CN NOTE 01/29

CN 01/29

Application layer

Application architectures

Client-Server

Server 

* Always on host
* Permanent IP

Client

* May have dynamic IP
* Not communicate directly with each other

P2P

Not always-on server. Peers request service from other peers.
Self scalability - new peers bring new service capacity as well as new service demands

Sockets

Process sends/receives messages through sockets.

  • Addressing processes
    To receive messages, process must have identifier.
    Q : Does IP address of host on which process runs suffice for identifying the process?
    A: No, many processes can run on same host
    Identifier includes both IP address and port numbers.