This is relatively straightforward when each client of a (potential) inbound gateway sends one message and waits for its response. It gets a little more tricky if a client multiplexes many messages over its connection. In this arena, we'd need a correlation id of some kind in the wire protocol so the client can associate a response with its corresponding request.

This is not so big an issue if the "other end" of the connection is a spring-integration outbound gateway because SI can use whatever wire protocol it likes. It is more difficult, though, for interop with non spring-integration clients. We may need something more robust than the current channel adapter pluggable wire protocol for tcp to handle more sophisticated wire protocols that include correlation data.

I see several options/phases; what can get done and when will depend on need and resource availability.

1. Inbound gateway that does not support multiplexed requests per connection.
+ blocking outbound gateway that single threads requests/responses over its connection.

2. Outbound/inbound gateways that support multiplexed requests over each connection, using a fixed wire protocol (albeit extensible via the current simple pluggable mechanism).

3. Build on 2 with a more sophisticated wire protocol pluggability.

am really looking forward to this feature. Any ideas when can we see it in trunk.

It's in the trunk now; see SimpleTcpNetInboundGateway.

	<int-ip:inbound-gateway id="telnetGateway"
		port="9876"
		request-channel="telnetInTransformerChannel"
		message-format="crlf" />

This configuration allows you to open a telnet session to 'localhost 9876'.

Please let us know whether it serves your needs; thanks.

SimpleTcpNetOutboundGateway was added to trunk last weekend.

Simple inbound and outbound gateways are now available.