Chapter 10: Web-Services Interface

Highlights

One of the most hyped technologies to be linked with .NET is web services. Microsoft calls .NET the platform for building and using web services, and there's no doubt that when they're used appropriately, web services are powerful and useful indeed. It's important to realize, however, that web services are fundamentally just a text format for data interchange ”they're not designed to simplify the process of creating object-oriented systems.

In my view, web services are just another type of interface to applications. We've already discussed and created Windows Forms and Web Forms interfaces, which allow a user to access our application as shown in Figure 10-1.

Figure 10-1: Accessing our application from Windows and Web Forms interfaces

Web services are another type of interface that our application can make available. The primary difference is that a web-service interface is designed for use by other applications , not directly by users. Another application can use web services to get or update data in our application. This other application that's consuming our data may or may not have users of its own. This concept is illustrated in Figure 10-2.

Figure 10-2: Accessing our application from another application through a web-service interface

Note  

I fully realize that web services are being sold as offering much more than this. We'll discuss my rationale some more before we actually implement the web services in this chapter.

In this chapter, we'll quickly review web services and SOAP (Simple Object Access Protocol) technology. Then we'll discuss the various roles that people often associate with web services in order to make it clear why they work best if viewed as I've described them here. After that, we'll create a web-services interface for our project-tracker business objects in order to illustrate how our business objects support the creation of web services.