nHibernate versus LLBLGen Pro

Question

I am trying to work out with ORM tool to move over to and have narrowed it down to two candidates.

nHibernate or LLBLGen Pro

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Answer 1

We use LLBLGen at work, and it's reviled -- namely because we have multiple similar schemas, but you need to have a different DLL/Class library for each schema, meaning that it becomes annoying to write code that can target any schema.

Of course, that's an unusual environment, so it may not apply to you.

Answer 2

Don't forget one of the greatest plus point of Hibernate: HQL. With HQL, your SQL skill is not wasted. And Hibernate provides very nice, seamless support for native query as well. If you have some weird, out-of-standard database, it's almost certain that you need your SQL skill at some point, and good luck with LLBL!

Answer 3

For me it boils down to database centric (LLBLGen Pro) vs. domain model centric (NHibernate).

Since I'm a DDD/OO guy, the choice has always been very easy for me, but I do see why LLBLGen Pro is popular.

Answer 4

I've used nHibernate, LLBLGen Pro, a custom data layer from my consulting company, the Enterprise Library, and LINQ. LLBLGen is by far my favorite and it allows writing one business layer that can talk to different types of databases using the same code providing database independence! Another incredible feature is it allows multiple connections to different databases. This is very useful when at a large company and one system is written in Sql Server and the other you have to interface with is in Oracle.

LLBLGen Pro is an amazing product backed up by Frans who is very active and works hard to fix issues. LLBLGen is like PhotoShop, it is an incredible tool and that can do amazing effects in the hands of someone who knows how to use. And like any tool that saves lots of time, it takes a week or two to learn how to use it, but will save months later on your project.

Not only did it speed up the DAL generation side of my app, it is also easy to create queries in the Business layer and send to the presentation layer. It made it easy to create an enterprise class application.

If one really wants to use nHibernate, start with LLBLGen Pro and generate the nHibernate code. If later on your department decides to switch from nHibernate to LINQ, you are covered. Want to switch from Sql Server to Oracle? This is possible and relatively easy with LLBLGen whereas with manually coded nHibernate code, you have to rewrite everything which is almost impossible to cost justify.

Frans was also available and answered some of my questions.

Answer 5

I typed up a fairly long answer before realizing this was a somewhat old question. Oh well. It's still very relevant.

You have narrowed your list to the two best candidates for an ORM in the .NET world. I have limited experience with either, but I've read extensively about the pros and cons of both. They really serve somewhat different needs in different ways.

In the upcoming LLBLGen Pro 3.0, Frans Bouma has talked about adding features to generate NHibernate mappings. So, it's not even necessarily an either/or decision.

If you want to do "class first" design (as opposed to "database first" design), NHibernate is pretty much your best and only option right now (neither LLBLGen Pro nor Entity Framework support this mode, although it sounds like Entity Framework is improving it's support in the next version).

NHibernate and LLBLGen Pro both work hard to work well with legacy databases which you can not change and have to live with. That is their common strength. They both also work with Linq. They both also support some amount of graphical modeling, although LLBLGen Pro is far superior in this regard (ActiveWriter for NHibernate feels like the LinqToSql designer in Visual Studio, but it's not really as feature rich).

LLBLGen Pro has much stronger code generation abilities, but too much code generation can lead to compromised testability and maintainability (one small tweak can cause massive amounts of code to need retesting).

While NHibernate wants to help you work through fairly complex object/relational mapping scenarios like class inheritance, LLBLGen Pro is really just exposing your database as a data layer and business objects in a very quick way.

If you can purchase LLBLGen Pro and have some time, I would try both and see which one better meets your needs. Learning both ORMs is good for your resume in any case.

So, in the end, I would say it's situational. The cost of NHibernate and its lack of serious flaws make a pretty compelling case in the majority of situations.

Answer 6

The major difference is that LLBLGen is a code generator, while NHibernate is a "true" ORM library.

LLBLGen advantages:

• Easy to use model designer. Can import your existing database schema
• Fully typed object model and query language

LLBLGen disadvantages:

• You need the designer application to change your model
• Not free
• Can bloat your code because a lot of code is generated

NHibernate advantages:

• No designer application needed. Only code
• Widely used (based on the most popular Java ORM, Hibernate)
• Very powerful for mapping any data model you can imagine
• Open source

NHibernate disadvantages:

• Hard to learn
• Not as strongly typed as one would like (especially queries)

Of course, this is just my personal point of view...