Distributed Computing: Many of the paradigms that we looked at involve middlewar
ID: 3847991 • Letter: D
Question
Distributed Computing:
Many of the paradigms that we looked at involve middleware, a software module that serves as an intermediary among the participants of an application.
Consider the publish/subscribe message system model. How does the middleware in the paradigm allow publish/subscribe?
How might a middleware program allow cross-platform support?
How might a middleware program provide asynchronous interprocess communication?
Which of the paradigms involves middleware? Explain.
PARADIGMS:
Message Passing Paradigms
Client-Server Paradigm
Peer-to-Peer Paradigm
Message System Paradigm
Distributed Objects Paradigm
Mobile Agent Paradigm
Network Services Paradigm
Collaborative Application Paradigm
Explanation / Answer
Publish–subscribe is a sibling of the message queue paradigm, and is part of a larger message-oriented middleware system. almost messaging systems support both the pub/sub and message queue models in their API.
This pattern provides great network scalability and a more dynamic network topology, with a resulting decreased flexibility to modify the publisher and the structure of the published data.
middleware does not use a broker in the middle.instead each publisher and subscriber in the pub/sub system shares meta-data about each other via IP multicast. The publisher and the subscribers cache this information locally and route messages based on the discovery of each other in the shared cognizance.
A common strategy used by middleware analysts with such pub/sub systems is to take down a publisher to allow the subscriber to work through the backlog.
A cross-platform support middleware (CPSM) is a software abstraction layer that guarantees the existence, and correct implementation, of a set of services on top a set of platforms.
he abstraction method in the CPSM development is the method used to compile the concrete source code for a given platform without compromising the abstract interfaces provided. The most commonly used abstraction methods in CPSM development are: conditional compilation and directory separation of sources.
The first method consists in embedding preprocessor instructions in the source code to conditionally select the source subtree compatible with a given platform.
The second method takes advantage of the filesystem organization to divide the source code in different folders, one for each incompatible platform. Thus delegating the selection problem to the build system.
Some distributions like MSYS and Cygwin may help build the cross-platform code in a Unix-like environment even on Microsoft Windows. Both distributions provide a decent version of GNU Make that can direct the build process in a cross-platform fashion.
middleware is software layer that provides a programming abstraction as well as masking the heterogeneity of the underlying networks, hardware, operating systems and programming languages.Message queuing systems or Message-Oriented Middleware (MOM). Support asynchronous persistent communication Intermediate storage for message while sender/receiver are inactive