push technology

[mandvi]

Push Technology


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Introduction

Push technology is a set of technologies used to send information to a client without the client requesting it
Push versus Pull
Pull technology is based on the traditional request/reply model. It requires that users know a priori where and when to look for data. It suffers from transmission latency and duplicate data traffic.
Push technology allows users to get information as soon as it become available and users do not have any knowledge about virtual information servers. This transfer of control from users to providers is a potential problem.
Focus is on Multicast-base push protocols
Multicasting is a 1-to-n form of communication for transmitting packets from one host to a set of member hosts in the same group.

CMP: Problems and Solutions

Server End
Problem: How to monitor the number of requests for a document at any moment, based on that to decide whether the document is popular or not
Solution: Polling the multicast channel periodically for the feedback but have to avoid the feedback implosion
Reliability
Forward Error Correction Code (FEC)
Client End
Problem: repeatedly receive the same information or mixed new and old information on a same channel because of the cyclically delivery
Solution: Layered Multicasting

RMTP Intro and Features

A protocol that uses IP multicasting for the reliable delivery of data from a sender to a group of receivers
Emphasis is on (1) reliability (2) scalability (3) heterogeneity
Reliability RMTP compensates for the reliability shortcomings of IP multicasting by monitoring ACKs responses from clients
Scalability (1) independent state information (2) uses a receiver-driven approach (3) groups receivers into local regions
Heterogeneity RMTP handles receivers in heterogeneous network environments in an efficient manner

Conclusion

CMP - Continuous Multicast Push
RMTP - Reliable Multicast Protocols