Dependency-conflict detection in real-time collaborative 3D design systems

Abstract

One core issue in real-time collaborative 3D design systems is dependency-conflict caused by concurrent access to object replicas in Dependency Graph (DG) states -- the common underlying structure of 3D design systems. Prior work has provided an Operational Transformation (OT) solution to dependency-conflict resolution, assuming dependency-conflict can be detected. But dependency-conflict detection is a complex and challenging issue because dependency relations among targets of concurrent operations -- a necessary condition for dependency-conflict -- is dynamic in nature and the detection must refer to prior DG states that are often unavailable during dependency-conflict detection. Conflict detection was never a difficult issue in prior OT work based on well-defined linear data models because conflict relations are readily derivable from operation position parameters without having to refer to prior document states. This work is the first to recognize and solve the dependency-conflict detection problem, which complements prior work in dependency-conflict resolution to provide a complete solution to dependency-conflict problem in real-time collaborative DG-based systems. Both theoretical verification and real implementation have been applied to validate the proposed dependency-conflict detection solution.