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Introducing Sybase Workplace SQL Server

Chapter 1: Overview of Workplace SQL Server

Client/Server Architecture

Client/Server Architecture

In a Sybase SQL Server environment, the databases and the RDBMS software reside on one or more servers, where multiple clients can access them concurrently over a network. Applications that access and manipulate the shared data, as well as the libraries that allow the applications to communicate with the RDBMS, reside on the clients. Figure 1-3 illustrates the Sybase client/server configuration.

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Figure 1-3: A Sybase client/server environment

The basic client/server relationship is one in which client applications request services from servers, and servers return results to client applications. A typical request for service in a client/server RDBMS is for the client to request that the server retrieve or modify the data that it is storing. A typical result is confirmation by the server that the request was successfully or unsuccessfully carried out, followed by the requested data. Figure 1-4 illustrates a basic client/server interaction.

Figure 1-4: Basic client/server interaction

Division of Tasks

A client/server model provides the best performance for data sharing among a large number of PCs and workstations because clients and servers share the work¾each performs the work it can do most efficiently. The server handles activities related directly to the maintenance and retrieval of shared data, while other tasks, such as displaying returned data or interpreting requests from users, are off-loaded to the clients. Figure 1-5 represents how the tasks are divided.

Figure 1-5: Division of tasks

Distributed Computing

The ability to distribute data among multiple servers provides a structure for distributed computing environments in which control is not centralized at a single data source or geographic location. Clients can access the data they need from any server.

Figure 1-6 shows a non-centralized, distributed computing configuration in which data is distributed over several sites and each site houses a different subset of the data.

Figure 1-6: Distributed client/server environment

Some organizations want each site to have a complete copy of the entire data set for two reasons, among others: to improve the time it takes to access the data, and to eliminate downtime in the case of one server's failure. Data replication offers a solution to these organizations.

Replication Server(R), a Sybase product you can purchase separately, can be integrated with your Workplace SQL Server setup. Replication Server replicates peer-to-peer data replication across a distributed environment, to and from heterogeneous hardware and data sources. All clients have equally fast and reliable access to all data.