SimpleNet 2.0 API Documentation

This is the documentation of SimpleNet, a simplistic network simulator. This is intended purely for educational purposes.

SimpleNet consists of a main engine that provides the basic network functionality, including some basic node functionalities, the network topology configuration, link-layer communication, and forwarding. The user must provide the implementation of a routing protocol. This is done by implementing a class that extends the simplenet.Router class.

Quick Example

The user implements a class MyRouter as follows:

import simplenet.*;

class MyRoutingMessage extends RoutingMessage {
    public int address;

    public MyRoutingMessage(int addr) {
        address = addr;
    }
}

public class MyRouter extends simplenet.Router {

    public void process_routing_message(RoutingMessage m, int ifx) {
        System.out.println("I got a routing message from interface " + ifx);
        System.out.println("Hello neighbor " + ((MyRoutingMessage)m).address);
    }

    public void initialize() {
        System.out.println("I am router " + my_address());
        System.out.println("I have " + interfaces() + " neighbors.");

        for(int i = 0; i < interfaces(); ++i) {
            send_message(new MyRoutingMessage(my_address()), i);
        }
    }
}

Assuming the simplenet.jar file is in the current directory, and obviously that this code is in a file called MyRouter.java this code can be compiled with the following command:

javac -classpath simplenet.jar MyRouter.java

We are now almost ready to run the simulation. Before doing that, we should define a network topology to use in our simulation. We ca do that by creating a file, called test1, containing the following lines:

1 2 3.0
2 3 4.0
3 4 1.0
4 1 9.0

The format of the input file will be discussed later. We can now run the simulation with the following command:

java -classpath simplenet.jar:. simplenet.Network MyRouter test1

Network Interface

A router implementation has access to a number of basic host/router functionalities. These are provided by the simplenet.Router class, and are documented there. The network model consists of a graph. Routers are connected through symmetric, duplex links. The cost of a link is a double value, and represents the latency of the link. Routers have one address. Addresses are int values. Each node has a number of interfaces, connecting it to its neighbors. Interfaces are numbered starting from 0, up to interfaces() - 1.

Topology and Workload

The format of the workload file is as follows: the workload starts with a topology specification. The topology specification consists of one or more lines, each one defining a link. The format of a link specification is:

source-address destination-address link-cost

Where source-address and destination-address are integer identifiers, and link-cost is a number (integer or floating point) representing the latency of the link. These elements are separated by one or more spaces.

After the topology specification, the workload may contain one or more message lines in the following format:

M send-time source-address destination-address message-text

Where send-time is a floating point representing the time when the message is sent, source-address is the source of the message, destination-address is the destination, and message-text is a string representing the message data.

For example,

1 2 3.0
2 3 4.0
3 4 1.0
4 1 9.0
M 100 1 3 ciao
M 150 4 2 hello!