Is DTO plus UnitOfWork pattern a good approach to design a DAL for a web application?

There are a number of things going on here...The assumption I'll make is that you're using a 3-Tier architecture. That said, I'm unclear on a few design decisions you've made and what the motivations were behind making them. In general, I would say that your ObjectContext should not be passed around in your classes.

There should be some sort of manager or repository class which handles the connection management. This solves your DB state management issue. I find that a Repository pattern works really well here.

From there, you should be able to implement the unit of work pattern fairly easily since your connection management will be handled in one place. Given what I know about your architecture, I would say that you should be using a POCO strategy. Using POCOs does not tightly couple you to any ORM provider.

The advantage is that your POCOs will be able to interact with your ObjectContext (probably via Repository of some sort) and this will give you visibility into change tracking. Again, from there you will be able to implement the Unit of Work (transaction) pattern to give you full control over how your business transaction should behave. I find this is an incredibly useful article for explaining how all this fits together.

The code is buggy but accurately illustrates best practices for the type of architecture you're describing: Repository, Specification and Unit of Work Implementation.

I was always believing that code can explain things better than worlds for programmers. And this is especially true for this topic. Thats why I suggest you to look at the great sample application in witch all consepts you expecting is implemented.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.