Projects

• PRCS

The Project Revision Control System is a version control system designed to be simple to use.  I began working on PRCS in fall of 1995 and have been maintaining it ever since.  The second version of PRCS is in the works and features client/server operation.
• Xdelta

Xdelta is a delta compression library I wrote for use in PRCS version 2.  It uses a fast, linear-space, probabilistic approximation of the standard greedy algorithm.  It does not use record delimiters such as line breaks to reduce the problem size, so it can be applied to many binary file formats.  It has much in common with rsync.  The second version of Xdelta implements delta-compressed storage and network transport.
• EnvDraw

EnvDraw is a Scheme environment diagrammer that I implemented under the direction of Brian Harvey in the summer of 1995 for use in the introductory computer science course CS61A.  It creates diagrams and box-and-pointer diagrams interactively while the user types commands into the interpreter.

Research

• Master's research

For my Master's thesis I implemented a system for delta-compressed storage and distribution based on Xdelta.  It combines the features of systems like RCS and SCCS with the advanced delta-compressed distribution features of CVSup into a decentralized system.  Decentralization is very important for implementing disconnected applications.  You can read it here.
• The Ninja Internet-scale Research Project

I began working with the Ninja group in Fall 1999 on version-controlled, distributed file system applications.
• Public Key Infrastructure and Decentralized File System Security

Slides and annotated bibliography for a presentation on this subject.
• The JavaTime project, part of WELD

I was part of the JavaTime research group from Spring 1997 through Spring 1999 where I worked on program transformation.  Though not terribly sucessful, you can read some post-mortem documentation and find releases here.

Course Work

• CS262 Fall 1997: Advanced Topics in Operating Systems

Andy Begel, Michael Shilman, and I worked on a project called Picothreads.  We implemented a continuation passing style code transformation on Java bytecodes in order to replace threads with lightweight co-routines.  See our report in Postscript or PDF.
• CS294-1 Spring 1998: Mobile Computing and Wireless Networking

My project was on the design of disconnected operation in PRCS, a feature that will arrive in PRCS version 2.  See my report in Postscript or PDF.
• CS263 Spring 1998: Design and Analysis of Programming Languages

My project was on the use of Presburger formulae for eliminating provably dead code from Java programs.  I used the Omega toolkit.  See my report in Postscript or PDF.
• CS261 Fall 1998: Computer Security

CS264 Fall 1998: Implementation of Programming Languages
I did a joint project for both of these classes on programming language security.  What resulted was a survey of proposed techniques for creating tamper-proof executables for secure program distribution.  See my report in Postscript or PDF.
• CS252 Fall 1999: Computer Architecture

I did a project with Ben Zhao on the cache performance of indexing data structures in main memory.  The study includes a comparison of top-down skip lists with B+-trees, and the results may surprise you.  See the preliminary report in Postscript or PDF.

Publications

• PRCS: The Project Revision Control System,

Joshua P. MacDonald, Paul N. Hilfinger, and Luigi Semenzato,
Proceedings System Configuration Management-SCM-8
Lecture Notes in Computer Science, Vol 1439, Springer-Verlag, July 1998.
Postscript, PDF
• Design and Specification of Embedded Systems in Java Using Successive, Formal Refinement,

James Shin Young, Joshua P. MacDonald, Michael Shilman, Abdallah Tabbara, Paul N. Hilfinger, and A. Richard Newton,
Proceedings of the 35th Design Automation Conference, San Francisco, CA, 1998.
PDF

Miscellaneous

• I gave a help session on Source Code Control, you can see the slides here.
• I gave a talk at the Stanford Computer Systems Laboratory Colloquium about PRCS and Xdelta.  You can see the slides here.
• Submit to the power of the XCF!!!
• Warrior needs food, badly... my incredibly space-efficient Gauntlet machine.
• Once upon a time I contributed somewhat to GTK and the GIMP. Here is a description of the GTK text widget that I wrote when I stopped working on it, along with an analysis of what failed and what succeeded.