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A communications server enables users to access various documents and services that reside on it and retrieve them using the HTTP. These servers support the standard multimedia document format the 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 IP addresses to simpler server domain names. When a user requests the URL of a certain Web page, for example, the 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 IDNS 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 DDE, the user would enter the URL as http://www.ddx.com, which contains the domain name ddx.
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 SSL protocol, which provides:
As with other types of Internet servers, vendors offer commerce servers preconfigured with the protocols necessary to support electronic commerce.
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 NNTP. The news servers 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 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.
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 SMTP ensures interoperability with other client/server messaging systems that support Internet mail or proprietary messaging systems with Internet mail gateways. The 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.
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.
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