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 Communications Software A communications server enables users to access various documents and services that reside on it and retrieve them using the hypertext transfer protocol (HTTP). These servers support the standard multimedia document format—the hypertext markup language (HTML)—for the presentation of rich text, graphics, audio, and video. Hyperlinks connect related information across the network, creating a seamless web. Client software such as Mosaic and Netscape is used for navigation. Some vendors offer servers preconfigured with these Internet protocols, allowing them to be quickly installed and put into operation. A key service performed by any Internet server is the translation of complex Internet Protocol (IP) addresses to simpler server domain names. When a user requests the uniform resource locator (URL) of a certain Web page, for example, the domain name server (DNS) replies with the numeric IP address of the server the user is contacting. It does this by checking a lookup table that cross-references server domain names and IP addresses. For example, the domain name ddx might stand for “dynamic data exchange.” This domain name might translate into the IP address 204.177.193.22. The translation capability of the DNS makes it easy for users to access Internet resources by not requiring them to learn and enter long strings of numbers. To access the Web page of Dynamic Data Exchange, the user would enter the URL as http://www.ddx.com, which contains the domain name ddx. Commerce Software A commerce server is used for conducting secure electronic commerce and communications on the Internet. It permits companies to publish hypermedia documents formatted in HTML and to deliver them using HTTP. To ensure data security, the commerce server provides advanced security features through the use of the secure sockets layer (SSL) protocol, which provides: •  Server authentication. Any SSL-compatible client can verify the identity of the server using a certificate and a digital signature. •  Data encryption. The privacy of client/server communications is ensured by encrypting the data stream between the two entities. •  Data integrity. SSL verifies that the contents of a message arrive at their destination in the same form as they were sent. As with other types of Internet servers, vendors offer commerce servers preconfigured with the protocols necessary to support electronic commerce. News Software A news server lets users create secure public and private discussion groups for access over the Internet and other TCP/IP-based networks using the standard network news transport protocol (NNTP). The news server’s support of NNTP enables it to accept feeds from popular Usenet newsgroups and allows the creation and maintenance of private discussion groups. Most newsreaders are based on NNTP; some support SSL for secure communication between clients and news servers. A news server should support the multipurpose Internet mail extension (MIME), which allows users to send virtually any type of data across the Internet, including text, graphics, sound, video clips, and many other types of files. Attaching documents in a variety of formats greatly expands the capability of a discussion group to serve as a repository of information and knowledge to support workgroup collaboration. Colleagues can download documents sent to the group, mark them up, and send them back. Mail Software Client/server messaging systems are implemented by special mail software installed on a server. Mail software lets users easily exchange information within a company as well as across the Internet. Mail software has many features that can be controlled by either the system administrator or each user with an E-mail account. The mail software should conform to open standards, including HTTP, MIME, SMTP, and POP3. MIME lets organizations send and receive messages with rich content types, thereby allowing businesses to transmit mission-critical information of any type without loss of fidelity. The simple mail transfer protocol (SMTP) ensures interoperability with other client/server messaging systems that support Internet mail or proprietary messaging systems with Internet mail gateways. The Post Office Protocol Version 3 (POP3) ensures interoperability with such popular client software as Zmail, Eudora, Pegasus Mail, Microsoft Exchange client (with the Microsoft “Plus” pack), and most other Internet-capable mail products. Proxy Software To improve the performance and security of communications across the TCP/IP-based Internet, many organizations use a proxy server. This kind of software offers performance improvements by using an intelligent cache for storing retrieved documents. The proxy’s disk-based caching feature minimizes use of the external network by eliminating recurrent retrievals of commonly accessed documents. This feature provides additional “virtual bandwidth” to existing network resources and significantly improves interactive response time for locally attached clients. The resulting performance improvements provide a cost-effective alternative to purchasing additional network bandwidth. Because the cache is disk-based, it can be tuned to provide optimal performance based on network usage patterns. The proxy server should allow dynamic process management, which allows the creation of a configurable number of processes that reside in memory waiting to fulfill HTTP requests. This feature improves system performance by eliminating the unnecessary overhead of creating and deleting processes to fulfill every HTTP request. The dynamic process management algorithm increases the number of server processes, within configurable limits, to efficiently handle periods of peak demand, resulting in faster document serving, greater throughput delivery, and better system reliability. 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