Debugging Applications in Windows Azure

In this lab, you will explore some simple techniques for debugging applications deployed in Windows Azure; and you will learn what features and techniques are available in Visual Studio and Windows Azure to debug applications once deployed to Windows Azure.

Overview

Using Visual Studio, you can debug applications in your local machine by stepping through code, setting breakpoints, and examining the value of program variables. For Windows Azure applications, the compute emulator allows you to run the code locally and debug it using these same features and techniques, making this process relatively straightforward.

Ideally, you should take advantage of the compute emulator and use Visual Studio to identify and fix most bugs in your code, as this provides the most productive environment for debugging. Nevertheless, some bugs might remain undetected and will only manifest themselves once you deploy the application to the cloud. These are often the result of missing dependencies or caused by differences in the execution environment. For addition information on environment issues, see Differences Between the Compute Emulator and Windows Azure.

Once you deploy an application to the cloud, you are no longer able to attach a debugger and instead, need to rely on debugging information written to logs in order to diagnose and troubleshoot application failures. Windows Azure provides comprehensive diagnostic facilities that allow capturing information from different sources, including Windows Azure application logs, IIS logs, failed request traces, Windows event logs, custom error logs, and crash dumps. The availability of this diagnostic information relies on the Windows Azure Diagnostics Monitor to collect data from individual role instances and transfer this information to Windows Azure storage for aggregation. Once the information is in storage, you can retrieve it and analyze it.

Objectives

In this hands-on lab, you will:

• Learn what features and techniques are available in Visual Studio and Windows Azure to debug applications once deployed to Windows Azure.
• Use a simple TraceListener to log directly to table storage and a viewer to retrieve these logs.

Prerequisites

The following is required to complete this hands-on lab:

• IIS 7 (with ASP.NET, WCF HTTP Activation)
• Microsoft .NET Framework 4.0
• Microsoft Visual Studio 2010
• Windows Azure Tools for Microsoft Visual Studio 1.6

Setup

In order to execute the exercises in this hands-on lab you need to set up your environment.

1. Open a Windows Explorer window and browse to the lab’s Source folder.
2. Double-click the Setup.cmd file in this folder to launch the setup process that will configure your environment and install the Visual Studio code snippets for this lab.
3. If the User Account Control dialog is shown, confirm the action to proceed.

Using the Code Snippets

Throughout the lab document, you will be instructed to insert code blocks. For your convenience, most of that code is provided as Visual Studio Code Snippets, which you can use from within Visual Studio 2010 to avoid having to add it manually.

If you are not familiar with the Visual Studio Code Snippets, and want to learn how to use them, you can refer to the Setup.docx document in the Assets folder of the training kit, which contains a section describing how to use them.

Exercises

This hands-on lab includes the following exercise:

1. Debugging an Application in the Cloud

Estimated time to complete this lab: 40 minutes.