Client / Server Computing

Client / Server Computing

n  The Basic concepts are client, server, glue, the logical client / server model and client/ server layers.

n  Client

n  Front end of the client/server system, the component with which user interacts.

n  In most systems the client has responsibility for presentation management (typically GUI management) and some application logic

n  Client contains the application logic relevant to the presentation

n  Server

n  Usually means the entity that provides share resources such as database that can be connected to multiple clients.

n  In general a Server runs on a larger-class machine than the client

n  Functional Approach of Server

n  File Server, Print Server, database server etc.

n  Transaction Server, Database Server, Native Server etc.

n  The Glue

n  Glue includes low level plumbing (TCP/IP), programming model and development tools.

n  Logical Client/Server Model

n  Client/Server can be viewed as logical one where it represent a paradigm in which element of a computing system  request service from each other

n  Roles of Client and Server are not fixed

n  Server can request other elements of the system (as client)

n  Server can connect to one or more clients

n  Client can communicate with multiple servers

n  Client-client or server-server communications are possible

n  Communicating partners can have a peer relationship or master/slave relation ship

n  Client and server elements can exits on distinct physical machine or on the same machine

n  Client/Server Layers

n  Hardware Element

n  Computers, printers, networking hardware , other devices

n  System Service

n  Operating System. Networking software, database, UI library etc

n  Application Layer

n  Software that run on the top of system service layer

n  Client/Server Architecture Model

n  Presentation, Logic, Data

 

Partitioning the system

n  Distributed Presentation

n  A Server-heavy configuration in which the client is responsible for only a portion of UI (dumb terminal, web client (no plug-in)

n  Remote Presentation

n  Client responsible for the entire UI but not for any application logic or data (screen scrapping)

n  Distributed Function

n  The Application Logic is split between client and server

n  Remote Data Access

n  Put Presentation and application logic on a client that retrieves data from a remote database

n  Distributed Database

n  Split the data management function between the client and and oner or more servers while the application logic and UI component