Design me Implementation of a Framework of Distributed Semaphore by Broadcast

Cerrado Publicado Nov 18, 2015 Pagado a la entrega
Cerrado Pagado a la entrega

Algorithm

The algorithm for distributed semaphore by broadcast given in the textbook (Fig. 9.13).

Design and Implement the Framework

As described by the algorithm, each semaphore user has a helper process which is in charge of

communications with other helper processes. These helpers are solely working for the semaphore

and are independent to any specific application. These helpers form a framework of the

distributed semaphore. A user of the framework should be able to activate a helper process

(class DisSemHelper) on each participant computer. An essential requirement of the

broadcast-based algorithms is to establish a connection to every other node from every node.

Therefore, every DisSemHelper object needs to know the IP addresses and port numbers of

all the other nodes. You are suggested to have an Initiator process (running on any one of

the nodes) and collect the IP addresses and port numbers of all the other nodes. In doing so, the

constructor of Initiator takes the port number that the process listens to. The constructor of

each DisSemHelper has four parameters: the node ID number, the port number of the

DisSemHelper, Initiator‘s IP address, and Initiator‘s port number.

In order to achieve flexibility, the framework should allow each application process to

communicate with its helper in either of the two ways: the application program instantiates the

helper as a thread, or the application program communicate with its helper process by messaging.

You should minimize application programmers’ involvement in messaging. One way to achieve

this is to write a class DisSem that has two public methods P() and V(). Conceivably, its

constructor takes information regarding the semaphore name (unique), the node address and the

port number of its helper process.

Applications

The distributed semaphore was originally proposed for a distributed database system in which

multiple database servers have dedicated network connections. You are encouraged to devise an

application of the distributed semaphore framework such as a controller of a floating software

license (resource sharing), online auction, and collaborative editing. The purpose of your

application is to illustrate your framework.

Implementation

You already prepared the Java socket-based simulation of channels in your Programming

assignment #1.

Your implementation of the algorithm in Figuire 9.13 must be divided into two parts, (1) the

distributed semaphore framework that includes the helpers (class Helper as process Helper); and

class DisSem which extract the messaging part in process User. (2) The application programs

that utilize distributed semaphore. When execute your program, each Helper object runs in a

computer. The user application programs can either be deployed in the computer that runs its

Helper object, or run in yet another computer. Every user application program communicates

with the framework by instantiating an DisSem object and then calls its methods P_op and V_op.

Method P_op first send semop[i](I, reqP, lc); …; then receive go[i](ts); … Method V_op just

send semop[i](I, reqV, lc); …

Testing

Be sure to have an adequate test plan for the implementations of your framework, and to prepare

four test cases for your application.

Diseño de productos

Nº del proyecto: #8929107

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