Initializing BizTalk Correlation Sets In a Loop (Thanks Tomas!)

You ever find that newsgroup post on a technical subject that absolutely saves the day? One of my projects has an orchestration that calls a web service. I call this service in a “loop” because if a call fails (for “business” or “technical” reasons), it may need to retried. So, until I set a “ProcessComplete” flag, the loop continues.

That said, if I DO get an error, I send the message out for review. If I don’t get a response within an hour, I auto-retry the service again. This is done with a transactional scope (long-running) and a timeout. So naturally I have to use correlation to send a message out of my orchestration, and potentially receive a message back. However, after setting this up the first time, I got a
Correlation set may be initialized only once
error. This makes sense since I had a global correlation set, and was potentially initializing it over and over in a loop. After staring at my computer for 4 minutes thinking, I did a quick search online and came across a newsgroup post where my new best friend, Tomas Restrepo, reminded me that a *scope* can have its own local correlations sets.

Sure enough, after moving the correlation set to the local scope, everything compiled fine.

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Author: Richard Seroter

Richard Seroter is Director of Developer Relations and Outbound Product Management at Google Cloud. He’s also an instructor at Pluralsight, a frequent public speaker, the author of multiple books on software design and development, and a former InfoQ.com editor plus former 12-time Microsoft MVP for cloud. As Director of Developer Relations and Outbound Product Management, Richard leads an organization of Google Cloud developer advocates, engineers, platform builders, and outbound product managers that help customers find success in their cloud journey. Richard maintains a regularly updated blog on topics of architecture and solution design and can be found on Twitter as @rseroter.

17 thoughts

  1. Hey, I’m glad I was able to help πŸ™‚
    What’s funny is that I found out about this while trying to do something pretty similar to your own stuff (i.e. manually handling retries in a webservice call) πŸ™‚

  2. Well if Thomas is your new best friend, you’re *my* new best friend, since your blog came up when I googled πŸ™‚

    Thanks for writing it out, for me to find. A scope – of course…

  3. Have you tried correlation with 2 different message. I am using your latest book SOA patterns but couldn’t find any note on that.
    Here is my problem…I am inserting a XML message in a db table via WCF sql send adapter (store procedure pInsertMsg). I am waiting for external process to update that message. I use WCF SQL recieve adapter (store procedure pGetMsg) to get that message back to my orchestration. I cannot correlate this message because of their different MessageType and root. Moreover the get has TypedPolling so it create a different xsd.

    Can you help?

  4. Thushar, the correlation shouldn’t be dependent on a different message type/root as long as you promote the fields in all the source schemas to the same property in the property schema. Have you already done that?

  5. I can not belive how simple the solution to my problem was. I am quite new to BizTalk-development and I have been struggeling with this issue for for more than a day. Thank you for posting this!

  6. Thanks a lot! Saved my day – incredible that I haven’t needed to do this earlier although I’ve been mostly working with BizTalk for the last 12 years…

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