Mastering Visual Studio .NET 1002003 [Electronic resources] نسخه متنی

4.1 Web Project Templates

When
you create a new project, the project template you choose determines
whether your project is web-based. A web-based project is one that is
accessed or managed via a web protocol, such as HTTP, HTTPS, or FTP.
The list of web project templates is listed in Table 4-1.

Although web projects look like normal projects when viewed in the
IDE, they behave quite differently behind the scenes. Any content
files (web pages, graphics, etc.) must reside on a web server; the
same is true for the build output (a managed or unmanaged DLL).

VS.NET has two completely different strategies for ensuring that all
of the necessary files are in the right place. One is used by C#,
VB.NET, and J# projects, and the other is used by Visual C++
projects. We will talk about each separately, in Section 4.2" and Section 4.3" later in this
chapter. Before we do that, we need to talk about IIS web
applications, since both types of projects depend on the separation
provided by web applications to function properly.

4.1.1 IIS Virtual Directories and Web Applications

In IIS, every
directory is considered to be either a
nonvirtual directory or a virtual directory. Nonvirtual directories
are stored under the web server's root directory. A
virtual directory can be anywhere on the server's
filesystem, but the URL that is used to access that content makes it
appear to the end user that it is physically below the root directory
(hence the term virtual).

For example, suppose that the web server root is in the default
location, c:\inetpub\wwwroot. If that directory
were to contain a file called default, a web
browser would use the address http://server/default to access that
resource. If there were a directory at
c:\inetpub\wwwroot\dir1 containing a file
foo, then the URL would be http://server/dir1/foo.
dir1 would be a nonvirtual directory within the
web server's root directory. The structure of
nonvirtual directories is presented directly through the structure of
the URLs used to access their contents.

IIS does not force us to have such a strict mapping between URLs and
the structure of our filesystem. Virtual directories allow us more
flexibility. For example, we could use the IIS administration tool
(located in the Administrative Tools section of the Control Panel) to
map the e:\website directory as a virtual
directory called dir2. (A virtual directory can
have a different name than the actual directory on which it is
based.) If e:\website contains a
page file, a web browser could access this
with the URL http://server. Because we set
up a virtual directory called dir2, IIS will map
the request for A web
application is a directory tree with its own application settings.
These application settings include security configuration, error
handling, and file extension mappings. By default, a directory
(virtual or not) will belong to its parent
directory's application. However, any directory can
be set as having its own application, at which point it gets its own
settings. (Of course, these settings will propagate to any
subdirectories that do not have their own application.)

You make a directory the root of a web application using the IIS
administration utility. Open the directory's
Properties page by right-clicking on the directory in the tree and
selecting Properties from the context menu. If the directory is not a
web application directory (i.e., if it picks up its application
settings from its parent), you will be able to turn it into a web
application by clicking on the Create button in the Application
Settings section of the Directory tab, which is shown in Figure 4-1. (If the directory is already a web
application, in place of a Create button, you will see a Remove
button, enabling you to remove the web applicationthis will
cause the directory to revert to using its parent's
settings.)

Figure 4-1. A directory's Properties page in IIS

Windows XP lets you add new virtual directories using Windows Explorer. The Properties page for a directory will have a Web Sharing tab. (Certain directories do not support web sharing, so the Web Sharing tab will not always be present.) If you share a directory in this way, Windows Explorer will create both a new virtual directory and a new web application for that directory.

A web server will always have at least one web applicationeven
if you do not create any web applications of your own, there is an
application for the web server's home directory. You
can configure this from the Properties page for the web site itself.
The tab has a different name in this caseit is labeled Home
Directory instead of just Directory, but it otherwise works in the
same way.

Once you create an application by clicking the Create button, all of
the code in that application and all of the directories below it (at
least those that are not applications themselves) now share
application-wide settings. In an ASP application, Session and
Application state are scoped by the web application. Process
isolation settings are also configured on a per-application basis. In
ASP.NET, the Session and Application state are partitioned in a
similar way, but the process isolation settings are ignored in favor
of an ASP.NET worker process.

Although ASP.NET ignores the IIS isolation settings, it gives each web application its own AppDomain, which serves a similar purpose. Web applications also determine the scope for configuration settings in the application's web.config.

4.1.1.1 Web applications and web projects

Whenever you create a new web
project, VS.NET creates a new web application (unless an appropriate
one already exists). This means there is a one-to-one mapping between
VS.NET web projects and IIS web applications. For a .NET web project,
VS.NET will also create a bin directory
underneath the web application directory. The
bin directory is where VS.NET places the
project's build output. (ASP.NET automatically loads
any assemblies in the bin directory into the web
application's AppDomain.)

aspnet_regiis -s W3SVC/1/ROOT/WebApp