Observing the User Experience: A Practitioners Guide to User Research

Web services bring about a new philosophy in software design. Theyre basically functions that are exposed (and that can be called) over the World Wide Web through Hypertext Transfer Protocol (HTTP). Web services use Simple Object Access Protocol (SOAP) by default over HTTP to allow communication between clients and servers, even through firewalls.

Because you can treat Web services just like any other HTTP request (except for having to decode the request from SOAP and encode the response to SOAP), ATL Server is the perfect place in the Visual C++ libraries to provide support for them. Thus, ATL Server not only allows developers to create high-end Web applications, but it also allows them to create high-end Web services. Just as with the Web application model, flexibility, control, reliability, scalability, and performance are all paramount in the design.

By taking advantage of the attribute feature in the Visual C++ .NET compiler, ATL Server makes Web service programming very similar to COM programming. This is made possible by the fact that Web services, like COM components , rely on having a well-defined interface and an interface description language (Web Services Description Language [WSDL] instead of Interface Definition Language [IDL]) to describe that interface with.

Not only does this attribute feature enable existing COM developers to leverage their knowledge of COM development when creating Web services, but it also makes it very easy to expose objects as both COM components and Web services. On top of this, developers can easily expose existing COM objects (or Web services) as Web services (or COM objects).

There are a few major advantages to having a native solution for Web services:

• Web services are just like regular Web application requests , except you need to be able to encode and decode SOAP. Developers needed a solution that would handle the networking, marshaling, transport, and other Web service issues for them on both the client and the server.

• Native Web services enable Web application developers using ATL Server (or ISAPI directly) to easily expose Web application functionality (or parts of their Web application) via Web services, which allows them to target a much broader market.

• Native Web services allow ATL COM developers to protect their existing investment in the knowledge they possess about developing and using components that rely on well-defined interfaces to communicate. They also help developers protect their existing code investment by making it easy to expose existing (and new) COM components as Web services. Its easy for ATL COM developers to expose Web services they develop in the future as COM components.

• Native Web services provide an ideal solution for developers who require the low-level control, flexibility, and performance that only a solution such as ATL Server can provide.