The extensible run-time infrastructure (XRTI) : an experimental implementation of proposed improvements to the high level architecture

Abstract

The establishment of a large-scale network of persistent shared virtual worlds depends on the presence of a robust standard for communicating state information between the applications that host and provide access to those worlds. The High Level Architecture (HLA) can serve as the basis for such a standard, but not before several of its shortcomings are resolved. First, it must be made easier to use. Second, it must specify a standardizable message protocol. Third, it must support dynamic object model extension and composition. Finally, its authors must provide an open-source, freely redistributable run-time infrastructure. This thesis documents the creation of the Extensible Run-Time Infrastructure (XRTI), an experimental platform that addresses the above requirements while retaining full backwards compatibility with the existing HLA standard. To increase ease-of-use, the XRTI provides a proxy compiler that generates customized sets of Java source files based on the contents of arbitrary Federation Object Model Document Data (FDDs). To encourage message protocol standardization, the XRTI uses a novel bootstrapping methodology to define its low-level interactions in terms of an HLA object model. The XRTI supports the dynamic composition and extension of such object models through its Reflection Object Model (ROM), and this thesis demonstrates that ability by depicting the integration of the XRTI into NPSNET-V, a dynamically extensible platform for virtual environment applications.