18-845 Individual Project (IP)
Assigned: Wed, Jan 15, 2014
Due: 2:30pm, Wed Feb 12, 2014
Note: in the following,
$coursedir refers to /afs/ece/class/ece845.
For this project, you will design and implement your own protocol for
serving dynamic Web content. The purpose is to give you some
practical context when we study the research issues.
The project has three parts:
Part I: Implement a baseline concurrent Web server in C.
- Part II:
Design an efficient protocol for serving dynamic
content, and then implement an optimized version of the
baseline concurrent server that uses your protocol.
Evaluate the performance of your baseline and optimized servers,
characterizing the performance improvement of your new server.
Part I: Baseline concurrent server
Here are the requirements for the baseline server:
- Implements HTTP/1.0 GET requests for static and dynamic content.
- Assumes one connection per request (no persistent connections).
- Uses the CGI protocol to serve dynamic content.
- Serves HTML (.html), image (.gif and
.jpg), and text (.txt) files.
- Accepts a single command-line argument: the port to listen on.
- Implements concurrency using either threads or I/O multiplexing.
Part II: Optimized concurrent server
The idea here is to improve the performance of your baseline server by
replacing the standard CGI protocol with a protocol of your own
design. This is entirely open-ended. Anything goes.
There are a number of existing standards for this kind of thing, such
as ISAPI (Microsoft), NSAPI (Netscape), and
fast-cgi. However, I would encourage you to forget about
these and start from first principles. Design something that is
simple and fast. A good design is likely to include some combination
of dynamic linking, threads, and code caches.
Part III: Evaluation of baseline and optimized servers
In this part, you will evaluate how well your baseline and optimized
servers can serve dynamic content. You should report the performance
of your baseline and optimized servers as server throughput (requests
per second measured on the server). The goal is to convince your
TA that your approach is significantly faster than CGI.
Some tools for performance benchmarking servers:
Tar up the directory containing your solution in a file called
where ANDREWID is your Andrew login name, and copy it
You have list and insert privileges only in this directory. If you
need to hand in twice, put a number after later handins, e.g.,
ANDREWID-1.tar, ANDREWID-2.tar, and so on.
Evaluation will be done by a live demo with the TA.
Please arrange your demo time with the TA. The projects are
open-ended and so is the evaluation. Here are the rough guidelines:
- Baseline server (35%). The goal here is just to get it working
serving multiple clients concurrently using standard CGI.
- Optimized server (35%). The idea here is to come up with a design
that attacks the biggest overheads associated with running CGI
programs: fork and exec.
- Evaluation (30%). The idea here is to develop a testing
infrastructure and workloads that will allow you to compare the
performance of the baseline server against the optimized server. You
will be demonstrating this testing infrastructure to the TA.
It's your responsibility to come up with a convincing evaluation
methodology and testing infrastructure.
Sources of information
- Students in a graduate class are expected to debug their own
programs. Your instructors are delighted to discuss design issues with
you, but please don't ask them to debug your programs.
- The 15-213 textbook, known as the CS:APP2e book, contains all of the
programming information that you need to complete the project, covering dynamic
linking, process control, Unix signals, Unix I/O, network programming,
and application-level concurrency and synchronization. The E&S Library
in Wean Hall has a copy on reserve.
Numerous code examples, including the csapp.c and
csapp.h files, and the Tiny Web server, are available from
CS:APP Student Web Site.
- Refer to the HTTP 1.0
specification for questions about HTTP.
- Volume 1 of Stevens is also an excellent reference for
advanced topics in sockets programming.
- Consider using curl, nc (netcat), or telnet as the client
to do basic debugging of your server.