If I understand you correctly, you want to generate multiple replies to a single request message.
If so, then, no, the gateway does not support that; it is for a strict request/reply scenario.
However, you should be able to achieve what you want with channel adapters - receive the request on an inbound channel adapter and send as many "replies" as you want to the outbound adapter.
You may need to inject a channel (or preferably a messaging gateway) into your service, so you can send the fragments while still processing the original input message. But, regardless, extending the gateway is not the right approach.
If you need more details, I can whip up a quick example using, say, stdin/stdout adapters.
Gary P. Russell
Spring Integration Team
SpringSource, a division of VMware