Clientserver models in distributed systems

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Client-server models in distributed systems

• Concepts
• Architectural models
• Client-server models

2
Distributed systems
Distributed (computer) system a collection of
autonomous computers linked by a computer
network, and communicate and coordinate their
actions only by massage passing.
3
Architectural models

• Client-server model
• E.g., WWW, most transaction systems
• Peer process model
• E.g., Napster, Freenet, GNUtella

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Basic client-server model
invocation
Client
result
Server
Client
Key
Process
Computer
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Variations of client-server models (1. three-tier
client-server model)
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Variations of client-server models (2. proxy
server)

• Partition of data or replication of the servers
• Caching of data by proxy servers and clients

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Variations of client-server models (3. applets)
A Client request results in the downloading of
applet code

• Web applets

Web server
Client
Applet code
B Client interacts with the applet
Web server
Client
Applet
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Variations of client-server models (4. multiple
servers)
server
Client
server
Client
server
Services
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Variations of client-server models (5. thin
clients)
Network computer or PC
Compute server
Application
Process
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Variations of client-server models (6. mobile
codes)
Mobile code
Client
Server