The role of HTTP in web services

The familiar Hypertext Transfer Protocol (HTTP) is most often associated with the World Wide Web. This is one of the transfer protocols in use on the internet. Others include File Transfer Protocol (FTP) and Simple Mail Transfer Protocol (SMTP). HTTP is by far the most used transport protocol for web services, and it plays a crucial role in REST.

Xcentrisity® Business Information Server (BIS) is an application server that plugs in to the two most popular HTTP servers, Microsoft IIS and the Apache HTTP Server. BIS receives requests from and supplies responses to web-based 'user agents'. BIS is described in more detail later.

The HTTP specification describes messages that represent requests from a client to a server and responses from a server to a client. A message from a client to a server indicates a method (i.e., an action) that is desired for a specific resource designated by a URI, (Universal Resource Identifier). URIs are simply formatted strings which identify by name, location or some other characteristic, a resource located on the internet.

HTTP methods include GET, PUT, POST, DELETE, HEAD, TRACE, and CONNECT. To create web services using BIS, only the first four methods are important. The last three methods are handled by the HTTP server above (in architectural terms) the BIS service programs.