 Client/Server ArchitectureClient/server type databases function in a completely different manner from desktop database systems. Client/server architecture uses a program that operates on a server to provide services to the database that would normally be provided by the workstations or clients in a desktop database system. Client/server architecture processes a request made by a client at the server level instead of at the client level as it does in the desktop database architecture. By understanding client/server architecture, it is easy to see how client/server databases that operate on a fast database server can drastically improve performance. Client/server systems are built using intelligent database servers. Instead of transferring complete files to client applications, database servers return only the requested information. As a result, network traffic is decreased and performance increased. The standard implementation of this architecture is based on database servers which use the SQL language to manipulate data (e.g.: MS SQL Server, Oracle, Sybase SQL Server, Informix).
The architecture that we have depicted consists of two components or two tiers. In general, the components of a client/server system can be categorized by the type of service they provide to the system: presentation, business, and data services. In its simplest implementation, the client application contains presentation services and business services and the server performs data services. In this type of architecture, the client is often known as a fat client, because it contains the majority of services. Often, a better solution is to place business services on the server as well (e.g.: in stored procedures). Such architecture is called fat server or two-and-a-half tier architecture. An improved variation on this architecture places the three different types of services on separate tiers. The result is known as three-tier architecture. Business services are provided by a transaction server.
Modern client/server architectures are often variations of these standard architecture types in the form of distributed or Web-based systems. See also: |
