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| Retry logic in a flow exposed as Web Service |
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| vsr |
 Posted: Fri Apr 06, 2007 7:36 am Post subject: Retry logic in a flow exposed as Web Service |
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Centurion
Joined: 04 Apr 2006
Posts: 104
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Hi Everyone ,
I am trying to implement retry logic using MB V6.0.2 . My flow design is as follows:
| Code: |
out
HttpInput ---->Compute1---->HttpRequest|--------> Compute2 ---->HttpReply
|--------> ErrorHandler
(error/ Subflow
catch)
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Domain is 'XMLNS' for both HttpInput and HttpRequest nodes .
I want to retry say 5times if first attempt fails in the error handling subflow .
I know I can use MQ backout queues using backout count if my input is MQInput . But here we are exposing flow as a webservice ...
I tried 2 ways :
In both methods I throw an error in the Error Handler if the Retry_count ( which is stored as Environment Variable and incremented for every retry ) is less than 5 .
1. Make use of HttpInput's catch terminal :
-----> Wired catch terminal to HttpRequest node .
2. Placed a Try-Catch terminal after Compute1 before HttpRequest .
-----> wired Catch terminal to Error Handler sub flow where i throw error .
But in both methods , when the message is sent back second time to input node ( HttpInput ) , then the message is being discarded ...
So , I wired the catch terminal of the TryCatch node to TryCatch 'IN' terminal .. so , as of now , flow is working for number of retrys i specified .
But , i am not sure whether this is the correct design !
Please advice me ! |
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| marcin.kasinski |
| Posted: Sat Apr 07, 2007 1:32 am Post subject: Re: Retry logic in a flow exposed as Web Service |
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Sentinel
Joined: 21 Dec 2004
Posts: 850
Location: Poland / Warsaw
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In similar scenario I wired error handling subflow out terminal to HTTPRequest input terminal.
In my error handling subflow I make all require checking and error processing.
_________________
Marcin |
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| elvis_gn |
| Posted: Sat Apr 07, 2007 5:32 am Post subject: Re: Retry logic in a flow exposed as Web Service |
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Padawan
Joined: 08 Oct 2004
Posts: 1905
Location: Dubai
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Hi vsr,
| vsr wrote: |
2. Placed a Try-Catch terminal after Compute1 before HttpRequest .
-----> wired Catch terminal to Error Handler sub flow where i throw error .
But in both methods , when the message is sent back second time to input node ( HttpInput ) , then the message is being discarded ... |
The reason why the message was being discarded was that you threw from the Error Handler and it was being caught at the try catch node, the TryCatch was connected to the ErrorHandler again....in this loop you incremented the counter to 5 and exited the flow....
Now, I guess you you found a work around, or should be able to change accordingly from the above....
The only concern I have is that you are possibly going to spend 25seconds to reply to a service call...its a long time....
Regards. |
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| vsr |
| Posted: Mon Apr 09, 2007 5:15 am Post subject: Re: Retry logic in a flow exposed as Web Service |
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Centurion
Joined: 04 Apr 2006
Posts: 104
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| elvis_gn wrote: |
The only concern I have is that you are possibly going to spend 25seconds to reply to a service call...its a long time....
Regards. |
Thank you for the reply Elvis . You are right ! As of now I set Request timeout to 2 seconds . So , if the webservice is down , for 5 retrys it takes 10 sec which is not desired for the request application ..
I wanted to make sure that if the request application can wait for late reply ( 10 sec ) then I should be in a position to make 5 retrys . So I was playing with the retrys in case ...
Thanks all ! |
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