Easiest to learn and use .NET ORM framework?

Question

We are re-writing one of our core web applications and I finally got the all clear from management to replace the horrible tangle of stored procedures with an ORM framework for implementing our data access layer.

Hooray for me. Now I have to choose one.

I have played around a little bit with the following

• NHibernate
• Castle ActiveRecord (We would use it to power our DTO objects)
• Subsonic

Now I know that NHibernate is the true Alt.Netty choice but the problem is that I am working with contractors who as far as I know have never heard of it, and NHibernate has a reputation for quite a learning curve. Subsonic in the meantime seems like a far more straightforward approach. I also am aware of the Entities Framework but am wary of its 'meh' reception and Linq to Oracle but am wary of the fact that I've hardly heard anything about it.

So the questions are:

1. Are there any more frameworks I should be considering?
2. Which do you recommend for my situation?

Some more considerations:

• When I say I have a played around a bit with these frameworks, I mean it. I have configured them and used them to pull in some data to make sure it all works. That's the extent of it.
• This is an Oracle database (as you might have guessed from the inclusion of Linq2Oracle)
• Since this is a re-write, the database already exists and has a stable schema
• I am not too worried about performance. Our application usually serves at most a couple people at a time.
• You guys are the ones who are going to have to answer the torrent of questions I'm gonna have

I'm leaning toward Subsonic, but I'm curious what people might have to say.

Answer 1

Have you checked out Telerik's OpenAccess ORM? They recently acquired Vanatec and their ORM product. It supports multiple database platforms (including Oracle), LINQ support, forward & reverse mapping, is integrated with Visual Studio, and in my opinion (granted I am somewhat biased) is a suitable replacement for LINQ to SQL if that is the kind of "ease of use" you are looking for.

Answer 2

CoolStorage.NET is my recommendation. If you're stuck doing .NET it's the simplest feature full solution.

Answer 3

NHibernate will let you decouple your domain entities from your data layer. It does that with XML mapping files to describe the relationship, and uses Castle DynamicProxy to magic up properties that lazy load.

NHibernate is several generations ahead of everyone else in terms of performance, flexibility, and configurability. However, as you said, it is complex. SubSonic is very straight forward, but it is basically generating up static proxy classes based off of your database, so you won't really have the RM out of ORM. IMO SubSonic, L2S, and Castle ActiveRecord are all DAL generators, not ORMs.

IMO it all depends on your needs. If you are talking 2-tier, then go for one of the DAL generators. It will get you moving faster, and your model probably isn't so complex that you can't just generate it up from your db schema. If you have n-tier, I would highly recommend NHibernate. Sure, the learning curve is higher (its not rocket science, but it isn't push button either), however it can actually handle the job that you need, and if you use one of the others you will just end up doing alot of stuff manually anyways.

Answer 4

Well the issue when considering an ORM is

• finding good information about it. Examples, Learning materials.
• do enough people use it (is the product mature)? the more companies use it the more likely the bugs have been found.

When I look at the ORM market for .Net I am finding more and more material on NHibernate

Links to helpful material about Nhibernate <- Videos, tools, and best practices

Castle is built ontop of NHibernate (It is using the Active Record pattern)

Have a google to see if the ORM;s have any tools which help you develop faster.

• Telerick says it comes with VS intergration
• Nhibernate has a couple of tools to reverse engineer a DB into classes, also there is NHProf (not free) which monitors the SQL between NH and SQL

if you are not into XML mapping files, see if you can find a Fleunt mappings. Which should mean compile time checking (some people find this to be easier to debug/refactor code)

fluent nhibernate

HTH

Bones

Answer 5

I would reconsider your evaluation of Microsoft's Entity Framework. You can use DevArt's DotConnect provider for Oracle as a solution until Oracle releases their own provider in the future. Using the Entity Framework, you would then not use "Linq to Oracle", but rather "Linq to Entities" which is a much better solution.

I've had VERY good results from my testing of read operations using the Entity Framework where the read operations were ~700% faster than its SqlCommand\SqlDataReader equivilent.

Answer 6

Checkout XmlDataMapper a simple free ORM (LGPL Licence) which leaves a low memory footprint compared to the other giants. The sample project provided should be good enough to get started.

To integrate XmlDataMapper all you need to do is 4 little steps

1. Create a Business Entity / DTO for the tables
2. Create an XML File with the mapping information between the table and the DTO.
3. Specify the DTO and xml file in the configuration.
4. Just call the DTOConverter.Convert(dataReader) and other such methods to convert your database record to DTO / Business Entity