Transfer how to deliver message to Gateway? - spring

Question

https://github.com/spring-projects/spring-integration-samples/tree/master/intermediate/tcp-client-server-multiplex
I saw this exmaple. So, I was changed architecture.
send model
receive model
And I have a question.
I don't understand transfer's role in send model.
I understand Aggregator delivery message to Transfer.
But, I don't understand How to deliver message to gateway.
How to deliver?
That is my spring integration config.
It is Send app setting,
<!-- telegram bean -->
<bean id="byteArrayRawSerializer" class="org.springframework.integration.ip.tcp.serializer.ByteArrayRawSerializer">
<property name="maxMessageSize" value="2000"/>
</bean>
<bean id="myCorrelationStrategy" class="com.test.util.MyCorrelationStrategy"/>
<!-- online connection factory -->
<int-ip:tcp-connection-factory id="server" type="server" port="20001" single-use="false" lookup-host="false" so-timeout="60000" serializer="byteArrayRawSerializer" deserializer="byteArrayRawSerializer" />
<int-ip:tcp-connection-factory id="client" type="client" host="localhost" port="10001" single-use="false" so-timeout="60000" serializer="byteArrayRawSerializer" deserializer="byteArrayRawSerializer" />
<!-- Send -->
<int:gateway id="sendGateway"
service-interface="com.test.MySendGateway"
default-reply-timeout="20000"
default-request-channel="sendChannel"/>
<int:publish-subscribe-channel id="sendChannel" />
<int-ip:tcp-outbound-channel-adapter id="sendAdapter" order="2" channel="sendChannel" connection-factory="client" />
<int:bridge input-channel="batchSendChannel" output-channel="toSendAggregator" order="1"/>
<int:channel id="toSendAggregator" datatype="byte[]"/>
<int:aggregator input-channel="toSendAggregator"
output-channel="toSendTransformer"
expire-groups-upon-completion="true"
correlation-strategy="myCorrelationStrategy"
correlation-strategy-method="getCorrelationKey"
release-strategy-expression="size() == 2" />
<int:transformer input-channel="toSendTransformer" expression="payload.get(1)"/>
<int-ip:tcp-inbound-channel-adapter id="sendReplyAdapter" channel="toSendAggregator" connection-factory="client" />
<!-- Receive -->
<int-ip:tcp-inbound-channel-adapter id="inboundAdapter" channel="batchInboundChannel" connection-factory="batchReceiveServer" />
<int-ip:tcp-outbound-channel-adapter id="outboundAdapter" channel="batchOutboundChannel" connection-factory="batchReceiveServer"/>
<int:channel id="batchInboundChannel" />
<int:channel id="batchOutboundChannel"/>
<int:service-activator id="myReceiveServiceActivator" method="receive" input-channel="batchInboundChannel">
<bean class="com.test.endpoint.MyReceiveServiceActivator" />
</int:service-activator>
And, It is Delivery app setting(center of picture),
<!-- Bean load -->
<bean id="byteArrayRawSerializer" class="org.springframework.integration.ip.tcp.serializer.ByteArrayRawSerializer">
<property name="maxMessageSize" value="2000"/>
</bean>
<!-- Connection factory -->
<int-ip:tcp-connection-factory id="server" type="server" port="30001" using-nio="true" single-use="false" lookup-host="false" so-timeout="10000" serializer="byteArrayRawSerializer" deserializer="byteArrayRawSerializer" />
<int-ip:tcp-connection-factory id="client" type="client" host="${RemoteTarget.ip}" port="${RemoteTarget.port}" using-nio="true" single-use="false" so-timeout="10000" serializer="byteArrayRawSerializer" deserializer="byteArrayRawSerializer" />
<!-- Connection factory -->
<int-ip:tcp-connection-factory id="inboundServer" type="server" port="10001" using-nio="true" single-use="false" lookup-host="false" so-timeout="${server.outbound.connectionTimeout}" serializer="byteArrayRawSerializer" deserializer="byteArrayRawSerializer" />
<int-ip:tcp-connection-factory id="inboardClient" type="client" host="localhost" port="20001" using-nio="true" single-use="false" so-timeout="10000" serializer="byteArrayRawSerializer" deserializer="byteArrayRawSerializer" />
<int-ip:tcp-inbound-channel-adapter id="receiveAdapter" channel="receiveChannel" connection-factory="server" auto-startup="true"/>
<int-ip:tcp-inbound-channel-adapter id="sendReplyAdapter" channel="sendReplyChannel" connection-factory="client" auto-startup="true"/>
<int:channel id="receiveChannel"/>
<int:channel id="sendReplyChannel"/>
<int-ip:tcp-outbound-channel-adapter id="receiveAdapter.inboard" channel="receiveChannel" connection-factory="inboundServer" />
<int-ip:tcp-outbound-channel-adapter id="sendReplyAdapter.inboard" channel="sendReplyChannel" connection-factory="inboardClient" />
<int-ip:tcp-outbound-channel-adapter id="sendAdapter" channel="sendChannel" connection-factory="client" />
<int-ip:tcp-outbound-channel-adapter id="receiveReplyAdapter" channel="receiveReplyChannel" connection-factory="server" />
<int:channel id="sendChannel" />
<int:channel id="receiveReplyChannel"/>
<int:router id="outRouter" input-channel="toRouter" method="route" auto-startup="true">
<bean class="com.test.endpoint.MyRouter"/>
</int:router>
<int:channel id="toRouter"/>
<int-ip:tcp-inbound-channel-adapter id="sendAdapter.inboard" channel="toRouter" connection-factory="inboundServer" auto-startup="true"/>
<int-ip:tcp-inbound-channel-adapter id="receiveReplyAdapter.inboard" channel="toRouter" connection-factory="inboardClient" auto-startup="true"/>
But, When I call gw.send(msg), it is not work,
(exactly, message stop at the delivery machine's 'sendAdapter.inboard' until timeout and router get this message....

Answer 1

I an not sure what is transfer in your ar3chitecture either.
According the sample you show, we have:
gateway -> outbound-channel-adapter
|-> aggregator
inbound-channel-adapter->aggregator->transformer
Where gateway sends its request to both TCP Outbound Channel Adapter and Aggregator, just because of <publish-subscribe-channel id="input" />.
As we know gateway is a request/reply component. When it sends requests, it waits for reply, because of the contract:
public interface SimpleGateway {
String send(String text);
}
In this case the Gateway add TemporaryReplyChannel as a replyChannel header to wait for reply.
The reply is produced when we don't specify the output-channel on the last downstream flow consumer.
In our case it is exactly the <transformer> after <aggregator>:
<transformer input-channel="toTransformer.client"
expression="payload.get(1)"/> <!-- The response is always second -->
I think that is a trick what you are looking for. It is called replyChannel header in the Consumer logic.