Conditional route-scoped onException

[Bernard Ligny <be...@gmail.com>]

I am trying to model the following logic for the error handling of one single
specific route.

1. Post a (large) xml document
2. If the post failed, then split original xml into into n smaller
documents, and repost them (step 1) individually.

That kind of recursive process needs of course a stopping condition (size of
batch > 1)


<route id="processBatch">
            <from uri="activemq:queue:solr-batches"/>
            <choice>
            	<when>
            		<simple>${headers.batch_size} &gt; 1</simple>
            		<onException>
		            	<exception>java.lang.Exception</exception>
		            	<handled><constant>true</constant></handled>            	
		            	<to uri="direct:splitAndResubmit"/>
            		</onException>
            	</when>
            </choice>            
            <to uri="http:..."/>  
</route>

According to the my observations, it seems the uri "direct:splitAndResubmit"
is *always* called. 

So the question is: is this allowed to have such logic, i mean a
<onException> inside a <choice> 
- or should it always directly follow a <from> element ?

Thx,

Bernard.




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Re: Conditional route-scoped onException

[Bernard Ligny <be...@gmail.com>]

Okay, i've just found a fully working solution. It is surely not the most
elegant one (as some code is repeated), but at least it works as expected...

The workaround consists in replacing the doCatch/onWhen (of previous post)
with an outer choice whose one branch contains the try/catch:

<route id="processUpdateBatch" errorHandlerRef="DLQ_solr_batches">
    <from uri="activemq:queue:solr-batches"/>
    <choice>
        <when>
            <simple>${headers.batch_size} &gt; 1</simple>
            <doTry>
                <to uri="http:..."/>       
                <doCatch>
                    <exception>java.lang.Exception</exception>                                                                                  
                    <to uri="direct:splitAndResubmit"/>                                         
                </doCatch>                                  
            </doTry>
        </when>
        <otherwise>                 
            <to uri="http:..."/> 
        </otherwise>
    </choice>                                  
</route>

Hoping this post could help someone else...

Regards,

Bernard.

NB: I'm still interested in knowing/understanding why previous attempts did
not work.



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Re: Conditional route-scoped onException

[Bernard Ligny <be...@gmail.com>]

I finally managed to rewrite my route using a conditional try-catch (ie with
<onWhen>):

<route id="processUpdateBatch" errorHandlerRef="DLQ_solr_batches">
            <from uri="activemq:queue:solr-batches"/>
            <doTry>
                <to uri=""http:..."/>            	
                <doCatch>
                   <exception>java.lang.Exception</exception>
                   <onWhen>            		
                       <simple>${headers.batch_size} &gt; 1</simple>
                   </onWhen>        			    			
                   <to uri="direct:splitAndResubmit"/>			                       			
               </doCatch>            	            		
            </doTry>		 	
 </route>

The only remaining (and serious) problem I am facing, is that the exchange
is *NOT* put in my DQL when the onWhen predicate is not satisfied (I guess
the handled flag is set by default to true in a try-catch ?)

But how can I model the following behaviour:
a) if (exception) AND (batch_size>1) : do a specific process (here:
splitAndResubmit) and silently ignore error
b) if (exception) AND (batch_size=1) : use the error handler specified on
the route level (in my case a DeadLetterChannel with a redeliveryPolicy) ?

In my solution, a) is working fine, but not b)






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Re: Conditional route-scoped onException

[Bernard Ligny <be...@gmail.com>]

I aslo tried to rewrite the route as:

<route id="processBatch" errorHandlerRef="DLQ_solr_batches">
            <from uri="activemq:queue:solr-batches"/>
            <onException>
              <exception>java.lang.Exception</exception>
              <choice>
              <when>
                  <simple>${headers.batch_size} > 1</simple>
                  <handled><constant>true</constant></handled>            
                  <to uri="direct:splitAndResubmit"/>
              </when>
              <otherwise>
                  <handled><constant>false</constant></handled> 
              </otherwise>
              </choice>
            </onException>            
            <to uri="http:..."/>   
</route>

But this is not conform to xml schema :-( 



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