A brief overview of thin client computing
Before the introduction of the personal computer in 1984, the first computer systems treated monitors and keyboards as simple input/output devices, not as a computing device. A user logged in to the central computer and began a session, sending keyboard entries to the computer and receiving back computer output on the monitor. Each monitor and keyboard was a client to the central computer, although ‘client’ was not the term used to describe this keyboard/monitor combination. The central computer served all the needs of its clients.
Having no computing power, the keyboard/monitor client was software thin, that is, the unit had only the hardware and firmware necessary to communicate with the central computer, but no software at all. Thin client computing was the first type of computing available to most computer users before the mid-1980s.
In the mid-1980s, the personal computer took root in business and by the 1990s, the keyboard/monitor client was replaced by micro-computers, usually with a Windows operating system. These computers had computing power, including memory, secondary storage, and peripheral connectivity to such devices as printers, faxes, and modems. Computing power was now available to most users, and software, simple and sophisticated, became available for micro-computing in nearly every application area.
Distributed, rather than centralized data processing, became the best model, now that computer power could be distributed throughout an organization. Each department had its own server and maintained its own data. Each ran its own software. Since one part of an organization will often have need of the data or processes of another part, as is the case with businesses, the inter-connections of computers was required. This interconnection enables computers to request services from other computers. Computers making a request to another computer is in the client role, while the computer receiving and processing the request is a server.
The server would certainly have the data and processes it owned. These would be used exclusively by the department. The same would be true of the client. The client is a role. The computer that fills the role of client may be a server in its own right. It may have programs and data that are exclusively for the use of the client. Any client that has programs and data that are relevant to the organization’s information system is known as a ‘fat’ client.
The difference between fat client computing and thin client computing is the source of all processes and data. With a fat client, some of the processes and data it requires comes from itself, the client, but other processes and data may come from a server. With thin client computing, no processes or data comes from the client. All processes and data are run on, maintained by the server. In thin client computing, your calculator, spreadsheet program, and word processor are all on the server and run on the server. The server holds and maintains your data. In thin client computing, the computer reverts back to the earlier role of the keyboard/monitor client. Some servers must act as a centralized computer for the thin client. Thin client computing requires session management.
Thin client computing may become the standard in years to come, but that will be a long time yet. Most computer users prefer to keep as much computing power at their finger tips, without relying on a service. Some prefer to serve themselves. Others continue to press the notion that thin client computing in a service oriented architecture will be the only reasonable way to go. Fat and thin client computing are likely to coexist side by side for years to come.
