RTI 2.0 Architecture Stephen T. Bachinsky Science Applications International Corporation 5400 Shawnee Road, Suite 110 Alexandria, VA 22312 703-333-5428 sbachinsky@std.saic.com Larry Mellon Science Applications International Corporation 1100 North Glebe Road, Suite 1100 Arlington, VA 22203 703-907-2552 lmellon@std.saic.com Glenn H. Tarbox, PhD Object Sciences Corporation 1835 North Powhatan St. Arlington, VA 22205 703-538-4115 glenn.h.tarbox@objectsciences.com Richard Fujimoto, PhD College Of Computing Georgia Institute of Technology Atlanta, GA 30332 fujimoto@cc.gatech.edu Keywords: High Level Architecture, Runtime Infrastructure, Time Management, Interest Management. ABSTRACT: A recent DMSO (Defense Modeling and Simulation Office) initiative resulted in a new RTI design and build effort. This paper describes the design constructs used in the RTI 2.0 architecture and the driving principles used throughout the design process. Key architectural features are identified and analyzed in terms of meeting the RTI's set of requirements. Concepts such as system scalability, runtime performance, federation-specific tuning, reliability, and maintainability are discussed within the confines of the RTI 2.0 architecture. This paper presents information representing the HLA development process underway by the DMSO and the DoD AMG (Architecture Management Group). 1 Introduction In order to create a common reusable infrastructure for distributed simulation the Architecture Management Group (AMG) has led the development of a standardized High Level Architecture (HLA) [1]. The AMG is composed of government representatives from Modeling and Simulation programs across the Department of Defense (DoD) Services. The AMG continues to provide support and guidance through the maturation process of the HLA. The HLA is a blueprint to be used to develop the necessary infrastructure in order to promote interoperability and reusability within the modeling and simulation community. A key component of the HLA is the Interface Specification that defines the standard services that simulations utilize for coordination and collaboration during an exercise. There are two sides to the Interface Specification; the services implemented by the individual simulations themselves and the services implemented by the common Runtime Infrastructure (RTI). While the HLA is an architecture, and is not software based, its core instrument in supporting the runtime services is the RTI software. As the RTI is an interface specification, it is envisioned that multiple implementations, potentially providing domain specific benefits, will be developed in the future. The RTI provides services that fall into six categories: (1) Federation Management, (2) Declaration Management, (3) Object Management, (4) Ownership Management, (5) Time Management, and (6) Data Distribution Management. The specification of these services has evolved through prototyping and working group activities. Implementation of a prototype RTI began in late 1995 and was used to support several HLA experiments that involved existing programs within different simulation domains: joint training, platform, analysis, and engineering. The initial RTI was used to gain experience with the early versions of the Interface Specification. In August of 1996 a baseline Interface Specification (labeled 1.0) was accepted by the AMG and subsequently the HLA was approved by the Under Secretary of Defense for Acquisition and Technology (USD(A&T)) as the standard technical architecture for all DoD simulations. Working from the baseline Interface Specification a familiarization version of the