Question

I have a scenario where I need to open multiple datacontexts which point to different databases. I am only writing to one of the databases though and reading from the others … so technically the transaction should only be against one of the databases.

I’d like to avoid having the TransactionScope upgrade into a distributed transaction so I don’t have to worry about MSDTC … is there any way to have only one context enlist in the transaction?

Answer 1

I have been looking at a similar issue with Linq to Sql – initially our solution is to use the same connection per request. Rick Strahl has done a series of blog posts on this which were worth looking at.

In our solution the DataContext constructor(s) have an overloaded constructor that retrieves the connection from a factory (if no connection exists, the connection passed is stored on the thread)

public DataContext1(connection)
    : base (ConnectionFactory.GetConnectionFromContext(connection))
{
}

This seems to work fine in a WCF scenario, the connection factory can store / retrieve from the ServiceModel.OperationContext.Items collection, and (more importantly) subscribe to the OperationComplete event in order to Close / Dispose the connection on the thread when all operations are done.

I found that we also needed to extend the connection object such that you can prevent automatic closure / diposal of the internal connection when the owning datacontext is disposed (e.g. after each operation scope completes).

I’m looking at the non-WCF scenarios now… TBH it’s not pretty. We also don’t have the ‘OperationCompleted’ event trigger that’s there in the WCF context.