SEO Search Engine Friendly URLs with ASP.NET and IIS

November 3, 2008 | Barry Wise | Code Samples, Search Engine Optimization
15 Comments

I decided it was about time for another code update, and since there are plenty of SEO tips for PHP hackers and Wordpress users, I’m going to help out the ASP.NET programmers out there still in the dark about SEO problems with their code.  The concept is useful for anyone; but the code is specifically for a function I programmed in VB.NET.

Web application programmers often like to name their files for the function they perform.  For example, you’ve programmed a pretty cool e-commerce app so you name the file shoppingcart.aspx.  Why not?  That’s what it does – it’s a shopping cart.  And without a care in the world you go on programming your shopping cart to create links on your site which look like his: /shoppingcart.aspx?id=4757.  Looks good, right?  It’s a shopping cart page showing a product with an ID of 4757.  It’s just a URL, and you know your customers don’t care what the URLs look like on your site – do they?

Well, they probably don’t.  But search engines do care – and after a while you notice all the clients who bought your shopping cart software are starting to complain that their product pages aren’t getting as much traffic from Google as they’d hoped.  But what if that URL was changed from /shoppingcart.aspx?id=4757 to something like /name-of-my-product.aspx?   Now anyone searching for the “name of my product” keywords might have a better chance of finding your page in Google since the keywords they are searching for are right in the URL of the page.

I’ll show you how to (kind of) easily accomplish this task with ASP.NET, IIS, and some simple URL rewriting in your global.asax file.  This will work in both IIS6 and IIS7, but IIS7 has an add-on module you can download which has another way of providing URL rewrites.  (For more info, check out my earlier post on using the global.asax file to fix canonical URL issues in IIS7 and 7)

I realize these functions are hard to read as inline code in this blog, so you can view all 3 functions in this text file: SEO Search Engine Friendly URL Functions for ASP.NET

First, here’s a function which will take the ID of a product, select the name of the product from a database table, and turn it into a search engine friendly URL.  It will turn /shoppingcart.aspx?id=4757 into /shoppingcart/4757/name-of-my-product.aspx.  You should call this function in your .NET pages where ever you link to product detail pages.

Function: seoPageUrls

Public Function seoPageUrls(ByVal thisProductId As Integer) As String

'### CONNECT TO DATABASE - CHANGE yourDSN
'### IN YOUR WEB.CONFIG FILE ACCORDINGLY
Dim myConnection as New oleDBConnection(ConfigurationManager.AppSettings("yourDSN"))
Dim myCommand as New oleDBCommand
Dim myReader As OleDbDataReader

Dim thisProductName As String = ""

'### GET THE ACTUAL PRODUCT NAME FROM THE DATABASE
myCommand.Connection = myConnection
myCommand.CommandText = "SELECT productName FROM productTable WHERE productId = " & thisProductId

Try
 myConnection.Open()
 thisProductName = myCommand.ExecuteScalar()

Finally
 myConnection.Close()
End Try

myConnection.Dispose()
 
'### GET RID OF NON-FRIENDLY URL CHARACTERS AND REPLACES SPACES WITH DASHES
thisProductName = Regex.Replace(thisProductName, "[^\w\@-]", " ").ToLower()
thisProductName = Regex.Replace(thisProductName.Trim(), "\s{1,}", "-")

'### JUST RETURN THE SEO SEARCH ENGINE FRIENDLY URL
Return "/shoppingcart/" & thisProductId & "/" & thisProductName
 
End Function

 

Now we need a way to tell IIS to rewrite the URLs as visitors (and search engines) request them.  So when someone clicks on a link which looks like /shoppingcart/4757/name-of-my-product.aspx they actually get directed to the page /shoppingcart.aspx?id=4757.  This is done via a technique called URL rewriting in the global.asax file.  The following function will intercept all incoming page requests and send them to the URL rewrite function:

Function: Application_BeginRequest

Sub Application_BeginRequest(ByVal sender as Object, ByVal e as EventArgs)

Try

Dim httpContext As System.Web.HttpContext = httpContext.Current()
Dim currentURL As String = Request.ServerVariables("PATH_INFO")

httpContext.RewritePath(rewriteUrl(currentURL))
 
Catch ex As Exception
 Response.Write("Error in Global.asax:" & ex.Message)
End Try

End Sub

 

You’ll notice it intercepts the incoming URL (contained in the variable currentURL) and sends it to a function called rewriteUrl.  The rewriteUrl function also goes in your global.asax file and it acutally changes the URL requested to one which the web server will understand. 

Function: rewriteUrl

Public Function rewriteUrl(byVal thisURL As String)

Dim currentFileName As String
Dim currentFileType As String
Dim currentFileID As String
Dim returnURL As String

'### THIS REGEX STRING IS LOOKING FOR A URL
'### IN THE FORM: /shoppingcart/4757/name-of-my-product.aspx
'### SO THE URL WILL GET READ LIKE THIS:
'### fileType = shoppingcart
'### identifier = 4757
'### fileName = name-of-my-product.aspx
 
Dim rewrite_regex As Regex = New Regex("^.*/(?<fileType>[^/]+)/(?<identifier>\d+)/(?<fileName>[^/]+)(\?.*)?", RegexOptions.IgnoreCase)
 
Dim match_rewrite As Match = rewrite_regex.Match(thisURL)
 
currentFileType = match_rewrite.Groups("fileType").Value.toString()
currentFileID = match_rewrite.Groups("identifier").Value
currentFileName = match_rewrite.Groups("fileName").Value.toString()

If currentFileID <> "" Then

 '### IF shoppingcart IS THE CURRENT URL, PERFORM THE URL REWRITE
 If currentFileType = "shoppingcart" Then
  returnURL = "/shoppingcart.aspx?id=" & currentFileID
 Else
  '### NO MATCH, NO URL REWRITING - JUST PASS TO REQUESTED URL
  returnURL = thisURL
 End If

Else
 returnURL = thisURL
End If

Return returnURL

End Function

Tags: .net, asp.net, code sample, IIS, iis6, is7, Search Engine Optimization, seo, url rewrite, vb.net

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