Message Template receive gives Dispatcher has no subscribers for channel - spring-integration

Question

This is my spring-integration inbound and out bound which gets a list from a end point.
<http:inbound-gateway id="webListGateway"
request-channel="fromWeb_List"
reply-channel="toWeb_List"
path="/api/profile/V1/get"
supported-methods="GET">
<http:header name="container" expression="#pathVariables.container"/>
<http:header name="groupName" expression="#pathVariables.groupName"/>
<http:header name="userId" expression="#pathVariables.userId"/>
</http:inbound-gateway>
<int:header-enricher input-channel="fromWeb_List" output-channel="toCloud_List">
<int:header name="apikey" value=“1234”/>
</int:header-enricher>
<http:outbound-gateway id="profileListGateway"
request-channel="toCloud_List"
reply-channel="sync_preferences"
url=“localhost:8081/containers/{container}/groups/{groupName}/values/hierarchy/{userId}"
http-method="GET"
expected-response-type="java.lang.String"
charset="UTF-8"
extract-request-payload="false"
header-mapper="headerMapper"
encode-uri="true" >
<http:uri-variable name="container" expression="headers.container"/>
<http:uri-variable name="groupName" expression="headers.groupName"/>
<http:uri-variable name="userId" expression="headers.userId"/>
</http:outbound-gateway>
This is my recipient-list-router which send backs the list to requestor and also saves the list in another end point.
<int:recipient-list-router id="syncRouter" input-channel="sync_preferences">
<int:recipient channel="toWeb_List"/>
<int:recipient channel="toCloud_Save"/>
</int:recipient-list-router>
I am also trying to call the outbound gateway from java code and trying to get the response from toWeb_List channel by using receive method on MessageTemplate, which is giving me error
MessagingTemplate template = new MessagingTemplate();
Message<String> message1 = MessageBuilder.withPayload("")
.setHeader("container", “fwd”)
.setHeader("groupName", “foo”)
.setHeader("userId", “user”)
.build();
template.send((MessageChannel) CONTEXT.getBean("fromWeb_List"),message1);
PreList pre = (PreList) template.receive((MessageChannel)CONTEXT.getBean("toWeb_List"));
error
Dispatcher has no subscribers for channel 'application:springboot.toWeb_List'
Any Idea what I am doing wrong here.

Answer 1

You can't use DirectChannel for the MessagingGateway.receive():
protected final Message<?> doReceive(MessageChannel channel, long timeout) {
Assert.notNull(channel, "MessageChannel is required");
Assert.state(channel instanceof PollableChannel, "A PollableChannel is required to receive messages");
Another issue that reply-channel="toWeb_List" has to be registered as correlator in the Inbound Gateway to be able to receive messages, as Gary pointed. And that is done on demand, on the first request. That's why you get
that Dispatcher has no subscribers.
And really, please, try to explain what you would like to do.
UPDATE
If you are going to reuse that <int:recipient-list-router> from the HTTP Inbound and from some other similar request-reply place, you should consider to drop off usage of the reply-channel and just rely on the replyChannel in headers.
I mean there can be that toWeb_List channel bean definition, but should not use it from the reply-channel. In this case your config should be like this:
<int:recipient-list-router id="syncRouter" input-channel="sync_preferences">
<int:recipient channel="toWeb_List"/>
<int:recipient channel="toCloud_Save"/>
</int:recipient-list-router>
<int:bridge input-channel="toWeb_List"/>
The bridge is such a components to shift message from input channel to the output one, if present. Otherwise it consults MessageHeaders for the replyChannel value. And this is is populated exactly via those Inbound request-reply components such as <http:inbound-gateway> or plain <int:gateway> when you call directly from Java.
See more information in the Reference Manual.