Re: [mule-user] Service Chaining with Dynamic ReplyTo

Ross Mason-x wrote:

Hi Todd,

Looking at the code there is no reason why we shouldn't pass the
returnMessage of the outbounRouter to the replyTo queue.  In all our
tests the replyTo component has never had an outbound endpoint thus the
result of the component call was the correct object to return.  I'll
change this to the way you suggest.

Cheers,

Ross

Todd Howitt wrote:

> I'm looking for an elegant way to handle a distributed operation and
> haven't found one yet.  Here's the scenario:
>  
> Two separate containers, call them Remote and HQ.  Remote exposes a
> WebService for local clients.  This WebService sends each
> request through a JMS topic to HQ and waits for the reply on
> a temporary topic (nevermind why topics are being used; the requests
> are being routed from remote JMS brokers over very-small-aperture
> satellite to a cluster of HQ brokers using SonicMQ's DRA).  HQ should
> handle each request by invoking a number of services
> serially/synchronously and sending the reply back via the message's
> embedded replyTo temporary topic.
>  
> The Remote WebService is implemented by a UMO that sends to a JMS
> endpoint through RequestContext.send().  It has an axis
> inboundEndpoint.  The JmsMessageDispatcher creates the temporary topic
> replyTo for us.  This works fine.
>  
> The HQ services are configured with the first service receiving on the
> JMS endpoint above.  Its outboundEndpoint is set to a VM endpoint to
> another service, which is connected to a third service.  This chain is
> a few services deep; your garden-variety Chain of Responsibility pattern.
>  
> My problem is that the first service at HQ sends its own results back
> rather than the results of its OutboundRouter (which represents the
> result of the services downstream).  I see this happening in MuleProxy:
>  
> ------onCall()------------
> UMOMessage result = invoker.execute();
> ...
> returnMessage = descriptor.getOutboundRouter().route(result,
>                                                        
>                          event.getSession(),
>                                                        
>                          event.isSynchronous());
> ...
> replyToHandler.processReplyTo(event, result, replyTo);
> --------------------------
>  
> In the case of a synchronous event, would it be possible to send
> returnMessage to the replyToHandler rather than result?
>  
> Such a feature would also allow the WebService on the Remote container
> to be a pass-through; configuring a synchronous outboundEndpoint would
> do the send operation and grab the result.  Perhaps I could implement
> a generic UMO that uses java.lang.reflect.Proxy to masquerade as
> whatever WebService interface is configured for it.  Essentially, it
> would allow an arbitrary chain of services (or a single service, for
> that matter) to look like a single WebService with no coding.
>  
> If that's not a desirable behavior, I'm looking for alternatives.
>  
> I've considered using a custom header to hold the reply endpoint, then
> configuring a special OutboundRouter on the last service to use it,
> but that would require some ugly hacks (getting the first service to
> not reply, configuring the last service to explicitly reply).  The
> latter could conceivably be done using the replyTo property of
> OutboundRouters, but that's not dynamic; I need to reply to the
> temporary topic embedded in the message.
>  
> Any help?
>  
> Thanks,
>   -- Todd


--
Regards,

Ross Mason
SymphonySoft Ltd

tel: 07005-978-001
fax: 07005-978-003
www.symphonysoft.com