The one big limitation of the URL Mapping functionality built in to ASP.NET 2.0 is that it doesn't support regular expressions. I ported my v1.1 URL Mapping implementation over to v2.0 and added support for regular expressions. It really wasn't too difficult; I only had to modify two lines of code to port it over to ASP.NET 2.0. Then I had to modify 4 lines of code to add RegEx support. My implementation works just like the ASP.NET 2.0 URL Mapping functionality with the addition of RegEx.chemas-microsoft-comfficeffice" />>>

My code allows to create Url Mappings similar to the following:
~/Chris.aspx to ~/Default.aspx?p=chris
~/Show154.aspx to ~/Default.aspx?p=154>>

Some Performance tips for using this code:>>

1.       Use as few Url Mapping definitions as possible since it parses them from the first to the last and stops when it finds a match. If a page requested doesn't match any of the definitions it will go through all of them before moving on to complete the page request. >>

2.       Put the most frequently used Url Mappings first in the list so that they the ones that are parsed first.>>

3.       The first Url Mapping in placed in my code (<add url="~/(.*)default\.aspx" mappedUrl="~/$1default.aspx" />) is a little trick that allows all requests for the Default.aspx page in the root or any sub-folder of the application to be completed with out having to parse through the entire list of Url Mappings.>>

Regular expression support just seems logical in the v2.0 URL Mapping functionality, but I don't know why Microsoft didn't add it. I guess they wanted me to have something to do.  :)>>

Enjoy!>>

Code for this implementation listed below:>>

/App_Code/RegExUrlMappingBaseModule.vb>>

Imports Microsoft.VisualBasic>>

Imports System.Web>>

Namespace RegExUrlMapping_HTTPModule>>

Public Class RegExUrlMappingBaseModule>>

Implements System.Web.IHttpModule>>

Sub Init(ByVal app As HttpApplication) Implements IHttpModule.Init>>

AddHandler app.AuthorizeRequest, AddressOf Me.BaseModuleRewriter_AuthorizeRequest>>

End Sub>>

Sub Dispose() Implements System.Web.IHttpModule.Dispose>>

End Sub>>

Sub BaseModuleRewriter_AuthorizeRequest(ByVal sender As Object, ByVal e As EventArgs)>>

Dim app As HttpApplication = CType(sender, HttpApplication)>>

Rewrite(app.Request.Path, app)>>

End Sub>>

Overridable Sub Rewrite(ByVal requestedPath As String, ByVal app As HttpApplication)>>

End Sub>>

End Class>>

End Namespace>>

/App_Code/RegExUrlMappingConfigHandler.vb>>

Imports Microsoft.VisualBasic>>

Imports System.Configuration>>

Imports System.Xml>>

Namespace RegExUrlMapping_HTTPModule>>

Public Class RegExUrlMappingConfigHandler>>

Implements IConfigurationSectionHandler>>

Dim _Section As XmlNode>>

Public Function Create(ByVal parent As Object, ByVal configContext As Object, ByVal section As System.Xml.XmlNode) As Object Implements System.Configuration.IConfigurationSectionHandler.Create>>

_Section = section>>

Return Me>>

End Function>>

''' Get whether url mapping is enabled in the app.config>>

Friend Function Enabled() As Boolean>>

If _Section.Attributes("enabled").Value.ToLower = "true" Then>>

Return True>>

Else>>

Return False>>

End If>>

End Function>>

''' Get the matching "mapped Url" from the web.config file if there is one.>>

Friend Function MappedUrl(ByVal url As String) As String>>

Dim x As XmlNode>>

Dim oReg As Regex>>

For Each x In _Section.ChildNodes>>

oReg = New Regex(x.Attributes("url").Value.ToLower)>>

If oReg.Match(url).Success Then>>

Return oReg.Replace(url, x.Attributes("mappedUrl").Value.ToLower)>>

End If>>

Next>>

Return "">>

End Function>>

End Class>>

End Namespace>>

/App_Code/RegExUrlMappingModule.vb>>

Imports Microsoft.VisualBasic>>

Imports System.Web>>

Imports System.Configuration>>

Namespace RegExUrlMapping_HTTPModule>>

Public Class RegExUrlMappingModule>>

Inherits RegExUrlMappingBaseModule>>

Overrides Sub Rewrite(ByVal requestedPath As String, ByVal app As HttpApplication)>>

''Implement functionality here that mimics the 'URL Mapping' features of ASP.NET 2.0>>

Dim config As RegExUrlMappingConfigHandler = CType(ConfigurationManager.GetSection("system.web/RegExUrlMapping"), RegExUrlMappingConfigHandler)>>

Dim pathOld As String, pathNew As String = "">>

If config.Enabled Then>>

pathOld = app.Request.RawUrl>>

''Get the request page without the querystring parameters>>

Dim requestedPage As String = app.Request.RawUrl.ToLower>>

If requestedPage.IndexOf("?") > -1 Then>>

requestedPage = requestedPage.Substring(0, requestedPage.IndexOf("?"))>>

End If>>

''Format the requested page (url) to have a ~ instead of the virtual path of the app>>

Dim appVirtualPath As String = app.Request.ApplicationPath>>

If requestedPage.Length >= appVirtualPath.Length Then>>

If requestedPage.Substring(0, appVirtualPath.Length).ToLower = appVirtualPath.ToLower Then>>

requestedPage = requestedPage.Substring(appVirtualPath.Length)>>

If requestedPage.Substring(0, 1) = "/" Then>>

requestedPage = "~" & requestedPage>>

Else>>

requestedPage = "~/" & requestedPage>>

End If>>

End If>>

End If>>

''Get the new path to rewrite the url to if it meets one>>

''of the defined virtual urls.>>

pathNew = config.MappedUrl(requestedPage)>>

''If the requested url matches one of the virtual one>>

''the lets go and rewrite it.>>

If pathNew.Length > 0 Then>>

If pathNew.IndexOf("?") > -1 Then>>

''The matched page has a querystring defined>>

If pathOld.IndexOf("?") > -1 Then>>

pathNew += "&" & Right(pathOld, pathOld.Length - pathOld.IndexOf("?") - 1)>>

End If>>

Else>>

''The matched page doesn't have a querystring defined>>

If pathOld.IndexOf("?") > -1 Then>>

pathNew += Right(pathOld, pathOld.Length - pathOld.IndexOf("?"))>>

End If>>

End If>>

''Rewrite to the new url>>

HttpContext.Current.RewritePath(pathNew)>>

End If>>

End If>>

End Sub>>

End Class>>

End Namespace>>

/Web.Config>>

<configuration>>>

<!-- Declare the custom 'RegExUrlMapping' section and handler -->>>

<configSections>>>

<sectionGroup name="system.web">>>

<section name="RegExUrlMapping" type="RegExUrlMapping_HTTPModule.RegExUrlMappingConfigHandler"/>>>

</sectionGroup>>>

</configSections>>>

<system.web> >>

<!-- Tell ASP.NET to use the RegEx URL Mapping HTTP Module -->>>

<httpModules>>>

<add type="RegExUrlMapping_HTTPModule.RegExUrlMappingModule" name="RegExUrlMappingModule"/>>>

</httpModules>>>

<!-- The RegEx URL Mapping parser goes through these in sequential order. -->>>

<RegExUrlMapping enabled="true"> >>

<add url="~/(.*)default\.aspx" mappedUrl="~/$1default.aspx" />>>

<add url="~/Chris.aspx" mappedUrl="~/Default.aspx?p=chris"/>>>

<add url="~/show(.*)\.aspx" mappedUrl="~/Default.aspx?p=$1&amp;section=3"/>>>

</RegExUrlMapping>>>

</system.web>>>

</configuration>>>

 >>

ASP.NET 1.1 Url Mapping code can be found here: http://pietschsoft.com/Blog/archive/2005/07/04/717.aspx>>

>Update 11/14/2005 - Scoth Guthrie has posted about why they didn't add Regular Expression support to the ASP.NET 2.0 URL Mapping on his blog. He has also posted a link to this blog entry in that blog post. It's pretty cool that my blog has gotten noticed by him.>

>http://weblogs.asp.net/scottgu/archive/2005/11/14/430493.aspx>