Use .NET to develop and implement a Web service solution

Web services have emerged from an intriguing concept to a technology that has taken the industry by storm. It has slowly been adopted, but its momentum shows no sign of slowing down. Microsoft quickly recognised the power of the Web services concept and fully embraced the technology with its many products. This is the first in a series of articles that focuses on developing a Web service from start to finish and consuming it with various clients.

The attack of the acronyms
Developers are constantly bombarded acronyms, such as WSDL, COM, DCOM, HTML, RSS, and HTTP. It is often hard to discern what deserves your attention. A good example is SOA (service-oriented architecture) which is being tightly embraced by Microsoft.

SOA is often associated with Web services. While this association is not incorrect, a Web service isn't a requirement for implementing SOA. SOA promotes a loose-coupling of systems. Systems are no longer viewed as isolated entities; they are open to communicate with other systems. A system may be called upon to perform a task by another system, and this other system does not need to know anything about the inner workings of the other.

This approach is not entirely new -- past technologies like DCOM had a similar slogan. The problem with DCOM and similar technologies was system setup and proprietary technologies. The arrival of XML on the technology landscape provided a way to effectively package data, and transport standards like SOAP make it possible to send XML over a network.

A Web service is, however, quickly becoming recognised by the IT industry as a key ingredient of implementing a SOA-based solution. This is certainly true with Microsoft's SOA efforts, where they demonstrate and preach SOA with the various products available within their arsenal. Our sample solution will utilise various members of the Microsoft staple in every aspect from development to consumption. Let's begin with an overview of the scenario before developing a solution.

Example scenario
In our example, we will utilise the popular Northwind database readily available with any SQL Server installation regardless of the version. The Northwindcompany wants to provide product information via an easy-to-use interface that requires no interaction with Northwind personnel.

A discussion with the Northwind personnel yields the fact that most of their customers utilise computer systems to request the information through their company Web site. A natural solution is providing the information via a Web interface, and this is on the right track. A more appropriate part of the solution is developing Web services to process the request for information. Consequently, these services may be utilised by a Web interface, called directly via a customer's application, or used by any other client application.

While this solution may not be able to completely reduce the need for Northwind personnel since all customers will not utilise a computer or Web connection, it will address the majority of their customer base and possibly make them attractive to others. Let's turn our attention to designing the solution.