Monthly Archives: May 2010


LINQ to XML and reading large XML files

LINQ to XML makes it relatively easy to read and query XML files. For example consider the following XML file:

Suppose you would like to find all records with groupid > 2. You could be tempted to issue the following query:

There’s a flaw in this method. XElement.Load method will load the whole XML file in memory and if this file is quite big, (more…)


Dynamic methods in .NET

Using reflection to invoke methods which are not known at compile time might be problematic in performance critical applications. It is roughly 2.5-3.0 times slower than direct method calls. Here’s a sample test I’ve conducted:

Here are the results:

Method CPU units
Direct method invocation 796
Reflection method invocation 1986

So using reflection to perform a single property read is 2.5 slower than direct property access.

Dynamic methods can be used to generate and execute a method at run time, without having to declare a dynamic assembly and a dynamic type to contain the method. They are the most efficient way to generate and execute small amounts of code. (more…)


Transactional NTFS (part 1/2)

Transactional NTFS and DotNet

Starting from Windows Vista and Windows Server 2008, Microsoft introduced a great new feature called Transactional NTFS (TxF).

It allows developers to write file I/O functions that are guaranteed to either succeed completely or fail completely.
Unfortunately there are no classes in the .NET framework that would allows us to perform, such operations.
We need to resort to P/Invoke to use the newly introduced functions CreateTransaction, CommitTransaction, RollbackTransaction and DeleteFileTransacted. (more…)


How we do ASP.NET MVC

Sample MVC Solution

In this post I will show a sample ASP.NET MVC 2.0 project structure illustrating different concepts such as data access, user input validation and mapping between the domain and the view model. The project is still under construction but the source code is available at github.

I will illustrate the usage of the following frameworks:

  • MvcContrib bringing useful extension methods and strongly typed helpers to ASP.NET MVC
  • AutoMapper enabling easy mapping between the domain and the view models
  • FluentValidation – a small validation library for .NET that uses a fluent interface and lambda expressions for building validation rules for your business objects
  • NHibernate – a popular ORM in the .NET world
  • FluentNHibernate – a statically compiled alternative to NHibernate’s standard hbm xml mapping
  • Spring.NET – object container and dependency Injection framework for .NET
  • Rhino.Mocks – A dynamic mock object framework for the .Net platform. It’s purpose is to ease testing by allowing the developer to create mock implementations of custom objects and verify the interactions using unit testing

 

Armed with this arsenal of frameworks let’s start exploring the solution structure. I’ve opted for 2 projects solution but in many real world applications more levels of abstraction could be brought to the business layer. Personally I favor to have less big assemblies rather than many small assemblies into the solution. Fewer the assemblies, faster the load time and faster the IDE. In this case particular attention should be brought to bring proper separation of concerns inside the same assembly

project_structure

 

(more…)