Client/Server Computing

The Server in a Client/Server model is a(ny) hardware platform, which handles requests and interface to a database. It is the server which receives request from applications running on workstations (clients) and processes them for each of its clients.

Requirements

Client server processing requires:
Reliable, robust communication between client and server.
Client/server co operative interactions that are initiated by client.
Application processing distribution between a client and its server.
Server based arbitration of conflicting client's requests.

Advantages of client/server computing

Allows increased processing power of desktops and workstations.
Facilitates better user interface and utilization of resources.
Client/server system can be designed to offer open architecture i.e. clients and servers running on different hardware/software platforms allows end users to free themselves from proprietary architectures.
Less Operational cost of client/server system in addition to decreased cost of server platforms, High Processing power of client work stations.
Client server solutions are based on distributed data processing and client has secured access to central database.

Distributed Processing in Client/server

In Client/server architecture, an individual system is designated as a client or as a server depending on which activity the system performs in a given node to node relationship. The network nodes can be classified as clients (which request services) and servers (which perform requested services).

The distributed processing comprises of:
• Presentation Logic: User Interface
• Application Logic : Business Rules in 4GL (say SQL)
• Database Logic
RDBMS

Client's Role and functions

A client is a front end process typically designed to interact with end users. So its functionality and implementation can be specialized for these interactions. The major functions performed by a client system in Client/Server architecture are presentation functions and business logic. End user interactions with an application are performed through presentation logic.

The interaction with and user includes handling of actual end user performed 1/0. It is the client that initiated a client server interaction by sending a request to its server. It would also do processing of local data.

Server's Functions

Architecturally, a server is a back end process that provide services to requesting processes. Hence servers should be able to provide large amounts of fast disk storage, significant processing power and ability to run many applications (clients) simultaneously.

The following are dedicated server functions :

File Sharing: In a workgroup environment, clients may need to share some data files. File server provides client with access to entire file.
Printer Sharing: All clients may send file print request so a print server.
Communication services : Clients can send their communication requests to a communication server.
d. Database Access : Database servers provide, clients with access to data that resides on a server and
also perform necessary manipulation on required data. Servers may also execute database logic.

Integrity and Security.
Concurrency control.

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