Extending Linden Scripting Language on OpenSim

OpenSim is a 3D virtual reality platform and now has been widely used in many fields. Its powerful scripting technology is helpful for third party development. Linden scripting language is the most important scripting language in OpenSim, which only supports virtual worlds´ common applications but is weak in domain-specific applications. In order to extend Linden scripting functions, a general extended scheme is proposed in this paper. The structure and rule of OpenSim´s scripting engine are analyzed. Then the management mechanisms of thread pool and queue are summed up. We present four extending approaches. Their implementations and scopes of applications are compared. We choose expanding service modules as the general extended scheme. By extending database service of the item bank, scripting functions (e.g., llMakeTest) are developed to support teaching evaluation in 3D virtual learning environments on OpenSim platform. The correctness of the extended scheme is proved by the case study. The scheme provides a guideline for developing Linden scripting functions for specific applications. It is verified that expanding OpenSim´s domain-specific applications based on scripting technology is feasible.