[jboss-dev-forums] [Design of JBoss ESB] - Re: Http Gateway - requirements please...

[tfennelly]

The old "using the mep" for sync/async responses chestnut again... Sorry Kev ;)

Here was what was said on IM that time...
anonymous wrote : (12:18:47) Tom Fennelly: another quick one... the mep issue
  | (12:18:55) Tom Fennelly: what was the issue with the?
  | (12:19:26) Tom Fennelly: you don't wanna use it to decide whether or not a respnse is sent back?
  | (12:19:33) Kevin Conner: The mep of the service has no bearing on the http gateway, it is an impleme
  | ntation config
  | (12:19:36) Kevin Conner: You can't
  | (12:19:57) Kevin Conner: A response can be sent back from a OneWay mep if it chains the request
  | (12:20:13) Kevin Conner: Service A (OneWay) -> Service B (RequestResponse)
  | (12:20:37) Kevin Conner: It is an implementation detail and not part of the service contract

I'm not trying to contradict Kev, but given our current model where the gateways are configured on the services, I don't understand why the service mep is not an indicator of whether or not the invoked http-gateway should return the service response as its response (mep=RequestResponse), or should simply return an empty response as its response (mep=OneWay).  

It seems to me like having an additional sync/async config on the gateway would be very confusing for users.  I think this is what's being proposed, right?

So, assuming we add a "sync" flag on the http-gateway, how should the gateway respond when...

1. gateway sync=true, service mep=OneWay?

2. gateway sync=true, service mep=RequestResponse?

3. gateway sync=false, service mep=OneWay?

4. gateway sync=false, service mep=RequestResponse?

If the http-gateway used the mep, what use case breaks, and how does it break i.e. what actually goes wrong e.g. with the chained services example outlined in the IM?

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