John Vlissides, a researcher at IBM's T.J. Watson Research Lab, is coauthor of Design Patterns: Elements of Reusable Object-Oriented Software (Addison-Wesley Publishing, 1995). John can be contacted at [email protected].
The first annual Pattern Languages of Programs conference (PLoP '94) was held August 4--6 at the University of Illinois. The goal of PLoP '94, which was attended by about 75 people from all over the world, was to provide a forum for the presentation, exchange, and refinement of patterns and pattern languages for computer programs. Patterns describe solutions to problems, and the reasoning behind those solutions. Patterns form a "language" when they combine to provide a sequence or process for the orderly resolution of problems. Although borrowed from architecture and building, the pattern approach has proven applicable to software design as well as many other areas of expertise. (For more information on patterns, see "Patterns and Software Development" by Kent Beck, Dr. Dobb's Journal, February 1994.)
The PLoP conference is unique in its structure. Because the field of software patterns is new, the emphasis this year (and likely in subsequent years) was on collective learning. Rather than on attendees sitting and listening to authors present their submissions, the conference centered around two tracks of "writer's workshops." A writer's workshop consists of a group discussing a paper, while the author listens but remains silent. The idea is to help the author see how people interpret the paper and hence learn how to improve it.
A writer's workshop was held for each of the 31 submissions which included papers entitled "Functionality la Carte," "A Development Process Generative Pattern Language," "Caterpillar's Fate: A Pattern Language for Transformation from Analysis to Design," and "Reactor: An Object Behavioral Pattern for Concurrent Event Demultiplexing and Dispatch." In each case, the author, a moderator, and several fellow authors are seated in a circle, with spectators seated in the periphery. The workshop begins with the author reading portions of his pattern or pattern language aloud. The idea here is to give the audience a chance to hear the pattern as the author intended it to sound. Then the author remains silent until the very end of the workshop. His fellow authors then act as if he's not there. The author listens to the discussion and takes notes. The audience outside the inner circle of authors listens as well.
First, one of the fellow authors summarizes the submission as he understands it. (Submissions were distributed to all authors before the conference. Thus everyone in the inner circle has a chance to read the paper.) Next, the fellow authors discuss only what they consider to be the positive aspects of the submission. After this discussion, the authors focus solely on the negative aspects. These discussions proved invaluable (and often humbling!) to the pattern author. Finally, the author can break his silence and ask questions of his fellow authors to clarify any points they made.
The writer's workshops were a great success. Nearly everybody got ideas about how to improve their papers. Consequently, nearly all the papers will be revised before they are published. The program committee expects to have a volume of papers from PLoP published in half a year or so.
Other conference highlights:
- "Home group" meetings, where attendees got a chance to write, refine, or just talk about patterns in an informal setting. Two home group meetings were held on the first day; one on each subsequent day. Home groups published significant results of each meeting in the Home Group News, a mini-newspaper distributed before each home group meeting.
- An open forum on the "ethics" of patterns. People discussed issues such as pattern ownership, publication, and plagiarism; copyrights and patents; proper citation; derivative works; and patterns as a competitive advantage.
- A "meet the authors" session, where Ralph Johnson and I discussed and circulated pre-pub copies of our upcoming book (coauthored with Erich Gamma and Richard Helm) entitled, Design Patterns: Elements of Reusable Object-Oriented Software.
All in all, PLoP '94 was highly successful, and preparations for PLoP '95 are already underway. Information on PLoP '95 will be posted to the Patterns Mailing List as plans firm up. This mailing list is a forum for pattern and pattern language-related discourse. To join the list, send a message to [email protected].
