I've been programming in C# 2.0 WinForms for a while now. I'm starting to get into ASP.NET and the new MVC framework and the new features of C# 3.5. I've only read a little on LINQ to SQL but have made a few test apps to try it out. In my WinForms apps, I usually had some sort of data access layer, and wrote all the SQL myself. Of course, if something can do that CRUD for me, I'm all for it.
I followed the tutorials on the www.asp.net/mvc website and did both the Entity Framework example and the LINQ to SQL example. So far, they both seem pretty similar. LINQ feels more like SQL, but the Entity Framework feels more like C#.
My questions are:
Is one method better than the other?
What are the benefits of one over the other?
Is it possible to see the SQL that is generate when using either of the methods?
Since I'm new to the ASP world, are web developers leaning on one side?
2: LINQ-to-SQL has the benefits of being simple (but still well engineered) - but the downside of being simple ;-p
LINQ-to-SQL only works on SQL Server (Entity Framework is pluggable; 3rd party variants of LINQ-to-SQL like DBLinq cover some other providers)
Entity Framework supports more abstraction between the data (storage) model and the object model - LINQ-to-SQL is literal table/column => class/property[|field]
LINQ-to-SQL is actually more "complete" in the stuff it does do:
EF doesn't support UDFs
EF doesn't support things like sub-expression invoke (for custom expression trees)
EF doesn't support some "obvious" methods like Single()
EF doesn't have some of the TSQL optimisations that LINQ-to-SQL uses
Basically EF at the moment is a bit more of a "v1" (or even "v0.9") product. However (and importantly) - EF is likely to have a proper next version in .NET 4.0 etc, where-as LINQ-to-SQL is going to see a lot less change. It is still being maintained, but famously Microsoft have chosen Entity Framework as the flagship product (rather than co-evolve both products essentially into each-other). You should think about the long term plans.
At the moment, I'm very happy to use LINQ-to-SQL, but EF is on the long term... so I'm using repository etc to hide some of the gory implementation details - a bit of a leaky repository, but pragmatic.
3: With LINQ-to-SQL, assign a TextReader to dataContext.Log; Console.Out works well - or I have one that writes to the trace.asax. With EF, ToTraceString.
4: I suspect it breaks down a lot by complexity. People using SQL Server with simple models, or who are happy to have a storage model that shines into the object model tend to be using LINQ-to-SQL at the moment (from what I see). People with more complexity and other databases tend to use NHibernate ;-p And then some EF. I'm wondering how much this will change when EF is next released in .NET 4.0...
Use the one that feels best for you, your team and your project. It doesn't really matter how you access the data, as long as you access it.
You could use plain old ADO.NET if you want.
Related
Hi I've programmed a fair bit of C#, but never with a database. I'd like to use SQL Server with C# with some framework. Microsoft seems to have shipped a number of frameworks through the lifetime of C#. This makes it difficult for me to search/choose.
Which one should I choose? I'm developing a simple 3-tier webapp. I've watched a few Entity Framework .Net 4.0 videos, but I get the feeling that things are too automatic. I need to do some SQL now and then..
And if I should go for the EF4.0, is this really the best reference http://msdn.microsoft.com/en-us/library/bb386876.aspx
Any recommendations?
Go with Entity Framework 4 - it is the current and future best approach to SQL Server database. It is the basis for WCF Data Services, and the idea of a conceptual model will show up in other Microsoft product, for sure (Reporting Services and others, possibly).
And it does give you a lot of hooks to allow you to execute "on the fly" SQL statements, and you can also integrate stored procedures very nicely into Entity Framework.
And for the "run of the mill" everyday tasks, it gives you nice C# objects - based on your database - to work with.
In my opinion, this is your best choice currently - and the one with the most flexibility and options. You can start with a database ("database first") and create your classes from existing tables; or you can start with a model and have EF4 generate your database for you, and EF v4.1 (due out pretty soon) will also offer "code-first" development where you don't even need a visual model but you can describe all your database objects and settings in just C# code.
Update:
Entity Framework 4 Overview
Learn Entity Framework - the site accompanying the book by the same name, by Julie Lerman, Goddess of EF :-)
ADO.NET team blog with lots of good EF stuff
Entity Framework team design blog
ASP.NET 4.0 and the Entity Framework 4 - Part 1 - Create a Database using Model-First Development - good intro for EF4 model-first approach; Vince has multiple articles here - click on his name to get a list of all his articles (many new ones EF4 related)
Introduction to Entity Framework (this was for v1 - but still good)
C#+ActiveRecord+NHibernate. Hide the implementation behind several WCF services.
You said you want to try some 'framework', so Entity Framework is that one. It is the result from best practices MS come up with after years of research. Of course, on the way, you can always use SQL (Dataset) anytime you want together with EF (mostly for performance tuning).
I would say Start with Rob Conery's Sub Sonic..
Its easy to start with..specillaly Simple Repository..
Site Link: http://www.subsonicproject.com/
Simple Repository using Sub Sonic:
http://subsonicproject.com/docs/Simple_Repo_5_Minute_Demo
Update:
I have seen one answer mentioning NHibernate and want to add a small addition to the same... and since OP mentinoned that you have good experience with C# I assume you have good OOPS knowledge and also the relationships amongs objects
I personally felt much easy to start with NHibernate when used it with Fluent NHibernate hence I would also suggest
C# + NHibernate + Fluent Nhibernate....
Take a look here for some information about performance/benchmarks on various ORM frameworks for .Net.
Given that I'm very good with SQL and c#,
Should I learn another layer on top like NHibernate ?
Is NHibernate just a library (that stores in a Database)? Or it's a service?
Should I use NHibernate or ADO.NET Entity Framework?
If you think I should learn/use an ORM, give me your top reason.
You should use an ORM as long as you need to convert database data to and from business objects, since it will save you a lot of work and will allow you to focus on your application logic.
NHibernate is a .NET library that does just that, mapping .NET objects to database tables according to how you configure it. In this sense it is the same as the Entity Framework, only that EF is already embedded in the .NET framework and NHibernate is a separate assembly that you must reference in your project.
Last but not least, if you use SQL Server you should add LINQ to SQL to the list of possible ORM candidates, it is simpler that EF and for many scenarios it is more than appropriate.
It depends on your applications.
NHibernate is a library. So it's a DLL.
Depends on what you want. NHibernate is based on Hibernate which is battle tested.
It doesn't matter how good anyone is with SQL or C#. There is a fundamental gap with the tools when dealing with SQL and C#. Aside from all the other productivity boosts that I've had when I learned to Stop Worrying and Just Use an ORM, I found only having to deal with C# most of the time has helped greatly. I have far fewer impedance mismatches in my work now and I do believe that contributes to fewer bugs.
Less code you have to write is less code you have to maintain. ORMs allow you to worry less about certain details so you are free to concentrate on higher level tasks.
No, I tried Fluent NH and Castle Active Record and Spring Framework NH Extensions but they all obscure basic operations and make things less visible. Start using native NH, then add a layer after a year.
Yes, NH is a library, not a service. But the way you use it in your code makes it feel almost like a service (e.g. a data repository service)
I tried EF and found it nauseating so I would go with NH
For OLTP-like systems, ORM is the way of the future. Not using ORM for me is like not using unit-tests or programming in non-OOP language.
Probably, but it depends on what kind of applications you normally write.
NHibernate is primarily a DLL, but there is more to it than that.
NHibernate (Read this for more details: NHibernate, Entity Framework, active records or linq2sql)
My top reason would be so you can use Linq. Right now, you pretty much need an ORM to use Linq.
Unless it's a very small application, then the answer is 'yes'.
Library.
I hear people swear by the EF, but I'm very leery of it. I also don't like tying myself to all Microsoft technologies. NHibernate would be my suggestion.
First, you don't want to go through the time and headache of writing all the SQL and classes and such; it's just not worth it. Second, it allows for greater ability to switch from one RDBMS to another without having to change much code. Third, it'll give you more control in the future in terms of database abstraction and such.
I am really having a hard time here. I need to design a "Desktop app" that will use WCF as the communications channel. Its a multi-tiered application (DB and application server are the same, the client goes through the internet cloud).
The application is a little complex (in terms of SQL and code logics) then the usual LOB applications, but the concept is the same: Read from DB, update to DB, handle concurrency etc. My problem is that now with Entity Framework out in the open, I cant decide which way to proceed: Should I use Entity Framework, Dataset or Custom Classes.
As I understand by Entity Framework, it will create the object mapping of my DB tables ALONG WITH the CRUD scripts as well. Thats all well and good for simple CRUD, but most of the times the "Select" is complex and it requires a custom SQL. I understand I can use Stored Procedures in EF (I dont like SP btw, i dont know why, I like to code my SQL in the DAL by hand, I feel more secure and comfortable that way).
With DataSet, I will use my custom SQLs and populate on the data set. With Custom classes (objects for DB tables) I will populate my custom SQLs on those custom classes (collections and lists etc). I want to use EF, but i dont feel confident in deploying an application whose SQL I have not written and cant see in the code. Am I missing something here.
Any help in this regard would be greatly appreciated.
Xeshu
I would agree with Marc G. 100% - DataSets suck, especially in a WCF scenario (they add a lot of overhead for handling in-memory data manipulation) - don't use those. They're okay for beginners and two-tier desktop apps on a small scale maybe - but I wouldn't use them in a serious, professional app.
Basically, your question boils down to how do you transform your rows from the database into something you can remote across WCF. This means some form of mapping - either you do it yourself, using DataReaders and then shoving all the data into WCF [DataContract] classes - you can certainly do that, gives you the ultimate control, but it's also tedious, cumbersome, and error-prone.
Or you let some ready-made ORM handle this grunt work for you - take your pick amongst Linq-to-SQL (great, easy-to-use, flexible, but SQL Server only), EF v4 (out by March 2010 - looks very promising, very flexible) or any other ORM, really - whatever suits your needs best.
Other serious competitors in the ORM space might include Subsonic 3.0 and NHibernate (amongst many many others).
So to sum up:
forget about Datasets
either you have 100% control and to the mapping between SQL and your objects yourself
you let some capable ORM handle that (Linq-to-SQL, EF v4, Subsonic, NHibernate et al) - which one really doesn't matter all that much, i.e. it's also a matter of personal preference and coding style
I can't advocate datasets, especially in an SOA environment like WCF - it'll work, but for mostly the wrong reasons. They simply aren't portable, and IMO don't really "work" over service boundaries. Of course, IMO they don't work in most other scenarios too ;-p
So then it comes down to how much plumbing you want to do. Most ORMs will create WCF-serializable types for you; personally I'd use LINQ-to-SQL at the moment; it is both simpler and more complete than EF, although EF 4.0 is meant to be much better than EF in 3.5sp1. You can use custom TSQL (via ExecuteQuery, which still does the mapping back to objects), but I tend to use either SPROC (for complex queries) or LINQ-generated queries (for simple requests).
Writing the types yourself is fine too, and will work with NHibernate etc. So many options.
While EF works with WCF and sounds very promising, you should consider the effort to get on speed with it. Especially when doing some non trivial stuff, the designer in VS2008 can't open the model anymore and you have to code your model in xml.
Also keep in mind that EF works on a very high abstraction level. Because of the law of leaky abstractions its not all that shiny as it supposed to be :)
The other way round that means, you have to deal with very crazy and hard to read sql statements sent to your database when it comes to troubleshooting / performance issues.
When I last worked in programming, we were trying to move away from DataReaders and the traditional ADO.NET API toward Object Relational Mapping (ORM).
To do this, we generated a DataContext of our DB via sqlmetal. There was then a thin data layer that made the DataContext private, and any code needing to access the database would have to use a public method in this thin data layer. These methods were basically stored procedures; they would perform queries on the database via LINQ to SQL.
Is this a common approach today? I mean, is everyone whose using the .NET 3.5 framework really running sqlmetal in their build process, or what? It almost seemed like a hack at the time.
Basically, I'd like to know if LINQ to SQL and sqlmetal is what to expect if I'm go to write a DAL today at a .NET 3.5 shop that doesn't employ a third-party, open-source ORM.
It is still considered best practice to have some sort of data access layer. Whether this is best achieved with a ORM is a heavily debated issue. There is one faction that generally argues that ORM's are the way to go. Another faction argues that stored procedures and database centric is the best route.
Also, this may not be exactly the poster you meant, but it similar (and also the one in my cubicle)
http://download.microsoft.com/download/4/a/3/4a3c7c55-84ab-4588-84a4-f96424a7d82d/NET35_Namespaces_Poster_LORES.pdf
Your approach is good. I currently use Astroria services (ADO.NET Data Services). There was a nice introduction in MSDN Magazine about this.
I also like the new PLINQO (requires CodeSmith Tools though). This is very slick in my opinion.
When I have such a DAL (service layer), I just consume this service from my client application (Silverlight or ASP.NET MVC).
I think it depends on your use but I'd say with such a thin data layer as you explained that would be your DAL. Most projects will build another layer on top of that mainly for edit/create logic and maybe some stitching logic for gets.
For most of my projects I design it like this.
Repository holds the instance of DataContext and exposes some basic add/delete methods
ProductRepository : Repository exposes general queries (IQueryable)
StoreService uses an instance of different repositories like ProductRepository, SalesRepository and handles all logic for creating something like a product.
So something like...
StoreService.CreateProduct(/* properites */)
This would return some sort of result class.
The best data layer is the one that is plain and simple and gets the job done without any bells any whistles. I have used the technologies you mentioned and written about them here:
The Only Pattern for Data Access is - There Are No Patterns for Data Access
This very site uses LINQ to SQL, so take that as you will.
Officially, Microsoft is supporting Entity Framework over LINQ to SQL in terms of new development. However, there's a vocal group of people who think EF is the wrong way to go. LINQ to SQL will still be around for some time, and is a very decent ORM, if somewhat limiting in terms of which DB backend you can use.
I would recommend LINQ as a great starting point for your ORM. If you need better, look into EF and/or NHibernate.
"Is this a common approach today? I mean, is everyone whose using the .NET 3.5 framework really running sqlmetal in their build process, or what?"
The people I know using the 3.5 Framework (and that's just about everyone) - the vast majority - are still using NHibernate. Version 2.0 is a very nice OR/M. I started using it on a recent project and it cut my data access code down significantly, to the point where I really don't want to use anything else in the future. And the Fluent NHibernate API is making some headway for folks who don't like the XML mapping.
The question header is clear, i want to know why its different and why, when to select it for my project?
I wrote a blog post on this a while ago. In short, it takes a fundamentally different approach to ORM than Hibernate, ECO, and the other ORMs that I have looked at. You may think this approach is better, worse, or unimportant, but if you look deep enough it's hard to dispute that it is different. But don't take my word on it. If you're really interested in this subject, I strongly recommend reading this technical paper and this interview in ACM Queue.
This is probably not the answer you are looking for but I dont think you should use it in your project. It is very young and not very complete. Wait until the next version comes out.
If you insist on using Entity Framework there are a few good things about it. A nice one is the way it allows for complex mapping in a very simple way. And of course because it is a microsoft technology the IDE integration is nice.
But like I said, I tried it and I dont beleive it is ready for real use.
Anyway good luck at your project
ADO.NET is not an ORM.
Basically the difference is the level of abstraction used in each one.
With ADO, you basically query the DB and use the results as objects, is like a bridge between the RDBMS and your objects.
You model your DB and then you create object from that model. That's why it is an Entity Framework ( db entities )
ORM are not for querying or represent database records as objects ( although that's how everyones uses them anyway - me included - ) but a way to persist your object model into a relational database.
They are Object to Relational Mapping ( not Relational to Object Mapping )
So, you choose one or the other, when you have a domain ( object ) model and you want something to persist it ( to a RDBMS ) or when you have a entity model and you want to use it as objects in your app.
From what I've read, it has good support for WCF remoting/binary serialization, which is something many ORMs don't support very well (if at all). It might be worth looking into if you want to create a rich client/server/remoting app with ORM on the client side.
What different? It didn't learn from all the other ORMs.
Here are the issues I've been tracking for InfoQ
Does LINQ-to-Entities really return different results depending on previous queries?
Working Around Entity Framework's Large Data Model Issues
No Change Tracking for ADO.NET Entity Framework 2010
And this tool is a must-have if you do decide to use it.
Meta-data Synchronization Tools for LINQ to SQL and ADO.NET Entity Framework
Some of the best talent in the ORM world in .NET seem to be working on projects such as NHibernate (free-open-source; I use it) and LLBLGen Pro (commercial).
NHibernate is the reigning standard for enterprise-quality full-scale multi-vendor ORM. NHibernate is also the reigning standard for a pure implementation of ORM, permitting you the developer to write domain models completely independently from the NHibernate infrastructure, and completely eliminating code-generated classes.
NHibernate may look scary at first. But it is actually fairly friendly once you work with it a bit, and work has been underway since July to make NHibernate nearly configuration-free.