View/Edit/Compile/Run
Web-based Programming Environment
Richard Perry
Villanova University
Department of Electrical and Computer Engineering
richard.perry@villanova.edu
http://ftp.ece.villanova.edu/
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Outline
- Introduction
- VECR Tour
- Courses and Projects
- VECR Implementation
- Conclusion and Future Work
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Introduction
- Problems:
- Variety of workstations available,
inconsistent environments
- May lack C and Java compilers, and Unix shells
- May only have overwhelming professional C++ development tools,
no easy way to use strict ANSI C
- May have old or deficient version of Java
- Solution:
- Web-based, easy to use
- Centralized and consistent environment
- Standard tools and options
- Plotting facility
- File security/privacy
- System backups, zip download
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VECR Tour -
Home page for student frodo
frodo - projects
a1,
a2,
a3,
a4,
a5,
a6,
a7,
a8,
a9,
a10,
zip - download all projects
documentation and
source code
Logout -
(UserID logout with empty password)
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VECR Tour -
Home page for instructor rperry
rperry - projects
a1,
a2,
a3,
a4,
a5,
a6,
a7,
a8,
a9,
a10,
zip - download all projects
documentation and
source code
Logout -
(UserID logout with empty password)
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VECR Tour -
a1 project page
frodo - a1
Home
Edit:
p1.c,
p2.c,
p3.c,
p4.c,
p1.java,
p2.java,
p3.java,
p4.java,
p1.sh,
p2.sh,
p3.sh,
p4.sh,
p1.txt,
p2.txt,
p3.txt,
p4.txt,
Makefile,
p1.h,
p2.h,
p3.h,
p4.h,
View:
464 Sep 2 11:48 Makefile
7440 Oct 16 15:28 p1
84 Oct 16 15:27 p1.c
83 Oct 15 18:22 p1.c.OLD
16 Oct 16 13:14 p1.in
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VECR Tour -
Editing a1/p1.c
frodo - a1/p1.c
a1
- Home
- preproc
- asm
- asmopt
- cerr
- reload
a1
- Home
- preproc
- asm
- asmopt
- cerr
- reload
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VECR Tour -
action links
- preproc - display C preprocessor output
- asm - display generated assembly code
- asmopt - display optimized assembly code
- cerr - insert compiler error messages as comments into the source code
- reload - reload the current page
- Compile - compile C or Java program
- Run - run C, Java, or sh executable
- Debug - run C program using gdb, or sh script using -x
- Plot - pipe program output into plotting program
- args - specify program command-line arguments
- Command - execute args input directly as command
- Update - save edit changes
- Upload - upload local source file (at the very bottom of the page)
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VECR Tour -
Compile and Run a1/p1.c
make p1
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gcc -ansi -pedantic -Wall -g -lm -o p1 p1.c
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Done.
./p1
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1 2
2 4
3 1
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Exit status = 0
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VECR Tour -
Plot a1/p1.c
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VECR Tour -
plot script
#! /bin/sh
umask 077; PATH="/usr/bin"; export PATH
exec 2>/dev/null
(echo "set term pbm\nset output\n\
plot '-' notitle with linespoints"; cat) |
/usr/local/bin/gnuplot |
/usr/local/netpbm/bin/ppmtogif
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Courses and Projects
- Two years ago,
initial setup allowed students to create one Bourne shell script,
with dynamic HTML output.
- Now expanded to 10 project areas,
with C, Java, Bourne shell, Makefile, text, and C header file editing.
- Used in sophomore and senior-level C programming courses,
graduate Unix/C programming course (C and shell programming),
senior/graduate computer communications security course (Java programming).
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Courses and Projects
Introductory C Programming
- Moving average smoothing of noisy sine-wave data
- Using math.h functions to draw a Valentine's day heart
- Monte-Carlo simulation with an array of counters
plotted as a probability density function
Advanced C Programming
- Provided students with header files and code for functions
such as dynamic matrix allocation,
matrix singular value decomposition, and network I/O
Java Programming
- Provided the current Java development environment,
with security extension packages,
and other packages developed by the instructor
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Current course project - interactive root locus
a3/p1
- a3
- Home
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VECR Implementation
Combination of C code, perl, and Bourne shell scripts,
available from http://ftp.ece.villanova.edu/
Implementation Details
- System Environment
- Authentication
- Project Directories
- Running as root
- Running as student userid
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System Environment
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Authentication
- Password authentication,
using Villanova LDAP and/or local password file
- Automatic assignment of unique per-user userid/groupid,
not a real login account
Project Directories Example
drwxr-x--- root 3004 home/frodo
drwx------ 3004 3004 home/frodo/a1
drwx------ 3004 3004 home/frodo/a2
drwx------ 3004 3004 home/frodo/a3
...
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Running as root
- Dangerous, complete control of the system,
can even break out of the chroot environment
- Necessary, to create files with proper owner/group,
to run student actions under their own userid/groupid
- Overall more secure than using a common userid for all users
Running as student userid
- Run time limited to 30 seconds real-time,
10 seconds CPU time,
8 MB RAM,
etc.
- Students can safely execute arbitrary Unix commands
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Conclusion and Future Work
- Current implementation has worked well,
and students like it
- Needs locking mechanism when creating new userid
- Needs ability to edit and upload arbitrary file names
- Needs ability to support interactive programs,
can be done via a Java process running on the server
with a network connection to an applet on the client