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This document describes the SOAP Usage Scenarios and how they may be 
 implemented using the SOAP 1.2 specification.
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.

 The WG has decided to discontinue work on SOAP Version 1.2 Usage Scenarios, and on this document. 
 The WG developed the SOAP Version 1.2 Usage Scenario to help develop SOAP Version 1.2. The scenarios have served their purpose in this regard, and the WG no longer intends to work on them.
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1. <a href="#intro"="">Introduction</a><br="">2. <a href="#description"="">Documentation of Usage Scenarios</a><br="">3. <a href="#N1052D"="">References</a><br="">A. <a href="#acks"="">Acknowledgements</a> (Non-Normative)<br="">
1. Introduction
2. Documentation of Usage Scenarios
2.1 S1 Fire-and-forget to single receiver
2.1.1 Scenario Definition
2.1.2 Description
2.2 S2 Fire-and-forget to multiple receivers
2.2.1 Scenario Definition
2.2.2 Description
2.3 S3 Request/Response
2.3.1 Scenario Definition
2.3.2 Description
2.4 S4 Remote Procedure Call (RPC)
2.4.1 Scenario Definition
2.4.2 Description
2.5 S5 Request with acknowledgement
2.5.1 Scenario Definition
2.5.2 Description
2.6 S6 Request with encrypted payload
2.6.1 Scenario Definition
2.6.2 Description
2.7 S7 Third party intermediary
2.7.1 Scenario Definition
2.7.2 Description
2.8 S8 Conversational message exchange
2.8.1 Scenario Definition
2.8.2 Description
2.9 S10 Message header and payload encryption
2.9.1 Scenario Definition
2.9.2 Description
2.10 S11 Communication via multiple intermediaries
2.10.1 Scenario Definition
2.10.2 Description
2.11 DS17 Asynchronous messaging
2.11.1 Scenario Definition
2.11.2 Description
2.12 S19 Sending non-XML data
2.12.1 Scenario Definition
2.12.2 Description
2.13 S20 Multiple asynchronous responses
2.13.1 Scenario Definition
2.13.2 Description
2.14 S21 Incremental parsing/processing of SOAP messages
2.14.1 Scenario Definition
2.14.2 Description
2.15 S23 Event notification
2.15.1 Scenario Definition
2.15.2 Description
2.16 DS24 Caching
2.16.1 Scenario Definition
2.16.2 Description
2.17 S805 Routing
2.17.1 Scenario Definition
2.17.2 Description
2.18 S807 Tracking
2.18.1 Scenario Definition
2.18.2 Description
2.19 S809 Caching with expiration
2.19.1 Scenario Definition
2.19.2 Description
2.20 S810 Quality of service
2.20.1 Scenario Definition
2.20.2 Description
3. References
3.1 Informative References
A. <a href="#acks"="">Acknowledgements</a> (Non-Normative)<br="">

 A sender wishes to send an unacknowledged message to a single receiver 
 (e.g. send a stock price update every 15 minutes).


 A fire-and-forget feature in scenario S1 requires a mechanism to send a 
 message to a single SOAP Receiver and is illustrated in Figure 1. The SOAP 
 Sender does not require any status information that the message has been 
 sent to or received by the recipient. The underlying transport protocol 
 may implement a response mechanism, but status on whether the message was 
 successfully sent or otherwise is not returned to the sending SOAP Processor. 

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Body>; 
 <;r:StockPriceUpdate xmlns:r="http://example.org/2001/06/quotes">;
 <;r:Symbol>;BigCo<;/r:Symbol>;
 <;r:Price>;34.5<;/r:Price>;
 <;/r:StockPriceUpdate>;
 <;/env:Body>;
<;/env:Envelope>;

 A sender wishes to send unacknowledged messages to a set of receivers 
 (e.g. send a stock price update every 15 minutes).


 Scenario S2 extends S1 to implement a fire-and-forget feature to multiple 
 SOAP Receivers and is illustrated in Figure 2. This requires a mechanism 
 to deliver the same message to multiple SOAP Receivers. The delivery of 
 the messages could be implemented using multicast distribution technology 
 if the underlying transport layer supports this. An alternative 
 implementation may use repeated applications of scenario S1 with a 
 distribution list of intended recipients.


 Two parties wish to conduct electronic business by the exchange of business 
 documents. The sending party packages one or more documents into a request 
 message, which is then sent to the receiving party. The receiving party then 
 processes the message contents and responds to the sending party. Examples of 
 the sending party's documents may be purchase order requests, manufacturing 
 information and patient healthcare information. Examples of the receiving 
 party's responses may include order confirmations, change control information 
 and contractual acknowledgements.


 Scenario S3 requires a request/response message feature. A request 
 containing some business document is sent by a SOAP Sender to a SOAP Receiver 
 where some business application is invoked. The business application 
 processes the request and generates a response, which is returned to the 
 SOAP Sender that originated the request. Two alternative solutions are 
 described which depend upon the characteristics of the underlying transport 
 layer. In either case, the SOAP Sender is informed of the status (successful 
 or otherwise) of the request message delivery.


 If the underlying transport protocol supports the correlation of a request 
 and its matching response directly, then the solution illustrated in Figure 3 
 may be appropriate. An example of such an underlying transport protocol would 
 be a synchronous HTTP POST. This implementation would make use of the 
 transport binding proposed in other XML Protocol WG documents. The business 
 document sent as a request by the SOAP Sender would be inserted as the 
 payload of the request message. Following the receipt of the request, the 
 processing application would generate a document which would be returned 
 as the payload of the response message with appropiate status codes. If for 
 whatever reason, the request message was not received or processed by the 
 intended business application, suitable status messages would be generated 
 by the underlying transport layer and reported to the SOAP Sender.


 If the underlying transport protocol does not support a request/response 
 model, then the configuration shown in Figure 4 may be appropriate. Examples 
 of such an underlying protocol may include unidirectional queuing middleware. 
 In this case, message identification and correlation is provided by SOAP 
 Headers. In the request SOAP message, a Message Identifier Handler is 
 responsible for generating a unique message identifier and inserting it into 
 a SOAP Header. This forms part of the SOAP request message and is sent from 
 SOAP Application 1 to the receiving SOAP Application 2. The request message 
 is processed by a business application and a response message is assembled. 
 This includes a SOAP Header built by a Message Correlation Handler which 
 links the response message to its associated request.

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Header>;
 <;n:MsgHeader xmlns:n="http://example.org/requestresponse">;
 <;n:MessageId>;uuid:09233523-345b-4351-b623-5dsf35sgs5d6<;/n:MessageId>;
 <;/n:MsgHeader>;
 <;/env:Header>;
 <;env:Body>;
 ........
 <;/env:Body>;
<;/env:Envelope>;
<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Header>;
 <;n:MsgHeader xmlns:n="http://example.org/requestresponse">;
 <;n:MessageId>;uuid:09233523-567b-2891-b623-9dke28yod7m9<;/n:MessageId>;
 <;n:ResponseTo>;uuid:09233523-345b-4351-b623-5dsf35sgs5d6<;/n:ResponseTo>;
 <;/n:MsgHeader>;
 <;/env:Header>;
 <;env:Body>;
 ........
 <;/env:Body>;
<;/env:Envelope>;

 The sender invokes the service by passing parameters that are serialized 
 into a message for transmission to the receiving server.


 Scenario S4 differs from scenario S3 in that the request message consists of 
 a set of serialized parameters used to invoke some remote procedure which 
 responds with a set of results. This is a different programming model to the 
 document exchange one illustrated by scenario S3. Scenario S4 requires a 
 request/response mechanism as in S3, with the parameter and result 
 serialization needed for the RPC programming model form the SOAP Body 
 element. 


 Figure 5 illustrates an RPC invocation over an underlying transport protocol 
 such as HTTP that supports request/response. In this case, no additional 
 headers are needed to correlate the request and response messages. Example 
 request and response SOAP messages are:

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Body>;
 <;r:GetLastTradePrice env:encodingStyle="http://www.w3.org/2001/09/soap-encoding"
 xmlns:r="http://example.org/2001/06/quotes">;
 <;r:Symbol>;DEF<;/r:Symbol>;
 <;/r:GetLastTradePrice>;
 <;/env:Body>;
<;/env:Envelope>;

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Body>;
 <;r:GetLastTradePriceResponse env:encodingStyle="http://www.w3.org/2001/09/soap-encoding"
 xmlns:r="http://example.org/2001/06/quotes"
 xmlns:rpc="http://www.w3.org/2001/09/soap-rpc">;
 <;rpc:Result>;34.5<;/rpc:Result>;
 <;/r:GetLastTradePriceResponse>;
 <;/env:Body>;
<;/env:Envelope>;


 In Figure 6, the underlying transport protocol does not support 
 request/response directly. The RPC request and response elements again form 
 the Body of the SOAP messages. Correlation of the request and response is 
 provided by the Message Identifier and Message Correlation handlers as 
 described in scenario S3.

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Header>;
 <;n:MsgHeader xmlns:n="http://example.org/requestresponse">;
 <;n:MessageId>;uuid:09233523-345b-4351-b623-5dsf35sgs5d6<;/n:MessageId>;
 <;/n:MsgHeader>;
 <;/env:Header>;
 <;env:Body>;
 <;r:GetLastTradePrice env:encodingStyle="http://www.w3.org/2001/09/soap-encoding"
 xmlns:r="http://example.org/2001/06/quotes">;
 <;r:Symbol>;DEF<;/r:Symbol>;
 <;/r:GetLastTradePrice>;
 <;/env:Body>;
<;/env:Envelope>;

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Header>;
 <;n:MsgHeader xmlns:n="http://example.org/requestresponse">;
 <;n:MessageId>;uuid:09233523-567b-2891-b623-9dke28yod7m9<;/n:MessageId>;
 <;n:ResponseTo>;uuid:09233523-345b-4351-b623-5dsf35sgs5d6<;/n:ResponseTo>;
 <;/n:MsgHeader>;
 <;/env:Header>;
 <;env:Body>; 
 <;r:GetLastTradePriceResponse env:encodingStyle="http://www.w3.org/2001/09/soap-encoding"
 xmlns:r="http://example.org/2001/06/quotes"
 xmlns:rpc="http://www.w3.org/2001/09/soap-rpc">;
 <;rpc:Result>;34.5<;/rpc:Result>;
 <;/r:GetLastTradePriceResponse>;
 <;/env:Body>;
<;/env:Envelope>;


 A sender wishes to reliably exchange data with a receiver. It wishes to be 
 notified of the status of the data delivery to the receiver. The status may 
 take the form of:

The data has been successfully delivered to the receiver, or
Some failure has occurred which prevents the successful delivery to the receiver.

 Figure 7 illustrates a request/response scenario with the SOAP Sender 
 requesting status information from the matching SOAP Receiver. This status 
 may provide delivery information to the sender in addition to other business 
 related responses that the receiving application may generate. Figure 7 
 assumes that the underlying transport protocol supports the request/response 
 exchange model. A Status Handler is registered with the SOAP Sender and 
 configured to request the status information. A matching handler on the SOAP 
 Receiver generates the requested status information and places it in the 
 response message which is then returned to the originating SOAP Sender.


 In the example SOAP messages below, a StatusRequest header element includes 
 an identifier for the message being sent. The inclusion of the StatusRequest 
 header results in the receiving SOAP processor including a StatusResponse 
 Header in the response. This includes information about the delivered message 
 including an enumerated status and timestamp.

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Header>;
 <;n:StatusRequest xmlns:n="http://example.org/status">;
 <;n:MessageId>;uuid:09233523-345b-4351-b623-5dsf35sgs5d6<;/n:MessageId>;
 <;/n:StatusRequest>;
 <;/env:Header>;
 <;env:Body>;
 -----
 <;/env:Body>;
<;/env:Envelope>;

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Header>;
 <;n:StatusResponse xmlns:n="http://example.org/status">;
 <;n:MessageId>;uuid:09233523-567b-2891-b623-9dke28yod7m9<;/n:MessageId>;
 <;n:MessageStatus>;DELIVERED<;/n:MessageStatus>;
 <;n:Timestamp>;2001-03-09T12:22:30Z<;/n:Timestamp>;
 <;/n:StatusResponse>;
 <;/env:Header>;
 <;env:Body>; 
 -----
 <;/env:Body>;
<;/env:Envelope>;


 A sender wishes to exchange data with a receiver and has agreed to encrypt 
 the payload. The sending and receiving applications agree on the encryption 
 methodology. Data is encrypted by the originating application and sent to 
 the receiver via SOAP. The data reaches the receiving application untouched, 
 and may then be decrypted in the agreed-upon manner.


 Scenario S6 describes two applications that wish to share encrypted data as an 
 opaque body in a SOAP message. It places no requirements on the SOAP messaging 
 layer. Figure 8 illustrates this scenario. 

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Body>;
 <;m:GetLastTradePrice xmln:m="some-URI">;
 <;m:symbol>;IBM<;/m:symbol>;
 <;/m:GetLastTradePrice>;
 <;/env:Body>;
<;/env:Envelope>;


 The following is the encrypted version of the above plain SOAP message. The 
 body entry <;m:GetLastTradePrice>; is encrypted using a symmetric key 
 identified by the key name "Symmetric Key" and replaced by the 
 <;xenc:EncryptedData>; element with an id "encrypted-body-entry". 
 A <;sec:Encryption>; header entry for this encrypted data is added 
 to the SOAP header. Note that the <;sec:EncryptedDataList>; element 
 in the header entry has a reference to the <;xenc:EncryptedData>; element. 
 The symmetric key used for encryption is stored in the <;xenc:EncryptedKey>; 
 element in the header entry in an encrypted form, that is, it is encrypted by 
 John Smith's RSA public key. 

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Header>;
 <;sec:Encryption xmlns:sec="http://schemas.xmlsoap.org/soap/security/2000-12"
 env:actor="some-URI"
 env:mustUnderstand="true">;
 <;sec:EncryptedDataList>;
 <;sec:EncryptedDataReference URI="#encrypted-body-entry"/>;
 <;/sec:EncryptedDataList>;
 <;xenc:EncryptedKey xmlns:xenc="http://www.w3.org/2001/04/xmlenc#"
 Id="EK"
 CarriedKeyName="Symmetric Key"
 Recipient="John Smith">;
 <;xenc:EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#rsa-1_5"/>;
 <;ds:KeyInfo xmlns:ds="http://www.w3.org/2000/09/xmldsig#">;
 <;ds:KeyName>;John Smith's RSA Key<;/ds:KeyName>;
 <;/ds:KeyInfo>;
 <;xenc:CipherData>;
 <;xenc:CipherValue>;ENCRYPTED 3DES KEY......<;/xenc:CipherValue>;
 <;/xenc:CipherData>; 
 <;xenc:ReferenceList>;
 <;xenc:DataReference URI="#encrypted-body-entry"/>;
 <;/xenc:ReferenceList>;
 <;/xenc:EncryptedKey>;
 <;/sec:Encryption>;
 <;/env:Header>;
 <;env:Body>;
 <;xenc:EncryptedData xmlns:xenc="http://www.w3.org/2001/04/xmlenc#"
 Id="encrypted-body-entry"
 Type="http://www.w3.org/2001/04/xmlenc#Element">;
 <;xenc:EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#tripledes-cbc"/>;
 <;ds:KeyInfo xmlns:ds="http://www.w3.org/2000/09/xmldsig#">;
 <;ds:RetrievalMethod URI="#EK" Type="http://www.w3.org/2001/04/xmlenc#EncryptedKey"/>;
 <;ds:KeyName>;Symmetric Key<;/ds:KeyName>;
 <;/ds:KeyInfo>;
 <;xenc:CipherData>;
 <;xenc:CipherValue>;ENCRYPTED BODY ENTRY......<;/xenc:CipherValue>;
 <;/xenc:CipherData>; 
 <;/xenc:EncryptedData>;
 <;/env:Body>;
<;/env:Envelope>;


 A blind auction marketplace serves as a broker between buyers and suppliers. 
 Buyers submit their requirements to the marketplace hub, which broadcasts 
 this information to multiple suppliers. Suppliers respond to the marketplace 
 hub where the information is logged and ultimately delivered to the buyer.


 Figure 9 illustrates an infrastructure where SOAP based messaging is used to 
 support a third party marketplace acting as an intermediary between buyers and 
 sellers. The market place business model involves the recruitment of multiple 
 suppliers for goods and services. Buyers may then connect to the marketplace 
 and take advantage of the services they provide. The marketplace acts as a 
 channel for the commercial transactions between a buyer and its chosen seller. 
 A marketplace can exist to serve both B2B and B2C transactions.


 In scenario S7, the marketplace acts as a blind intermediary. A buyer connects 
 to the marketplace and places an order for items or services it requires. The 
 buyer may be as simple as a browser or as complex as a procurement application. 
 Once the marketplace has received the buyer&rsquo;s order, it contacts an appropriate
 set of sellers who then provide competitive bids aginst the order. The 
 marketplace can then select the most attractive bid and connect the winning 
 seller to the buyer. A purchasing process is then initiated with the 
 marketplace acting as an intermediary in the transaction.


 From a SOAP messaging point of view, the scenario illustrated in Figure 9 
 consists of a set of request/response messages between the buyer and the 
 marketplace resulting in the buyer&rsquo;s order being registered. Once received, 
 the marketplace then contacts its set of selected sellers again by a set 
 of request/response messages. Design decisions made during the implementation 
 of the marketplace software will determine whether supplier messages are sent 
 from a single SOAP Sender to multiple SOAP Receivers, one at each of the 
 seller&rsquo;s sites. Alternatively, a SOAP Sender could be instantiated for each 
 supplier and a physical 1:1 relationship established. Prior agreements on 
 message qualities such as reliability, security and structure would be put in 
 place between the marketplace and its sellers. These qualities would define 
 what additional SOAP Handlers were needed for the message exchange patterns 
 between the marketplace and sellers.


 Two partners are engaged in a long-running process, which involves multiple 
 message exchanges. Examples of such processes may be complex supply chain 
 management, dynamic manufacturing scheduling or information retrieval. There 
 may be multiple instances of the same process in progress between the same 
 two partners.


 Interactions between business partners are usually more complex than a 
 single request/response message exchange. A long running set of message 
 exchanges may, for example be used to implement a business interaction such 
 as procurement of goods or services. In this case there are advantages in 
 grouping individual messages into a longer running set of exchanges. Such an 
 exchange of messages is known as a conversation. Conversations may continue 
 between a pair of trading partners for a long time. Completion of a 
 conversation instance may take days, weeks or months.


 A conversation between two trading partners may be defined by shared 
 configuration information such as an ebXML Trading Partner Agreement (TPA). 
 A TPA includes information such as expected response times, business process 
 actions that each party undertakes to complete, security information and 
 message content structures. In a procurement process, an example conversation 
 may be:

A buyer request a quotation for some goods, the seller responds with the quote.
The buyer places a puchase order which the seller accepts.
The seller informs the buyer of delivery dates, the buyer accepts.
The buyer acknowledges delivery of the goods, the seller acknowledges.
The buyer provides payment, the seller issue a receipt.

 All of the example message exchanges are related an instance of the TPA 
 between the two partners. For a message to be valid as part of the agreed 
 rules, each partner has to check whether the current message is valid within 
 the scope of the TPA.


 Figure 10 illustrates how this scenario could be implemented. Each partner&rsquo;s 
 SOAP processor has access to a database which is configured by the TPA agreed 
 between the two partners. A Conversation State Handler in the SOAP Sender 
 configures its SOAP Block with information that identifies a message with 
 conversation instance it is part of. A matching handler in the SOAP Receiver 
 uses the sender&rsquo;s information to test whether the received message is 
 acceptable within the rules of the TPA. It does this by checking with its own 
 rules database where the state information on each of the conversation 
 instances currently active is stored. If a message violates the rules of the 
 TPA, then the application can raise a fault condition.


 Note that Figure 10 does not include handlers for other message headers to 
 support reliability or security which may be required under the agreed TPA.


 In the following request and response examples, a ConversationState Header 
 is used to identify which agreement governs the exchange between the two 
 trading partners (AgreementId). To support multiple concurrent conversations 
 under the same agreement, a ConversationId element is included. The values of 
 AgreementId and ConversationId will remain constant for the lifetime of a 
 particular conversational exchange and will appear in both request and 
 response messages. 

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Header>;
 <;n:ConversationState xmlns:n="http://example.org/conversation">;
 <;n:AgreementId>;uuid:09233523-345b-4351-b623-5dsf35sgs5d6<;/n:AgreementId>;
 <;n:ConversationId>;uuid:02957815-38fh-39gp-0dj2-dm20fusy1n5j<;/n:ConversationId>;
 <;/n:ConversationState>;
 <;/env:Header>;
 <;env:Body>;
 -----
 <;/env:Body>;
<;/env:Envelope>;

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Header>;
 <;n:ConversationState xmlns:n="http://example.org/conversation">;
 <;n:AgreementId>;uuid:09233523-345b-4351-b623-5dsf35sgs5d6<;/n:AgreementId>;
 <;n:ConversationId>;uuid:02957815-38fh-39gp-0dj2-dm20fusy1n5j<;/n:ConversationId>;
 <;/n:ConversationState>;
 <;/env:Header>;
 <;env:Body>;
 -----
 <;/env:Body>;
<;/env:Envelope>;


 Two trading partners engaged in a message exchange may agree to 
 cryptographically sign and verify either the message header, the routing 
 header(s) and/ or the payload. The sender or originating application may 
 perform the signing of the payload. The sending message handler signs the 
 message header. A routing header may be appended to the message header. 
 The routing header may also be signed by a message service handler.


 In scenario S6, two applications communicated using encrypted payloads. 
 These opaque payloads had no impact on the SOAP processing layer. In this 
 scenario, the action of signing and/or encrypting the headers or payload 
 is the responsibility of the SOAP processing layer. Figure 11 illustrates 
 how the encryption agreements are accessible to a Message Signing Handler 
 on the SOAP Sender and a matching Message Verification Handler on the SOAP 
 Receiver. An additional Message Routing Header may also be part of the SOAP 
 message. This header may also be signed and verified if needed by the security 
 requirements of the message exchange.


 An intermediary forwards a message to the ultimate receiver on behalf of an 
 initial sender. The initial sender wishes to enforce the non-repudiation 
 property of the route. Any intermediate message service handler that appends 
 a routing message must log the routing header information. Signed routing 
 headers and the message readers must be logged at the message handler which 
 passes the message to the ultimate receiver to provide the evidence of 
 non-repudiation.


 Scenario S11 requires an audit chain to be created between a SOAP Sender that 
 originates the message and the ultimate SOAP Receiver including any SOAP 
 Intermediaries that the message passes through. Figure 12 illustrates a 
 possible implementation of this scenario. Each SOAP Node on the message 
 path has access to a persistent store (typically a database) that can be 
 used to store an audit record for each message. A Routing Logging Handler 
 on each SOAP Node has the responsibility of logging each message in the 
 persistent store. A further responsibility of the handler is to sign the 
 message routing header before passing the message on to the next SOAP Node 
 in the path. Support for certificates and other artifacts required for signing 
 a message are not shown.


 A sender sends a message asynchronously to a receiver expecting some response 
 at a later time. The sender tags the request with an identifier allowing the 
 response to be correlated with the originating request. The sender may also 
 tag the message with an identifier for another service (other than the 
 originating sender) which will be the recipient of the response.


 Scenario DS17 is the same as the basic request/response pattern described in 
 scenario S3. The difference is that the request and response messages are 
 separated in time and implemented as two unidirectional messages. The sending 
 SOAP Application does not block and wait for the response to return. The 
 sending SOAP Application is notified when a response is received by its SOAP 
 Receiver. It then uses the correlation information within the received message 
 to match the response to a message it sent some time earlier.


 Figure 11 illustrates a possible implementation. In the request SOAP message, 
 a Message Identifier Handler is responsible for generating a unique message 
 identifier and inserting it into a SOAP Header. This forms part of the SOAP 
 request message and is sent from SOAP Application 1 to the receiving SOAP 
 Application 2. The request message is processed by a business application 
 and a response message is assembled. This includes a SOAP Header built by 
 a Message Correlation Handler which links the response message to its 
 associated request.

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Header>;
 <;n:MsgHeader xmlns:n="http://example.org/requestresponse">;
 <;n:MessageId>;uuid:09233523-345b-4351-b623-5dsf35sgs5d6<;/n:MessageId>;
 <;/n:MsgHeader>;
 <;/env:Header>;
 <;env:Body>;
 ........
 <;/env:Body>;
<;/env:Envelope>;
<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Header>;
 <;n:MsgHeader xmlns:n="http://example.org/requestresponse">;
 <;n:MessageId>;uuid:09233523-567b-2891-b623-9dke28yod7m9<;/n:MessageId>;
 <;n:ResponseTo>;uuid:09233523-345b-4351-b623-5dsf35sgs5d6<;/n:ResponseTo>;
 <;/n:MsgHeader>;
 <;/env:Header>;
 <;env:Body>;
 ........
 <;/env:Body>;
<;/env:Envelope>;

 A digital camera wishes to transmit image data over a wireless link using 
 SOAP to a remote server. The binary image data (non-XML) accompanies the 
 message. The digital camera represents a situation in which connections from 
 the receiver to the sender may not be permitted due to device limitations or 
 firewalls.


 Support for non-XML data has been described elsewhere. The SOAP with 
 Attachments <a href="#SOAPAttach"="">[2]</a> note to the W3C has been adopted by the ebXML 
 Message Services specification <a href="#EBXML"="">[1]</a> as the basis for defining a message 
 structure which can support non-XML data. Supporting non-XML data requires 
 additional packaging of the message which can be provided by a MIME multipart 
 structure and impacts the binding of a message to its underlying transport 
 protocol. Figure 14 illustrates a unidirectional SOAP message path. A Message 
 Manifest Handler is implemented which creates a set of references to the 
 different parts of a multipart MIME package. Each part is referenced by its 
 content identifier.


 Figure 15 illustrates how different parts of a message are packaged using MIME 
 multipart. The outermost MIME envelope packages a set of individual MIME parts. 
 The first MIME part contains a SOAP message which includes the Manifest Header 
 block created by the Message Manifest Handler. The second and subsequent MIME 
 parts contain payload(s) which may be XML documents or any other MIME content 
 type such as image, audio or video data. The SOAP manifest header can contain 
 elements that reference the separate MIME parts using their content identifiers. 
 This may be achieved using XLink references as shown in the following example. 
 The XLink role attribute may be used to further qualify the type of data 
 contained within the payload.

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Header>;
 <;n:Manifest xmlns:n="http://example.org/manifest">;
 <;n:Reference n:id="image01" 
 xlink:href="cid:payload-1"
 xlink:role="http://example.org/image">;
 <;n:Description>;My first holiday photograph<;/n:Description>;
 <;/n:Reference>;
 <;n:Reference n:id="image02"
 xlink:href="cid:payload-2"
 xlink:role="http://example.org/image">;
 <;n:Description>;My second holiday photograph<;/n:Description>;
 <;/n:Reference>;
 <;/n:Manifest>;
 <;/env:Header>;
 <;env:Body>;
 ........ 
 <;/env:Body>;
<;/env:Envelope>;


 An application requests some information from a server, which is returned at a 
 later time in multiple responses. This can be because the requested information 
 was not available all at once (e.g., distributed web searches).


 Scenario S20 is an extension of scenario DS17 - asynchronous messaging. 
 Instead of a single response message, more than one can be sent by the 
 receiving application to the originator. A simple architecture would be 
 the same as DS17 with multiple responses received by the originating 
 application and corelated to the original request by a Message Correlation 
 Handler. Figure 15 illustrates an extension to this using a Sequence Handler. 
 The Sequence Handler ensures that a unique sequence number is added to each 
 response message. If the responding application knows in advance that there 
 will be a fixed number of multiple responses, then the Sequence Handler may 
 use an N of M format to indicate how many response messages are to be expected.

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Header>;
 <;n:MsgHeader xmlns:n="http://example.org/requestresponse">;
 <;n:MessageId>;uuid:09233523-345b-4351-b623-5dsf35sgs5d6<;/n:MessageId>;
 <;/n:MsgHeader>;
 <;/env:Header>;
 <;env:Body>;
 ........ 
 <;/env:Body>;
<;/env:Envelope>;

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Header>;
 <;n:MsgHeader xmlns:n="http://example.org/requestresponse">;
 <;!-- MessageId will be unique for each response message -->;
 <;!-- ResponseTo will be constant for each response message in the sequence-->;
 <;n:MessageId>;uuid:09233523-567b-2891-b623-9dke28yod7m9<;/n:MessageId>;
 <;n:ResponseTo>;uuid:09233523-345b-4351-b623-5dsf35sgs5d6<;/n:ResponseTo>;
 <;/n:MsgHeader>;
 <;s:Sequence xmlns:s="http://example.org/sequence">;
 <;s:SequenceNumber>;1<;/s:SequenceNumber>;
 <;s:TotalInSequence>;5<;/s:TotalInSequence>;
 <;/s:Sequence>;
 <;/env:Header>;
 <;env:Body>;
 ........ 
 <;/env:Body>;
<;/env:Envelope>;

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Header>;
 <;n:MsgHeader xmlns:n="http://example.org/requestresponse">;
 <;!-- MessageId will be unique for each response message -->;
 <;!-- ResponseTo will be constant for each response message in the sequence-->;
 <;n:MessageId>;uuid:40195729-sj20-pso3-1092-p20dj28rk104<;/n:MessageId>;
 <;n:ResponseTo>;uuid:09233523-345b-4351-b623-5dsf35sgs5d6<;/n:ResponseTo>;
 <;/n:MsgHeader>;
 <;s:Sequence xmlns:s="http://example.org/sequence">;
 <;s:SequenceNumber>;5<;/s:SequenceNumber>;
 <;s:TotalInSequence>;5<;/s:TotalInSequence>;
 <;/s:Sequence>;
 <;/env:Header>;
 <;env:Body>;
 ........ 
 <;/env:Body>;
<;/env:Envelope>;


 An SOAP sender generates a lengthy SOAP message that is incrementally 
 transmitted and received by a SOAP receiver. The SOAP receiver employs a 
 SOAP handler that can incrementally process the body as it is received 
 (e.g., employing a SAX-style XML parser on the body as it arrives). Note 
 that the entire message need not be present at one time at any point in its 
 existence.


 This would be particularly helpful for memory-limited processors. It is also 
 very efficient for services which are consistent with incremental, real-time 
 transformations of the data, direct archiving of received data, etc. It would 
 also be useful in scenarios in which voluminous body data can be directly 
 transduced into application data structures or events by a SOAP (module) 
 processor. In particular, there is no need for the explicit construction of a 
 DOM model of the data. Support for various data models might still be possible 
 even with incremental processing if the models are incrementally constructible.


 Scenario S21 requires the incremental parsing and processing of a SOAP message 
 by a receiver. This is a general scenario with memory-limited processor 
 requirements forming a subset of the scenario. If the SOAP Body contains a 
 large amount of data, then it may be processed incrementally by a SAX parser 
 if the data is chunked as in the following example. The SAX parser will have a 
 handler triggered by the BodyDataChunk element.

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Header>;
 <;!--Set of headers processed before Body -->;
 <;/env:Header>;
 <;env:Body>;
 <;b:BodyDataChunk xmlns:s="http://example.org/2001/06/chunking">;
 <;b:DataLength>;1024<;/b:DataLength>;
 <;b:Data>;kfkk34jkhfSomeBase64EncodedDatajdsgkjgjajgo34093589uvsjv.....jhfjhf350giqhf<;/b:Data>;
 <;/b:BodyDataChunk>;
 
 <;!-- More BodyDataChunk elements -->;
 
 <;b:BodyDataChunk xmlns:s="http://example.org/2001/06/chunking">;
 <;b:DataLength>;1024<;/b:DataLength>;
 <;b:Data>;oqjrj45cmoLastLotOfBase64EncodedData12r9vnhofjhckzlmxjws.....skfjk23ogkkjhq<;/b:Data>;
 <;/b:BodyDataChunk>;
 <;/env:Body>;
<;/env:Envelope>;


 If a SOAP request is being streamed and processed incrementally, then the 
 matching response message may be streamed to the original sender. In this 
 case, the design of the receiving application is critical with respect to 
 timing and error handling.

If errors are generated by the SOAP request Headers, then a SOAP Fault is 
 inserted in the response and processing of the request message is terminated.
The SOAP receiving application may treat each BodyDataChunk element as 
 atomic. A positive or negative acknowledgement is streamed to the SOAP 
 response depending on whether the BodyDataChunk element was successfully 
 processed or not. The SOAP response message is terminated once the end of 
 the SOAP request is reached.
Alternatively, the SOAP receiving application may process each BodyDataChunk 
 until either the end of the SOAP request is received or a fault occurs. In 
 the case of a fault, a SOAP Body fault element is streamed to the SOAP 
 response and processing of the SOAP request is terminated.

 An application subscribes to notifications of certain named events from an 
 event source. When such events occur, notifications are sent back to the 
 originating application (first party notification) or to another application 
 (third party notification). For example, an application can subscribe to 
 notification of various aspects of a printer's status (e.g., running out of 
 paper, ink etc.). The notifications of such events could be delivered to a 
 management application.


 Scenario S23 describes event notification using a publish subscribe mechanism. 
 An implementation of this scenario uses an example of the request/response 
 scenario S3 to register a subscription and fire-and-forget to multiple 
 receivers scenario S2 for the notification. Figure 17 illustrates how a 
 request/response message pattern can be used with a Subscription Request 
 Handler to register an interest (or subscription) in some set of events. 
 The registration is made with some subscription service. The success or 
 otherwise of the registration is returned to the subscribing application 
 using a Subscription Ack Handler which provides an acknowledgement to the 
 subscribing application. 


 Delivery of an event noification to a set of subscribers may be implemented 
 using the fire-and-forget to multiple receivers scenario S2. The subscription 
 service provides the list of valid applications that have registered an 
 interested in a particular event. This list may then be converted into a 
 group address or distribution list to support the implementation of the 
 fire-and-forget scenario.


 A subscription request may include a list of events within the SOAP Body as 
 in the following example.In this example, a subscription is registered with 
 a stock price notification service. The subscribing application will be 
 informed of company BigCo&rsquo;s stock price, volume traded and time whenever 
 the price is greater than 100.

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Body>;
 <;s:StockNotificationSubscription xmlns:s="http://example.org/2001/06/subscribe">;
 <;s:Notify>;PRICE<;/s:Notify>;
 <;s:Notify>;VOLUME<;/s:Notfy>;
 <;s:Notify>;TIMESTAMP<;/s:Notfy>;
 <;s:When>;
 <;s:Company>;BigCo<;/s:Company>;
 <;s:Price range="GreaterThan">;100<;/s:Price>;
 <;/s:When>;
 <;/s:StockNotificationSubscription>;
 <;/env:Body>;
<;/env:Envelope>;


 An acknowledgement may include an identifier to the subscription as in the 
 following example:

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Body>;
 <;s:StockNotificationSubscriptionAck xmlns:s="http://example.org/2001/06/subscribe">;
 <;s:SubscriptionId>; uuid:40195729-sj20-pso3-1092-p20dj28rk104<;/s:SubscriptionId>;
 <;/s:StockNotificationSubscriptionAck>;
 <;/env:Body>;
<;/env:Envelope>;


 The identification may be used in subsequent notifications to the application 
 as a result of the subscription:

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Body>;
 <;n:StockNotification xmlns:n="http://example.org/2001/06/notification">;
 <;n:SubscriptionId>; uuid:40195729-sj20-pso3-1092-p20dj28rk104<;/n:SubscriptionId>;
 <;n:Company>;BigCo<;/n:Company>;
 <;n:Price>;100.56<;/n:Price>;
 <;n:Volume>;102345<;/n:Volume>;
 <;n:Timestamp>;2001-03-09T12:22:30Z<;/n:Timestamp>;
 <;/n:StockNotification>;
 <;/env:Body>;
<;/env:Envelope>;


 Some applications may wish to make caching possible for latency, bandwidth 
 use or other gains in efficiency. To enable this, it should be possible to 
 assign cacheability in a variety of circumstances. For example, "read" 
 caching might be used to store messages at intermediaries for reuse in the 
 response phase of the request/response message exchange pattern. Such caching 
 might be on the scope of an entire message, a SOAP module, or scoped to 
 individual SOAP module elements.


 Similarly, "write" caching may be useful in situations when a 
 request message in a request/response message exchange pattern (as well as 
 similar messages in other message exchange patterns) does not need to be 
 immediately forwarded or responded to. Such cachability might be scoped by 
 different methods, as outlined above.


 Cacheability scoped by different elements might be associated by an attribute 
 to the target element, through use of XML Query or XPath to describe the 
 target elements in a header, or implied by the document schema, for example.


 Cacheability mechanisms applied to messages, bodies or elements might include 
 time-to-live (delta time), expiry (absolute time), entity validation, temporal 
 validation, subscription to invalidation services, and object update/purge.


 Finally, some applications may be capable of describing the dependencies and 
 relationships between message elements. For example, a response element may 
 be applicable to a wide range of requests; it would be beneficial to describe 
 this element's relationship with request elements, so that it may satisfy a 
 wide range of requests in an economical fashion. Similarly, the presence of a 
 particular element may be a trigger for a cacheability mechanism to be applied 
 to another element, such as validation or invalidation.


 Caching is frequently used as an optimization in distributed systems. It can 
 be used to avoid re-doing computations or complex database access when the 
 results remain valid for an extended period of time. In this case, subsequent 
 requests for the same information can be served with the cached version rather 
 than repeat the processing with the associated overheads. Another use of 
 caching is in the transmission of data where copies may be held at leaf 
 servers for local service provision rather than repeatedly access a central 
 information repository. This has the combined effect of providing faster 
 access to the information, reducing network bandwidth requirements and 
 reducing the workload on a central server. Caching may be provided as part 
 of an underlying transport infrastructure but in the case of this scenario, 
 it is assumed that the caching is independent of any underlying transport.


 An example of this kind of scenario is the caching of the response to a 
 request in situations where a subsequent request can be safely answered 
 with the same result. This example coincides with scenario S809 (Caching 
 with expiry) where a catalog is updated at 8am each morning. Once the catalog 
 has been updated, all price queries against it are valid until 8am the 
 following day. If a price query request is repeated against the same item, 
 then a cached response can be returned to the SOAP Sender otherwise the 
 request is forwarded to the catalog server and its response is cached. All 
 entries in the cache are purged at the time of the updated catalog being 
 available. Figure 18 illustrates a possible architecture.


 SOAP Application 1 initiates a request for catalog price information 
 illustrated in the following example.

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Body>;
 <;c:CatalogPriceRequest xmlns:c="http://example.org/2001/06/catalog">;
 <;c:PartNumber>;ABC-1234<;/c:PartNumber>;
 <;/c:CatalogPriceRequest>;
 <;/env:Body>;
<;/env:Envelope>;


 The caching intermediary SOAP Application 2 is unable to fulfil the request 
 from its local store so it forward the request which ultimately arrives at 
 the catalog server SOAP Application 3. The catalog server process the request 
 and assembles a response message containing the requested price information. 
 An additional SOAP Header is placed in the response to control any caches that 
 may exist in the return path. The CacheControl Header contains a CacheKey 
 which allows matching of future requests to the cached response together with 
 an Expires element that sets the time the local copy must be purged. This 
 response is returned via the caching intermediary.

<;?xml version="1.0" ?>;
<;e nv:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Header>;
 <;ca:CacheControl xmlns:ca="http://example.org/2001/06/cache">;
 <;ca:CacheKey>;ABC-1234<;/ca:CacheKey>;
 <;ca:Expires>;2001-03-09T08:00:00Z<;/ca:Expires>;
 <;/ca:CacheControl>;
 <;/env:Header>;
 <;env:Body>;
 <;c:CatalogPriceResponse xmlns:c="http://example.org/2001/06/catalog">;
 <;c:PartNumber>;ABC-1234<;/c:PartNumber>;
 <;c:PartPrice c:currency="USD">;120.37<;/c:PartPrice>;
 <;/c:CatalogPriceResponse>;
 <;/env:Body>;
<;/env:Envelope>;


 At the caching intermediary, the CacheControl header information is used to 
 make a local copy of the response message, keyed by the CacheKey. The copy 
 will be purged at the time specified by the Expires element. The CacheControl 
 header element is removed by the intermediary and the catalog price 
 information is returned to the original sender. The request/response path for 
 this message is the complete roundtrip between the original SOAP Sender and 
 SOAP Receiver and is shown by <em="">Message Path 1</em> in Figure 18.

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Body>;
 <;c:CatalogPriceResponse xmlns:c="http://example.org/2001/06/catalog">;
 <;c:PartNumber>;ABC-1234<;/c:PartNumber>;
 <;c:PartPrice c:currency="USD">;120.37<;/c:PartPrice>;
 <;/c:CatalogPriceResponse>;
 <;/env:Body>;
<;/env:Envelope>;


 Since there is now a local copy of the price information for item ABC-1234 
 in the intermediary cache, subsequent requests for price information can be 
 fulfilled by the intermediary. This is the shorter request/response path 
 <em="">Message Path 2</em>.


 A developer wishes to force an explicit message path through certain 
 intermediaries - for instance, he might use an anonymizing intermediary 
 to make a call to a specified remote service without allowing the target 
 service to track the identity/IP of the caller. In this case, the 
 intermediary is responsible for calling the target service and returning 
 the results to the caller, using its own authentication credentials if 
 any are required by the target service.


 A service provider wishes to track incoming messages to see exactly which processing 
 intermediaries have touched it by the time it arrives at its destination. It 
 therefore requires a tracking extension to be included by all clients, and by 
 any processing intermediaries along the message paths from the clients to the server.


 Scenario S805 describes a routing requirement whch is addressed in detail by the 
 WS-Routing <a href="#WSRP"="">[4]</a> (formerly SOAP-RP) specification. This describes how a message 
 may be reouted through some messaging infrastructure. Once the message has arrived 
 at its ultimate receiver, the route the message has taken may be required for 
 auditing purposes. A track of the message path may be created by adding a tracking 
 header to the message in addition to any routing information.


 This is illustrated in the following example. A routing header has been added to 
 the message in accordance with WS-Routing <a href="#WSRP"="">[4]</a>. A TrackingHeader is used to 
 maintain a list of Intermediary names and associated Timestamp elements. As the 
 message passes through each intermediary, a Tracking Handler appends a Via element 
 to the TrackingHeader. The Via element contains the name of the intermediary 
 together with the date/time the message arrived or was forwarded by the intermediary. 
 The list of Via elements therefore forms the audit trail for the message.

<;?xml version="1.0" ?>;
<;env:Envelope xmlns:env="http://www.w3.org/2001/09/soap-envelope">;
 <;env:Header>;
 <;t:TrackingHeader xmlns:t="http://example.org/2001/06/tracking">;
 <;t:Via>;
 <;t:Intermediary>;soap://A.com/some/endpoint<;/t:Intermediary>;
 <;t:Timestamp>;2001-03-09T08:00:00Z<;/t:Timestamp>;
 <;/t:Via>;
 <;t:Via>;
 <;t:Intermediary>;soap://B.com<;/t:Intermediary>;
 <;t:Timestamp>;2001-03-09T08:01:00Z<;/t:Timestamp>;
 <;/t:Via>;
 <;t:Via>;
 <;t:Intermediary>;soap://C.com<;/t:Intermediary>;
 <;t:Timestamp>;2001-03-09T08:02:00Z<;/t:Timestamp>;
 <;/t:Via>;
 <;t:Via>;
 <;t:Intermediary>;soap://D.com/some/endpoint<;/t:Intermediary>;
 <;t:Timestamp>;2001-03-09T08:03:00Z<;/t:Timestamp>;
 <;/t:Via>;
 <;/t:TrackingHeader>;
 <;wsrp:path xmlns:wsrp="http://schemas.xmlsoap.org/rp">;
 <;wsrp:action>;http://www.im.org/chat<;/wsrp:action>;
 <;wsrp:to>;soap://D.com/some/endpoint<;/wsrp:to>;
 <;wsrp:fwd>;
 <;wsrp:via>;soap://B.com<;/wsrp:via>;
 <;wsrp:via>;soap://C.com<;/wsrp:via>;
 <;/wsrp:fwd>;
 <;wsrp:from>;soap://A.com/some/endpoint<;/wsrp:from>;
 <;wsrp:id>;uuid:84b9f5d0-33fb-4a81-b02b-5b760641c1d6<;/wsrp:id>;
 <;/wsrp:path>;
 <;/env:Header>;
 <;env:Body>;
 .....
 <;/env:Body>;
<;/env:Envelope>;

BizCo updates their online price catalog every morning at 8AM. 
 Therefore, when remote clients access their SOAP inventory service, 
 clients and intermediaries may cache the results of any price queries 
 until 8AM the next day.


 A SOAP sender (not necessarily the initial SOAP sender) wants the SOAP 
 message to be handled with specific quality of service as it traverses 
 the SOAP message path to include multiple SOAP Processing intermediaries. 
 Information in the SOAP message is used to select appropriate QoS 
 mechanisms (e.g., RSVP, Diffserv, MPLS, etc.). Selection of QoS may be 
 constrained by QoS policies, Service Level Agreements (SLAs), Service 
 Level Specifications (SLS).


 A SOAP header block is one possible approach to implementing this scenario. The 
 SOAP 1.2 specification does not define this hypothetical SOAP Quality Of Service 
 (QoS) block. An initial SOAP sender sends a SOAP message containing a QoS header 
 block through one or more SOAP intermediaries to an ultimate SOAP receiver. The 
 intermediary is targeted by the initial SOAP sender from within the SOAP message 
 by inserting a role attribute within the QoS Block to be used at the SOAP 
 intermediary as described in the SOAP processing model (Part 1, section 2.5). 
 The SOAP specifications do not state how the role attribute is to be used by 
 the SOAP sender. Potentially, it can be used in the context of the SOAP binding 
 framework to provide a hint for message routing. However, message routing is not within the scope of the SOAP 1.2 
 specifications. The SOAP intermediary must examine the SOAP QoS Block, and 
 determine how to invoke the QoS capabilities exposed via the SOAP binding. If 
 the SOAP QoS Block is marked mustUnderstand, then the intermediary is expected 
 to be QoS-aware. If it is not QoS-aware, then a SOAP fault is generated, as this 
 mandatory header cannot be processed. If it is QoS-aware, but cannot honor the 
 specific QoS parameters carried in the QoS Block, then any fault or other 
 response to the sender or elsewhere (e.g., log file) is not defined in the SOAP 
 specifications. The specification of the QoS extension, when defined, would need 
 to describe error handling, negotiations, or other processing under all 
 circumstances.


 If the intermediary is QoS-aware, then presumably the information in the QoS 
 Block is used when forwarding the SOAP message further along on its message path 
 toward the ultimate SOAP receiver. In addition to the use of SOAP Blocks to 
 extend the functionality of SOAP, this scenario may also require extensions to 
 the HTTP binding, or a completely new binding. The Binding Framework allows for 
 additional properties, outside the SOAP envelope, that may be required to invoke 
 the lower layer QoS mechanisms. Additional properties (within the Binding 
 Framework) may be required. For sake of discussion, lets assume that the SOAP 
 node will send the SOAP message using HTTP, but traffic classification of this 
 HTTP flow would be done using diffserv so particular per-hop behaviors can be 
 used within the network en-route to the next SOAP node. Traffic classification 
 for diffserv can be done by the SOAP node sending the SOAP message, or by network 
 devices (assuming they know how to recognize the particular HTTP flow). If 
 traffic classification is handled by a network device, perhaps communications 
 would be needed between the SOAP node and the network device, for example, to 
 provide the network device with the TCP/IP port numbers and IP addresses of the 
 HTTP connection. This would presume some way to obtain this port and address 
 information, which probably involves an API or properties that are beyond the 
 scope of the SOAP 1.2 specifications.


 For example, to state that a separate spec can define properties in accordance 
 with the binding framework to extend the capability of the HTTP binding (or any 
 other binding). In the case of SOAP RPC, a QoS extension at the ultimate SOAP 
 receiver may attempt to insert a QoS Block in RPC response. The RPC response 
 may succeed, but perhaps the desired QoS cannot be delivered on the return 
 message path. It is not clear if a SOAP fault should be generated. Likewise, if 
 a SOAP Intermediary on the return message path cannot honor the QoS Block 
 (assumed to be marked mustUnderstand), is it permissible to convert the SOAP RPC 
 response to a SOAP fault? A SOAP extension in the initial SOAP sender is needed 
 to insert this SOAP QoS Block. The sender may need to use properties as defined 
 by the SOAP binding framework to communicate QoS parameters to be used by the 
 underlying network. Since a SOAP binding must define the rules for how the data 
 is exchanged using the underlying protocol, a custom or supplemental binding may 
 be required to support this QoS usage scenario. The HTTP binding described in the 
 SOAP 1.2 specification does not explicitly support QoS properties. The SOAP 1.2 
 specification does not preclude extensions to this HTTP binding, which would 
 provide the capability to define either QoS properties or a requirement to 
 examine the SOAP envelope (i.e., SOAP QoS Block) to determine the QoS used for 
 transmission. Alternatively, a completely new binding can be specified that 
 includes QoS explicitly, rather than as an extension to an existing binding

This specification is the work of the W3C XML Protocol Working Group.
Members of the Working Group are (at the time of writing, and in
 alphabetical order): Carine Bournez (W3C),
David Fallside (IBM),
Tony Graham (Sun Microsystems),
Martin Gudgin (Microsoft Corporation, formerly of DevelopMentor),
Marc Hadley (Sun Microsystems),
Gerd Hoelzing (SAP AG),
Oisin Hurley (IONA Technologies),
John Ibbotson (IBM),
Kazunori Iwasa (Fujitsu Limited),
Mario Jeckle (DaimlerChrysler R. &; Tech),
Mark Jones (AT&;T),
Anish Karmarkar (Oracle),
Jacek Kopecky (Systinet/Idoox),
Yves Lafon (W3C),
Michah Lerner (AT&;T),
Noah Mendelsohn (IBM, formerly of Lotus Development),
Jeff Mischkinsky (Oracle),
Nilo Mitra (Ericsson),
Jean-Jacques Moreau (Canon),
Masahiko Narita (Fujitsu Limited),
Eric Newcomer (IONA Technologies),
Mark Nottingham (BEA Systems, formerly of Akamai Technologies),
David Orchard (BEA Systems, formerly of Jamcracker),
Andreas Riegg (DaimlerChrysler R. &; Tech),
Hervé; Ruellan (Canon),
Jeff Schlimmer (Microsoft Corporation),
Miroslav Simek (Systinet/Idoox),
Pete Wenzel (SeeBeyond),
Volker Wiechers (SAP AG).

Previous members were: Yasser alSafadi (Philips Research),
Bill Anderson (Xerox),
Vidur Apparao (Netscape),
Camilo Arbelaez (WebMethods),
Mark Baker (Idokorro Mobile (Planetfred), formerly of Sun Microsystems),
Philippe Bedu (EDF (Electricité; de France)),
Olivier Boudeville (EDF (Electricité; de France)),
Don Box (Microsoft Corporation, formerly of DevelopMentor),
Tom Breuel (Xerox),
Dick Brooks (Group 8760),
Winston Bumpus (Novell),
David Burdett (Commerce One),
Charles Campbell (Informix Software),
Alex Ceponkus (Bowstreet),
Michael Champion (Software AG),
David Chappell (Sonic Software),
Miles Chaston (Epicentric),
David Clay (Oracle),
David Cleary (Progress Software),
Conleth O'Connell (Vignette),
Ugo Corda (Xerox),
Paul Cotton (Microsoft Corporation),
Fransisco Cubera (IBM),
Jim d'Augustine (eXcelon),
Ron Daniel (Interwoven),
Glen Daniels (Macromedia, formerly of Allaire),
Dug Davis (IBM),
Ray Denenberg (Library of Congress),
Paul Denning (MITRE),
Frank DeRose (Tibco),
Mike Dierken (DataChannel),
Andrew Eisenberg (Progress Software),
Brian Eisenberg (DataChannel),
Colleen Evans (Sonic Software),
John Evdemon (XMLSolutions),
David Ezell (Hewlett-Packard),
Eric Fedok (Active Data Exchange),
Chris Ferris (Sun Microsystems),
Daniela Florescu (Propel),
Dan Frantz (BEA Systems),
Michael Freeman (Engenia Software),
Dietmar Gaertner (Software AG),
Scott Golubock (Epicentric),
Rich Greenfield (Library of Congress),
Hugo Haas (W3C),
Mark Hale (Interwoven),
Randy Hall (Intel),
Bjoern Heckel (Epicentric),
Erin Hoffman (Tradia),
Steve Hole (MessagingDirect Ltd.),
Mary Holstege (Calico Commerce),
Jim Hughes (Fujitsu Software Corporation),
Yin-Leng Husband (Hewlett-Packard, formerly of Compaq),
Ryuji Inoue (Matsushita Electric),
Scott Isaacson (Novell),
Murali Janakiraman (Rogue Wave),
Eric Jenkins (Engenia Software),
Jay Kasi (Commerce One),
Jeffrey Kay (Engenia Software),
Richard Koo (Vitria Technology Inc.),
Alan Kropp (Epicentric),
Julian Kumar (Epicentric),
Peter Lecuyer (Progress Software),
Tony Lee (Vitria Technology Inc.),
Amy Lewis (TIBCO),
Bob Lojek (Intalio),
Henry Lowe (OMG),
Brad Lund (Intel),
Matthew MacKenzie (XMLGlobal Technologies),
Murray Maloney (Commerce One),
Richard Martin (Active Data Exchange),
Highland Mary Mountain (Intel),
Alex Milowski (Lexica),
Kevin Mitchell (XMLSolutions),
Ed Mooney (Sun Microsystems),
Dean Moses (Epicentric),
Don Mullen (Tibco),
Rekha Nagarajan (Calico Commerce),
Raj Nair (Cisco),
Mark Needleman (Data Research Associates),
Art Nevarez (Novell),
Henrik Nielsen (Microsoft Corporation),
Kevin Perkins (Compaq),
Jags Ramnaryan (BEA Systems),
Vilhelm Rosenqvist (NCR),
Marwan Sabbouh (MITRE),
Waqar Sadiq (Vitria Technology Inc.),
Rich Salz (Zolera),
Krishna Sankar (Cisco),
George Scott (Tradia),
Shane Sesta (Active Data Exchange),
Lew Shannon (NCR),
John-Paul Sicotte (MessagingDirect Ltd.),
Simeon Simeonov (Macromedia, formerly from Allaire),
Aaron Skonnard (DevelopMentor),
Nick Smilonich (Unisys),
Soumitro Tagore (Informix Software),
James Tauber (Bowstreet),
Lynne Thompson (Unisys),
Patrick Thompson (Rogue Wave),
Jim Trezzo (Oracle),
Asir Vedamuthu (WebMethods),
Randy Waldrop (WebMethods),
Fred Waskiewicz (OMG),
David Webber (XMLGlobal Technologies),
Ray Whitmer (Netscape),
Stuart Williams (Hewlett-Packard),
Yan Xu (DataChannel),
Amr Yassin (Philips Research),
Susan Yee (Active Data Exchange),
Jin Yu (Martsoft).

The people who have contributed to discussions on
<a href="mailto:xml-dist-app@w3.org"="">xml-dist-app@w3.org</a>
are also gratefully acknowledged.