A host computer processes, produces, and stores all the information for mobile commerce applications. This component is similar to that used in an electronic commerce system because the host computers are usually not aware of differences among the targets, browsers, or microbrowsers they serve. It is the application programs that are responsible for apprehending their clients and responding to them accordingly . Most of the mobile commerce application programs reside in this component, except for some client-side programs such as cookies. This component contains three major components : a Web server, a database server, and application programs and support software.
A Web server is a server-side application program that runs on a host computer and manages the Web pages stored on the Web site's database. There are many Web server software applications, including public domain software from NCSA and Apache and commercial packages from Microsoft, Netscape, and others. Since April 1996, Apache has been the most popular HTTP server on the Internet; in May 1999, it was running on 57% of all Web servers. It was developed in early 1995 based on code and ideas found in the most popular HTTP server of the time, NCSA httpd 1.3. It has since evolved to rival (and probably surpass) almost any other Unix-based HTTP server in terms of functionality and speed. It features highly configurable error messages, DBM-based authentication databases, and content negotiation.
A database server manages database access functions, such as locating the actual record being requested or updating the data in databases. Some popular databases are Oracle9 i , Microsoft Access, and IBM DB2. Other than the server-side database servers, a growing trend is to provide a mobile database or an embedded database to a handheld device with a wide range of dataprocessing functionality. The functionality is frequently very sophisticated, and the flat file system that comes with these devices may not be able to adequately handle and manipulate data. Embedded databases have very small footprints and must be able to run without the services of a database administrator and accommodate the low-bandwidth constraints of a wireless-handheld network. Some leading embedded databases are Progress Software databases, Sybase's Anywhere products, and Ardent Software's DataStage (Ortiz, 2000).
Web and database servers are mandatory for mobile commerce systems; application programs handle all server-side processing. However, to facilitate mobile commerce applications, some other support software is needed. For example, various programming languages, including Perl, Java, Visual Basic, C/C++, etc., and the CGI (Common Gateway Interface) are necessary to transfer information between a Web server and a CGI script are necessary.