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Mobile Agents by Wilhelm R. Rossak, Peter Braun

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Chapter
9
Running a Tracy Agency
In the last part of this book we introduce you to an existing mobile agent
toolkit named Tracy and the applied programming of stationary and mobile
software agents.
We begin in this chapter with a brief introduction to the architecture of
Tracy; first the basic conceptual model, which actually consists of software
agents, services that agents can use in order to fulfill their task, and the basic
Tracy agency software that provides these services as well as hosts software
agents; then details of configuring and starting an agency and the main user
interface with which agents can be started and maintained.
Contents
9.1 Welcome to Tracy ..........................................................................327
9.2 Installation of Tracy ........................................................................332
9.3 Starting and Stopping a Tracy Agency .................................................339
9.4 Installation and Usage of Basic Plugins ...............................................340
9.1 Welcome to Tracy
We have already stated that dozens of mobile agent toolkits have been devel-
oped over the last few years. Although this number reflects an enormous
research output by different groups all over the world, it also reveals the
premature status of research and the lack of coordination between projects.
Today’s mobile agent toolkits are almost all stand-alone software systems
unable to communicate with each other, and sometimes not more than
prototypes tailored to a specific research issue.
328 Chapter 9 Running a Tracy Agency
Current Status of Mobile Agent Toolkits
This is a result of the lack of any reference architecture for agencies for mobile
agents as well as the absence of an open and extendable implementation.
Therefore, each research group has to develop its own prototype. Because
of the complexity of developing a prototype and limited resources of the
research groups, this prototype is more a proof-of-concept implementation
focusing on a single research issue and leaving out the elementar y functional
components necessary for a full mobile agent toolkit. The research commu-
nity has to admit that such a reference architecture has been developed in
the area of distributed ar tificial intelligence in the form of the FIPA standard
[O’Brien and Nicol, 1998], for which a widely used implementation exists as
the Jade toolkit [Bellifimine et al., 2003].
We also face disparate perceptions of basic concepts of mobile agents, for
example:
What should a mobile agent be from the programmers point of view: an
object of a specific type, which defines several basic functions for mobile
agents like communication and migration, or just any serializable object?
What level of communication is necessary: a simple one between agents
residing at the same agency or a complex one which also allows for
remote communication?
What level of security is necessary: one that protects hosts against only
malicious agents, or is it necessary to protect agents against malicious
agencies too?
What kind of mobility is necessary?
The disadvantageous consequence of these isolated islands of research is that
findings cannot be transferred between projects in the form of definite imple-
mentations (e.g.,software components that could be installed inothermobile
agent toolkits). Sometimes even the general research idea cannot be adapted
to another mobile agent toolkit because of the differences in basic concepts,
as previously described. Another deficit is the number of different migra-
tion protocols that currently exist. Except for two toolkits (i.e., Aglets and
Grasshopper) that suppor t the MASIF migration protocol proposed as OMG
standard in 1998, it is virtually impossible to make two toolkits interoperable.
Although the MASIF standard provides a common migration protocol,
because of its complexity (which makes it difficult to implement the complete

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