Chapter 3 The Client-Server Model and Software Design

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Chapter 3 The Client-Server
Model and Software Design

• Why the Client Server Model?

• TCP/IP provides peer-to-peer communication
  channels for data transfer
• But, it does not dictate when, why, how
  programmers should organize application programs.
• To ensure that computers are ready to communicate
  (background process) and start automatically when
  the OS boots (daemon).

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Terminology Concepts

• Client
• Server
• Usually, server provides some additional
  functions for access control or security, such as
  authentication, authorization, data security,
  privacy and protection.

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• Two broad classes of client applications

(1) TCP/IP standard services Telnet,
FTP, and SMTP (e-mail) (2) TCP/IP non standard
services, built by users. Port number
Protocols TCP or UDP
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• Stateless and Stateful servers
• Solution of Stateless Server - Idempotent
  operation
• Server as client

Internet
Time Server
File Server
Client
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Concurrent processing in Client- Server Software

• Concurrency in networks
• Concurrency in servers
• Program examples

• A sequential C program
• A concurrent version
• Timingslicing
• Making processes diverge
• System call - select