16.6. Worker Roles

A worker role is Azure's version of a Windows service. Worker roles are used for continual or long-running tasks, such as processing data held in an Azure queue (we will look at Azure queues shortly). Worker roles cannot be accessed directly like a web role or ASP.NET page, but they do allow the creation of HTTP-based endpoints for inter-role communication. Please see the Azure samples' November training kit (www.microsoft.com/downloads/details.aspx?FamilyID=413e88f8-5966-4a83-b309-53b7b77edf78&displaylang=en), which contains a thumbnail image generator example.

In many Azure projects, you will want to use both web and worker roles. To add a worker role to an existing project, just right-click the ~/Roles/ directory, and then select to add a new worker role. You may remember you also had the option to add a role when creating a project.

Let's take a quick look at worker roles:

  1. Right-click the Roles directory, and select Add — New Worker Role Project.

  2. Call it Chapter16.WorkerRole.

  3. Open WorkerRole.cs if it is not already open, and you should see code similar to the following (shortened to save space). Note how a worker role at its most basic level is little more than a big loop for you to put your code inside.

    public override void Run()
    {
        Trace.WriteLine("WorkerRole1 entry point called", "Information");

        while (true)
        {
            Thread.Sleep(10000);
            Trace.WriteLine("Working", "Information");
        }
    }

    public override bool OnStart()
    {
        ServicePointManager.DefaultConnectionLimit = 12;
        DiagnosticMonitor.Start("DiagnosticsConnectionString");

        RoleEnvironment.Changing += RoleEnvironmentChanging;
        return base.OnStart();
    }
}

..................Content has been hidden....................

You can't read the all page of ebook, please click here login for view all page.
Reset
18.227.134.133