how to write concise apache camel xml - apache-camel

Question

I am new to Apache Camel. I have setup my application to use Apache Camel using XML based configuration. My configuration contains multiple routes which have similar set of steps. I was trying to find if there a way to place common or repeating parts of these different routes in one place and refer them from routes instead of repeating them again and again ?
for e.g. in my below camel route configuration, route 2 is repeating few steps from route 1. So is there a way to extract the common steps of the route 1 and route 2 and then refer extracted part from route 1 and 2?
<context:property-placeholder location="classpath:quartz.properties" />
<context:component-scan base-package="com"></context:component-scan>
<camel:route>
<camel:from uri="quartz://deadlines/SDGWD?cron=15+34+14+?+*+MON-SUN+*" />
<camel:onCompletion>
<camel:to uri="seda:checkAnyPendingDeadlines"/>
</camel:onCompletion>
<camel:to uri="bean:sdgwdNotifier" />
<camel:choice>
<camel:when>
<camel:method ref="deadlineHandler" method="canProcessDeadline" />
<camel:bean ref="deadlineHandler" method="prepareDeadline" />
<camel:bean ref="sdgwdProcessor" method="initiateMessageProcessing" />
<camel:bean ref="schedulerXdrTransformer" method="marshall" />
<camel:to uri="wmq:SU.SES" />
<camel:bean ref="sdgwdProcessor" method="waitForAcknowledgment" />
<camel:bean ref="sdgwdProcessor" method="afterMessageProcessed" />
<camel:bean ref="deadlineHandler" method="onDeadlineProcessingCompletion" />
</camel:when>
<camel:otherwise>
<camel:bean ref="deadlineHandler" method="enqueDeadline" />
</camel:otherwise>
</camel:choice>
</camel:route>
<camel:route>
<camel:from uri ="seda:checkAnyPendingDeadlines"/>
<camel:onCompletion>
<camel:to uri ="seda:checkAnyPendingDeadlines"/>
</camel:onCompletion>
<camel:to uri="bean:deadlineHandler?method=getNextProcessableDeadline" />
<camel:choice>
<camel:when>
<camel:method ref="deadlineHandler" method="canProcessDeadline" />
<camel:bean ref="deadlineHandler" method="prepareDeadline" />
<camel:choice>
<camel:when>
<camel:simple>${body.deadline} == ${type:settlementcontrol.scheduler.model.Deadline.SDGW} </camel:simple>
<camel:bean ref="sdgwdProcessor" method="initiateMessageProcessing" />
<camel:bean ref="schedulerXdrTransformer" method="marshall" />
<camel:to uri="wmq:SU.SES" />
<camel:bean ref="sdgwdProcessor" method="waitForAcknowledgment" />
<camel:bean ref="sdgwdProcessor" method="afterMessageProcessed" />
<camel:bean ref="deadlineHandler" method="onDeadlineProcessingCompletion" />
</camel:when>
</camel:choice>
</camel:when>
<camel:otherwise>
<camel:bean ref="deadlineHandler" method="enqueDeadline" />
</camel:otherwise>
</camel:choice>
</camel:route>
Thanks,
Vaibhav

Answer 1

Is common route, which contains repeating part of your flow, sufficient? If so, then create something like this:
<camel:route id="myCommonPartOfFlow">
<camel:from uri="direct-vm:common-in"/>
[common part]
</camel:route>
You can invoke your sub (myCommonPartOfFlow) route from your main routes now:
<camel:to uri="direct-vm:common-in/>

Answer 2

You can either use a direct component to create subroutes that factor out common parts or split your routes so that the common routes have their own route and then other routes can send messages to the common route. For example, if you have two routes that do the following processes "Process A" -> "Process B" -> "Process C" and "Process D" -> "Process B" -> "Process E" then you can separate Process B into its own route and do the following:
from("jms:queue:processB") - "Process C" -> end()
Process A -> set Header "JMSReplyTo", jms:queue:processC -> to("jms:queue:processB")
Process C -> set Header "JMSReplyTo", jms:queue:processE -> to("jms:queue:processB")
The for the sake of brevity I used Java DSL but the same can be done with XML DSL. I also used "process A" and the like to abstract what could be multiple steps in the route. The concepts of linking the routes is the same no matter what the process is. The advantage to this approach is that it allows federation of "process B" to handle the extra load and distribute processing around your infrastructure. Once you go to Asynchrounous programming, your capabilities rise quite a bit.