WebSphere brand IBM WebSphere Telecom Web Services Server, Version 7.1

Default Access Gateway flow

The default message processing flow for the Access Gateway makes use of the various mediation primitives in a single sequence or in a set of sequences.

Upon receipt of a Web service request, the following mediation primitives are executed in this sequence:
Figure 1. Default Access Gateway mediation flowDefault message processing flow
Note: To prevent a warning message when you are utilizing WebSphere® Integration Developer (WID), the format of the mediation flow has been altered. This has been done to reduce the size and also improve the performance of the flow execution.
  1. The Message Element Remover mediation primitive checks the user principal against the requester exception list. If the requester is not on the list, and if headers exist, the message element remover removes the TWSS headers from the request (using the appropriate XPath selector element).
  2. The Transaction Identifier mediation primitive adds SOAP headers with the global transaction ID requester and name. If the global transaction ID and requester name have already been provided from an upstream element, then those values are used.
  3. The Policy Retrieval mediation primitive retrieves the policy information from the Service Policy Manager.
  4. If transaction recording is enabled by policy attributes, then the information about the transaction–such as the unique ID, requester, service, and operation–is recorded to a database table. (If the transaction recorder is disabled, then network statistics must also be disabled because of the database structure.)
  5. If the Network Statistics mediation primitive is enabled, it records statistical information about the request. The Transaction Recorder mediation primitive must be enabled so that Network Statistics can record the details. The Network Statistics record corresponds to the Transaction Recorder's transaction ID.
  6. If applicable, authorization is verified based on requester, service requested, and operation.
  7. The request is checked to verify that it is a Parlay X request whose parameters may contain a list of URIs, some of which may be groups.
    • If it is not such a Parlay X request, skip to step 9.
    • If it is such a Parlay X request, URI groups expand into a flat list of member URIs, by resolving groups through the IBM® WebSphere XML Document Management Server Component (IBM XDMS).
  8. If message capture is enabled by policy, the Message Interceptor mediation primitive logs the required part of the message to a database. If address tracking is enabled by policy, the mediation primitive compares the addresses specified by the policy with the target addresses in the message. If a match is found, the target addresses are logged to the database with the corresponding message.
  9. If the SLA Enforcement mediation primitive is enabled, then monitoring information is adjusted and the statistics information is checked to ensure that a request can be processed.
  10. The backend Web service is invoked.
  11. If enabled for the particular service operation, response statistics are recorded.
  12. The filter step checks whether message capture is enabled by policy. If so, the message is logged to a database using the mediation primitive provided by WebSphere ESB.
  13. The Message Element Remover mediation primitive checks the user principal against the requester exception list. If the requester is not in the list, and if TWSS headers exist, the Message Element Remover removes the TWSS headers element, using an appropriate XPath selector.

Upon completion of the flow, the response object is returned through the SCA export invocation, as the Web service response. If a failure occurs during the execution of the request portion of the flow, then fault handling segment of the flow is invoked. See the topic Access Gateway fault flow for details.




Terms of use
(C) Copyright IBM Corporation 2009. All Rights Reserved.