Handbook of Local Area Networks, 1998 Edition:Applications of LAN Technology Click Here! Search the site:   ITLibrary ITKnowledge EXPERT SEARCH Programming Languages Databases Security Web Services Network Services Middleware Components Operating Systems User Interfaces Groupware & Collaboration Content Management Productivity Applications Hardware Fun & Games EarthWeb sites Crossnodes Datamation Developer.com DICE EarthWeb.com EarthWeb Direct ERP Hub Gamelan GoCertify.com HTMLGoodies Intranet Journal IT Knowledge IT Library JavaGoodies JARS JavaScripts.com open source IT RoadCoders Y2K Info Previous Table of Contents Next Design Tools New design tools are available that address the maintenance and testing issue by providing the means to visualize the creation, maintenance, and navigation of whole collections of online documents. Where traditional Web tools such as browsers and HTML editors focus on the Web page, these tools address the Web site, which may be either physical or logical in structure. These tools include a system to identify which pages are included in the site and another to describe how the pages are interconnected. The construction of a site is facilitated by providing templates for creating pages and scripts and linkage to tools for editing and verifying HTML documents. In addition to offering high-level views of a site—either graphical or hierarchical—the design tools check for stale links (either local or remote), validate the conformance level of HTML pages, and make broad structural changes to the site architecture by using a mouse to drag and drop sections of the Web hierarchy into a different location. Agents or Robots Although design tools address document creation and maintenance at the site level, they do not comprehensively address the maintenance needs of distributed hypertext infrastructures that span multiple Web sites. This task can be handled by special software known as agents or robots. These programs can be given a list of instructions about what data bases to traverse, whom to notify for problems, and where to put the resulting maintenance information. For example, the agent or robot may be tasked to provide information about the following conditions that typically indicate document changes: •  A referenced object has a redirected URL (i.e., a document has been moved to another location). •  A referenced object cannot be accessed (i.e., there is a broken or improperly configured link). •  A referenced object has a recently modified date (i.e., the contents of a document have changed). •  An owned object has an upcoming expiration date (i.e., a document may be removed or changed soon). To get its instructions, the agent or robot reads a text file containing a list of options and tasks to be performed. Each task describes a specific hypertext infrastructure to be encompassed by the traversal process. A task instruction includes the traversal type, an infrastructure name (for later reference), the “top URL” at which to start traversing, the location for placing the indexed output, an E-mail address that corresponds to the owner of that infrastructure, and a set of options that determine what identified maintenance issues justify sending an E-mail message. THE COMMON GATEWAY INTERFACE An Internet server should support the Common Gateway Interface (CGI), which is a standard for interfacing external applications with information servers, such as HTTP or Web servers. Gateway programs handle information requests and return the appropriate document or generate one spontaneously. With CGI, a Web server can serve information that is not in a form readable by the client (i.e., an SQL data base) and act as a gateway between the two to produce something that clients can interpret and display. Gateways can be used for a variety of purposes, the most common being the processing of form requests, such as data base queries or online purchase orders. Gateways conforming to the CGI specification can be written in any language that produces an executable file, such as C and C+. Among the more popular languages for developing CGI scripts are Practical Extraction and Report Language (PERL) and Tool Command Language (TCL), both derivatives of the C language. An advantage of using PERL and TCL is that either language can be used to speed the construction of applications to which new scripts and script components can be added without the need to recompile and restart, as is required when the C language is used. Of course, the server on which the CGI scripts reside must have a copy of the program itself—PERL, TCL, or an alternative program. SUMMARY The client/server architecture of the Internet and its use of open protocols for information formatting and delivery makes it possible for any connected computer to provide services to any other computer. With this capability, businesses are able to extend communications beyond organizational boundaries and serve the informational needs of all users. The type of services that are available depends on the application software that runs on one or more servers. A server may be dedicated to a specific Internet application or multiple applications, depending on such factors as system resources and the specific needs of the organization. A careful evaluation of the hardware platform, operating system, and application software in terms of features and conformance to Internet standards ensures that the current and emerging needs of the organization and its users are met in an efficient and economical manner. 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