International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B2. Istanbul 2004
affected if that node fails. The concept of an agent moving
between network nodes gives it the ability to 'survive' and to
reach as many resources as possible. This is useful for mobile
computer users due to the fact that they can log on, launch an
agent, log off and check later on its progress.
4.1.3 Peer-to-peer communication: A failure of the
client/server paradigm is the inability of servers to
communicate. Mobile agents are considered to be peer entities
and, as such, can adopt whichever stance is most appropriate to
their current needs. For example, when a mobile agent is
interrogating a resource it takes the role of a client. However,
when another mobile agent wishes to query it, then it becomes
a server. This allows for great flexibility in dealing with
network entities and distributed resources(Buehler, Kurt and
McKee, Lance, 1998).
5. DESIGNING AGENT-BASED GISERVICES USING
UML
Designing software based on UML specification. includes
several steps. First of all, system analysis and problem
definition must be respected. Our specification system is a
prototype for integrating simple GIS software in a mobile agent
framework. The problem, which thesis is challenged with, is to
transform typical GIS software as an Agent for moving to
remote address.
5.1 Analysis
Object-Oriented analysis emphasize on finding and describing
the objects or concepts. Our system is a simple prototype so it
does not need to an extended analysis. We need an interface to
invoke system, GIS system as an object. and finally a mobile
object for carrying GIS object (figure 5).
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Figure 5: Usecase diagram of the system
5.2 Finding objects, variables and methods
After usecase diagram (figure 5) and identification of scenarios,
another fundamental step is defining of class for the class
diagram. Classes are created using their instance (objects) and
their variables and methods. For receiving such goal the simple
way is to consider name
description
Using founded objects and their methods and variables now
classes can be created for each object. By this way DataLoad
class (as a interface), MapDisp class, TelAgent class and Run
Class are composed.
and verb in system functionality
5.3 Class diagram
On of the important aspect of object-oriented system is placing
objects and classes in a hierarchical form. There are various
relations in UML that programming languages like java have
not special method for visualizing it. In our system we have
two relations. First association which is simple relation
between our own created classes and also aggregation relation
which our own classes have this relation with imported classes
(figure 6).
Run «interface» 2
MapDis
DataLoad pn
TelAgent
Voyager OpenMap
Figure 6: Class diagram of the system
5.4 Description of behavior
Now we cau describe the scenarios relative to the use-case
diagram using sequence diagram .by this way behavior of agent
can be described (figure 7).
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Figure 7: Sequential diagram of the system
6. DEVELOPING PROTOTYPE
The application has been developed in Jbuilder environment.
Jbuilder is a visual environment for debugging JDK
applications .for Java application we used JDK 1.3.0 02.
Jbuilder facilities make code debugging simpler than JDK own
environment (figure 8).
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