Key Web Service Terms

It can be important for developers to understand the key concepts and standard terms around web services. This knowledge ensures that you know what is happening in your application. It also helps when you are reading the .NET documentation and articles related to building web service applications. Therefore, we have put together the following glossary of key terms related to web services:

Web service—A web service represents a cohesive set of application logic that performs actions and provides data. A web service groups this logic as methods that can be called over HTTP. Not all services are web services; only those that work over the Internet are considered web services.

Web service method (or web method)—A web service method represents a method exposed by a web service. A web method can take parameters and return a response.

XML (Extensible Markup Language)—XML is used to both represent and describe data in a platform-neutral manner. XML can represent both simple and complex data elements and relationships. It is the XML standard that makes web services possible.

JSON (JavaScript Object Notation)—JSON was created as a reaction to overly large XML messages. It is a lightweight data-interchange format that is human readable and built on simple collections of name-value pairs.

WSDL (Web Service Description Language)—WSDL is used to describe the contents of a web service and its web methods. The WSDL provides the message data contracts that enable clients to work with a given service.

XSD (XML Schema Document)—XSD contains a set of predefined types (string, decimal, and so on) and a standard language for describing your own complex types. An XML Schema Document (also referred to as an XSD) uses these types to describe (and restrict) the contents of an XML message.

SOAP—SOAP is an XML-based protocol for communicating between the client and the web service. It is helpful to think of SOAP as representing the format of the messages as they pass over the wire. SOAP wraps XML messages (in envelopes) for communication across the Web. Most SOAP messages are sent over HTTP. However, they can also be sent with transport protocols such as Simple Mail Transfer Protocol (SMTP) and File Transfer Protocol (FTP).

HTTP (Hypertext Transfer Protocol)—HTTP represents the communication protocol used by web services to transfer SOAP-formatted (or encoded) messages. HTTP is also the way standard web page requests (GET and POST) communicate.

UDDI (Universal Description, Discovery, and Integration)—UDDI is used to define a registry of web services. This capability is useful for the publication of services for developers to find and consume.

URI (uniform resource identifier)—URIs provide a means for locating items on the web. In most cases, URIs are URLs (uniform resource locators) that point to a given service.

DISCO (Discovery Document)—A DISCO file provides information that links to other key elements of a web service. This includes links to XSDs, SOAP bindings, and namespaces. A program can use a DISCO file to determine how to work with a given web service.

WS-*—This term represents the overall standards for web services.