代写实现分布式计算中网络模型，考察Linux下Socket编程能力。
Requirement
The objective of this assignment is to familiarize you with UNIX socket
programming.
This assignment is worth 15% of your overall grade in this course. It is an
individual assignment and no collaborations are allowed. Any cheating will
result in an automatic F in the course (not just in the assignment).
If you have any doubts/questions, post your questions on Piazza. You must
discuss all project related issues on Piazza. We will give those who actively
help others out by answering questions on Piazza up to 10 bonus points.
Problem Statement
Social networks are nowadays in every moment of our lives. The information
built upon interactions among people has led to different types of
applications. Crowdsourced apps such as Uber, Lyft, Waze use information for
navigation purposes. Other apps such as dating apps provide matching
algorithms to connect users who share similar behaviours and increase their
compatibility chances for future success. In this project we shall implement a
simplified version of a matching app that’ll help us understand how matching
systems work in the real world. Specifically, you’ll be given a network
topology consisting of social connections between different users in the
network. This will consist of nodes representing users and the edges between
them. Beside social network topology, you will also be given a database
consisting of compatibility test scores. This database will be in plain text
and consist of multiple key (the user), value (the corresponding score) pairs.
In this project, you will implement a model of a social matching service where
two clients issue a request for finding their compatibility. This request will
be sent to a Central Server which in turn interacts with three other backend
servers for pulling information and data processing. The Central server will
connect to the Topology server (server T) which has the user social network
information. Central server has to connect as well to the Score server (server
S) which stores the compatibility scores for each user. Finally, the server
will use the network topology and scores to generate a graph that connects
both users, and provide the smallest matching gap between them. The procedure
to complete this task is provided in phase 2’s description. Both the matching
gap and the graph generated will be sent back to both clients.
Server T has access to a database file named edgelist.txt, and Server S has
access to a database file named scores.txt. Both clients and the Central
server communicate over a TCP connection while the communication between
Central and the Back-Servers T, S & P is over a UDP connection. This setup is
illustrated in Figure 1.
Source Code Files
Your implementation should include the source code files described below, for
each component of the system.
- Central: You must name your code file: central.c or central.cc or central.cpp (all small letters). Also you must include the corresponding header file (if you have one; it is not mandatory) central.h (all small letters).
- Back-Server T, S and P: You must use one of these names for this piece of code: server#.c or server#.cc or server#.cpp (all small letters except for #). Also you must include the corresponding header file (if you have one; it is not mandatory). server#.h (all small letters, except for #). The “#” character must be replaced by the server identifier (i.e. T or S or P), depending on the server it corresponds to. Note: You are not allowed to use one executable for all four servers (i.e. a “fork” based implementation).
- ClientA: The name of this piece of code must be clientA.c or clientA.cc or clientA.cpp (all small letters) and the header file (if you have one; it is not mandatory) must be called clientA.h (all small letters).
- ClientB: The code file for the monitor must be called clientB.c or clientB.cc or clientB.cpp (all small letters) and the header file (if you have one; it is not mandatory) must be called clientB.h (all small letters).
Application workflow phase Description
Phase 1
Phase 1A: establish the connections between the Clients and Server C
All four server programs (Central Server, Topology Server, Score Server and
Processing Server) boot up in this phase. While booting up, the servers must
display a boot message on the terminal. The format of the boot message for
each server is given in the onscreen messages tables at the end of the
document. As the boot message indicates, each server must listen on the
appropriate port information for incoming packets/connections.
Once the server programs have booted up, two client programs should run. Each
client displays a boot message as indicated in the onscreen messages table.
Note that each client code takes an input argument from the command line that
specifies the username(s). The two input usernames from the two clients could
calculate the matching score between these two users, which will be described
in the next section.
The format for running each client code is:
The command for the client A should be
./clientA
The command for the client B should be
./clientB
The usernames from the ClientA and ClientB are the inputs for computing the
matching gap between themselves. As an example, to find the matching gap
between Victor and Oliver, the two clients should be run as follows
./clientA Victor
./clientB Oliver
After booting up, the ClientA and ClientB establish TCP connections with the
server.
After successfully establishing the connections, the two clients first send
the usernames to server C. Once these are sent, each client should print a
message in the format given in the table 8 & 9. This ends Phase 1A, and we
now proceed to Phase 1B.
Phase 1B: establish the connections between Server C and all other backend
servers as shown in the figure 1.
In Phase 1A, you read what should be sent from ClientA and ClientB to Server C
over the TCP connections. In Phase 1B, Server C will send messages to the
three back-servers (Server C, Server T and Server P) with UDP connections. The
request will be sent to their respective back-end server depending on which
information they need to get and which operation they need to execute.
This ends Phase 1B.
Phase 2
After receiving messages from both clients, server C will firstly contact
server T (where the social network graph is stored) and server S (where
compatibility test scores are stored) to retrieve related data to compute the
final results. After server C receives related data from both server T and S,
server C will forward these to server P. Server P will then use this
information to find a social network path that has the smallest matching gap.
Let’s take a look at an example below. Figure 2 and Table 1 demonstrate
examples of data that can be stored in server T and server S.
If the clients’ usernames are Victor and Oliver, server T should send the
graph in the red square to server C. The highlighted graph contains both
Oliver and Victor. Server C should then ask Server S for the necessary
compatibility test scores. In this example, server S shall send compatibility
test scores of Rachael, Victor, King and Oliver to server C. After server C
received all necessary messages, it will forward them to server P. Server P
will find a social connection that bridges Victor and Oliver with the smallest
compatibility gap. Server P should also be able to realize connecting certain
people are impossible(King and Rachit). Given two compatibility test scores
1and 2 , matching gap between two people are computed using equations below.
Them atching gap between Victor and Rachael is: between Rachael and Oliver and
matching gap. If there are more than two edges connecting two people, the
matching gap of that path will be the summation of the matching gap of all the
edges. The matching gap of connecting Victor and Oliver through Rachael is
1.06.
Phase 3
After processing the results in the backend server P, results have to be sent
back to the Central server. As mentioned in phase 2, the processing server
will calculate the matching gap between the two clients’ usernames requested.
Using the previous example, we will have as a result a graph with Victor —
Rachel –Oliver and the matching gap equal to 1.06 .This information will be
sent to the Central server and will be forwarded to each of the clients. The
format can be seen on the on-screen messages table shown later.
If there is no path that connects both username’s requests on the network, the
processing server has to provide to the central server that no matching can
occur.
Phase 4
If you want to earn 10 extra points, you can implement an extra operation
where client B provides two usernames and the system compares both of their
matching gaps with the client A username. This operation cannot be done
separately, i.e, it should be on the same command line “ ./clientB <usernameX> <usernameY> “, You need to find both matching gaps and provide
the results to client A and client B.
NOTE: The extra points will only work when you don’t get full 100 points. The
maximum points for this socket programming project is only 100. For example,
you get 97 + 10 = 100.
Required Port Number Allocation
The ports to be used by the clients and the servers for the exercise are
specified in the following table.
Assumptions:
- You have to start the processes in this order: Server C, Server T, Server S, Server P, Client A and Client B.
- If you need to have more code files than the ones that are mentioned here, please use meaningful names and all small letters and mention them all in your README file.
- You are allowed to use blocks of code from Beej’s socket programming tutorial (Beej’s guide to network programming) in your project. However, you need to mark the copied part in your code.
- When you run your code, if you get the message “port already in use” or “address already in use”, please first check to see if you have a zombie process (see following). If you do not have such zombie processes or if you still get this message after terminating all zombie processes, try changing the static UDP or TCP port number corresponding to this error message (all port numbers below 1024 are reserved and must not be used). If you have to change the port number, please do mention it in your README file and provide reasons for it.
- You may create zombie processes while testing your codes, please make sure you kill them every time you want to run your code. To see a list of all zombie processes, try this command:
>>ps -aux | grep ee450. Identify the zombie processes and their process number and kills them by typing at the command-line: ]]kill -9 processNumber.
Requirements
- Do not hardcode the TCP or UDP port numbers that are to be obtained dynamically.
Refer to Table 1 to see which ports are statically defined and which ones are
dynamically assigned. Use getsockname() function to retrieve the locally-bound
port number wherever ports are assigned dynamically as shown below. - The host name must be hard coded as localhost (127.0.0.1) in all codes.
- Your clients should terminate themselves after all is done. And the clients can run multiple times to send requests. However, the backend servers and the Central server should keep being running and be waiting for another request until the TAs terminate them by Ctrl+C. If they terminate before that, you will lose some points for it.
- All the naming conventions and the on-screen messages must conform to the previously mentioned rules.
- You are not allowed to pass any parameter or value or string or character as a command-line argument except while running the clients in Phase 1.
- All the on-screen messages must conform exactly to the project description. You should not add anymore on-screen messages. If you need to do so for the debugging purposes, you must comment out all of the extra messages before you submit your project.
- Please do remember to close the socket and tear down the connection once you are done using that socket.
Programming platform and environment
- All your submitted code MUST work well on the provided virtual machine Ubuntu.
- All submissions will only be graded on the provided Ubuntu. TAs won’t make any updates or changes to the virtual machine. It’s your responsibility to make sure your code works well on the provided Ubuntu. “It works well on my machine” is not an excuse.
- Your submission MUST have a Makefile. Please follow the requirements in the following “”Submission Rules” section.
Programming languages and compilers
You must use only C/C++ on UNIX as well as UNIX Socket programming commands
and functions. Here are the pointers for Beej’s Guide to C Programming and
Network Programming (socket programming): http://www.beej.us/guide/bgnet/
(If you are new to socket programming
please do study this tutorial carefully as soon as possible and before
starting the project) http://www.beej.us/guide/bgc/
You can use a unix text editor like emacs to type your code and then use
compilers such as g++ (for C++) and gcc (for C) that are already installed on
Ubuntu to compile your code. You must use the following commands and switches
to compile yourfile.c or yourfile.cpp. It will make an executable by the name
of “yourfileoutput”. gcc -o yourfileoutput yourfile.c g++ -o yourfileoutput
yourfile.cpp
Do NOT forget the mandatory naming conventions mentioned before!
Submission Rules
- Along with your code files, include a README file and a Makefile. In the
README file write
* a. Your Full Name as given in the class list
* b. Your Student ID
* c. What you have done in the assignment, if you have completed the optional part (suffix). If it’s not mentioned, it will not be considered.
* d. What your code files are and what each one of them does. (Please do not repeat the project description, just name your code files and briefly mention what they do).
* e. The format of all the messages exchanged.
* g. Any idiosyncrasy of your project. It should say under what conditions the project fails, if any.
* h. Reused Code: Did you use code from anywhere for your project? If not, say so. If so, say what functions and where they’re from. (Also identify this with a comment in the source code.) - Compress all your files including the README file into a single “tar ball” and call it: ee450_yourUSCusername_session#.tar.gz (all small letters) e.g. my filename would be ee450_nanantha_session1.tar.gz. Please make sure that your name matches the one in the class list. Here are the instructions:
* a. On your VM, go to the directory which has all your project files. Remove all executable and other unnecessary files. Only include the required source code files, Makefile and the README file. Now run the following commands:
* b. Now, you will find a file named “ee450_yourUSCusername_session#.tar.gz” in the same directory. Please notice there is a star(*) at the end of first command. - Upload “ee450_yourUSCusername_session#.tar.gz” to the Digital Dropbox on the DEN website. After the file is uploaded to the dropbox, you must click on the “send” button to actually submit it. If you do not click on “send”, the file will not be submitted.
- D2L will and keep a history of all your submissions. If you make multiple submission, we will grade your latest valid submission. Submission after deadline is considered as invalid.
- D2L will send you a “Dropbox submission receipt” to confirm your submission. So please do check your emails to make sure your submission is successfully received. If you don’t receive a confirmation email, try again later and contact your TA if it always fails.
- Please take into account all kinds of possible technical issues and do expect a huge traffic on the DEN website very close to the deadline which may render your submission or even access to DEN unsuccessful.
- Please DO NOT wait till the last 5 minutes to upload and submit because some technical issues might happen and you will miss the deadline. And a kind suggestion, if you still get some bugs one hour before the deadline, please make a submission first to make sure you will get some points for your hard work!
- After receiving the confirmation email, please confirm your submission by downloading and compiling it on your machine. If the outcome is not what you expected, try to resubmit and confirm again. We will only grade what you submitted even though it’s corrupted.
- You have plenty of time to work on this project and submit it in time hence there is absolutely zero tolerance for late submissions! Do NOT assume that there will be a late submission penalty or a grace period. If you submit your project late (no matter for what reason or excuse or even technical issues), you simply receive a zero for the project.
