4.3 Visual C++ Projects
VC++
web projects act more like nonweb VS.NET projects than like the
managed web projects described earlier. All of the solution, project,
and source files are kept on the local hard disk and not the web
server. When you build a VC++ web project, all of the usual build and
debug build directories are used, and not the local web cache folder.
The only real difference between a nonweb project and a VC++ web
project is that a VC++ web project has a final build step that copies
the appropriate DLLs and content files to the web server.
4.3.1 Creating a New VC++ Web Project
Creating a
new unmanaged web project is similar to creating a nonweb project.
Unlike with managed web projects, you do not specify a remote web
server in the New Project dialog—you just specify a folder on
the local filesystem as usual. When you build an unmanaged web
project, VS.NET communicates with IIS via DCOM
(Distributed Component Object Model) and
creates the appropriate web application for your project. (By
default, it will use the project name, but you can change this in the
Project Property Pages dialog—in the Web Deployment settings,
the General section contains a Virtual Directory Name property that
you can use to control where VS.NET will send the build output.)
The two basic types of VC++ web projects are ATL Server and ASP.NET
Web Service (or Managed C++ Web Service as it was called in VS.NET
2002). Although they create different kinds of output, these projects
interact with the web server in the same way.
- ATL Server
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An ATL Server project creates a new web application whose main
executable is an ISAPI (Internet Server Application Programming
Interface) extension DLL. This ISAPI extension responds dynamically
to HTTP requests. There are two ATL Server project templates. ATL
Server Project creates an ISAPI DLL that uses
.srf files to create dynamic HTML UIs. ATL
Server Web Service creates an ISAPI DLL that exposes a web service
via SOAP (Simple Object Access Protocol). See ATL
Internals, Second Edition (Addison-Wesley) for a more
detailed discussion of ATL Server.
- ASP.NET Web Service
-
An ASP.NET Web Service in Managed C++ is similar to ASP.NET Web
Services in other managed languages. The ASP.NET Web Service template
creates a project that provides a SOAP-based web service. The project
builds a .NET assembly. It puts this assembly in the
bin directory of a web application and then
links a type in that assembly to an .asmx file
(via the .asmx file's
WebService directive).
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The documentation for .asmx files is
scant. Their purpose is to map the URL for a web service onto the
class that implements the service. The easiest way to see how they
work is to look inside one, although that is easier said than
done—VS.NET tries to stop you from editing their contents by
always showing you the codebehind file instead of the
.asmx file itself. (You can force it to open the
.asmx file by right-clicking on the file in the
Solution Explorer, selecting Open With, and choosing Source Code
(Text) Editor.)
Most .asmx files contain just one line, a
@WebService directive. This contains a
Class attribute, which tells ASP.NET the name of
the class that will handle web service requests directed to this
endpoint. VS.NET places the class in a codebehind file (and it adds a
Codebehind attribute to the directive so that it
can find the relevant source file). ASP.NET also allows the source
for the class to be placed inside the .asmx file
itself, after the directive. (You can supply a
Language attribute to tell ASP.NET which compiler
it should use.) However, VS.NET doesn't make use of
that—it always places the class definition in a codebehind
file.
Here is a typical .asmx file generated by VS.NET:
<%@ WebService Language="c#" Codebehind="Svc1.asmx.cs"
Class="WebSvc.Svc1" %>
It indicates that all web service requests directed to this
file's URL will be handled by a class called
WebSvc.Svc1, and the Codebehind
hint tells VS.NET that this class is implemented in a file called
Svc1.asmx.cs.
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4.3.2 Files
VC++ web projects manage files in the
typical VS.NET manner, keeping all of the source files in the project
directory. Content files are copied to the web server automatically
as part of the build process. (You can tell VS.NET which files are
content by selecting the files in the Solution Explorer and setting
their Content property to true.)
4.3.3 Building and Debugging
When a project is built, the files
necessary for the web application are copied to the corresponding
directory on the web server. If you need to deploy a VC++ project to
another server, you will have to move the appropriate files by hand
(as well as set up an appropriate IIS application).
When building an unmanaged project for debugging, all you need to do
is make sure that you are building a Debug configuration. Otherwise,
debugging is the same as any other project. See Chapter 3 for more detailed information about
debugging.
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