Starting in .NET 3.5 is a feature called extension methods. Extension methods allow developers to extend classes with their own instance methods. This is a concept often called mix-ins in other languages.
Category: C#
Silverlight Progress Bar
Silverlight 2 provides an attractive platform for creating Rich Internet Applications, however when first getting started both the oddities of the layout model and the strange absence of certain controls and class and be puzzling.
One such puzzling absence from the Silverlight tool chest is a progress bar control. WPF has a progress bar, WinForms has a progress bar, but not Silverlight. Fortunately implementing one is not that hard and provided a great introduction to Silverlight’s layout model.
Silverlight and layers
Unlike ASP.NET, and many other forms technologies, Silverlight uses a multiple layer positioning system. The Canvas control is especially useful for allowing multiple controls to be layered.
Take for example this simple block of XAML:
<Canvas x:Name="LayoutRoot" Background="WhiteSmoke"> <Rectangle Width="60" Height="60" Fill="Green" /> <Rectangle Width="60" Height="60" Fill="Gray" /> <Rectangle Width="60" Height="60" Fill="LightBlue" /> </Canvas>
Silverlight MessageBox
Silverlight oddly enough lacks a MessageBox class. Fortunately Silverlight’s HTML Bridge exposes the JavaScript Alert method, which is functionally the same thing.
Community Coding Contest
Developing an open source project is a very rewarding experience. But sadly (as an open source developer that is) open source projects rarely get the feedback they deserve. Often the developers only hear feedback from their users when their software is broken, because of this it is often difficult to know when an author’s work is truly appreciated.
aspNETserve Without GAC Install
The topic has come up many times, and that is “Why do I have to register aspNETserve.Core.dll in the GAC to run aspNETserve?”. The answer to this question has to do with how aspNETserve uses the ASP.NET hosting facilities, so first some background information.
aspNETserve 1.3: What’s New
As I mentioned in my last post, aspNETserve 1.3 has just been released. And with it comes some exciting changes. Here is an outline of some of the most notable changes:
aspNETserve’s goal is to target version 1.1 of the HTTP protocol, and prior to version 1.3 of aspNETserve it had an obvious shortcoming in that goal. It did not even attempt to keep “Keep-Alive” (aka, persistent) connections around. The server naively closed the connection after each request.
The new aspNETserve.Server object in version 1.3 has full support for persistent connections, and with it introduces a couple of new properties:
MaxConnections
This property represents the maximum number of simultaneous connections allowed. Once the maximum amount has been reached additional requests will be declined.
KeepAliveRequestTimeout
A period of time (in milliseconds) that aspNETserve will wait for subsequent communications on a previously established connection.
A Windows service called aspNETserve.Ice (pun intended) allows aspNETserve to process requests in the background. Additionally, this allows request processing without a user having to first login and launch the SimpleServer UI.
aspNETserve.Ice reads it configuration from an XML file whose schema is define on the wiki page ConfigSchemaOverview.
Here is a simple example of what the XML file looks like:
<?xml version="1.0" encoding="utf-8"?>
<server xmlns="http://aspnetserve.googlecode.com/svn/tags/Release%201.3/aspNETserve/Configuration/Xml/aspNETserve.config.xsd">
<application physicalPath="c:\temp">
<domain name="www.example.com" virtualPath="/" />
<endpoint ip="127.0.0.1" port="80" />
<endpoint ip="127.0.0.1" port="443" secure="true" />
</application>
</server>
ASP.NET MVC: A Guided Tour
We’ve all read about what MVC is, but how does it really work? What are the nuts and bolts that make that MVC magic happen? Fortunately Microsoft has released the source code to ASP.NET MVC and we can read the details in all their glory. But if you are like myself reading source code is something far different than truly understand how an application works. Luckily since the source code has been released we can do much more than read it, we can use the debugger to step through it.
The debugger in Visual Studio is an extremely helpful tool for the modern developer. I often use the debugger as my first debugging route for development code. Interestingly enough we can put that same debugger to use to walk through ASP.NET MVC to get a better feel for how it operates.
The first thing we need to do is download the source code to ASP.NET MVC and compile it with debugging enabled. The source code can be downloaded from it’s CodePlex page. The download contains a Visual Studio 2008 project. Simply open the project and do a rebuild. Once completed you should see four files in the bin directory located directory in the folder you extracted the downloaded source code into.
Of those files we are only interested in two of them. System.Web.Mvc.dll and System.Web.Mvc.pdb. Make note of where those files are located on your computer, because we will need to add a reference to those shortly.
In a new instance of Visual Studio lets create a new ASP.NET MVC application. The first thing we need to do is to delete the reference to System.Web.Mvc. Expand the references folder, and right-click System.Web.Mvc and select remove.
With the reference to System.Web.Mvc removed you will now need to add it back. Only this time instead of referencing the DLL that shipped with the ASP.NET MVC we will reference the DLL that we just compiled. By right clicking on the references folder and selecting “Add Reference…” you will be given the option to browse for the reference. Simply navigate to the path I asked you to remember earlier and select the System.Web.Mvc.dll file and click “OK”.
Now we are all ready to start debugging the innards of ASP.NET MVC. For starters navigate to the pre-generated HomeController and put a break point on the first line of the Index method. Now start the site with debugging enabled.
Once everything gets done compiling and the application starts your Visual Studio instance should immediately stop at your break point.
At this point in your Call Stack window you should see entries for System.Web.MVC.DLL, and those entries should be in black (not gray). This means that Visual Studio has the debugging information that it needs to show us source code for those methods. This is precisely what we were trying for, Visual Studio will now all us to step through the ASP.NET MVC code in a very similar fashion to our code. Lets start by analyzing the call stack in detail.
In the call stack we see the following:
MvcApplication1.DLL!MvcApplication1.Controllers.HomeController.Index() System.Web.Mvc.DLL!System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(...) System.Web.Mvc.DLL!System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters.AnonymousMethod(...) System.Web.Mvc.DLL!System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(...) System.Web.Mvc.DLL!System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters.AnonymousMethod() System.Web.Mvc.DLL!System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(...) System.Web.Mvc.DLL!System.Web.Mvc.ControllerActionInvoker.InvokeAction(...) System.Web.Mvc.DLL!System.Web.Mvc.Controller.Execute(...) System.Web.Mvc.DLL!System.Web.Mvc.Controller.System.Web.Mvc.IController.Execute(...) System.Web.Mvc.DLL!System.Web.Mvc.MvcHandler.ProcessRequest(...) System.Web.Mvc.DLL!System.Web.Mvc.MvcHandler.ProcessRequest(...) System.Web.Mvc.DLL!System.Web.Mvc.MvcHandler.System.Web.IHttpHandler.ProcessRequest(...)
aspNETserve Update
It has been a while since I have mentioned anything about aspNETserve, so I figured it was due time for an update. Since the last update in December of 2007 there wasn’t any activity until recently. Between being distracted with a plethora of personal and professional obligations the project took a back seat.
Friendly 404 Errors In ASP.NET MVC
Custom file not found (404) error pages can help to create a more rewarding user experience for your site visitors. Links become outdated and there is nothing more frustrating for a user than to have found a link to exactly what they are looking for and to come across the infamous “file not found” screen.
Testing Software Contracts Using ContractTest
Contracts, both explicit and implied, are key in designing a working software system. An example of an explicit contract in C# would be the implementation of an interface, while an implied contract would be something along the lines of all business objects have default constructors. Contracts of both types are critical to the success of a software system, but how do you test for and enforce these contracts?
Explicit contracts are often enforced by the compiler and are not nearly as fragile as implied contracts. Using the ContractTest testing framework you can write test cases for many common implied contracts. You can incorporate ContractTest assertions directly into your existing unit tests. For the following examples I will be using NUnit syntax, but you could use most any other unit test framework.
For example, assume you want to test for the presence of a publicly accessible default constructor on one of your business objects. Such a test using ContractTest would look like.
using ContractTest.Assertions; using NUnit.Framework; using MyNamespace.BusinessObjects; [TestFixture] public class SampleTests{ [Test] public void Test1(){ ContractAssert.Type.HasPublicDefaultConstructor<BizObjectA>(); } }