Generic Timing Model

  • Start date: 01.01.2000
  • End date: 31.12.2001
  • Funded by: Universität Augsburg
  • Local head of project: Prof. Dr. Theo Ungerer



© University of Augsburg


JMessengers is a Java based mobile agent system particularly designed for distributed computing in heterogeneous computer networks.


Autonomous Internet agents have appeared as a solution to handle data retrieval and search operations through large numbers of loosely connected entities. The idea of those agents is to allow programs to navigate freely between computers and help the user to manage large quantities of information that would be difficult to handle without the help of such agent systems. Internet agents come in two different flavors: stationary agents and mobile agents. 


Mobile agent systems are characterized by their ability to autonomously migrate code, data, and execution state of the agent incarnations. Mobile agents define a new paradigm for distributed computing. Typically mobile agents are used for electronic commerce and therefore hindered for high-performance distributed computing by their inherent security features that slow down execution speed. For distributed computing cooperative agents are applied, thus security issues may be dropped. 


The combination of those ideas, high-performance computing with distributed machines and mobile software agents to navigate a network, brings us to the MESSENGERS project of the Department of Computer Science at the University of California, Irvine. The goal of the MESSENGERS project is to combine the computing power of a large number of LAN-connected machines and then have mobile agents use the resources of the whole structure to cooperate on a large problem.


One of the shortcomings of the MESSENGERS-C system is its limitation to 64 machines that must be arranged in a homogeneous LAN-cluster. Today, most networks consist of machines using a number of different operating systems. But since all major systems support Java as programming language, we decided to take the very flexible and stable paradigms of MESSENGERS and re-implement the whole system in Java without the limitations of a homogenous network or a maximum of 64 machines.


Our goal was to build an easily scalable platform for high-performance, mobile agent based, distributed computing that can spread programs over Internet, use heterogeneous computer platforms, does not restrict the number of computers used and enables object-oriented programming.


The JMessengers system was created as a flexible and fast software platform for mobile agents. JMessengers and all its components are written in Java and are therefore not limited to any special type of machine. A JMessengers network may consist of hundreds of different connected machines. The only requirement for the participating machines is an implementation of Sun's JDK 1.2 standard with RMI (see paper of M. Gmelin et al.).


Recent research redesigned the synchronization classes of the JMessengers system introducing newly developed locality-based synchronization construct besides the well-known time-based synchronization constructs (see paper of U. Wolf et al. in German). Moreover we try to employ the JMessengers system in ubiquitous computing for context management.






  • Einsatz mobiler Agenten in verteilten ubiquitären Systemen
    Faruk Bagci, Jan Petzold, Wolfgang Trumler, Theo Ungerer
    19. PARS-Workshop, Basel, Switzerland, March 20-21, 2003, (in German)


  • Einsatz von XML zur Kontextspeicherung in einem agentenbasierten ubiquitären System
    Faruk, Bagci, Jan Petzold, Wolfgang Trumler, Theo Ungerer
    XMIDX-Workshop, Berlin, Germany, February 17-18, 2003, (in German)




  • Synchronisation im JMessengers Agentensystem
    U. Wolf, J. Kreuzinger, Th. Ungerer
    PARS-Workshop, München, 8.-9. Oktober 2001 (in German)


  • Agent-based Distributed Computing with JMessengers
    M. Gmelin, J. Kreuzinger, M. Pfeffer, Th. Ungerer
    I2CS Innovative Internet Computing Systems, Ilmenau, Feb. 22-23, 2001, Springer-Verlag LNCS 2060, 131-145




  • Mobile Agenten und Cluster Computing am Beispiel des Messengers-Systems
    Christian Wicke, Theo Ungerer, Lubomir Bic, Michael Dillencourt
    Cluster-Computing, Tagungsband zum 2. Workshop, Universität Karlsruhe, 25.-26.3.1999, Chemnitzer Informatik-Berichte CSR-99-02, Seite 145-154 (in German, compilation-based MESSENGERS agent system)