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276

answers:

1

This problem is not readily reproducible in a simple example here but was wondering if anyone has any experience and tips, here is the issue:

  • using Entity Framework
  • have many points in application where (1) data is written to some entity table e.g. Customer, (2) data is written to history table
  • both of these actions use Entity Framework, HOWEVER, they use different contexts
  • these actions need to be both in one transaction: i.e. if one fails to write, the other should not write, etc.
  • I can wrap them with a TransactionScope,

like this:

using (TransactionScope txScope = new TransactionScope()) {
    ...
}

but this gives me:

Microsoft Distributed Transaction Coordinator (MSDTC) is disabled for network transactions.

Our database admin has told me that MSDTC is disabled by choice and can not be installed.

Hence I am making changes trying to create my own EntityConnection with a MetadataWorkspace with the idea that each context will use the same EntityConnection. However, this is proving near impossible trying to get it to work, e.g. currently I continue to get the above error even though theoretically both contexts are using EntityConnection. It's difficult to understand where/why Entity Framework is requiring the MSDTC for example.

Has anyone gone down this road before, have experience or code examples to share?

+3  A: 

Well, the problem is quite easy.

If you are using sql server 2008 you should not have that problem because you have promotable transaction, and as .net knows that you are using the same persistence store (the database) it wont promote it to dtc and commit is as local. http://msdn.microsoft.com/en-us/library/ms172070.aspx <-- look into promotable transaction with sql server 2008.

As far as I know Oracle is working in its driver to support promotable transactions, but I do not know the state, MS oracle driver does not support it. http://www.oracle.com/technology/tech/windows/odpnet/col/odp.net_11.1.0.7.20_twp.pdf

If you are using a driver that do not support promotable transactions it is imposible for .net to use local transaction doing two connections, you should change your architecture or convince the database admin for installing msdtc.

Pablo Castilla
hmmm, we actually are using SQL Server 2008, it seems to not actually know that we are using the same database in both connections: my hence my current approach is to build two EntityConnection objects, both from ONE SqlConnection object, and perhaps that these SQLConnection objects are teh same in both contexts EF will not promote it to DTC.
Edward Tanguay
UPDATE: sorry, the database is actually still SQL Server 2005, which as you noted seems to be the problem, I double-checked the version after reading this most excellent post with lots of recorded data as he worked through exactly this problem: http://stackoverflow.com/questions/1690892/transactionscope-automatically-escalating-to-msdtc-on-some-machines
Edward Tanguay
so at the end you have two options: changing the sqlserver to 2008 or changing the code.Good luck!
Pablo Castilla