaded state machines. It is approximated by the use of the second binding for the response, with no constraints placed upon timing of the start or finish of the 2nd binding. Secondly, this binding uses a second binding with Robust in-only mep for the response part of the request-response mep. The SOAP binding framework does not specify any scoping rules for such a nesting of bindings, and particularly for the properties or features used. However, it is not precluded so this binding assumes that nesting is possible. Thirdly, this binding adds properties that are not specified in the binding framework or in any of the used meps. The binding framework does not appear to preclude extending the binding framework in this way.
The One-way + Optional Additional Connection SOAP HTTP binding is optional and SOAP nodes are NOT required to implement it. A SOAP node that correctly and completely implements the One-way + Optional Additional Connection SOAP HTTP binding SOAP HTTP Binding may to be said to "conform to the WS-Addressing One-way + Optional Additional Connection SOAP HTTP Binding."
The WS-Addressing One-way + Optional Additional Connection SOAP HTTP binding defines a base URI according to the rules in HTTP/1.1 [RFC 2616]. I.e. the base URI is the HTTP Request-URI or the value of the HTTP Content-Location header field.
This binding of SOAP to HTTP is intended to make appropriate use of HTTP as an application protocol. For example, successful responses are sent with status code 200, and failures are indicated as 4XX or 5XX. This binding is not intended to fully exploit the features of HTTP, but rather to use HTTP specifically for the purpose of communicating with other SOAP nodes implementing the same binding. Therefore, this HTTP binding for SOAP does not specify the use and/or meaning of all possible HTTP methods, header fields and status responses. It specifies only those which are pertinent to the ??? or the ???, or which are likely to be introduced by HTTP mechanisms (such as proxies) acting between the SOAP nodes.
Certain optional features provided by this binding depend on capabilities provided by HTTP/1.1, for example content negotiation. Implementations SHOULD thus use HTTP/1.1 [RFC 2616] (or later compatible versions that share the same major version number). Implementations MAY also be deployed using HTTP/1.0, although in this case certain optional binding features may not be provided.
Note:
WS-Addressing One-way + Optional Additional Connection SOAP HTTP binding implementations need to account for the fact that HTTP/1.0 intermediaries (which may or may not also be SOAP intermediaries) may alter the representation of SOAP messages, even in situations where both the initial SOAP sender and ultimate SOAP receiver use HTTP/1.1.
Particularly when used with the ???, the HTTP messages
produced by this binding are likely to be
indistinguishable from those produced by non-SOAP implementations
performing similar operations.
Accordingly, some degree of interoperation can be made possible between SOAP nodes and other HTTP
implementations when using this binding.
For example, a conventional Web server (i.e. one not
written specifically to conform to this specification) might be used to respond
to SOAP-initiated HTTP GET's with representations of
Content-Type"application/soap+xml".
Such interoperation is not a normative feature of this specification.
Even though HTTP often is used on the well-known TCP port 80, the use of HTTP is not limited to that port. As a result, it is possible to have a dedicated HTTP server for handling SOAP processing on a distinct TCP port. Alternatively, it is possible to use a separate virtual host for dealing with SOAP processing. Such configuration, however, is a matter of convenience and is not a requirement of this specification (see SOAP 1.2 Part 1 [SOAP Part 1]Binding to Application-Specific Protocols).
Conforming implementations of this binding:
MUST be capable of sending and receiving messages serialized using media type "application/soap+xml" whose proper use and parameters are described in ???.
MAY send requests and responses using other media types providing that such media types provide for at least the transfer of SOAP XML Infoset.
MAY, when sending requests, provide an HTTP Accept header field. This header field:
SHOULD indicate an ability to accept at minimum "application/soap+xml".
MAY additionally indicate willingness to accept other media types that satisfy 2 above.
This binding is identified by the URI (see SOAP 1.2 Part 1 [SOAP Part 1]SOAP Protocol Binding Framework):
"http://www.w3.org/2005/6/ws-addr/bindings/onewayHTTPandoptionaladditionalconnection/"
An implementation of the WS-Addressing One-way + Optional Additional Connection SOAP HTTP binding MUST support at least BOTH of the following message exchange patterns (MEPs):
An implementation of the WS-Addressing One-way + Optional Additional Connection SOAP HTTP binding MUST support the following features:
"http://www.w3.org/2003/05/soap/features/action/" (see ???)
An implementation of the WS-Addressing One-way + Optional Additional Connection SOAP HTTP binding MUST support the following properties:
"http://www.w3.org/2005/6/ws-addr/binding/responsebinding" A binding for the response of the request-response mep
"http://www.w3.org/2005/6/ws-addr/binding/responseURI" A uri for the response of the request-response mep
For binding instances conforming to this specification:
A SOAP node instantiated at an HTTP client may assume the role (i.e. the
property http://www.w3.org/2003/05/soap/bindingFramework/ExchangeContext/Role) of
"RequestingSOAPNode".
A SOAP node instantiated at an HTTP server may assume the role (i.e.
the property http://www.w3.org/2003/05/soap/bindingFramework/ExchangeContext/Role) of
"RespondingSOAPNode".
The remainder of this section describes the MEP state machine
and its relation to the HTTP protocol. In the state tables below,
the states are defined as values of the property http://www.w3.org/2003/05/soap/bindingFramework/ExchangeContext/State
(see ??? and ???), and are of type xs:anyURI.
For brevity, relative URIs are used, the base URI being the value of http://www.w3.org/2003/05/soap/bindingFramework/ExchangeContext/Role.
The message exchange pattern in use is not indicated in this binding. This information SHOULD be conveyed by a mechanism outside of this binding.
The overall flow of the behavior of a requesting SOAP node follows a state machine description consistent with either ??? or ??? (differences are indicated as necessary.) This binding supports streaming and, as a result, requesting SOAP nodes MUST avoid deadlock by accepting and if necessary processing binding-specific response information while the SOAP request is being transmitted (see 2.3 State Machine Description). The following subsections describe each state in detail.
In the "Init" state, a HTTP request is formulated according to ??? and transmission of the request is initiated.
| Field | Value |
|---|---|
| HTTP Method | According to the http://www.w3.org/2003/05/soap/features/web-method/Method property. POST is the only value supported by this binding. |
| Request URI | The value of the URI carried in the
http://www.w3.org/2003/05/soap/mep/ImmediateDestination property of the
message exchange context. |
Content-Type header field | The media type of the request entity body (if present) otherwise,
omitted (see ??? for a description of permissible media types).
If the SOAP envelope infoset in the http://www.w3.org/2003/05/soap/mep/OutboundMessage property is null,
then the Content-Type header field MAY be omitted. |
action parameter | According to the value of the |
Accept header field (optional) | List of media types that are acceptable in response to the request message. |
Additional header fields | Generated in accordance with the rules for the binding specific expression of any optional features in use for this message exchange. For example, a Content-Encoding header field (see HTTP [RFC 2616], section 14.11) may be used to express an optional compression feature. |
| HTTP entity body | SOAP message serialized according to the rules for
carrying SOAP messages in the media type given by the
Content-Type header field. Rules for carrying SOAP messages in
media type "application/soap+xml" are given
in ???. If the SOAP envelope infoset in the
|
In the "Requesting" state, sending of the request continues while waiting for the start of the optional fault response message. ??? details the transitions that take place when a requesting SOAP node receives an HTTP status line and response header fields. For some status codes there is a choice of possible next state. In cases where "Fail" is one of the choices, the next state is "Fail".
| Status Code | Reason phrase | Significance/Action | NextState |
|---|---|---|---|
| 2xx | Successful | ||
| 200 | OK | "Sending+Receiving" or "Success" | |
| 3xx | Redirection | The requested resource has
moved and the HTTP request SHOULD be retried using the URI carried in the
associated Location header field as the new value for the
| "Init" |
| 4xx | Client Error | ||
| 400 | Bad Request | Indicates a problem with the received HTTP request message. | "Sending+Receiving" or "Fail" |
| 401 | Unauthorized | Indicates that the HTTP request requires authorization. If the simple authentication feature is unavailable or the operation of simple authentication ultimately fails, then the message exchange is regarded as having completed unsuccessfully. | "Requesting" or "Fail" |
| 405 | Method not allowed | Indicates that the peer HTTP server does not support the requested HTTP method at the given request URI. The message exchange is regarded as having completed unsuccessfully. | "Fail" |
| 415 | Unsupported Media Type | Indicates that the peer HTTP server does not support the Content-type used to encode the request message. The message exchange is regarded as having completed unsuccessfully. | "Fail" |
| 5xx | Server Error | ||
| 500 | Internal Server Error | Indicates a server problem or a problem with the received request | "Sending+Receiving" or "Fail" |
??? refers to some but not all of the existing HTTP/1.1 [RFC 2616] status codes. In addition to these status codes, HTTP provides an open-ended mechanism for supporting status codes defined by HTTP extensions (see RFC 2817 [RFC 2817] for a registration mechanism for new status codes). HTTP status codes are divided into status code classes as described in HTTP [RFC 2616], section 6.1.1. The WS-Addressing One-way + Optional Additional Connection SOAP HTTP binding follows the rules of any HTTP application which means that an implementation of the WS-Addressing One-way + Optional Additional Connection SOAP HTTP binding must understand the class of any status code, as indicated by the first digit, and treat any unrecognized response as being equivalent to the x00 status code of that class, with the exception that an unrecognized response must not be cached.
Note:
There may be elements in the HTTP infrastructure configured to modify HTTP response entity bodies for 4xx and 5xx status code responses. For example, some HTTP origin servers have such a feature as a configuration option. This behavior may interfere with the use of 4xx and 5xx status code responses carrying SOAP fault messages in HTTP and it is recommended that such behavior is disabled for resources accepting SOAP/HTTP requests. If the rewriting behavior cannot be disabled, SOAP/HTTP cannot be used in such configurations.
In the "Sending+Receiving" state (??? only), the transmission of the request message and receiving of the optional fault message is completed. This response message is assumed to contain an empty body or a fault. This response message may contain a SOAP envelope serialized according to the rules for carrying SOAP messages in the media type given in the Content-Type header field. Such usage is considered non-normative, and accordingly is not modelled in the state machine.
The response MAY be of content type other than "application/soap+xml". Such usage is considered non-normative, and accordingly is not modeled in the state machine. Interpretation of such responses is at the discretion of the receiver.
The overall flow of the behavior of a responding SOAP node follows a state machine description consistent with either ??? or ??? (differences are indicated as necessary). The following subsections describe each state in detail.
In the "Init" state, the binding waits for the start of an inbound request message. ??? describes the errors that a responding SOAP node might generate while in the "Init" state. In this state no SOAP message has been received, therefore the SOAP node cannot generate a SOAP fault.
| Problem with Message | HTTP Status Code | HTTP Reason Phrase (informative) |
|---|---|---|
| Malformed Request Message | 400 | Bad request |
| HTTP Method is not POST | 405 | Method Not Allowed |
| Unsupported message encapsulation method | 415 | Unsupported Media |
In the "Receiving" state, the binding receives the request and any associated message and waits for the start of a response message to be available. ??? describes the HTTP response header fields generated by the responding SOAP node. ??? describes the HTTP status codes that can be generated by the responding SOAP node.
| Field | Value |
|---|---|
| Status line | 200, or set according to ??? if a SOAP fault was generated. |
Content-Type header field | The media type of the response body, see ??? for a description of permissible media types. |
Additional header fields | Generated in accordance with the rules for the binding specific expression of any optional features in use for this message exchange. For example, a Content-Encoding header field (see HTTP [RFC 2616], section 14.11) may be used to express an optional compression feature. |
| HTTP Entity Body | It MAY contain a SOAP Fault message serialized according to the rules for carrying SOAP messages in the media type given by the Content-Type header field. Rules for carrying SOAP messages in "application/soap+xml" are given in ???. |
| SOAP Fault | HTTP Status Code | HTTP Reason Phrase (informative) |
|---|---|---|
| env:VersionMismatch | 500 | Internal server error |
| env:MustUnderstand | 500 | Internal server error |
| env:Sender | 400 | Bad request |
| env:Receiver | 500 | Internal server error |
| env:DataEncodingUnknown | 500 | Internal server error |
In the "Receiving+Sending" state the binding completes receiving of the request message, transmission of the optional Fault response message and transmission of any response message. If the mep selected is request-response ??? then the response message is sent. The response binding is specified by http://www.w3.org/2005/6/ws-addr/binding/responsebinding property. If the property is empty or contains no value, then this binding is selected. The response location is specified by the http://www.w3.org/2005/6/ws-addr/binding/responseURI property. In using the response binding, the one-way MEP is specified for sending the response. It is an error for the request-response MEP to be selected and the http://www.w3.org/2005/6/ws-addr/binding/responseURI to be unset, but there is no constraint specified for when the property must be set in the state machine. It is possible that the property will be set after the responding node has finished sending the HTTP response.
The One-way + Optional Additional Connection SOAP HTTP Binding (see ???) can be considered as an extension of the HTTP application protocol. As such, all of the security considerations identified and described in section 15 of the HTTP specification [RFC 2616] apply to the WS-Addressing One-way + Optional Additional Connection SOAP HTTP binding in addition to those described in SOAP 1.2 Part 1 [SOAP Part 1]Security Considerations. Implementors of the WS-Addressing One-way + Optional Additional Connection SOAP HTTP binding should carefully review this material.