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There are many reasons to deploy an application or services onto Azure, the Microsoft cloud services platform. These include reducing operation and hardware costs by paying for just what you use, building applications that are able to scale almost infinitely, enormous storage capacity, geo-location … the list goes on and on.
Yet a platform is intellectually interesting only when developers can actually use it. Developers are the heart and soul of any platform release—the very definition of a successful release is the large number of developers deploying applications and services on it. Microsoft has always focused on providing the best development experience for a range of platforms—whether established or emerging—with Visual Studio, and that continues for cloud computing. Microsoft added direct support for building Azure applications to Visual Studio 2010 and Visual Web Developer 2010 Express.
This article will walk you through using Visual Studio 2010 for the entirety of the Azure application development lifecycle. Note that even if you aren’t a Visual Studio user today, you can still evaluate Azure development for free, using the Azure support in Visual Web Developer 2010 Express.
Creating a Cloud Service
Start Visual Studio 2010, click on the File menu and choose New | Project to bring up the New Project dialog. Under Installed Templates | Visual C# (or Visual Basic), select the Cloud node. This displays an Enable Azure Tools project template that, when clicked, will show you a page with a button to install the Azure Tools for Visual Studio.
Before installing the Azure Tools, be sure to install IIS on your machine. IIS is used by the local development simulation of the cloud. The easiest way to install IIS is by using the Web Platform Installer available at microsoft.com/web. Select the Platform tab and click to include the recommended products in the Web server.
Download and install the Azure Tools and restart Visual Studio. As you’ll see, the Enable Azure Tools project template has been replaced by a Azure Cloud Service project template. Select this template to bring up the New Cloud Service Project dialog shown in Figure 1. This dialog enables you to add roles to a cloud service.
Figure 1 Adding Roles to a New Cloud Service Project
A Azure role is an individually scalable component running in the cloud where each instance of a role corresponds to a virtual machine (VM) instance.
There are two types of role:
- A Web role is a Web application running on IIS. It is accessible via an HTTP or HTTPS endpoint.
- A Worker role is a background processing application that runs arbitrary .NET code. It also has the ability to expose Internet-facing and internal endpoints.
As a practical example, I can have a Web role in my cloud service that implements a Web site my users can reach via a URL such as http://%5Bsomename%5D.cloudapp.net. I can also have a Worker role that processes a set of data used by that Web role.
I can set the number of instances of each role independently, such as three Web role instances and two Worker role instances, and this corresponds to having three VMs in the cloud running my Web role and two VMs in the cloud running my Worker role.
You can use the New Cloud Service Project dialog to create a cloud service with any number of Web and Worker roles and use a different template for each role. You can choose which template to use to create each role. For example, you can create a Web role using the ASP.NET Web Role template, WCF Service Role template, or the ASP.NET MVC Role template.
After adding roles to the cloud service and clicking OK, Visual Studio will create a solution that includes the cloud service project and a project corresponding to each role you added. Figure 2 shows an example cloud service that contains two Web roles and a Worker role.
Figure 2 Projects Created for Roles in the Cloud Service
The Web roles are ASP.NET Web application projects with only a couple of differences. WebRole1 contains references to the following assemblies that are not referenced with a standard ASP.NET Web application:
- Microsoft.WindowsAzure.Diagnostics (diagnostics and logging APIs)
- Microsoft.WindowsAzure.ServiceRuntime (environment and runtime APIs)
- Microsoft.WindowsAzure.StorageClient (.NET API to access the Azure storage services for blobs, tables and queues)
The file WebRole.cs contains code to set up logging and diagnostics and a trace listener in the web.config/app.config that allows you to use the standard .NET logging API.
The cloud service
project acts as a deployment project, listing which roles are included in the cloud service, along with the definition and configuration files. It provides Azure-specific run, debug and publish functionality.
It is easy to add or remove roles in the cloud service after project creation has completed. To add other roles to this cloud service, right-click on the Roles node in the cloud service and select Add | New Web Role Project or Add | New Worker Role Project. Selecting either of these options brings up the Add New Role dialog where you can choose which project template to use when adding the role.
You can add any ASP.NET Web Role project to the solution by right-clicking on the Roles node, selecting Add | Web Role Project in the solution, and selecting the project to associate as a Web role.
To delete, simply select the role to delete and hit the Delete key. The project can then be removed.
You can also right-click on the roles under the Roles node and select Properties to bring up a Configuration tab for that role (see Figure 3). This Configuration tab makes it easy to add or modify the values in both the ServiceConfiguration.cscfg and ServiceDefinition.csdef files.
Figure 3 Configuring a Role
When developing for Azure, the cloud service project in your solution must be the StartUp project for debugging to work correctly. A project is the StartUp project when it is shown in bold in the Solution Explorer. To set the active project, right-click on the project and select Set as StartUp project.
Data in the Cloud
Now that you have your solution set up for Azure, you can leverage your ASP.NET skills to develop your application.
As you are coding, you’ll want to consider the Azure model for making your application scalable. To handle additional traffic to your application, you increase the number of instances for each role. This means requests will be load-balanced across your roles, and that will affect how you design and implement your application.
In particular, it dictates how you access and store your data. Many familiar data storage and retrieval methods are not scalable, and therefore are not cloud-friendly. For example, storing data on the local file system shouldn’t be used in the cloud because it doesn’t scale.
To take advantage of the scaling nature of the cloud, you need to be aware of the new storage services. Azure Storage provides scalable blob, queue, and table storage services, and Microsoft SQL Azure provides a cloud-based relational database service built on SQL Server technologies. Blobs are used for storage of named files along with metadata. The queue service provides reliable storage and delivery of messages. The table service gives you structured storage, where a table is a set of entities that each contain a set of properties.
To help developers use these services, the Azure SDK ships with a Development Storage service that simulates the way these storage services run in the cloud. That is, developers can write their applications targeting the Development Storage services using the same APIs that target the cloud storage services.
Debugging
To demonstrate running and debugging on Azure locally, let’s use one of the samples from code.msdn.microsoft.com/windowsazuresamples. This MSDN Code Gallery page contains a number of code samples to help you get started with building scalable Web application and services that run on Azure. Download the samples for Visual Studio 2010, then extract all the files to an accessible location like your Documents folder.
The Development Fabric requires running in elevated mode, so start Visual Studio 2010 as an administrator. Then, navigate to where you extracted the samples and open the Thumbnails solution, a sample service that demonstrates the use of a Web role and a Worker role, as well as the use of the StorageClient library to interact with both the Queue and Blob services.
When you open the solution, you’ll notice three different projects. Thumbnails is the cloud service that associates two roles, Thumbnails_WebRole and Thumbnails_WorkerRole. Thumbnails_WebRole is the Web role project that provides a front-end application to the user to upload photos and adds a work item to the queue. Thumbnails_WorkerRole is the Worker role project that fetches the work item from the queue and creates thumbnails in the designated directory.
Add a breakpoint to the submitButton_Click method in the Default.aspx.cs file. This breakpoint will get hit when the user selects an image and clicks Submit on the page.
protected void submitButton_Click(
object sender, EventArgs e) {
if (upload.HasFile) {
var name = string.Format("{0:10}", DateTime.Now.Ticks,
Guid.NewGuid());
GetPhotoGalleryContainer().GetBlockBlob(name).UploadFromStream(upload.FileContent);
Now add a breakpoint in the Run method of the worker file, WorkerRole.cs, right after the code that tries to retrieve a message from the queue and checks if one actually exists. This breakpoint will get hit when the Web role puts a message in the queue that is retrieved by the worker.
while (true) {
try {
CloudQueueMessage msg = queue.GetMessage();
if (msg != null) {
string path = msg.AsString
To debug the application, go to the Debug menu and select Start Debugging. Visual Studio will build your project, start the Development Fabric, initialize the Development Storage (if run for the first time), package the deployment, attach to all role instances, and then launch the browser pointing to the Web role (see Figure 4).
Figure 4 Running the Thumbnails Sample
At this point, you’ll see that the browser points to your Web role and that the notifications area of the taskbar shows the Development Fabric has started. The Development Fabric is a simulation environment that runs role instances on your machine in much the way they run in the real cloud.
Right-click on the Azure notification icon in the taskbar and click on Show Development Fabric UI. This will launch the Development Fabric application itself, which allows you to perform various operations on your deployments, such as viewing logs and restarting and deleting deployments (see Figure 5). Notice that the Development Fabric contains a new deployment that hosts one Web role instance and one Worker role instance.
Figure 5 The Development Fabric
Look at the processes that Visual Studio attached to (Debug/Windows/Processes); you’ll notice there are three: WaWebHost.exe, WaWorkerHost.exe and iexplore.exe.
WaWebHost (Azure Web instance Host) and WaWorkerHost (Azure Worker instance Host) host your Web role and Worker role instances, respectively. In the cloud, each instance is hosted in its own VM, whereas on the local development simulation each role instance is hosted in a separate process and Visual Studio attaches to all of them.
By default, Visual Studio attaches using the managed debugger. If you want to use another one, like the native debugger, pick it from the Properties of the corresponding role project. For Web role projects, the debugger option is located under the project properties Web tab. For Worker role projects, the option is under the project properties Debug tab.
By default, Visual Studio uses the script engine to attach to Internet Explorer. To debug Silverlight applications, you need to enable the Silverlight debugger from the Web role project Properties.
Browse to an image you’d like to upload and click Submit. Visual Studio stops at the breakpoint you set inside the submitButton_Click method, giving you all of the debugging features you’d expect from Visual Studio. Hit F5 to continue; the submitButton_Click method generates a unique name for the file, uploads the image stream to Blob storage, and adds a message on the queue that contains the file name.
Now you will see Visual Studio pause at the breakpoint set in the Worker role, which means the worker received a message from the queue and it is ready to process the image. Again, you have all of the debugging features you would expect.
Hit F5 to continue, the worker will get the file name from the message queue, retrieve the image stream from the Blob service, create a thumbnail image, and upload the new thumbnail image to the Blob service’s thumbnails directory, which will be shown by the Web role.
Next installment, we will look at the Deployment Process
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