Suggestions/Tips

• Start small. Implement a skeleton manager process that simply creates one child process, waits for the child to exit and then exits itself. Have the child print a "hello world" message and exit. Then make sure all processes have exited gracefully. Use the "ps" command to check. Hint: write different parent and child functions. Once you fork, have the parent process call the parent () function and the child process call the child () function (see the tutorial on fork). This way you can have the code for parent and child in separate files. This means you will have a main () function that calls parent () and child (). The main function will also use the wait () call after the parent and the child have exited.
• Have the manager and the child print their pid on the terminal. Then, have them print it in a file. Note that you can have the manager create the file before forking the child, and the child will inherit the file descriptor. Now both the parent and the child can write to the same file.
• Once you have your manager working with one process, add a loop to create N processes. Read N from a file. Make sure all processes print "hello world" and exit gracefully. Test the kill command if they don't. Note that it is safe to run the kill command if the pids do not exist.
• Write simple client-server programs using TCP sockets. Have the client send a simple message such as "Hi" to the server, and the server send a simple reply back. Have both programs print a trace of what they are doing at each step (e.g., created socket, connected to the server, sent message "Hi", received reply "Hi to you too"). Then, add a timestamp before each message. Finally, have the messages go to different output files, one for the client and one for the server.
• Make the client portion your router and the server portion your manager. Have each router contact the manager as soon as it is created and ask for an ID. Create a ID.out file as soon as you learn your ID and start logging mesages there. Send that ID back to the manager and exit.
• Have the manager accept connections from all the routers, send them their ID and print their response. Then make sure you can print these messages in the trace file.
• Test to ensure you can create N processes, where N is less than 10. Start small, test with one child process first, then two, etc.
• Now it's time to implement the shortest path tree algorithm. Decide on the data structures first, because this will determine how to write your code. Implement the LS algorithm as a fuction. Pass it an adjacency matrix (typically a NxN array with costs between all the nodes) and a pointer to the forwarding table so that the next hop fields can be filled.
  
• Implement a lookup function that takes as arguments the pointer to the forwarding table and the destination address and returns the link id the packet needs to go out on.
• We will add more hints as we get feedback from you.