3.2 Making Provisions For Applications And Services

Question 1

How Data Requests Occur and Are Filled?

Answer 1

1. Client/server model
2. Application layer services and protocols
3. Peer-to-peer networking and applications

Question 2

Advantages of client/server model

Answer 2

• Centralized administration
• Security is easier to enforce

Question 3

Client/Server Mode

Answer 3

• Resources are stored on the server
• Files are uploaded from the client to the server and downloaded from the server to the client
• A client is a hardware/software combination that people use directly

Question 4

Servers

Answer 4

• Any device that responds to requests from client applications
• Usually a computer that contains information to be shared with many client systems
• Example: web pages, documents, database, pictures, videos, audio files
• In other cases, such as network printer, the print server delivers the client print requests to the specified printer
• Server daemon
  
  • a service, or process the server runs
• Repositories of information
• Processes control the delivery of files to clients

Question 5

Application Layer Services and Protocols

Answer 5

• Multiple Clients’ Service Requests

Question 6

Peer-to-Peer (P2P) Networking and Applications

Answer 6

• P2P networking involves 2 distinct forms:
  
  1. Peer-to-peer network design
  2. Peer-to-peer applications
     Both forms have similar features but in practice work very differently

Question 7

Peer-to-Peer (P2P) Networks

Answer 7

• Two or more computers are connected through a network and are able to share resources such as printers and files without having a dedicated server
• Every connected end device, know as peer, can function as a client or server on a ‘per request’ basis
• In a peer-to-peer exchange, both devices are considered equal in the communication process
• Resources are decentralized (information can be located anywhere) on a network
• Difficult to enforce security and access policies
• User accounts and access rights have to be set individually on each peer device

Question 8

P2P Applications

Answer 8

• Unlike P2P networks, a device can act as both the client and server within the same communication session
• Require that each end device provide user interface and run a background service
• Can be used on P2P networks, client/server networks and across the internet

Question 9

P2P Hybrid System

Answer 9

• Utilizes a centralized directory called an index server even though the files being shared are on the individual host machines
• Each peer accesses the index server to get to the location of a resource stored on another peer
• The index server can also help connect two peers, but after they are connected, the communication takes place between the two peers without additional communication to the index server