Impact of SQL Transaction in WCF Transaction

Question

I am calling a wcf service and its purpose is to insert some details in sql server table. I am using sql transactions and after insert operation I also commit that transaction of sql server. Now this service is called by a client which has initiated its own transaction and inside its transaction, calling this service. So my query is :-

If transaction is committed by SQL server commit transaction command and some exception occurs at client end after calling other service(This service functionality is executed successfully but client is calling one another wcf service which throws exception) so will the data inserted will be rolled back on database of 1st service or not and if yes how it will happen.

Answer 1

This example appears relevant to your question: Tansactions in WCF

It has a client calling into 2 WCF services in a transaction. Each service itself issues a transaction on a DB. The example tests the case where the call to first server suceeds but then an exception is thrown - no data from first call is written to db as client transaction is rolled back due to exception after first server call.

The question of how this works is a good one as there does seem to be an element of magic involved! I'm no expert on this (so probably better to wait to hear from one!) and all I can suggest is that when you declare your WCF method [OperationBehavior(TransactionScopeRequired = true)] then WCF does some reflection magic on the method code to wrap database activity in a transaction - and it handles rolling that generated transaction back on the db on exception - but I can't give insight into the details of that mechanism (I'm sure someone else can) - you might want to reword a new question that focuses more clearly/directly on that point.

You could also gain insite by experimenting with the functionality of your service method - i.e if you change the db code to instead write a file you will probably find that the file is written if there is an exception or not.

Update: There is some detail about how TransactionScope works in this answer.

Answer 2

SQL transaction works separately and the the commit done in the WCF service will be available even if client rollback the transaction at its end. I have faced the similar situation and observed the above result.