Vista - Using DataContext with WCF services

Hello,

I'm creating a WCF service in which I use LINQ to SQL to do all my data access.
I have a couple of architectural questions about using LINQ to SQL from WCF
services:

1) What is the right way to use DataContext in this scenario?

The service will obviously be used by multiple clients simultaneously. Should
I be creating a "global" DataContext object that I use from within each of
my WCF operations, or should I create a DataContext within each operation?
My guess is that a global DataContext object is the right approach, but in
this case, how would I ensure that when I call SubmitChanges it only submits
the changes requested by a specific client?

2) What is the right way to pass data to/from WCF operations?

Is it possible to return the entity classes from an operation? If it isn't
(which I'm guessing is true), then how do I use LINQ to SQL's conflict detection
and resolution? If my DataContext object is local to each operation, would
it be able to detect conflicts at all?



Thanks,
-- Ragesh Krishna.

> Should I be creating a "global" DataContext object that I use fromI would argue "local" - there are lots of issues otherwise, not least
thread safety.
I don't really understand the question - perhaps re-phrase?

One common approach here is to keep both the original and new version
(at the client) - send them both up the wire and use the overload that
allows you to add them to the data-context; this enables change/conflict
detection.

Alternatively, look at ADO.NET Data Services (aka Astoria), which does
all this for you - i.e. it provides a client data-context that can talk
to your IQueryable<T> service over WCF.

Marc