Comments on: Linq to SQL with WCF in a Multi Tiered Action – Part 1

By: John Leitch

John Leitch — Tue, 09 Feb 2010 21:37:52 +0000

I wrote a tool that automates most of this. It can be found at http://wcfmetal.codeplex.com/

By: Sidar Ok

Sidar Ok — Thu, 13 Aug 2009 11:58:24 +0000

@zed

The user object is not null here, are you sure the db and mappings are done correctly ?

By: Sidar Ok

Sidar Ok — Thu, 13 Aug 2009 11:57:17 +0000

@Kyle

Thanks a lot. Indeed there was no disconnected example on the internet when I wrote this article, even seen people from Microsoft mentioning that Disconnected scenario is not possible. So I was burnt a lot to extract this out at the time, I am really glad that people like you still find it helpful and time saving.

By: Kyle

Kyle — Tue, 11 Aug 2009 16:07:21 +0000

Nice man - someone else said it, but it wouldn’t hurt to repeat it: there’s a big gap in terms of actual real-life, multi-tiered app examples out there for all of the microsoft technologies… thanks for putting this out there…

as an aside: we use linq in an “enterprise” application - it works…but it takes some beating up as I think you show here in your post.

By: zed

zed — Wed, 21 Jan 2009 10:40:27 +0000

Test method FavoritesDAL.Tests.UsersDataAccessTest.BatchUpdateUsers threw exception: System.NullReferenceException: Object reference not set to an instance of an object..
FavoritesDAL.Tests.UsersDataAccessTest.BatchUpdateUsers() in C:\DevProjects\LinqWcfMultitier\LinqWcfMultitier\LinqWcfMultitier.Web.Site\FavoritesDAL.Tests\UsersDataAccessTest.cs: line 94

the user object is null - is that correct?

By: Sidar Ok

Sidar Ok — Wed, 24 Dec 2008 10:17:57 +0000

@Andrey,

Thanks a lot.

The enums are serializable by default since they are nothing more than integers, so you don’t need DataContract on enums. The tests are still passing, could you copy the error you are having ? I suspect that the problem is elsewhere.

By: Andrey

Andrey — Mon, 22 Dec 2008 23:56:41 +0000

Excellent article, got me started very fast.
One thing I couldn’t get working right away is serializing the enum property.

Modified the enum definition to include EnumMemberAttribute and it worked.

[DataContract]
public enum EntityStatus
{
[EnumMember]
None = 0,
[EnumMember]
New = 1,
[EnumMember]
Updated = 2,
[EnumMember]
Deleted = 3
}

By: Sidar Ok

Sidar Ok — Tue, 27 May 2008 08:30:08 +0000

Hi Javi, thanks for the nice thoughts. In the next post, I’ll write the sample for data layer, and you are right, for select operations we are going to turn the Object Tracking off and it is more performant. But for Create, Update and Delete, since we need to call SubmitChanges in the context, Data Context can not be turned into readonly mode, otherwise it will throw InvalidOperationException - InvalidOperationException ObjectTrackingRequired.

But as you said, when the data is read only, such as in Get operations, there is no need to turn object tracking on and there will be a significant performance increase in that.

By: Javier Crespo

Javier Crespo — Tue, 27 May 2008 07:17:53 +0000

Great walkthrough, I’ve seen other posts about linqtosql and they mainly focus in a 1 layer application so I really appreciate a sample that fits the Application design/architecture requirements that I’m usually exposed to.
I’m looking forward to the second part.
A question for you: Would it be good performance wise to turn off ObjectTracking for this scenario where the DataContext is not kept alive beyond the DataAccess layer?