This appendix contains explanations of all the acronym-ridden Internet technologies that are used to make the .NET Framework such an exciting environment—and that have made XML Web Services possible. | MCAD MCSD MICROSOFT CERTIFIED APPLICATION DEVELOPER MICROSOFT CERTIFIED SOLUTION DEVELOPER D The Technologies 2 Appendix D The Technologies T his appendix contains explanations of all the acronym-ridden Internet technologies that are used to make the .NET Framework such an exciting environment and that have made XML Web Services possible. HTTP The Hypertext Transfer Protocol HTTP is a stateless application-level protocol that is based on a request-response system. That HTTP is an application-level protocol means that it will need a lower-level network protocol to achieve communications between computers. The most common network protocol is the Transmission Control Protocol TCP protocol from the TCP IP suite. Although HTTP can use other network protocols the proliferation of TCP IP has made it the only real choice today. HTTP when used with TCP IP uses one of the well-known ports 80 defined for connections between the client and the server. This predictable behavior means that HTTP proxies can be used to provide a means for clients situated behind a firewall access to HTTP servers outside that firewall. This is one of the things that make HTTP a common choice for developing client server applications. HTTP is a stateless protocol. A stateless protocol does not remember anything between one transmission and another it has no context each request is an independent connection to the server. HTTP is the current standard from the World Wide Web Consortium W3C . HTTP has actually been a standard since 2000. The current work on applicationlevel protocols within W3C is with the XML protocol. To find additional information about the HTTP standard visit the W3C web site for HTTP at http Protocols . Next you need to look at some of the specifics of HTTP. URIs URLs and URNs A Universal Resource Identifier URI is used to unambiguously locate a resource on the network. These resources can be files programs e-mail addresses XML web services or indeed .
