Programación Distribuida: Diseño e Implementación de un Servicio Distribuido de Semáforos utilizando Suzuki-Kasami.

Project as part of the course of Distribuited Systems at the "Universidad Tecnica Federico Santa Maria", based in Valparaiso, Chile.

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Grupo : Antolini Charlotte, Dorel Joachim & Legeron Camille

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1. Launch of the project

1. Launch of the RMI-Registry

make run-rmiregistry

2. Launch of the Token Engine

make run-tokenEngine

3. Launch of a Semaphore¹

Each semaphore takes 4 arguments :

• id an unique id for the semaphore
• n the total number of semaphores
• initialDelay the initial delay for a semaphore to enter into his critic section
• bearer if the semaphore is holding the token originally or not

make run-trafficLightServerClient id={id} n={n} initialDelay={initialDelay} bearer={bearer}

4. Connection of all the semaphores

Once all the semaphores are created, we must connect them all to each other. This command takes one argument :

• n the total number of semaphores

make run-client n={n}

2. Architecture of the project

The project is centered around the use of RMI. In order to implement the Suzuki-Kasami algorithm, we used the way RMI interacts between clients and servers. Each semaphore corresponds in our code as both a Client and a Server. It is a Client of the n-1 other remote semaphores, each one also being its Client.
The interaction between the semaphores is done through the interface they all share. Locally, they manage their local RN list, while they exchange between themselves the token and then update its LN list, list which corresponds to the number of time each one have entered in critical section, and the queue which corresponds to the next semaphores waiting to enter into a critic session.

To understand better the architecture of Suzuki Kasami, we followed the architecture in the following video : https://www.youtube.com/watch?v=aWne_qIR2XI

Footnotes

1. In our project, a semaphore corresponds to a TrafficLightServerClient, or more simply to a traffic light. This change was made to have a better understanding of the logic of a semaphore. ↩