1. In our communications lecture we talked about different ways of defining comm
ID: 3911058 • Letter: 1
Question
1. In our communications lecture we talked about different ways of defining communications:
- Persistent vs Transient
- Synchronous vs Asynchronous
- Connection-oriented vs Connectionless
- Discrete vs Streaming
Each distributed system needs to decide which one of the 4 choices to make.
a. If you are concerned with performance (in terms of response time of a distributed program), which choices would you prefer and why?
b. If you are concerned with scalability (in terms of ability to have the system span hundreds or thousands of nodes in possibly very geographically distributed areas), which choices would you prefer and why?
Explanation / Answer
Q1) If you are concerned with performance (in terms of response time of a distributed program), which choices would you prefer and why?
1. Synchronous vs Asynchronous - The characteristic feature of asynchronous communication is that a sender continues immediately after it has submitted its message for transmission. This means that the message is (temporarily) stored immediately by the middleware upon submission. Here there is no delay in sending message from the sender's end. Once it sends out a message, quickly without waiting it will send out another. Hence faster response we can get in this case.
2. Discrete vs Streaming - Streaming involves sending multiple messages, one after the other, where the messages are related to each other by the order they are sent, or because there is a temporal relationship. In this case also, the messages are being sent one after another without any wait in an orderly manner. Thus we can expect faster response as messages are always in a flow to be received. So Response Time will be less as the sender is continously responding with the message packets.
Q2) If you are concerned with scalability (in terms of ability to have the system span hundreds or thousands of nodes in possibly very geographically distributed areas), which choices would you prefer and why?
1. Connection-oriented vs Connectionless - With connection oriented protocols, before exchanging data the sender and receiver first explicitly establish a connection, and possibly negotiate the protocol they will use. When they are done, they must release (terminate) the connection. The telephone is a connection-oriented communication system. With connectionless protocols, no setup in advance is needed. The sender just transmits the first message when it is ready. Also no physical medium is required for communication to take place (eg cables, optical fibres, CAT-Link wires, etc)
Please let me know in case of any clarifications required. Thanks!
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