This project implements "Chord: A Scalable Peer-to-peer Lookup Protocol for Internet Applications" algorithm. All the informations about protocol specifications can be found in the original paper. Moreover if you want to have a detailed view about the architecture of this implementation please read this report.
Our simulator is based on Repast Symphony, an agent-based modeling toolkit and cross-platform Java-based modeling system. This technology allows represent graphically a complex system with the usage of efficient visualization features. Data for statistics is collected using Repast and analyzed with gnuplot.
- Clone the repository
- Import the project as a Repast project into Eclipse IDE
- Run the project
or
- Download the jar from here
- Install the project following the guided procedure
- Run the project
When the simulator is running, a GUI is showed to the user which presents some input boxes that can be used to modify the parameters of the simulation. Such parameters are:
- Number of Nodes
- Probability of single node crash
- Number of Lookups per Stabilization Round
- Number of Lookups/40 ticks
More on the parameters in the report.
To evaluate that in our implementation the communication cost and the state maintained by each node scale logarithmically with the number of nodes, we performed some experiments. Results of the are computed before at the end of a stabilization round. We basically analyze the following 3 probability distributions:
- Number of Keys per Node - from which we calculate the mean, 1stand 99th percentiles.
- Lookup Path Length - from which we compute mean
- Number of Timeouts per Lookup - from which we compute the mean
If the reader of this report desires to test such computed measures, it has to execute the code in development mode and inspect its IDE's console. An example of the output is the following:
########## SIMULATION 1578266879519##########
Nodes: [459282, 1053995, 14729669, 14948457, 16542290, ...]
Space Dimension; Num. of Keys; Mean Num. of Keys; 1st percentile; 99th percentile
2147483647;1000;2147483.647;16272;9780939
Num. of Keys per Node Distribution: [1065;1096;3224;3307;4776;5803;7669;10324;....]
Mean Path Length: 6.7025779917745005
Mean Num. of Timeouts: 0.003912127595546194
Ion Stoica, Robert Tappan Morris, David Liben-Nowell, David R. Karger, M. Frans Kaashoek, Frank Dabek, Hari Balakrishnan: Chord: a scalable peer-to-peer lookup protocol for internet applications.IEEE/ACM Trans. Netw. 2003: 17-32