<p>Within an n-tier app that makes use of a WCF service to interact with the database, what is the best practice way of making use of LinqToSql classes throughout the app?</p>

<p>I've seen it done a couple of different ways but they seemed like they burned a lot of hours creating extra interfaces, message classes, and the like which reduces the benefit you get from not having to write your data access code.</p>

<p>Is there a good way to do it currently?  Are we stuck waiting for the Entity Framework?</p>

This seems to work; not sure how useful it is, though:
```
```
a[1] = 2
a[2] = 3
a[3] = 5
a[6] = 8
Part[DownValues[a], All, 1, 1, 1]
```
```