In early 1999, VA Software launched a project to understand how the Internet development community had been able to produce software such as Linux, Apache and Samba that was generally developed faster and with higher quality than comparable commercially available alternatives [1,2,3,20]. Our goal was simple: determine how to make more software development projects successful.We discovered that successful Internet community projects employed a number of practices that were not well characterized by traditional software engineering methodologies. We now refer to those practices as Collaborative Software Development or CSD. Late in 1999 we developed the SourceForge platform to make it easy for even small software development projects to employ those practices, and in November of 1999 launched the SourceForge.net web site based on the SourceForge platform.The site was an overwhelming success, and in less than two years, grew to support more than 27,000 software development projects and over a quarter million software developers worldwide. SourceForge.net affords us an unequaled test bed for understanding CSD. In response to demand from companies seeking to enable CSD within their organizations, we announced a commercial version of the SourceForge platform, SourceForge Enterprise Edition, in August 2001.This paper describes the principles of CSD, the software development pain points those principles address, and our experience enabling CSD with the SourceForge platform.

Rapide is an event-based, concurrent, object-oriented language specifically designed for prototyping system architectures. Two principle design goals are: (1) to provide constructs for defining executable prototypes of architectures and (2) to adopt an execution model in which the concurrency, synchronization, dataflow, and timing properties of a prototype are explicitly represented. This paper describes the partially ordered event set (poset) execution model and outlines with examples some of the event-based features for defining communication architectures and relationships between architectures. Various features of Rapide are illustrated by excerpts from a prototype of the X/Open distributed transaction processing reference architecture.>

RAPIDE is a concurrent, object-oriented language specifically designed for prototyping large concurrent systems. One of the principle design goals has been to adopt a computation model in which the synchronization, concurrency, data flow, and timing aspects of a prototype are explicitly represented and easily accessible both to the prototype itself and to the prototyper. This article describes the partially ordered event set (poset) computation model and the features of RAPIDE for using posets in reactive prototypes and for automatically checking posets. An example prototyping scenario illustrates uses of the poset computation model, with and without timing.

A detailed description is given of the timing model of VHDL (VHSIC hardware description language). VHDL uses a two-level timing model based on discrete event simulation. Timed assignment statements are preemptive, and two forms of preemption are supported in the language: inertial and transport. The author describes the VAL (VHDL annotation language) timing model and features of VAL designed to work with the VHDL timing model. VAL introduces assertions that understand the two-level timing framework in VHDL. In contrast to the preemptive assignment of VHDL, VAL models the same behavior using only anticipatory semantics (no preemption). The anticipatory model enables VAL descriptions to be treated as constraints on the input/output behavior of a device that may be directly translated into predicates. The author demonstrates by a simple example the application of formal techniques for manipulating these predicates.>