GZipping all content served up by ASP.NET

Update – I now realise this post is kind of pointless, there is a module for compression of dynamic content, called unsurprisingly DynamicCompressionModule… But the approach described may be useful for someone somewhere…

I couldn’t find anything that will GZip all the content returned by ASP.NET. There’s a module for compression of static files but nothing for dynamic content. There may be a good reason for this, perhaps the overhead of GZipping content on the fly can kill your server, but since my current project has no static content I thought it would be useful to give it a go. The solution is pretty simple, register the following module in web.config and you’re good to go.

using System;
using System.IO.Compression;
using System.Web;

namespace MyNamespace
{
  public class GzipModule : IHttpModule
  {
    public void Dispose()
    {
      
    }

    public void Init(HttpApplication context)
    {
      context.BeginRequest += new EventHandler(context_BeginRequest);
    }

    void context_BeginRequest(object sender, EventArgs e)
    {
      HttpApplication app = (HttpApplication)sender;
      if ((app.Request.Headers["Accept-Encoding"] != null) &&
            (app.Request.Headers["Accept-Encoding"].Contains("gzip")))
      {
        app.Response.Filter = new GZipStream(app.Response.Filter, CompressionMode.Compress);
        app.Response.AppendHeader("Content-encoding", "gzip");
        app.Response.Cache.VaryByHeaders["Accept-encoding"] = true;
      }
    }
  }
}

Registration is as follows

    <modules>
            <add name="GzipModule" type="MyNamespace.GzipModule" />
    </modules>

Fixing 404 errors when using ASP.NET 4 routing

It took me a while to figure this out. Routing is meant to be baked into ASP.NET 4 but when i tried to set it up, all I got was 404 errors. I did a lot of Googling but couldn’t find anything. It turned out all I was missing was this in web.config

<system.webServer>
    <modules runAllManagedModulesForAllRequests="true"></modules>

Northern Ireland postcode data

The OS Code-Point Open dataset is great, except for a few omissions. It doesn’t include data for Northern Ireland, the Isle of Man or the Channel Islands. It turns out that the Northern Irish postcode data can be found here. Unfortunately that data is in ESRI and MapInfo formats, which I’m not sure how to read. Fortunately Jamie Thompson has converted it to CSV, which is a little easier to deal with.

From that CSV file, it’s quite simple to import the data into SQL Server or MySql using code slightly modified from my Code-Point examples (SQL Server here and MySql here). The only thing to note is that the CSV file uses Irish grid references rather than OS grid references.

Now to figure out where to get hold of the Isle of Man and Channel Islands data…