Implementation of Paxos

This GitHub project extends the groundwork laid in Project #3 by introducing fault tolerance and consensus mechanisms to a replicated Key-Value Store Server setup. The primary goal is to enhance system resilience against replica failures and achieve synchronized updates using the Paxos algorithm, as elucidated in Lamport's "Paxos made simple" paper. By integrating Paxos roles, including Proposers, Acceptors, and Learners, the project delves into the intricacies of implementing the algorithm, understanding the steps required for consensus, and addressing nuances related to event ordering. Notably, the architecture accommodates dynamic client requests to replicas while providing the option to implement leader election for proposers. Furthermore, a key requirement involves the periodic failure of acceptor threads, showcasing Paxos' adeptness at handling replicated server failures.

System Requirements

• Java Development Kit (JDK) 11

How to Use

1. Go to the /jar folder and open a CLI.

2. To start the server, run the following command:
   java -jar Server.jar <port> <remoteObject>
   

   Replace <port> with the desired port number on which the server will provide remote methods for the client. Also, replace <remoteObject> with the chosen remote object registry name, through which the client can access the server's methods. For instance: java -jar Server.jar 6001 KSS

3. To initiate the client, execute the following command:
   java -jar Client.jar <hostname> <port> <remoteObject>
   

   Replace <serverAddress> with the server's IP address or hostname, and <serverPort> with the port number on which the server exposes remote objects. In this project, the serverPort can be set as localhost. For example: java -jar Client.jar localhost 6001 KSS

4. The initial step involves pre-populating the key store with values. Following this, the system will perform 5 operations including GET, DELETE, and PUT.

5. The client will prompt you to input the desired operation along with the Key and Value, as per the chosen operation. If the input is incorrect, it will ask you to re-enter the data. The server processes the operation and returns a response to the client indicating the success of the operation. If "EXIT" is entered as the operation, the client will exit the system.

6. Example Input:

   PUT key0 abc
GET key0
DELETE key0
   

7. Available Client Operation inputs: GET , PUT , DELETE . The inputs are case-sensitive.
   Output: The returned value for the given Key is: , Key: has been added with Value: , Value for Key: has been deleted.

8. Screenshots for reference can be found in the /res folder.