Question

we are using Spring Integration 2.1 for persisting messages into database sent by clients.

There is a queue which will be filled by a custom adapter. The configured service activator polls this queue and releases the message to a spring managed @Repository bean. All errors will be captured to an error channel and will be handled by a service. The configuration works so far fine.

My concern is that if the database is not available the service-activators polls all incoming message from the queue and puts them into the error channel. Is there a way to prevent the service-activator to poll the message if the database is obviously not available, for example by sending a test query ?

My configuraton:

<int:channel id="inChannel">
   <int:queue />
</int:channel>
<bean id="service" class="some.service.Service" />
<int:service-activator ref="service" 
      method="write" input-channel="inChannel">
   <int:poller fixed-rate="100" task-executor="srvTaskExecutor" 
      receive-timeout="90" error-channel="errChannel" />        
</int:service-activator>
<task:executor id="srvTaskExecutor" pool-size="2-10" 
      queue-capacity="0" rejection-policy="DISCARD" />
<int:channel id="errChannel" />
<int:service-activator input-channel="errChannel" 
      ref="errorService" method="write"/>

Regards.

Answer 1

If you give the polling service-activator an “id”, you can refer to that instance and call start() or stop() on it based on the DB being available or not. Most likely you’d want to set auto-startup=”false” on that service-activator as well.

Additionally, you can even define a “control-bus” element and then send messages like “myActivator.start()” and “myActivator.stop()” to that control bus’ input-channel.

Hope that helps,
Mark