Why use a web service with Linq to SQL?

Question

Can anyone tell me what the need/advantage is to using a web service with an asp.net gui and using Linq to SQL? The web service layer seems unnecessary. Linq to SQL is completely new to me and I am researching as I am setting up a new project. Does anyone have any experience with this?

Answer 1

You would expose services for those cases in which other applications may need to access your data (such as a smart client, another application, a winforms app, etc.). A lot of people will develop using web services to prevent themselves from having to restructure to web services in the future.

In almost any professional/enterprise web application you want to separate the UI tier from the data access layer so you would not embed Linq to SQL calls in the UI tier. Instead you would have a service tier in between, whether its web services, WCF, or just a DLL with business logic that orchestrates your data access layer. Independent tiers are easier to maintain, update, refactor, and learn so the up front investment in creating them is worth the effort.

Answer 2

It is certainly not necessary, but can be handy in case you want to keep your data access layer on a separate server from your presentation server (ASP.NET). A web service allows you to restrict communication between the two servers to only port 80.

Note that this could apply to plain old ADO.NET or anything else too.