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Day in the life of a coder | Aspicio.meum. by Arek Bochinski                       

Assignment 4 for CSC209 at University of Toronto in Software Tools and Systems Programming

Introduction

One of the interesting features of MSN Messenger is that you can see if a person is online and be able to look up their personal status . Some fields can be used to indicate a status such as : at work or at home

The task in this assignment is to write a server and a client that allows user to register with the server and see which other registered users are on .

Specification

A user will run the heythere client and connect to a heythere-server . Every N seconds, the server will send to the client a list of users that are currently registered and their status.

Client

The client first sends the user name to the server. The second message the client sends to the server is the location of the client . Other messages can be sent to the server. User can change their user name, the location and it may add a message tag .

Every time interval in seconds, the server will send a complete list of the currently logged on users. The client will print these out to stdout .

Each message has a strict format described as following:

First 3 characters describe the type of message the client is sending followed by a space and then the content of the message .

Location: usr

Hostname: loc

Message: tag

Server

Server is written to support up to 30 clients at a time. It uses select to multiplex between different clients. If the command-line arguments -t <time interval> are not given, the default value for the number of seconds between printing to the clients is 10 seconds . Information will be written on line per client in the following format:

<user name> <location> <message tag>

To handle client data, the server collects the information from all connected clients.

Zip archive is located here: http://zenebo.com/csc209a4.zip

Assignment 1 for CSC209 course at University of Toronto in Software Tools and Systems Programming

Build

In this assignment a student is required to write a program in Bourne shell that performs some of the same operations that make does . A simpler file format for a build file is specified , which does not follow all rules of the make program .

Build file format

There are 4 types of valid lines in a build file:

1. A blank line. I.e., a line containing nothing but whitespace.
2. A line whose first character is # which indicates that the remainder of the line is a comment.
3. A line whose first character is an @ followed by a space, and then followed by one or more words separated by a single space. This type of line marks the beginning of a build rule. The @ is ignored. The first word in the sequence is the target of the rule, and the remaining words, if any, are the prerequisites for the rule.
4. Other lines are considered action lines which should be executable statements.

In example:
#Comment line
@target prerequisite1 prerequisite2
action
action with arguments


Functionality and Implementation

build program will take one or two arguments. The first argument is the target that you want to build. The second argument is the name of the build file to the program will read. If the second argument is not present, the program will try to read a file in the current working directory called buildfile.

Steps:

1. Read the build file looking for the appropriate rule. If found:
2. Update prerequisites. (as with make, each prerequisite corresponds to a target in the buildfile, so we might need to execute another rule to ensure that a prerequisite is up to date.)
3. If the target is a file and has been modified more recently than all of its prerequisites, then the actions are not executed.
4. If the target is not a file, or any of the prerequisites are newer than the target, then the rule's actions are executed.

Exceptions:

• If a rule has no prerequisites, then the rule will always be executed when it is encountered. Note that this differs from make where a rule with no prerequisites is only executed if it is called explicitly.
• You don't need to handle recursive targets and prerequisites.

The build process will likely want to call the build program from within the build program. (Recursion comes in many forms.) The best way to do this is to make sure that build is in a directory in the PATH variable.

Testing

Another obvious use for shell scripts is to automate testing programs. We will also write a shell script called testbuild that will run several tests of the build program.

The testbuild program will run at least 3 different test cases that test different parts of the program. We will also need to include one or more build files and possibly some other files. The touch (see "man touch") command will come in quite handy when we want to change a file's modification time automatically.

Zip archive can be obtained here: http://zenebo.com/csc209a1.zip