JPA consumer doing constant polling

[mohithanda]

Hi Guys,

I am trying to write a route which is triggered by a JMS message on a queue. It then polls the database using JPA endpoint, converts the row to an entity. Then I want to do some processing on that entity and finally persist it back to the db.

Following is my route

from("localjms:queue:Test.Queue")

.from("jpa:com.mycompany.servicebus.services.entities.test.TestEntity?consumer.query=select t from com.mycompany.servicebus.services.entities.test.TestEntity t where t.id = 1&consumeDelete=false")

.process(new Processor() {

                        @Override

                        public void process(Exchange exchng) throws Exception {

                            TestEntity entity = exchng.getIn().getBody(TestEntity.class);

                            if(entity != null){

                                                entity.doSomeStuff();

                            }

                        }

                    })

.to("jpa:com.mycompany.servicebus.services.entities.test.TestEntity")

.end();

Now the issue that I am facing is that the route constantly polls the db, reads the row and does the aforementioned processing. But I want it to be once off. i.e. when a message is sent to the inbound JMS queue. Can you think of a way by which I could achieve this?

I could inject the entity manager and use plain java code. But I would prefer to use DSL.

Any suggestions? Please advise.

Regards,

Mohit

[davsclaus]

You can stop the route using API on CamelContext.

You can also use a RoutePolicy and attach to the route, and control logic to start/stop the route. We have out of the box policy that uses a timer/quartz cron scheduler, so you can define "opening hours" etc.

http://camel.apache.org/routepolicy

And there is also this FAQ to stop a route from a route

http://camel.apache.org/how-can-i-stop-a-route-from-a-route.html

Also there is a delay option on the JPA endpoint, where you can specify polling frequency. eg delay=1h, to poll once per hour.

[mohithanda]

Ok. Thanks Claus!