how should a message look like to be a response

问题

I have read and followed the example in http://docs.spring.io/spring-integration/reference/html/ip.html#ip-correlation

I have a spring-integration server

<int-ip:tcp-connection-factory
    id="socketserver"
    type="server"
    port="30124"
    using-nio="true"
    mapper="mapper"
    deserializer="jsonSerializer"
    serializer="jsonSerializer"
    single-use="false"/>

with this mapper from above link:

<bean id="mapper"
  class="org.springframework.integration.ip.tcp.connection.MessageConvertingTcpMessageMapper">
<constructor-arg name="messageConverter">
    <bean class="org.springframework.integration.support.converter.MapMessageConverter">
        <property name="headerNames">
            <list>
                <value>correlationId</value>
                <value>sequenceNumber</value>
                <value>sequenceSize</value>
            </list>
        </property>
    </bean>
</constructor-arg>

with inbound and outbound adapter

<int-ip:tcp-inbound-channel-adapter id="inboundServer"
    channel="inputChannel"
    connection-factory="socketserver"/>

<int-ip:tcp-outbound-channel-adapter id="outboundServer"
    channel="outputChannel"
    connection-factory="socketserver"/>

<int:channel id="inputChannel"/>
<int:channel id="outputChannel"/>

<int:service-activator input-channel="inputChannel"
           output-channel="outputChannel"
           ref="echoService"
           method="test"/>

<bean id="echoService" class="com.example.HelloReply" />

I'm sending Messages to a connected client with

Map<String, Object> headers = new HashMap<String, Object>();
Map msgMap = new HashMap();
msgMap.put("message", "test");
headers.put(IpHeaders.CONNECTION_ID, <the connection id>);
headers.put("correlationId", "boo");
headers.put("sequenceNumber", 100);
headers.put("sequenceSize", 5);
Message<Map> msg = new GenericMessage<Map>(msgMap, headers);

MessagingTemplate template = new MessagingTemplate();

Message reply = template.sendAndReceive(outputChannel, msg);

The last line blocks forever, because I can't figure out how to reply to that message properly from my legacy client (telnet).

The sent message is:

{"headers":{"sequenceNumber":101,"sequenceSize":5,"correlationId":"boo"},"payload":{"message":"test"}}

I thought that it would be the correlationId and the same sequenceNumber to match so I tried to response from client to the server with

{"headers":{"sequenceNumber":101,"sequenceSize":5,"correlationId":"boo"},"payload":{"result":"OK"}}

But it is interpreted as a new inbound message, not recognized as an answer for the initial send-message.

So what does sendAndReceive expect and is there some documentation/specification for that special usecase (sendAndReceive communication with non-spring clients).

回答1:

What do you mean by

channels "sendAndReceive"

Which APIs are you using? Unless you use a gateway, you are responsible for reply correlation.

The TCP Client-Server Multiplex Sample shows one technique (an aggregator) to correlate replies when not using a gateway.

Show your complete configuration (edit the question, don't add in a comment; it doesn't render well).

EDIT:

The framework can't do the correlation for you automatically (with template.sendAndReceive()). It doesn't know anything about your custom headers and, in any case, there's no way to get a reference to the automatic reply queue in the template for this message.

You have to write your own code to do the correlation.

template.send(...);
// wait for incoming message with the same correlation id

For example, you could use, say, a Map<String, BlockingQueue>, keyed by the correlation id and poll for the response.

Invoke another method in the class via a <service-activator/> and put the reply into the BlockingQueue for the correlation id. You could also use a map of QueueChannels.

This use case (block the thread waiting for some asynchronous event) has come up several times and we are considering adding a component to make things easier.

来源：https://stackoverflow.com/questions/30841348/how-should-a-message-look-like-to-be-a-response

标签

java

tcp

spring-integration