Her is a simple example of Mediator re-sequencing - a not so well known SOA Suite feature.
Very interesting for AIA style integrations e.g. multiple order updates in EBS being passed on to Siebel.
I have the following simple scenario -
Order processing - orders are defined as follows -
Notice the key fields - orderID / msgID. There can be multiple messages for the same orderID. Unfortunately they do not always come in the required sequence. For example we could receive -
Fortunately we have the Mediator which can do the re-sequencing for us, so that our output will be as follows -
orderID=1 msgID=1 orderID=1 msgID=2
To illustrate this, I create the following composite -
ReadOrder - is a ReadFileAdapter based on the XSD above.
WriteOrder - is a WriteFileAdapter based on the XSD above.
The Mediator is configured as follows -
Resequencing level is set to component, I could also set this to operation. This is useful when a mediator supports multiple operations and resequencing is not required for all of them.
I set the mode to standard - others are Best Effort and FIFO.
I set the Group By to orderID and the sort criteria (ID) to msgID. In other words, for each orderID - sort the messages in msgID order starting with msgID 1. Note the increment setting is also equal to 1.
Deploy and test.
I drop the orders into the inbox in the order - order1-3 (orderID=1/msgID=3), order1-2, order1-1.
I then re-test with the next 3 in the sequence order1-6 (orderID=1/msgID=6), order1-5, order1-4
I then view the outbox -
The meta-data is stored in the MEDIATOR_RESEQUENCER_MESSAGE table for Standard re-sequencing.
The last 6 entries are from my test today.
Now If I re-submit (orderID=1/msgID=6), order1-5, order1-4 - I get an error
Another interesting table is MEDIATOR_GROUP_STATUS -
Note the entries for /ResequenceRoute - my Mediator.
So we see the next expected sequence id = 7.
The following blog post explains purge strategies for the above tables -
SOA Purge Strategies
We can purge the completed messages from the MEDIATOR_RESEQUENCER_MESSAGE table
There are my messages with status=2 which signals that they are completed.
btw. the relevant purge scripts are available at -