In order to speed up the development of distributed CAD (DCAD) software applications and offer the end-users a friendly environment for collaborative design, Collaboration Abstraction Layer (CAL) is proposed. CAL aims to develop a pluggable software module that can be embedded into standalone CAD applications. Through summarizing and abstracting out the common characteristics of distributed CAD software, a set of foundation/helper classes for the important collaborative functionalities are enclosed in CAL, which include a 3D streaming service, a collaborative design management service, a constraint checking/solving service and a file versioning/baseline service. The 3D streaming service incorporates a geometrical simplification algorithm that supports selective refinement on level of details (LOD) model and a compact data structure represented in an XML format. The collaborative management service effectively schedules and manages a co-design job. The constraint checking/solving service, which composes of a design task dispatch interface, a collision detection algorithm, and an assembly constraint algorithm, coordinates designing and assembling based on constraints. The CAD file versioning/baseline service is to manage the history record of the CAD files and the milestones in the collaborative development process. By simulating the real collaborative design process, CAL designs a new collaboration mechanism which is different from most collaboration products in market. For the future potential development, CAL is built on an open-sourced software toolkit. It is coded to interfaces and kernel libraries so as to provide an immutable API for commonly used collaborative CAD functions. CAL enables rapid development of DCAD software, and minimizes application complexity by packaging the needed technology. Moreover, CAL is intending to be a partner to the current CAD software, not competitor, making it an ideal tool for future distributed CAD system development.
