Distributed Agreement

Javier Palomares and Matt Molter

This is an implementation of the Weighted Distributed Agreement using Byzantine Paxos. For complete details on the algorithm, please see Distributed_Agreement.pdf and Distributed_Agreement_Presentation.pdf. Both are attached to this repo. Additionally, visit www.javierpalomares.net/my-blog/2020/4/5/the-byzantine-distributed-agreement-problem for a quick run down of the Paxos and Byzantine Paxos algorithms

What follows are the instructions for running the server and client. The project is built and executed with maven.

Running Server

The server is implemented in distributed/DistributedAgreement.java. The class takes 2 arguments:

1. Path to servers list
2. Server Id

Run it with:

mvn clean compile exec:java -Dexec.mainClass="distributed.DistributedAgreement" -Dlog4j.configuration=file:"./src/main/resources/log4j.properties" -Dexec.args="<path_to_servers_list> <server_id>"

For example:

mvn clean compile exec:java -Dexec.mainClass="distributed.DistributedAgreement" -Dlog4j.configuration=file:"./src/main/resources/log4j.properties" -Dexec.args="./src/main/resources/hosts.yaml 1"

The servers list defines the ip address, port, server id, and weight given to each server. The weights must add up to 1.0

For example:

ipAddress: "127.0.0.1"
port: 8080
serverId: 1
weight : .6
---
ipAddress: "127.0.0.1"
port: 8081
serverId : 2
weight : .4
---

Running Client

The client is implemented in distributed/client/Client.java. The class takes the path to serverst list as argument.

Run it with:

mvn clean compile exec:java -Dexec.mainClass="distributed.client.Client" -Dlog4j.configuration=file:"./src/main/resources/log4j.properties" -Dexec.args="<path_to_servers_list>"

For example:

mvn clean compile exec:java -Dexec.mainClass="distributed.client.Client" -Dlog4j.configuration=file:"./src/main/resources/log4j.properties" -Dexec.args="./src/main/resources/hosts.yaml"

Malicious Implementations

The algorithm is Byzantine, so it can handle malicious servers and clients that lie. Again, take a look at the attached pdfs for full details on how this works.

Running Malicious Server

Run it with:

mvn clean compile exec:java -Dexec.mainClass="distributed.malicious.MaliciousDistributedAgreement" -Dlog4j.configuration=file:"./src/main/resources/log4j.properties" -Dexec.args="<path_to_servers_list> <server_id>"

Running Malicious Client

Run it with:

mvn clean compile exec:java -Dexec.mainClass="distributed.malicious.client.MaliciousClient" -Dlog4j.configuration=file:"./src/main/resources/log4j.properties" -Dexec.args="<path_to_servers_list>"