Web Servers in Visual Studio for ASP.NET Web Projects

By default, Visual Studio 2010 SP1 uses the Visual Studio Development Server for Web site projects and Web application projects. However, you can use IIS Express instead. (For Web application projects, you can use IIS.) For more information, see How to: Specify the Web Server for Web Projects in Visual Studio.

IIS Express includes many of the features of IIS 7 Web server without requiring you to install and manage IIS 7 on your computer. Because IIS Express is similar to IIS 7, it lets you transition Web sites to IIS more smoothly than the built-in Visual Studio Development Server does.

Note
Support for IIS Express was introduced in Visual Studio 2010 Service Pack 1.

IIS Express offers the following features:

• It supports and enables the same extensibility model and Web.config file settings as IIS 7.

• It does not require changes in your Web application code.

• It can be installed side-by-side with the full IIS web server as well as with the Visual Studio Development Server. You can choose a different Web server for each project.

In corporate environments, IIS Express offers the following features:

• It does not require an administrator account in order to run or debug applications.

• It does not serve requests to a browser on another computer, making its approval easier in corporate environments.

• It supports multiple developers on the same computer. Configuration files, settings, and Web content are maintained on a per-user basis under the %systemdrive%\users\<username> folder.

• It can be installed on versions of Windows that do not support IIS 7.

Tip
Although IIS Express is derived from IIS and supports the core features of IIS, there are some differences between these servers. For more information, see IIS Express Overview.

IIS Express Requirements

Installing IIS Express

Using the IIS Express System Tray Application

IIS Express starts automatically when you run a project in Visual Studio, and it stops when you close the Web site or Web application project in Visual Studio. When IIS Express is running, it displays an icon in the system tray.

The following table lists typical tasks for IIS Express and how to perform them.

Task	Steps
Display a list of all sites that are running on IIS Express	Right-click the IIS Express icon in the system tray, and then click Show All Applications.
View a Web site directory location, configuration path, and .NET Framework version	Select the Web site in the IIS Express window. The information will appear beneath the list of Web sites.
Stop IIS Express	Right-click the tray icon and select Exit. Note In most cases, you do not have to shut down IIS Express manually. However, if you are using SQL Server Express, you might have to stop IIS Express manually before you can access a SQL Server Express .mdf file (for example, from SQL Management Studio).

If you do not want to use IIS Express or IIS as your Web server, you can use the Visual Studio Development Server. If you are working with a file-system Web site or a Web application project, by default Visual Studio automatically uses the Visual Studio Development Server. The Visual Studio Development Server is a Web server that runs locally on Windows operating systems, including Home Edition versions. As with IIS Express, it is specifically built to run ASP.NET on the local computer. It will not serve requests to another computer. Additionally, it will not serve files that are outside the application scope. The Visual Studio Development Server is one way to test your Web site or application locally before you publish it to a production server running IIS. However, if the production server that you will be publishing to is IIS 7 or a later version of IIS, you should use IIS Express because it is functionally closer to IIS 7.

The Visual Studio Development Server does not include all of the extra facilities of IIS. For example, like IIS Express, the Visual Studio Development Server does not support SMTP or FTP. If your Web project involves sending email messages, you must have access to an IIS SMTP virtual server to test email.

When you test a file-system Web site using the Visual Studio Development Server, static files such as images and style sheets are subject to ASP.NET authorization. For example, Visual Studio Development Server will not serve static files in a file-system Web site if they are in a folder that restricts anonymous users from accessing it and if you are testing the site as an anonymous user.

When you create a new file-based Web site or Web application project, a random port is selected for the project. For example, if you are testing a page called ExamplePage.aspx, when you run it on IIS Express or the Visual Studio Development Server, the URL of the page might be:

http://localhost:31544/ExamplePage.aspx

If you want to run IIS Express or the Visual Studio Development Server on a specific port, you can configure the server to do so. You might do this in these scenarios:

• You have copied a Web application project or Web site project and you want to debug and work on both simultaneously. In that case you will have a port collision and will need to change the port number for one of the projects.

• Your project includes a reference to a client project or Web service that is bound to a specific port.

• The code in your project listens to a specific port and you want to be able to test the application using IIS Express or the Visual Studio Development Server.

For more information, see How to: Specify a Port for the Development Server.

An important difference between the development servers in Visual Studio and IIS is the security context in which the servers run your ASP.NET pages. This difference can be a source of problems when you deploy a Web site or Web application to run on IIS.

When you run a page using IIS Express or the Visual Studio Development Server, the page runs in the context of your current user account. For example, if you are running as an administrator-level user, a page running in the Visual Studio Development Server will have administrator-level privileges. In contrast, in IIS 7, by default ASP.NET runs in an account that has limited privileges. For more information, see Application Pool Identities on the IIS.net Web site.

If you are simply reading and running the code in ASP.NET pages, this difference is not very important. However, the different security contexts for the two Web servers can affect your testing of the following:

• Database access   When you work with IIS Express or the Visual Studio Development Server, you can typically use Windows Integrated authentication to access SQL Server. However, when the same page runs in IIS, the page will be running in the context of the application pool identity. You can either use SQL Server authentication instead or add the application pool identity that the page runs under as a SQL Server login. For more information, see Accessing SQL Server from a Web Application, ASP.NET Security Architecture, and Application Pool Identities.

• Code access security   If your page runs in medium trust (as most Web hosting providers require), the page might run differently under the server in Visual Studio than it does in IIS.

• Access to other resources that the page requires   This can include reading and writing files other than Web pages, reading and writing the Windows registry, and so on.

The production Web server for Microsoft operating systems is IIS, which can include a Web server, File Transfer Protocol (FTP) server, Simple Mail Transfer Protocol (SMTP) virtual email server, and other facilities. In order to run IIS, you must be working with one of the versions of Windows that is listed in the following table.

Advantages of Using IIS as a Development Server with Visual Studio

Disadvantages of Using IIS as a Development Web Server

Installing and Configuring IIS to Work with Visual Studio

Tasks

Concepts

Other Resources