O/R Mapper

NHibernate and Castle ActiveRecord Tutorial for the Uninitiated

Dave Hayden — Mon, 28 Apr 2008 09:24:00 GMT

If you are interested in Castle ActiveRecord, The NHibernate FAQ has a new tutorial on getting started with Castle ActiveRecord.

Retina.net O/R Mapper for the .NET Framework - Data Access Layer Generation

Dave Hayden — Mon, 28 Apr 2008 08:54:00 GMT

Retina.net is an O/R Mapper for the .NET Framework that appears to be active once again on CodePlex.

SubSonic 2.1 - Repository Pattern LINQ To Subsonic SubStage - Data Access Layer Generation

Dave Hayden — Mon, 31 Mar 2008 23:07:00 GMT

SubSonic 2.1 - Repository Pattern LINQ To Subsonic SubStage - Data Access Layer Generation

by David Hayden, Florida .NET Developer Filed: .NET Tools, Code Generation, O/R Mapper

SubSonic is a cool code generation tool and O/R Mapper that helps you generate a data access layer for your ASP.NET and Winform .NET Applications.

A new version of SubSonic, 2.1 Beta, includes a number of bug fixes as well as a new Repository Base Class for those who don't appreciate ActiveRecord and would prefer business classes void of data access code similar to the Repository Pattern in Domain-Driven Design. SubSonic has a new Query Tool as well as a feature called SubStage. There is also some talk of LINQ To SubSonic as well.

If you are looking for a tool / framework to help you generate a data access layer for your ASP.NET Web Applications, certainly give SubSonic a spin as it is a very active community with new code generation and O/R Mapping features being added often.

You can learn more by visiting the new SubSonic Project Home here. I recommend looking at LINQ To SQL, too.

High Performance LINQ To SQL - Compiled Queries - O/R Mappers - Ecommerce Websites

Dave Hayden — Tue, 19 Feb 2008 19:30:00 GMT

High Performance LINQ To SQL - Compiled Queries - O/R Mappers - Ecommerce Websites

by David Hayden, Florida ASP.NET Developer, Filed: LINQ To SQL

It should be of no surprise that an O/R Mapper will add overhead to performance as compared to the performance one would receive from a DataReader in ADO.NET. LINQ To SQL is no different. It adds a lot of services on top of ADO.NET, such as:

Connection Management
Query Translation and Execution
Object Identity
Change Tracking

This, of course, all comes at a little bit of a performance overhead. For most applications and user stories the slower performance is irrelevant. The value of the O/R Mapping services greatly outweigh any degradation in performance.

Sometimes, however, there may be a couple of database activities that are very expensive and we may want to achieve as optimal performance as possible even at the expense of maintainability. LINQ To SQL has a solution for these times - Compiled Queries.

LINQ To SQL Compiled Queries

Let's pretend we have an e-commerce website and getting Products By Category is an expensive operation. We have optimized the database as much as we can using proper indexing and covering indexes and it just isn't enough. We are using LINQ To SQL and we decide it is time for Compiled Queries. LINQ To SQL Compiled Queries allow the translation of the query to happen once at compile time and the query to be consumed many times. The lack of translation at each call will greatly improve performance for our e-commerce store.

Using Northwind, I create a partial class of the NorthwindDataContext and add my compiled query:

public partial class NorthwindDataContext
{
    public static Func<NorthwindDataContext, int, IQueryable<Product>>
        ProductsByCategoryID = CompiledQuery.Compile
            ((NorthwindDataContext context, int categoryID) =>
            context.Products.Where(p => p.CategoryID == categoryID));

    public IQueryable<Product> GetProductsByCategoryIDFast(int
                                                        categoryID)
    {
        return ProductsByCategoryID(this, categoryID);
    }
}

Everything above is compiled except for the category I am searching on. Note we are using Expression Trees, which are new to C# 3.0. This will greatly improve the performance of getting the products by category in my e-commerce store.

Now in my e-commerce website I will use the higher performance method of accessing the products in my product catalog by category:

NorthwindDataContext db = new NorthwindDataContext();

List<Product> products = db.GetProductsByCategoryIDFast(1).ToList();

Here I am getting all the products in my product catalog in the CategoryID = 1. The improvement in performance is much better and very close to the performance of the speed of the DataReader in ADO.NET. This should make my e-commerce website perform much quicker than when not using a LINQ To SQL Compiled Query.

For more information on the performance one achieves by using LINQ To SQL Compiled Queries, I recommend reading Rico Mariana's blog:

http://blogs.msdn.com/ricom/archive/2007/06/22/dlinq-linq-to-sql-performance-part-1.aspx

There are actually several parts to his LINQ To SQL performance testing that you can read on his blog.

Conclusion

LINQ To SQL offers the option of Compiled Queries when you need to achieve DataReader like performances in ADO.NET. This comes at a bit of a price of maintenance, because you will need to create compiled queries for those operations you feel are expensive.

LINQ To SQL Tutorials

Author: David Hayden, Florida Website Developer

Site: http://www.davidhayden.com/

LightSpeed O/R Mapper - High Performance .NET Domain Model and O/R Mapping Framework

Dave Hayden — Fri, 21 Dec 2007 19:58:00 GMT

LightSpeed O/R Mapper - High Performance .NET Domain Model and O/R Mapping Framework

by David Hayden, Filed: .NET O/R Mapper

Writing data access code for a rich domain model is tedious and complicated. You need to get yourself an easy-to-use and performant O/R Mapper built using solid patterns & practices to handle it for you. I haven't tried LightSpeed yet, but it is on my list as I appreciate many of the values in the O/R Mapper's description:

"LightSpeed is an innovative, high performance .NET domain model and O/R mapping framework designed to accelerate your development while, at the same time, providing your application with a solid foundation based on best practice domain-driven design patterns. With features like convention-over-configuration, fast data access, model validation and data binding, it allows you to focus your efforts where they should be: Solving business problems and not writing tedious infrastructure and "plumbing" code."

They just released a version 1.1 and the features look pretty impressive. If you are interested, they have an express edition you can download for free!

Learn more.

eXpressApp Framework Released - ASP.NET Web Rapid Application Development ( RAD )

Dave Hayden — Fri, 21 Dec 2007 19:29:00 GMT

eXpressApp Framework Released - ASP.NET Web Rapid Application Development ( RAD )

by David Hayden ( Florida .NET Developer ), Filed: .NET Tools, O/R Mappers, Code Generation

Developer Express released their eXpressApp Framework, which is a winform and ASP.NET rapid application development framework that utilizes a number of their other tools and components in DXperience. Per the website:

“The eXpressApp Framework by Developer Express is a powerful instrument for creating business applications quickly and easily. A strong modular architecture allows for platform independent domain specific extensions. Examples of typical applications include business/sales/CRM systems, projects, documentation, HR and training class management, and many others. The currently supported target platforms are Windows Forms and ASP.NET 2, and our open architecture allows extensions of either of these platforms as well as the introduction of completely new targets (WPF support is part of our plans for the future).”

Keep in mind that it is a 1.0 version, but if you are looking for a framework to rapidly build winform and ASP.NET 2.0 applications, you may want to take the trial download for a spin. I suspect that just like with most frameworks there is probably a decent learning curve before you can become really productive, but it may pay off in the long run.

Learn more here.

LLBLGen Pro v2.5 Released - Code Generation of the Data Access Layer

Dave Hayden — Thu, 23 Aug 2007 14:09:00 GMT

LLBLGen Pro v2.5 Released - Code Generation of the Data Access Layer

by David Hayden ( Florida .NET Developer ), Filed: O/R Mappers, Code Generation

A new version of LLBLGen Pro has been released, version 2.5, with a number of interesting features:

Auditing - Define auditors which record audit information during the entity's life cycle and provide audit entity objects (of the type you provide) to the framework to be persisted automatically when the audited entity is part of a transaction with the database. This gives great flexibility what to audit and when and frees the developer from the hassle to persist the audit entities at some point in time.
Authorization - You can define, using whatever authorization mechanism you want to use, if a user at runtime is allowed to perform an action on / with an entity object or set of entity objects: field get/set, entity load, entity save (insert), entity save (update), entity delete, updates of entities directly in the database and deletes of entities directly in the database.
Dependency Injection - 'Inject' instances of types at runtime into for example entity objects. This mechanism makes writing validation classes, concurrency predicate factories, authorizers etc. much easier as you don't have to add the code to inject instances of these classes into entity objects at runtime.
Fast and compact serialization/deserialization
Even better prefetch paths
Singularization and pluralization of names
Abbreviation support
In-memory hierarchical filtering and projections
Excluding fields for fetching
Sybase ASA and ASE support, SqlServer CE Desktop support

Frans has the complete scoop on his blog.

I am really interested in those top 3 features. I will have to play with the new version this weekend.

News Feed: David Hayden ( Florida .NET Developer )

Filed: O/R Mappers, Code Generation

LINQ To SQL Debugger Visualizer Revisited - Same Concerns Better UI :)

Dave Hayden — Mon, 20 Aug 2007 11:02:00 GMT

LINQ To SQL Debugger Visualizer Revisited - Same Concerns Better UI :)

by David Hayden ( Microsoft MVP C# ), Filed: LINQ To SQL

Update: Mentioned this on CodeBetter, too :) Check the comments. Scott Guthrie sent an email to the developer about looking into it.

In the previous post I mentioned some concerns I have with the LINQ To SQL Debugger Visualizer in that the query it displays is not the whole story:

LINQ To SQL Debugger Visualizer in Visual Studio 2008 Has Limited Value - LINQ To SQL Tutorials

Turns out I wasn't even using the Debugger Visualizer - DOH! Here is the real LINQ To SQL Debugger Visualizer, which is a separate download:

So, the debugger visualizer is much easier to work with than I previously mentioned in the earlier post, but it still suggests only 1 query will be executed when in actuality it will execute 40+ (correction: 90+ queries if you are using a non-modified Northwind which I downloaded again because I keep screwing with it ) queries to the database using the following code in beta 2:

using (NorthwindDataContext context =
                            new NorthwindDataContext())
{           
    DataLoadOptions options = new DataLoadOptions();
    
    options.LoadWith<Customer>(c => c.Orders);
    options.LoadWith<Order>(o => o.Order_Details);


    context.LoadOptions = options;
    
    var query = from c in context.Customers
                      select c;
}

I talked more about that in the previous post mentioned above.

A little deceptive if you ask me, but still useful in other ways.

News Feed: David Hayden ( Microsoft MVP C# )

Filed: LINQ To SQL

Repository Factory - Nice Improvements to the Data Access Guidance Package

Dave Hayden — Sun, 19 Aug 2007 19:56:00 GMT

Repository Factory - Nice Improvements to the Data Access Guidance Package

by David Hayden ( Microsoft MVP C# ), Filed: Code Generation

I had some time this weekend to take a quick peek at the Repository Factory, which is a new guidance package from the Microsoft Patterns & Practices Team that replaces the Data Access Guidance Package. I talked about the Data Access Guidance Package in the following screencast:

Create Data Access Layer Using Data Access Guidance Package Screencast

Anyway, the team has already created a number of new improvements and features that were really exciting to play with this weekend:

Improved Mapping of Stored Procedure Parameters to Entity Properties

Generates an Interface for each Repository Class

Generates a RepositoryFactory Class for Retrieving Individual Repositories

Repositories Registered via Configuration Section in App.config / Web.config

Common and Base Repository Classes in Separate Repository Assembly

Very, very cool. You can see some code samples and photos over on PnPGuidance:

Repository Factory - New and Improved Data Access Guidance Package

Well worth using over the old Data Access Guidance Package starting now for that data access layer code generation!

DataContext.Log - Logging LINQ To SQL Output to Console or Debugger Output Window

Dave Hayden — Fri, 17 Aug 2007 13:57:00 GMT

DataContext.Log - Logging LINQ To SQL Output to Console or Debugger Output Window

by David Hayden ( Microsoft MVP C# ), Filed: LINQ To SQL, O/R Mappers

Another quick tutorial on LINQ To SQL to append to the rest:

Although you can always use SQL Server Profiler to view the SQL generated by LINQ To SQL, there is a DataContext.Log Property that you can assign a TextWriter to view the SQL generated.

For playing in a console application, you have the option of assigning Console.Out, which will display the SQL output to the console:

using (NorthwindDataContext context =
                           new NorthwindDataContext())
{          
    context.Log = Console.Out;

    Customer customer = context.Customers.Single<Customer>
                       (c => c.CustomerID.Equals("ALFKI"));
}

However, displaying the SQL code in the debugger output window for non-console applications and even console applications is better using something like DebuggerWriter, which is a wrapper around System.Diagnostics.Debugger:

using (NorthwindDataContext context =
                         new NorthwindDataContext())
{          
    context.Log = new DebuggerWriter();

    Customer customer = context.Customers.Single<Customer>
                        (c => c.CustomerID.Equals("ALFKI"));
}

You can write your own DebuggerWriter, or you could check out the code from Kris Vandermotten:

Sending the LINQ To SQL log to the debugger output window

Very cool, Kris!

News Feed: David Hayden ( Microsoft MVP C# )

Filed: LINQ To SQL, O/R Mappers