Mule async request-reply

Question

I actually invoke an exe with the expression-component through a http-request on port 8081. The exe sends a http-request on port 8082 and I'm able to log the output. Finally i have to send the output of the reply-flow back to the main-flow but i dont know how...

Here is my code:

<flow name="mainFlow" doc:name="mainFlow">
    <http:inbound-endpoint exchange-pattern="request-response" address="http://localhost:8081" doc:name="HTTP" />
    <request-reply timeout="10000">
        <vm:outbound-endpoint path="request" exchange-pattern="one-way"/>
        <vm:inbound-endpoint path="reply" exchange-pattern="one-way"/>
    </request-reply>
</flow>

<flow name="request" doc:name="request">
    <vm:inbound-endpoint path="request" doc:name="VM" />
    <expression-component doc:name="Expression">Runtime.getRuntime().exec("C:\\myfile.exe arg1");</expression-component>
</flow>

<flow name="reply" doc:name="reply">
    <http:inbound-endpoint address="http://localhost:8082" doc:name="HTTP" exchange-pattern="one-way" />
    <logger message="#[message.inboundProperties['test']]" level="INFO" doc:name="Logger"/>
    <vm:outbound-endpoint path="reply" doc:name="VM" exchange-pattern="one-way"/>
</flow>

Answer 1

You have to make sure you are carrying the MULE_CORRELATION_ID message property through the exe down to http://localhost:8082 otherwise the request-reply message processor has no way to correlate the asynchronous reply with the current request.

For example, pass the correlation ID has a second argument to the exe:

<expression-component doc:name="Expression">
  Runtime.getRuntime().exec("C:\\myfile.exe arg1 " + message.correlationId);
</expression-component>

And make sure the exe propagates the correlation ID towards http://localhost:8082 in an HTTP header named X-MULE_CORRELATION_ID.