23.2. Conversational Web Services

Seam uses a SOAP header element in both SOAP request and response messages to carry the conversation ID between the consumer and the service. One example of a web service request containing a conversation ID is: 
<soapenv:Envelope 
         xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" 
         xmlns:seam="http://seambay.example.seam.jboss.org/">
                  
  <soapenv:Header>
    <seam:conversationId xmlns:seam='http://www.jboss.org/seam/webservice'>
      2
    </seam:conversationId>
  </soapenv:Header>
  
  <soapenv:Body>
    <seam:confirmAuction/>
  </soapenv:Body>
  
</soapenv:Envelope>
The above SOAP message contains a conversationId element, which contains the conversation ID for the request — in this case, 2. Because web services can be consumed by a variety of web service clients written in a variety of languages, the developer is responsible for implementing conversation ID propagation between individual web services to be used in a single conversation's scope.
The conversationId header element must be qualified with a namespace of http://www.jboss.org/seam/webservice, or Seam will be unable to read the conversation ID from the request. An example response to the above request message is: 
<env:Envelope xmlns:env='http://schemas.xmlsoap.org/soap/envelope/'>
  <env:Header>
    <seam:conversationId xmlns:seam='http://www.jboss.org/seam/webservice'>
      2
    </seam:conversationId>
  </env:Header>
  <env:Body>
    <confirmAuctionResponse 
       xmlns="http://seambay.example.seam.jboss.org/"/>
  </env:Body>
</env:Envelope>
Note that the response message contains the same conversationId element as the request.

23.2.1. A Recommended Strategy

Since web services must be implemented as either stateless session beans or POJOs, we recommend that conversational web services implement the web service as a facade for a conversational Seam component.
If the web service is written as a stateless session bean, it can be transformed into a Seam component by annotating it with @Name. This allows Seam bijection, and other features, to be used in the web service class itself.