IBM FileNet P8, Version 5.2.1            

Correlating web conversations

A correlation set provides an identifier between two Web Services so that one can identify an appropriate message from another. For example, with purchase orders, there might be several exchanges of messages between the buyer and the seller. You need to ensure that each message stays with the appropriate conversation.

You can define a correlation set for any of the Web Services system functions: Receive, Reply, and Invoke. If you are using Parameter mode, the Correlation Set tab is available for Receive, but not for Invoke. A correlation set is required for any Receive step that is not the first step after the Launch step.

To correlate a conversation between two processes:

Do the following steps in accordance with the appropriate message type.

Parameters

  1. On the Correlation Set tab, select a Web Service parameter that contains a unique value to differentiate one workflow instance from another. For example, you might use an invoice number.
  2. Select the data field in the current workflow definition that contains the value to be matched. The correlation value to be compared must be a string because all incoming data is in string format. For example, if the data field in the current workflow definition were an integer, you can use the following expression to convert it to a string: convert(field_name, string).

XML

  1. On the Correlation Set tab, specify a name for this correlation set. (You can specify more than one correlation set.)
  2. Under Properties, specify a name and the XPath Query to the appropriate element in the schema. You can specify more than one name/XPath Query pair to define the correlation expression. For example, you might use a combination of an account number and invoice number to identify the appropriate incoming message.

    A template version of the schema displays to help you in creating the XPath Query. For an example of a correlation set that uses XML, see Web Services Correlation example.

    In addition to setting up the Correlation set in the Receive step, do the following assignment: assign the correlation value to the system field F_Corr<Correlation_Set_Name> at some point in the workflow before the Receive step.



Last updated: October 2015
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