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system. The Master Control Agent is assigned process 0. Agents use:
if( process ID % 2 == 1
)
to determine the control agents, and the information Agents for each Control Agent use the result of
process ID / 2
to determine which information agent they will be. Figure 3 illustrates the startup
sequence for each agent and the determination of the type of agent.
Web Interface
In order to provide a mechanism for a Web server to communicate with the Agent system, a CGI
program was required to gather the data submitted by the user and send the data to the agent system.
WEBAGENT.EXE is the program developed to satisfy this requirement.
The Master Control Agent provides a socket interface that can be used to communicate with the
agent system. Described below is the process that WEBAGENT.EXE uses to send a request to the
Agent system.
•
The data from the Web forms are copied from the QUERY_STRING environment variable
•
The QUERY_STRING values are translated into an INPUTJOB structure
•
The INPUTJOB structure is translated into a string value
•
The string value containing the INPUTJOB structure is sent to the Agent system
•
WEBAGENT.EXE receives a string from the Agent system containing the result of the command
operation
•
The string received from the Agent system is translated into a Result Code and Result Message
pair
•
From the Result code and Result message pair, the Web page is built and sent back to the Web
server
WEBAGENT.EXE provides the mechanism for connecting the Web server to the agent system.
f uture Plan
The above example gives us a prototype of applying the method to the design of MASs in large applica-
tions. Here we briefly describe an ongoing project of designing an online education system. The task is
to design an infrastructure of an educational grid comprised of PC clusters and PCs in networked labs.
The barrier in front of us is the integration of various networking technologies into one client/server
model to provide a uniform lab environment for different lab activities in the form of grid services. We
use the chemical reaction model as a formal language for specifying MASs that implement the grid
services.
The system will be developed (the Design Theme) and evaluated (the Application Theme) in a
sequence of major steps in a pyramid-shaped model illustrated in Figure 2. A bottom-up strategy
will be used in the Design Theme. We will extend our grid and design lab modules using existing
toolkits, such as Globus Toolkit 4, Java, and Apache Server. The services provided by the system will
be implemented in the client/server architecture. A Java based user interface will deliver the services
on the Web. Servers will run on the clusters. Multiple servers interact with one another in the agent
based infrastructure. A formal definition of the interfaces of functional units of the system will form
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