Latest Version: version 1.3 + patch4

The autonomous component architecture mimics the IC design architecture in the closest possible way. The behavior of J-Sim components are defined in terms of contracts (in much the same way IC chips are defined in the specification in the cookbook) and can be individually designed, implemented, tested, and incrementally deployed in a software system.  A system can be composed of individual components in much the same way a hardware module is composed of IC chips. Moreover, components can be plugged into a software system, even during execution.

For the purpose of network modeling and simulation, we have defined, on top of the autonomous component architecture, a generalized packet switched network model.  The model defines the generic structure of a node (either an end host or a router) and the generic network components, both of which  can then be used as base classes to implement protocols across various layers.  Although the model is derived by featuring out the common attributes of network entities in the current best-effort Internet, it is general enough to accommodate other network architectures, such as the IETF differentated services architecture, the mobile wireless network architecture, and the WDM-based optical network architecture. 

J-Sim has been developed entirely in Java^TM.  This, coupled with the autonomous component architecture, makes J-Sim a truly platform-neutral, extensible, and reusable environment.  J-Sim also provides a script interface to allow integration with different script languages such as Perl, Tcl, or Python. In the current release,  we have fully integrated J-Sim with a Java implementation of the Tcl interpreter (with the Tcl/Java extension), called Jacl. So, similar to ns-2, J-Sim is a dual-language simulation environment in which classes are written in Java (for ns-2, in C++) and "glued" together using Tcl/Java.  However, unlike ns-2, classes/methods/fields in Java need not be explicitly exported in order to be accessed in the Tcl environment.  Instead, all the public classes/methods/fields in Java can be accessed (naturally) in the Tcl environment.

We outline the salient features of J-Sim below:

• Loosely-coupled, component-based programming model.
• Real-time process-driven simulation.
• Implementation of an (almost) complete suite of Internet Integrated, Differentiated, and Best Effort Services protocols.
• A dual-language environment that allows auto-configuration and on-line monitoring.
• Implementation of generic interface classes for trace-driven simulation.
• Partial realization of network emulation.

J-Sim consists of several packages, containing about 125K lines of source codes.  The current release can be approximately broken down as follows (size as in class files, uncompressed):

Active Contributors (in alphabetical order): Wei-peng Chen, Ye Ge, Guanghui He, Chunyu Hu, Hwangnam Kim, Lu-chan Kung, Ning Li, Hyuk Lim, Ahmed Sobeih, Hung-ying Tyan, Honghai Zhang, Rong Zheng.

Past Contributors: Yuan Gao, Yifei Hong, Yung-Ching Hsiao, Shankar Kalyanaraman, Wei Lin, Seok-Bae Park, Ling Su, Bin Wang, Yi Ye, Jing Zhang.

Project Supervisor: Jennifer Hou.

Sponsors: This project has been partially supported by NSF Next Generation Software program, DARPA/IPTO network modeling and simulation program, MURI/AFOSR, Cisco Systems, Inc., Ohio State University, and University of Illinois at Urbana-Champaign.

Last updated: 01/28/2005

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