System Programming Final Project Solution

Context and objective

There is no denying the existence of cheating students. And unfortunately, the proliferation of technology has widened their opportunities. More specifically, your greedy boss has come up with an idea of an application focusing on getting together people that solve homeworks for money (henceforth the providers), and cheating students that want to pay to get their homework done (henceforth the clients).




The main idea is to have a server, with a pool of provider threads. Each provider thread is associated with three numerical parameters: the provider’s price (a flat rate between 50 to 1000TL) per homework, performance(quality) (between 1-worst and 5-best) and login duration (i.e. the number of seconds the provider will be active). A provider thread solves all homeworks in its queue, and waits otherwise, until eventually its login time is over.




A client on the other hand will connect to a server, send his/her homework through the socket and a priority parameter (either cost C, quality Q or time T) to the server. Depending on the chosen priority parameter, the server will forward the homework to either the cheapest, best performing or least busy provider. Once the homework is done the client will collect the result of computation and terminate.




Risks

- Some providers will logout earlier than others, so the provider ranks (in terms of cost and quality)

are not constant.

- Every client will submit her/his homework and wait for collecting its result. Careful with synchronization.




How

- For the sake of simplicity all homeworks consist of an integer value (in degrees) whose cosine must be calculated using the Taylor series.

- Your server is threaded, every new connection MUST be handled as a new thread. This new thread will post the job to provider(if available) and wait for it to finish.

- All server/provider messages must be logged at a log file and printed on stderr.

- The task queue of every provider has size 2. If for instance the client prioritizes performance and the best performing provider’s queue is full, then the server must forward the task to the next best performing provider.




a) server

Admits as command line argument:

- the connection port for listening to clients

- file of providers

- and the log file




You are provided with a file data.dat containing the list of providers and their parameters. e.g. Murat 2 200 360 means




Murat is his name, 2 is his performance (i.e. quality of homeworks solved), 200TL is his price and he’ll remain logged in for 360 seconds in total.

Your server will read this file at startup, and create one thread per provider, and then wait for client connections.




Once a client connects, your server will forward the homework to the corresponding provider. If no provider is available an error message “NO PROVIDER IS AVAILABLE” will be sent to the client. Your server will continue to work until a termination signal is received, in which case it will first close up all client sockets by sending a polite message such as “SERVER SHUTDOWN” and terminate all provider threads.




b) client

Every client will consist of a separate process with the following commandline arguments:

- client name as a string

- her/his priority ‘C’ for low cost or ‘Q’ for high quality/performance or ‘T’ for high speed

- the homework as an integer denoting degree

- server address

- server port address




and will connect to the server send a request in the form of a simple string:




e.g. “Hileci C 45” means the client’s name is Hileci, his priority is low cost and the homework is cos(45)




“Hileci2 Q 55” means the client’s name is Hileci2, his priority is high performance and the homework is cos(55)




“Hileci3 T 30” means the client’s name is Hileci3, his priority is high speed and the homework is cos(30).




Sample output for a client console:

Client Hileci is requesting Q 45 from server 127.0.0.1:5555

Hileci’s task completed by Ayse in 7.53 seconds, cos(45)=0.707, cost is 900TL,

total time spent 7.89 seconds.




c) provider

Every provider will wait for tasks in her/his queue, complete the task, sleep for a random duration between 5-15 seconds (to simulate hard work...), and return its result to the client. Once the login time is up, the provider will logout and her/his thread will be terminated.




Sample output for a provider processing a task:

Provider Ayse is waiting for a task

Provider Ayse is processing task number 1: 45

Provider Ayse completed task number 1: cos(45)=0.707 in 7.53 seconds.

Provider Ayse is processing task number 2: 55

Provider Ayse completed task number 2: cos(55)=0.573 in 9.71 seconds.

Provider Ayse is waiting for a task










If everything goes well your application should print on screen something like the following:




- server (together with providers)

$homeworkServer 5555 data.dat log.dat

Logs kept at log.dat

7 provider threads created

Name Performance Price Duration

Ayse 5 900 60

Fatma 3 500 180

Murat 2 200 360




Hakan
4
750
240
Cengiz
1
75
600
Nuray
3
450
90
Ertan
4
600
120
Provider Ayse waiting for tasks Provider Fatma waiting for tasks Provider Cengiz waiting for tasks Provider Murat waiting for tasks Provider Nuray waiting for tasks Provider Ertan waiting for tasks Provider Hakan waiting for tasks

Server is waiting for client connections at port 5555

Client Hileci2 (Q 45) connected, forwarded to provider Ayse

Provider Ayse is processing task number 1: 45

Client Hileci10 (Q 99) connected, forwarded to provider Ayse

Client Hileci10 (C 11) connected, forwarded to provider Cengiz

Provider Ayse completed task number 1: cos(45)=0.707 in 7.53 seconds.

...

...

Termination signal received

Terminating all clients

Terminating all providers

Statistics

Name
Number of clients served
Ayse
2
Fatma
1
Murat
0
Hakan
1
Cengiz
2
Nuray
1
Ertan
1
Goodbye.











Evaluation

In order to simulate intensive client connections, use a shell script with a list of consecutive client connections;




e.g.

clientApp Hileci1 C 45 127.0.0.1 5555 clientApp Hileci2 Q 99 127.0.0.1 5555 clientApp Hileci3 T 11 127.0.0.1 5555 clientApp Hileci4 C 19 127.0.0.1 5555

...




Your code will be evaluated with a different data.dat file and our own script of client connections.




Rules

a) Your program must handle eventual errors gracefully according to the POSIX traditions.

b) Your program must print usage information in case of incorrect or missing command line arguments.

c) "You are expected to submit a report explaining in detail how your project design provides the required behavior and how you have solved any eventual problems you have encountered." Report format will be pdf.

d) Provide a makefile to compile your homework. Do not run your program inside makefile. Just compile it.

e) Test your homework using the Virtual Machine given to you. f) No late submissions.

g) Use POSIX and Standard C libraries. You can write your program using C11 standards.




Project format: StudentID_FP_CSE344.tar.gz

|→ Makefile

|→ Source files (.c .h)

|→ StudentID_FP_report.pdf




Good luck.