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Ch55-I044963.fm Page 275 Tuesday, August 1, 2006 9:39 PM
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Figure 4: Overall Structure of the Implementation

database, (2) calculating certain expression and store the result inside and (3) sending message to
some client agents.

The Glue Logic is designed to make building manufacturing work-cell control systems easy and
flexible, and also coordinates agents by means of followings;
• Providing field of coordination
• Implementing shared data space among agents
• Virtualizing agents within the shared data name space
• Controlling message passing among agents
• Implementing mutual execution primitives
• Prompting agents to start processing
• Adapting control systems to real-time and network processing environment
As the Glue Logic supports event notification and condition monitoring features based on active
database scheme, users can easily build real-time and event-driven application agents, only waiting
for notification messages from the Glue Logic.

Each agents in an application system can be developed concurrently, and can be added, deleted
or changed freely without modifying other existing agents. As the result of these, the Glue Logic
compliant agents are easy to re-use, and the users can build large libraries of application agents.

In this implementation, the flow of its data processing is as follows.
1. When a WIP reaches a gate, or when a due time of a demand changes, the corresponding
agent is activated via a CGI for the WWW user interface. These agents updates the actual
achievement records for WIPs or the due time requirement records for demands. These records
are kept in the shared data space in the Glue Logic.
2. When shared data is changed, some messages are sent from Glue Logic to agents which is going
to handle the data items. This time, the agents keeping preceding lists or priority lists are
informed, and update those contents.
3. When the contents of preceding lists or priority lists are changed, the notification message is
sent to the allocation agent. The allocation agent reads preceding lists and priority lists, and
then makeup associations between demands and WIPs.

5 EVALUATION

We implement whole system on a Sun Netra Tl processor running on Solaris 8 operating system.
Through this implementation, we found following performance considerations.