CODEWITHSUNDEEP
javaspringspring-integrationmessaging
anon
anon

Reputation:

spring service-activator does not work for output-channel attributes in XML configuration

Understanding spring integration basics from tutorials and trying to implement a small exam result process. In the below code, the service-activator gets invoked for input-channel="exam" and the output-channel set on the same service activator is output-channel="result" but it never gets called as a result the <int:outbound-channel-adapter> also never gets called.

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:int="http://www.springframework.org/schema/integration"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:int-jdbc="http://www.springframework.org/schema/integration/jdbc"
       xmlns="http://www.springframework.org/schema/beans"
       xsi:schemaLocation="http://www.springframework.org/schema/integration http://www.springframework.org/schema/integration/spring-integration.xsd
      http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/integration/jdbc http://www.springframework.org/schema/integration/jdbc/spring-integration-jdbc.xsd">
      
 <bean id="written" class="com.example.nora.service.ExamService"/>

 <int:inbound-channel-adapter channel="exam" ref="hallticket" method="check">
   <int:poller fixed-delay="1000"/>
 </int:inbound-channel-adapter> 
 <int:channel id="exam"/>
 

 <int:service-activator input-channel="exam" output-channel="result" ref="written" method="write"/>
 <int:service-activator input-channel="result" ref="sc" method="testScservice"/>
 <int:outbound-channel-adapter channel="result" ref="resultServic" method="test">
 </int:outbound-channel-adapter>
 <int:channel id="result"/>
 
 <bean id="hallticket" class="com.example.nora.service.Hallticket"/>
 <bean id="resultServic" class="com.example.nora.service.ResultService"/>
 <bean id="sc" class="com.example.nora.service.ScService"></bean>
      
 </beans>

So, Basically it tries to invoke another service-activator from the output-channel set on one service-activator. Please let me understand this behavior.

Upvotes: 0

Views: 303

Answers (1)

Artem Bilan
Artem Bilan

Reputation: 121552

First of all your write method must return something which is going to become a reply message payload to be sent to that result channel .

Secondly, if you want to have that message to be processed in both next service-activator and outbound-channel-adapter, the result channel must be a publish-subscribe-channel instead of direct one as it is by default. In your current case the messages are processed in round-robin manner , so the first message goes to the service-activator, the second to the outbound-channel-adapter and so on flipping on each message appeared in the result channel.

See docs about those channels nature :

https://docs.spring.io/spring-integration/docs/current/reference/html/core.html#channel-implementations-publishsubscribechannel

https://docs.spring.io/spring-integration/docs/current/reference/html/core.html#channel-implementations-directchannel

Upvotes: 1

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