Easy Event Logging on Windows Azure

By Simon|Cloud Computing|1 Comment

I’ve been working on an application that has a need to log many events on a Web Role running on Windows Azure.   Effective logging can be difficult to setup.  Do a search, and you’ll find a handful of articles that cover logging to the blobstore, mounting drives to extract the logs, etc. 

Instead, I wanted an easy way to log custom events and exceptions in my application.  This is how to do it:

1. Create a class that inherits from System.Diagnostics.TraceListener. 

public class AzureTraceListener : TraceListener   

{    

public static List<String> Events = new List<String>(); 

    public override void Write(string message)       {            Events.Add(message);        } 

    public override void WriteLine(string message)       {            Events.Add(message);        }  

} 

2.  In your web role, add a reference to your custom trace listener.  This is done by adding the following two lines in your OnStart() method.

AzureTraceListener atl = new AzureTraceListener();   Trace.Listeners.Add(atl);

 

3.  In your application, log your events using the Trace.Write(string) method.

4.  To display your events, create a new page called Traceviewer.aspx with the following block of HTML:

<h1>Trace Log</h1>   <% foreach (String eventitem in WebRole1.AzureTraceListener.Events)        {            Response.Write("<h4>"+eventitem+"</h4>");       } %>

That’s it.  Deploy your application and simply call Traceviewer.aspx to look at all of your generated events.