Operating Systems

Scuola Superiore Sant’Anna

Project Assignments

Operating Systems

Project 1

• A multi-threaded server

– the goal is to provide a file repository – similar to ftp

– the server should be able to accept requests for

• showing the list of files in the repository

• getting one or more files

• putting one or more files

– Access should be regulated through a configuration file

• the file contains the username and password and permissions of the users

• all registered users can read all the files

• “special” users can also put files in the server

– Communication through TCP sockets

Project 2

• A variation of project 1

• Two servers on two computers

– the two computers contain exactly the same files – when a client requests a file

• the first half of the file is obtained by server 1

• the second half of the file is obtained by server 2

• the two halves are transferred in parallel

– E.g. BitTorrent

• Hint

– Both the client and the server must be multi-threaded programs – In particular, the client should be able to receive two streams in

parallel (with two threads)

Project 3

• A distributed environment

– The goal is to automatically distribute the load across a server farm – N computers, each one running a server

– One of these runs a special server S

– Clients send requests of running a program “dummy” to S – S forwards the request to one of the N computers

– The program standard output is forwarded back to the client

Server

Client A

Client B

stdout

Project 3 – cont

• Structure of the dummy

– The dummy program simply sends some output back on the std output

– Does not open files or it does not access any other local resource – For example, it could be a program that periodically sends out a

random number on stdout

– However, such output should be sent back to the client!

• Structure of server S

– The server should be able to “balance” the load between the N computers

– It should send the request to the free server first, and then to the one

with less serving requests

Project 4

• Distributed memory

– Simulate a distributed memory in the following way:

– N computers

– Each computer stores M blocks of memory, each one of 4 Kb

– A client can access a block of memory with the following functions:

• lock(int block);

• read(int block, void* pointer);

• write(int block, void *pointer);

• unlock(int block);

– This is translated to a request to the corresponding server

– Different clients on different computers can access the same block

Project 5

• A simple Peer to Peer with notifications

– Each client has a list of files to share

– One special client contains the list of all clients that are on-line

• A client can:

– search for a specific file (with wildcards) – transfer files (optional)

– add files to its repository (to share with others)

– get notifications when a file is added

Project 5: notifications

• The client can “register” its requests, so that it will be notified later

– for example, the client could ask: “notify me when the following file is made available by some other client”

– the notification mechanism is up to you! (it must be a remote notification, using sockets)

– the notification will expire after some time (for example, a few hours or days)

– the registration can be centralized or distributed