مرکز منطقه ای اطلاع رساني علوم و فناوري - New Communication Models for Open Source Portico RTİ

Abstract :

The communication model between federates and the federation is an important point that should be considered carefully when designing run-time infrastructure (RTI) software. Some of the communication methods and protocols used in existing closed-source systems include shared memory, UDP and TCP/IP. Portico has a very special place among other open source RTIs since it has a well-written code, flexible architecture and it is actively supported by its developers. Portico RTI currently has 2 different communication models. First of these models is Jgroups based communication model. Jgroups is an IP multicast based library. Federates, distributed over network, can communicate with each other and run together by following the HLA (High Level Architecture) standard rules. Since Jgroups is a network based library, it may cause some latency. The need for new communication models has risen for the scenarios where simulations run on the same computer. As a result of this need, JVM (Java Virtual Machine) communication model has been developed for Portico RTI. Simulations, running on the same computer, are invoked as separate threads in JVM model which has some deficiencies. Failing one of simulation threads may cause JVM process to fail which in turn makes other simulations fail which breaks the interoperability rule. Another problem of JVM model is that a wrapper class is needed to invoke simulations as separate threads. This prevents simulations from running directly without any need for a wrapper class. A need for new communication models have raised because of the deficiencies current communication models have. In shared memory model, simulations run as separate processes and communicate through a shared memory region. Shared memory model overcomes the problems JVM model has and provides a faster communication model to simulations. JNI (Java Native Interface) technology will be used in order to realize memory operations in Portico which is a Java based software. Not only shared memory model but also a hybrid communication model will be presented in this paper. In hybrid communication model, simulations running on the same computer will communicate through shared memory model and simulation running on different computers will communicate through Jgroups communication model. Both shared memory and hybrid communication model perform better than Jgroups communication model. Since both hybrid and shared memory communications model have not been developed for Portico until now, this study proposes new communication models for Portico and improves the total communication times of simulations communicating through Portico.