2.2 Project 3: chat application using nachos networking module  (Page 2/3)

The Chat client receives the user messages and user configuration, sets up commands and passes them to the server. Sometimes it is also possible to process some of the commands (Ex: Number of messages displayed) locally. MsgProcessor in Figure 2 Chat Client is responsible for interpreting messages from the user. Sender and receiver are for communicating with the server. Messages are constructed as described in the protocol below.

A chat server receives the commands and messages from the chat clients and processes them. MsgInterpreter is for unpacking, parsing and delegating the commands to the appropriate units on the server side. MsgMaker constructs the messages to be sent back according to the protocol described below.

We will use nachos sockets for communication between the server and the client.

Chat Protocol:

Protocols such as TCP and HTTP provide rules for communication. They specify details of message formats; they describe how an application responds when a message arrives, and how to handle abnormal and error conditions. We describe the protocol we will use for the chat service in Section 8.

Implementation details

Phase 1: Study all the codes associated with the nachos networking.

Phase 2: Perquisites: Lock and Condition: (15%) Implement the lock and condition the skeleton for which are in threads directory. Test it. Run the nettest application in network directory by opening up two xterms/terminals and running two nachos processes (network id 0, 1) communicating with each other.

Implement lock and condition.

Go into network directory, gmake

Run nachos on two xterm/terminals using these commands:

nachos –rs 1234 –m 0 –o 1

nachos –rs 1234 –m 1 –o 0

You will observe the two processes sending messages and acknowledging.

Phase 3: Ring Network: (5%) Update the nettest.cc so that a set of nachos process with network ids (0, 1,2,3..) can communicate. To test this form a ring of at least three nachos processes representing three network nodes, node 0 sends message to node 1, node 1 receives and transmits the same message to node 2 and node 2 receives and transmits the message back to node 0 thus successfully completing a trip around the ring.

Phase 4: (45%) Chat Server: Implement the chat server that behaves according to the protocol described in Section 8. Test it with dummy data/hard coded data.

Phase 5: (25%) Chat Client and Integration with Server: Implement the chat client and a simple text interface and integrate it with the server.

Phase 6: (10%) Documentation:

This includes internal documentation (comments) and a BRIEF, BUT COMPLETE external document (read as: paper) describing what you did to the code and why you made your choices. DO NOT PARAPHRASE THIS LAB DESCRIPTION AND DO NOT TURN IN A PRINTOUT OF YOUR CODE AS THE EXTERNAL DOCUMENTATION.

Deliverables and grading

When you complete your project, remove all executables and object files. If you want me to read a message with your code, create a README.NOW file and place it in the nachos code directory. Tar and compress the code, and submit the file using the online submission system. It is important that you follow the design guidelines presented for the system calls. I will be running my own shells and test programs against your code to determine how accurately you designed your lab, and how robust your answers are. Grading for the implementation portion will depend on how robust and how accurate your solution is. Remember, the user should not be able to do anything to corrupt the system, and system calls should trap as many error conditions as possible.