COMPUTER NETWORKING:OVERVIEW OF NETWORK-BASED APPLICATIONS

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OVERVIEW OF NETWORK-BASED APPLICATIONS

As mentioned at the beginning of this chapter, computer networking has gradually entered all possible fields of applications. Providing an exhaustive overview of the many applications would be practically impossible, so only a brief overview will be given here of what is (and what still will be) available. Classification itself is subjective in this case, so the aspects mentioned below provide only an ap- proach to systematic handling of the wide spectrum of network-based applications.

First, applications can be categorized by what kind of community is interested in them. The two main groups are:

• Public applications, available for any individual or group / organization of individuals

• Private applications, available only to a certain subset of individuals or groups / organizations

Although the realizations of the applications within the two distinct groups are not different in principle from each other, there are at least two basic differences in the background attributes. On one hand, the infrastructure behind an application closely reflects the width of its user community (wide area public network, in contrast to intranet / extranet-type solutions using private or virtual private networks). On the other hand, security issues are definitely different: on top of the general security and privacy requirements, special security and authorization aspects require special firewall techniques in the case of private applications.

Second, applications can be distinguished by how they are utilized. The three main classes are:

• Personal applications (individual and family use)

• Administrative applications (use by governments, municipalities, etc., in many cases with over- all, or at least partly authorized, citizen access)

• Industrial applications (practically any other use, from agriculture to manufacturing to com- mercial services)

The major differences among these three classes are the required levels of availability, geograph- ical distribution, and ease of access. As far as networking is concerned, the classes differ in the required quality of service level / grade.

Third, there is a well-structured hierarchy of the networked applications based on their complexity. This hierarchy more or less follows the hierarchy of those single-computer applications that are enhanced by the introduction of network-based (distributed, dislocated) operation:

• Low-level applications in this hierarchy include distributed word processing, database handling, document generation, computer numerical control, etc.

• Medium-complexity applications include network-integrated editing and publishing, networked logistics and inventory control, CAD (computer aided design), CAM (computer aided manu- facturing), etc.

• High-complexity applications include integrated operations management systems, such as in- tegrated management and control of a publishing / printing company, integrated engineering / management of a CAD-CAM-CAT system, etc.

Note that high-complexity applications include lower-complexity applications, while low- complexity applications can be integrated to build up higher-level applications in the hierarchy. Com- puter networking plays an important role not only in turning from single-computer applications to network-based / distributed applications but also in the integration / separation process of moving up and down in the hierarchy.

Finally, network-based applications can be classified by the availability of the related application tools (hardware and software). The possible classes (custom, semicustom, and off-the-shelf solutions) will be considered later in Section 13.

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