The goal of this project is to give you more experience with linked lists and queues. You will use real data to implement a program that simulates basic message delivery in mobile networks. Your program will take as input actual traces of the on/off patterns of several laptops (henceforth referred to as nodes). It will also take as input synthetic data representing messages each node must send to the other nodes and the amount of time it takes to send each message. The output of your program will be a record of when each message transfer was successfully completed, for each interrupted transfer the time at which the interrupt occurred, and a list of the transfers that did not complete during the simulation period.
Your simulator will take as input N trace files, where N is the number of nodes being simulated. The files will be named node1.dat, node2.dat...nodeN.dat and will be stored in the directory where the program is run. Rather that pass N as a parameter to your program, your program will use the java.io.File class (see the isDirectory method and the list method) to dynamically determine the number of nodes being simulated.
Each trace file will contain several lines where each line is of the form
time state. Time tells you the time at which the node changed
state and state tells you the new state of the node. For example, 12
on indicates that the node turned on at time 12. Similarly, 52
off indicates that the node turned off at time 52. You may assume that
each file is sorted by time.
Your program will preprocess the files and store the data in a linked list that you have implemented. The data portion of each list node will contain a time and all of the events that happen at that time. For example, if node 1 turns on at time 15 and node 2 turns off at time 15, the linked list will contain one node containing time 15 and <node 1 turns on, node 2 turns off>. Note that several events may occur during each time slot. Also note that you will need to design an appropriate class(es) to represent this data.
Once you have preprocessed the data, your simulator can easily determine the time of the next event(s) by retrieving the data from the first node in your list of events. At the bottom of this page, you will find several sample trace files.
Your simulator will also take as input N files containing synthetic data you will use to initialize your message queues. The files will be named node1.config, node2.config...nodeN.config and will also be stored in the directory where your program is run. See the discussion of Trace File Processing for hints on how to find these files.
Each config file will contain several lines where each line is of the form
destination_node transfer_time. The destination_node is the
receiver of the message and the transfer_time is the total number of time
units it will take to transfer the message. You will implement a queue
class and, for each node (the source), you will create a queue and
enqueue an object (containing the destination node and transfer time) for
each message represented in the node's config file. You will find several
sample config files at the bottom of this page.
The main logic of your simulator will start at time 0 and will process events until there are no more on/off events. The two primary events are (1) a node turns on (goes online) and (2) a node turns off (goes offline). However, you will also have to determine, based on the simulation time and the state of each node in the network, whether any of the following events occur:
a to node b and
either a or b goes offline. The output of your program will be a log of the completed transfers, interrupts, and undelivered messages. Undelivered messages are the messages that remain in the source node's message queue at the end of the simulation run. The completed transfers will be logged in the form time: Completed from: source_node_id to: destination_node_id (example 18: Completed from: 2 to: 0). The interrupts will be logged in the form time: Interrupt from: source_node_id to: destination_node_id (example 31: Interrupt from: 0 to: 1). The undelivered messages will be logged in the form Incomplete transfer from: source_node_id to: destination_node_id. Below, you will find complete samples including .dat files, .config files, and output files. As part of your testing procedure, run your program on the sample input and compare your output to the sample output files. You may want to familiarize yourself with the Linux tool diff for this purpose
Each zip file below contains the .dat files, .config files, and output for a run of the simulator.
The zip file below contains several node.dat files you may use for testing.
The python file below contains a small python program you can use to generate new config files.
A demonstration is not required for this project. However, I will award extra credit to students who make an appointment on or before December 12 to demonstrate a complete, working program.