As with any XML technology, there are underlying technologies that make the overall concept of Web Services work.
Remember that a Web Service is the actual node out on the Internet that performs some sort of function and then returns data.
The underlying technologies that allow you to use a Web Service include the protocol that moves the data across the Internet or network (such as HTTP) and SOAP. Other technologies that allow you to use and discover Web Services include Web Service Description Language (WSDL) and Universal Discovery, Description, and Integration (UDDI). This section briefly introduces these standards and chapters later in this book go into greater detail.
SOAP, as mentioned earlier in this chapter, is the underlying XML standard that allows Web Services to work cross platform because the data is transmitted in a standard way. SOAP is a constantly evolving standard; soon it will no longer be known as SOAP but as the XML Protocol (XMLP). Chapter 3 goes into great detail about the SOAP standard, its terminology, and syntax.
Communication about the location, needed parameters, necessary tools, and other information about a set of remote objects turned out to be another difficulty when developers deployed these technologies. There was no standard way to describe the objects or location to put the description. Usually a document created by developers circulates internally with all the classes and methods available. This works great within the corporate infrastructure.
If these objects need to be shared across the Internet with thousands of users, the documentation will need to reach them. This can be done with a Web page, but somehow the users would need to discover this information. UDDI provides a standard way to discover and describe Web Services without human intervention.
UDDI appears to have two roles. In one of its roles, it’s an XML standard that describes where to find particular Web Services. In addition, there are several Web sites that use UDDI to advertise available Web Services. Some sites to look at for Web Services include www.uddi.org, www.xmethods.com, and uddi.microsoft.com. Chapter 4 discusses UDDI and discovery in more detail.