Project I- Client-Server Model

CS/CE/TE 6378: Project I

1 Requirements
• Source code must be in the C /C++ /Java programming language.
• The program must run on UTD lab machines (dc01, dc02, ..., dc45).
2 Client-Server Model
In this project, you are expected to implement Lamport’s Mutual Exclusion Algorithm. Knowledge of threads
and socket programming and its APIs in the language you choose is expected. Each process (server/client)
must execute on a separate machine (dcxx).
3 Description
Implement a solution that mimics a replicated file system. The file system consists of four text files:
f1, f2, f3, and f4. All four files are replicated at three file servers. To achieve file replication, choose any
three of the dcxx machines. Each of these machines will store a copy of all the files. Five clients, executing
at different sites (and different from the three sites that replicate the files), may issue append to file requests
for any of these files. The clients know the locations of all the other clients as well as the locations of all
file servers where the files are replicated. All replicas of a file are consistent, to begin with. The desired
operations are as follows:
• A client initiates at most one append to file at a time.
• The client may send a append to file REQUEST to any of the file replication sites (randomly selected)
along with the text to be appended. In this case, the site must report a successful message to the client
if all copies of the file, across the all sites, are updated consistently. Otherwise, the append should not
happen at any site and the site must report a failure message to the client. We do not expect a failure
to happen in this project unless a file is not replicated at exactly four different sites.
• On receiving the append to file REQUEST, the receiving site initiates a REQUEST to enter critical
section, as per Lamport’s mutual exclusion algorithm. Obviously each REQUEST should result in a
critical section execution regarding that particular file. In the critical section the text provided by the
client must be appended to all copies of the file.
• Concurrent appends initiated by different clients to different files must be supported as such updates
do not violate the mutual exclusion condition.
• Your program does NOT need to support the creation of new files or deletion of existing files. However,
it must report an error if an attempt is made to append to a file that does not exist in the file system.
• All clients are started simultaneously.
• Each client loops through the following sequence of actions 100 times: (a) waits for a random amount of
time between 0 to 1 second, (b) issues an append to file REQUEST, (c) waits for a successful or failure
message. So, for this project you need to worry about concurrent read/write requests for the same file
but issued by different clients. Your client should gracefully terminate when all 100 REQUESTS have
been served (either successfully or unsuccessfully).
The teaching assistant will upload a sample configuration file for the servers. You must follow that
standard. Your code is evaluated in terms of functionality, readability and documentation (comments and
README file). A separate file describing your code is appreciated but is not mandatory.
4 Submission Information
The submission should be through eLearning in the form of an archive consisting of:
• File(s) containing the source code.
• The README file, which describes how to run your program.
• DO NOT submit unnecessary files.
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