I recently posted a question regarding NHibernate. This lead me to check Codesmith's framework PLINQO for NHibernate.
At the same time, i was reading a tutorial on nhibernate at their official site (as i was looking at the generated project by PLINQO).
I am not an expert on NHibernate but what i am looking at right now (PLINQO Generated NHibernate project) looks to me very sloppy, pretty much a recipe for disaster. It creates a set of "Entities" that i am guessing is the business object? A big mess to my eyes.
Does anyone has experience with Codesmith's NHibernate?
Can anyone point me to a mc daddy of NHibernate. I have found so many variants so far that i am already overwhelmed with all this.
Thanks you.
I work for CodeSmith Tools. How do you feel the generated project looks sloppy? How would you improve it? We try to separate out the entities (POCOs) / hbm's for consistency and easy of use (as Randy detailed above). The Entities are generated directly from what is defined in the hbm file, which can be customized without losing your changes.
The generated project follows the architecture of Linq-to-SQL and Entity Framework. We feel this allows developers on the Microsoft Stack to switch between backends quickly (NHibernate to EF or EF to NHibernatE) while minimizing the amount of code changes.
The generated datacontext manages the NHibernate sessions for you while giving you access to query extensions, caching and much more. Also, you don't lose any core NHibernate features as we just extend the core libraries. All of the core features are available on the DataContext under an advanced property.
P.S., The best place to post questions and get a timely response is via our forums.
Related
I have some experience with NHibernate and I'm trying to get started with Castle Nhibernate Facilities OR Castle NhibernateIntegration. I'd like to know, where I can find a demonstration project of how to configure and perform transactional control (with attributes) in a service layer (business, class library project)? There is no documentation, and I have a really difficult to find some content to getting started.
I found some samples on the web but only with pieces of code and not the demonstration project... I would like to download something to study. I'm not finding to a complete solution, just the configuration and transactional control in business classes (class library).
Sorry for this kind of thread here, but I do know how to start.
Thank you!
If you want to see an full example of Castle Windsor integrating with nHibernate then I would check out Sharp Architecture
Sharp is an attempt at a 'best practice' template project and utilises a number of tech's (Castle and nHibernate included). While some of the things it does may not be to your taste it will clearly show you one of the ways that it can all fit together.
You may need to go hunting into the source repository on GitHub if you want to see what is going on at a low level as Sharp uses it's own base classes in the template project that are pre-compiled (tho its still open source so you can see what is going on if you want).
It was an invaluable help to me when I was putting my architecture together and I can honestly say that Castle and nHibernate are the way to go, so you are very much on the right track.
EDIT FOR COMMENT 1: Perhaps I am a little confused here. According to the Castle notes
Facilities are main way of extending the container. Using facilities
you can integrate container with external framework, like WCF or
NHibernate, add new capabilities to the container like event wiring,
transaction support... or to components (synchronization, startable
semantics...).
To the best of my knowledge both Castle Nhibernate Facilities and Castle NhibernateIntegration are Facilities and must be based on a container.
If you want to work without a container then you need to use some form of Singleton Factory to manage the SessionFactory. There is an example of this here.
In terms of attributes controlling Transactions then this is how Sharp does it (see here). You may get away with reusing this code and replacing NHibernateSession with your own Singleton like theirs.
You don't need to implement UnitOfWork as nHibernate is effectively doing this for you. What you really need is an architecture that allows you to manage a transaction at a single point of control (Singleton) and is available in every repository.
I would basically like to know things such as:
Advantages/disadvantages between the two?
Similarities/differences between the two frameworks?
How are they similar/different architecturally?
How much boilerplate code is needed to use each?
Can the Entity Framework be used efficiently outside of Visual Studio compared to NHibernate? Is the Entity Framework more efficient than NHibernate when used with Visual Studio?
Note: This question refers to the Entity Framework 2 (currently still in development).
Disclaimer: This post is based on my current knowledge of what the next version of Entity Framework will be like. That might be inaccurate or it might change until the next version is actually relased.
General Approach:
The main approach of Entity Framework (EF) is using their graphical designer tool to create an Entity Data Model and to generate domain classes as well as mapping from that model. There is support for other approaches as well, but that way of working will probably always be the main one.
NHibernate (NH) is a text based tool which requires the user to write all the domain classes and mapping manually, if you don't turn to third party software for code generation, such as MyGeneration of CodeSmith, or additional convention over configuration support, such as Fluent NHibernate.
Code Generation:
Code generation is a major part of standard EF usage, either by using their graphical designer tool or by using their command line tools. The availability of both GUI and command line tools is a plus since makes EF easy to get started with as well as allowing for more advanced usage that can be automated, for example in a build process.
Code generation is not supported by NHibernate, except for the schema generation stuff if you want to count that as code gen. You can get code generation if you turn to third party software though.
Database Schema Generation:
EF will add support for model first development, by allowing the user to generate a schema from an Entity Data Model. NHibernate has had schema generation support for a long time. The difference here is how you create your "model", as mentioned earlier.
LINQ:
EF will have improved their whacky LINQ implementation from v1 and NH have now reached version 1.0 of LINQ to NH, so there should not be any major differences between the two in that regard.
POCO:
EF will add better support for the Domain Driven Design approach and the use of domain classes that are separated from the data access layer. However, since POCO is not the main use case of EF I can't really see how their POCO support could ever reach the level of NHibernate. The POCO support in EF is still young, and to me it feels more like that it is a bonus if you are a POCO/DDD supporter and you find yourself working on EF for some reason.
The entire NHibernate framework is build for POCO development, by DDD people, and they have reached version 2.1 as well as taking advantage of all the work put into Hibernate on the Java side. NHibernate will probably remain the no 1 choice for the DDD/POCO/ALT.NET crowd for quite some time.
Lazy Loading:
The next version of EF will include support for automatic lazy loading. Automatic lazy loading has been an important part of NHibernate for a long time.
Learning Curve:
Both frameworks are complex and powerful, and hence take a long time to master. But EF is quite beginner friendly since it is integrated into Visual Studio, with its graphical designer tool, and since it can generate a lot of stuff for you without you having to know just about anything about the framework. However, if you want to dig deeper into EF and really learn the framework, you should be prepared to spend quite a lot of time using it.
NHibernate has a notorious learning curve, but some recent improvements have reduced it a bit. Now that LINQ to NH is at v1.0 the query syntax will be easier to understand for developers new to NH, and the Fluent NHibernate project is improving the mapping experience, and even working on automatic mapping, which is getting better and better all the time.
Can anyone throw some light on tools that can be used with NHibernate and which perform the below mentioned tasks:
Generates the Mapping File
Generates the Entity Class
Generates the Configuration file
And also provide information whether these tools are open source or licensed.
Thanks
One tool I've used that did a decent job was CodeSmith. It looked at the existing database and created the entities, mappings and configuration file. However, this is only to be used as a starting point as there are many tweaks you'll likely want to do to make it more usable and better performing. Things such as when to lazy load vs. eager load, creating subclasses or components. This tool really just mimics the database structure in your entities which is not always the best way to represent in code.
This is a licensed solution but it includes a fully functional demo you can use to gen your files initially. After that, you'll most likely just enhance just as you would your database.
Another is MyGeneration. Same thing, it'll get you 75% of the way there in most cases.
Just be cautious as to which version of NHibernate these tools are producing. They may be using an older version which may have some obsolete code.
I really like Visual NHibernate (http://www.slyce.com/VisualNHibernate/).
Not free, but has a nice set of features, including the definition of templates for the entities, and generating both HBM.XML as well as Fluent NHibernate mappings.
A similar question with some answers you might find useful is already on SO.
NHibernate Generators
As mentioned in that question's answers, fluent NHibernate is a good option. It just went RTM. You can find more info at http://fluentnhibernate.org/
Check out LLBLGen Pro. It's got a competing ORM but can also act as a code generator for nhibernate. Very good for DB first work.
I need to collect some information about existing ORM solutions.
Please feel free to write about any programming language.
Can you tell about the best ORM framework you ever use and why is it better then others?
I used NHibernate and Entity Framework.
Current stable version of entity framework is very immature. It is too difficult, or impossible to perform common tasks. Testing your code is also difficult since you cannot really separate your entities from your data access classes. But it perfectly integrates with visual studio ide. Setting up is easy and updating all the models from database takes just a few seconds. Upcoming version of EF (4.0) will solve some of this problems.
NHibernate is quite powerful. It supports plain old clr objects, so you can work with simple entities. Configurations provide great control in great detail. Framework capabilities are satisfying and it has a large and active community and good documentation. Setting up and updating entities is a little difficult since you must use generators that looks up your database and generates entities and xml files. It may be tricky to find a generator or a template that exactly fits your needs. But once you set all things up, you will love it.
I found LINQ to SQL to be a pretty straight forward solution. The first time I used it, I'd say I had a basic ORM working within a few hours, and was creating LINQ queries with it.
Microsoft has an additional ORM (Entity Framework), which I've heard is more complex but may be useful for highly complex distributed applications with multiple data sources etc.
Overall I found LINQ to be an easy and fast to use ORM.
I have been looking at Telerik Open Access for last few months, in genernal this ORM has been a pain to work with, it was advertised as having extensive linq support but in reality many of the linq features you would normally expect dont work server side and are performed on the client. I also had problems using multiple conditions in a where clause, see my last question. Here are a few things that i found
No support for views
Unable to map more than one entity to the same table
Inheritance and Interface support requires you to make changes to you database schema
No visual designer like LINQ to SQL and Entity Framework
If you want to perform an insert any related entities must be fetched first
Rohan
LINQ2SQL was nice, EF makes sense, but is very complex and SQL Server oriented. NHibernate is special and Telerik OpenAccess (fully .NET / Visual Studio) got a broad set of functionality and professional support.
Since I know the product I can comment on Rohan's concerns:
Existing Views can be used and full Views support is coming up
Mapping more than one entity to the same table "works" for class hierarchies, limitation with reverse mapping exists
Inheritance and Interfacer support "do not require" changes to the the database schema, again limitation with reverse mapping exists though
Visual Designer will come, Forward and Reverse Mapping Wizards allow you already to do anything in an easy way
There is a workaround for the insert issue mentioned and it will be fixed generally
Check out the Telerik site to find happy customers and feel free to use the telerik forums and support resources for any question.
-Peter
Im new to OpenAccess ORM and we are using two products. Reporting and OpenAccess.
I think there are some features that people missed.
OpenAccess uses graphical designers while nHibernate still uses handwritten xml files
OpenAccess is not limited to SQl Server as EF4 and similiar frameworks
using it is easier and the forums are pretty helpful.
With ORM there are multiple possibilities, all depends what you want.
As a real ORM mapper I strongly recomment NHibernate and Fluent NH mappings. You need a lot of research to put together a nice architecture, but then nothing stands in your way. With minimal compromises you get real flexibility.
EF6x (core is not prod.-ready IMHO) is called an ORM, but what it generates is more closer to a DAL. There are some thing's you can't do effectively with EF6. Still, this is my favorite tool for a read-model, while I do combine it with NHibernate (where NH I use for a DDD/write model).
Now to performance - its always pro and cons. If you deep deeper into ORM architecture (see my article: avoid ORM bad habits) then you will find intuitively the ways to make it faster. Here's my another article on how to make EF6x 5x faster (at least for read situations): EF6.x 5x faster
I just want to do a quick poll to see if Fluent Nhibernate is well received or if it is having lot of issues. I like Nhibernate but I definitely see the problem with xml to do mapping.
So, I am looking forward to community members for some insight and help me pick one over the other.
I am not considering either linq2sql or entity framework at this time.
I like Fluent NHibernate and I think it's mature enough if you are going to start a new project. Using it on a new project should allow the Fluent NHibernate project to continue to mature as yours progresses. There is a possibility for breaking changes (as happened recently with the convention mappings) but you should be able to deal with those. I've had a few issues with the mappings but the project is pretty responsive to bug reports and has mostly worked as expected.
The mapping options are:
Xml mappings - Standard of NHibernate. The maintenance headaches are well known but the advantage is that you have access to all of the configuration options provided by NHibernate. There are a few less-used configuration options are still being added to Fluent (at least last time I paid attention). So, if you are anticipating some crazy mappings, you may want to consider this option.
Standard Mapping - Provided by Fluent. You can create the mappings through code and is much better for refactoring and authoring. Not much to say about it, in my experience, other then that it works well and is a big improvement on the xml option.
Auto Mapping - Provided by Fluent. Allows you to map object properties by convention and it attempts to create the mappings automatically. It's a good idea but I think it still has some maturing to do. I'm currently using this mapping method and it works fine but I have ended up writing a large number of conventions and specifying the object relationships that it doesn't feel like it's saved much effort from the standard mappings.
Fluent NHibernate also provides nice test helpers for testing your mappings and some configuration APIs that can make it easier to configure NHibernate. Overall, it's a good project and it provides some nice additional functionality to NHibernate.
edit:
One additional thing to note: If you start off with Fluent NHibernate and decide it isn't going to work for your scenario, you can easily migrate back to the xml mappings. Fluent NHibernate allows you to export the mappings it creates and you can use those exports to not lose whatever mapping work you've already done.
One of the best advantages of using Fluent Nhibernate over vanilla NH is nice integration testing with PersistenceSpecification<T>:
[Test]
public void TestProductSave()
{
new PersistenceSpecification<Product>()
.CheckProperty(x => x.ProductName, "Wax")
.CheckProperty(x => x.Price, 20)
.VerifyTheMappings();
}
I've been using fluent on a new project of mine. The only minor bump I've hit so far is that it doesn't play so well with Castle Windsor out of the box, but it was quite easy to extend Windsor to do the job. Other than that I've been loving it. It's much more concise than the XML mappings.
The nice thing about fluent is that it isn't an all or nothing investment. You can write most of your mappings in fluent and if you find any issues you can map those classes in the standard XML mapping until the fluent issues are resolved.
Like any good answer, it depends.
I didn't get as much mileage out of the automapping features as I would have wanted to. I often have to work with preexisting databases.
I already had several projects using NHibernate under my belt, so using the hbm mapping wasn't difficult. After I figured out how to include in the hbm schema, it was much easier.
The one real advantage I gained from having fluent-nhibernate is being able to refactor my domain classes and have my mappings automatically change. I didn't really notice that much of a speed increase in writing the mappings.
Like anything, YMMV.
I am using FNH for a new project. What I like the best is the ability to generate and build the database directly from the entity classes.
I have had to write a few conventions for the properties but I'd rather that then maintain more than one list for each class.