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spring-integrationspring-integration-dsl

Spring integration DSL :: facing issue when calling channel from the xml

I did one simple DSL which retrieves the data from database and doing simple conversion in the service activator.

    @Bean
public IntegrationFlow mainFlow() {
    return IntegrationFlows.from("userChannel")
                .channel("queryChannel")
                .handle("sampleConvertor","convertUser")
                .get();

queryChannel is a jdbc outbound gateway and sampleConverter is the service Activator.

<int-jdbc:outbound-gateway query="select * from employee where employee_id=:payload"
request-channel="queryChannel" data-source="dataSource"/>

The issue is after retrieving the data from database, the flow is not going to serviceActivator and it simply returns back the database response.

In xml configuration, I used to invoke gateway inside the chain like below.

<int:gateway id="query.gateway" request-channel="queryChannel"/>

Please suggest what I am doing wrong here. Thanks in advance.

Solution

  • That's a bit unusual to combine Java DSL and XML configuration, but they still work together.

    Your problem I think that you are missing the fact that your queryChannel has two subscriber at runtime, not a chain of call.

    The first one is <int-jdbc:outbound-gateway> and the second is that .handle("sampleConvertor","convertUser"). Right, when you declare a channel in the IntegrationFlow, the next EIP-method produces a subscriber for this channel. At the same time when you use a channel like request-channel or input-channel in the XML configuration that brings a subscriber as well.

    So, you have two subscriber on the DirectChannel with the RoundRobinLoadBalancingStrategy and therefore only one of them will handle a message and if it is a request-replly component, like that <int-jdbc:outbound-gateway> it will produce a message into the output-channel or to the replyChannel in the headers. In your case the story is exactly about a replyChannel and therefore you don't go to the .handle("sampleConvertor","convertUser") because it's not the next in the chain, but just a parallel universe by the round-robin algorithm.

    If you really would like to reach that .handle("sampleConvertor","convertUser") after calling the <int-jdbc:outbound-gateway>, you should consider to use .gateway("queryChannel") instead of that .channel().