CorrelationID

The CorrelationID element is used to specify a correlation ID for a message.

Format

The CorrelationID element consists of an Expression element that uses one or more Operation elements to specify the string to use as the correlation ID.

<ic:CorrelationID>  
  <ic:Expression>  
    <!-- Operations -->  
  </ic:Expression>  
</ic:CorrelationID>  

Remarks

The following common operations are not allowed in correlation ID expressions:

• And

• Equals

Example

The following Workflow Foundation (WF) interceptor sample configuration block uses "OrderNum" to establish a correlation ID. Using the WF and common operations, you can build sophisticated expressions to construct an appropriate correlation ID for your workflow.

<ic:CorrelationID>  
  <ic:Expression>  
    <wf:Operation Name="GetWorkflowProperty">  
      <wf:Argument>OrderNum</wf:Argument>  
    </wf:Operation>  
  </ic:Expression>  
</ic:CorrelationID>  

For Windows Communication Foundation (WCF) applications, you can use WCF-specific and common operations to construct a correlation ID. The following sample uses the XPath operation and XPath to retrieve a credit card number from a message for use as a correlation ID:

<ic:CorrelationID>  
  <ic:Expression>  
    <wcf:Operation Name ="XPath">  
      <wcf:Argument>//s:Body/creditCard:CreditCardNumber</wcf:Argument>  
    </wcf:Operation>  
  </ic:Expression>  
</ic:CorrelationID>  

See Also

Interceptor OnEvent Element