6. SOAP-Supplied Message Exchange Patterns and Features

6.4 SOAP One-way Message Exchange Pattern

This section defines the message exchange pattern (MEP) called "One-way". 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.

6.4.1 SOAP Feature Name

This message exchange pattern is identified by the URI (see SOAP 1.2 Part 1 [SOAP Part 1] SOAP Features):

  • "http://www.w3.org/2003/05/soap/mep/one-way/

6.4.2 Description

The SOAP one-way MEP defines the exchange of a single SOAP message between a sender and a receiver. In the absence of failure in the underlying protocol, this MEP consists of exactly one SOAP message.

In the normal operation of a message exchange conforming to the one-way MEP, the message is first transferred from the sending SOAP node to the receiving SOAP node.

Abnormal operation during a One-way message exchange is be caused by a failure to transfer the message. Such failure might be silent at either or both of the sending and receiving SOAP nodes involved, or might result in the generation of a SOAP or binding-specific fault (see 6.4.4 Fault Handling). Also, during abnormal operation the SOAP nodes involved in the message exchange might differ as to whether the message exchange completed successfully.

The scope of a one-way MEP is limited to the exchange of single message between one sending and one receiving SOAP node. This pattern does not mandate any correlation between multiple messages nor specific timing for multiple messages. Implementations MAY choose to support more complex patterns of interaction.

6.4.3 State Machine Description

The One-way MEP defines a set of properties described in Table 3.

Table 3: Property definitions for Request-Response MEP
Property Name Property Description Property Type
http://www.w3.org/2003/05/soap/mep/OutboundMessage An abstract structure that represents the current outbound message in the message exchange. This abstracts both SOAP Envelope and any other information structures that are transferred along with the envelope. Not specified
http://www.w3.org/2003/05/soap/mep/ImmediateDestination The identifier of the immediate destination of an outbound message. xs:anyURI

To initiate a message exchange conforming to the One-way MEP, the sending SOAP node instantiates a local message exchange context.Table 4 describes how the context is initialized.

Table 4: Instantiation of a Message Exchange Context for a requesting SOAP node
Property Name Property Value Notes
http://www.w3.org/2003/05/soap/bindingFramework/ExchangeContext/ExchangePatternName "http://www.w3.org/2003/05/soap/mep/one-way/"  


A relative URI whose base URI is the value of http://www.w3.org/2003/05/soap/bindingFramework/ExchangeContext/ExchangePatternName



A relative URI whose base URI is the value of http://www.w3.org/2003/05/soap/bindingFramework/ExchangeContext/ExchangePatternName



A relative URI whose base URI is the value of http://www.w3.org/2003/05/soap/bindingFramework/ExchangeContext/Role

http://www.w3.org/2003/05/soap/mep/OutboundMessage An abstraction of the message  
http://www.w3.org/2003/05/soap/mep/ImmediateDestination An identifier (URI) that denotes the receiving SOAP node  

There may be other properties related to the operation of the message exchange context instance. Such properties are initialized according to their own feature specifications.

Once the message exchange context is initialized, control of the context is passed to a (conforming) local binding instance.

The diagram below shows the logical state transitions at the requesting and responding SOAP nodes during the lifetime of the message exchange. At each SOAP node, the local binding instance updates (logically) the value of the http://www.w3.org/2003/05/soap/bindingFramework/ExchangeContext/State property to reflect the current state of the message exchange. The state names are relative URIs, relative to a base URI value carried in the http://www.w3.org/2003/05/soap/bindingFramework/ExchangeContext/Role property of the local message exchange context.

<figure omitted>

Figure 2: One-way MEP State Transition Diagram.

When the requesting and responding SOAP nodes transition between states, the local binding instance (logically) updates a number of properties. Table 6 and Table 7 describe these updates for the requesting and the responding SOAP nodes, respectively.
Table 6: SendingSOAP Node State Transitions
CurrentState Transition Condition NextState Action
"Init" Message transmission failure "Fail" Set http://www.w3.org/2003/05/soap/bindingFramework/ExchangeContext/FailureReason to "transmissionFailure"
Completed message transmission
Table 7: Receiving SOAP Node State Transitions
CurrentState Transition Condition NextState Action
"Init" Message reception failure "Fail" Set http://www.w3.org/2003/05/soap/bindingFramework/ExchangeContext/FailureReason to "receptionFailure".
Message received. Message available in http://www.w3.org/2003/05/soap/mep/InboundMessage "Success"

6.4.4 Fault Handling

This MEP makes no claims about the disposition or handling of SOAP faults generated by the either SOAP node.