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Creating a Custom Itinerary Service Using a BizTalk Orchestration

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The itinerary framework that is part of the ​Microsoft BizTalk ESB Toolkit supports execution of itinerary steps using orchestrations. You can implement a custom itinerary service as a Microsoft BizTalk Server orchestration based on your functional requirements, which may include the following:

  • Multiple service invocations (as demonstrated by the Installing and Running the Scatter-Gather Sample)

  • Protocol mediation and message correlation (for example, HTTP-MQSeries)

  • Complex routing decisions based on message enrichment from external data sources

  • Business processing logic

    Every itinerary service implemented using a BizTalk Server orchestration is responsible for the following:

  • Exception and error handling using the ESB Exception Handling Framework or optional custom exception handlers that support resubmission (one-way itineraries)

  • Advancing the itinerary and publishing outbound messages through BizTalk Server so that the next itinerary service step can execute

To create a custom itinerary service using a BizTalk Server orchestration

  1. Create new BizTalk Server project containing a new orchestration; for example, MyCustomeItineraryService.odx.

  2. Add references to the following assemblies:

    • Microsoft.Practices.ESB.Itinerary

    • Microsoft.Practices.ESB.Itinerary.Schemas

    • Microsoft.Practices.ESB.ExceptionHandling

    • Microsoft.Practices.ESB.ExceptionHandling.Faults

  3. Define a logical direct-bound receive port and an activated receive shape in the orchestration.

  4. Define a subscription filter to activate the orchestration from the message itinerary context so that the orchestration executes the MyCustomItineraryService step. The following code shows an example of a suitable filter.

    (Microsoft.Practices.ESB.Itinerary.Schemas.ServiceName   
    == "MyCustomItineraryService")   
&& (Microsoft.Practices.ESB.Itinerary.Schemas.ServiceState == "Pending")  
&& (Microsoft.Practices.ESB.Itinerary.Schemas.ServiceType   
    == "Orchestration")

  5. Define an orchestration of type Microsoft.Practices.ESB.Itinerary.ItineraryStep. Add an expression activity to the orchestration that populates this variable, as shown in the following code.

    // Retrieve the current itinerary step.  
itinerary = new Microsoft.Practices.ESB.Itinerary.SerializableItineraryWrapper();  
step = new Microsoft.Practices.ESB.Itinerary.SerializableItineraryStepWrapper();  

itinerary.Itinerary = Microsoft.Practices.ESB.Itinerary.ItineraryOMFactory.Create(InboundMessage);  
step.ItineraryStep = itinerary.Itinerary.GetItineraryStep(InboundMessage);

  6. Add your custom implementation to the itinerary that creates the outbound message for the next itinerary steps; for example, OutboundMsg.

  7. Advance the itinerary using the following expression activity that uses the message context from inbound message.

    OutboundMessage(*) = InboundMessage(*);   
itinerary.Itinerary.Advance(OutboundMessage, itineraryStep.ItineraryStep);

  8. Send the outbound message with the updated itinerary through a direct-bound send port to activate the next itinerary service.

    For more information about implementing a custom itinerary service using BizTalk Server orchestrations, see Installing and Running the Itinerary On-Ramp Sample and Installing and Running the Scatter-Gather Sample.