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uses NetLogo 3.1.5
requires Java 5 or newer
(system requirements)

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WHAT IS IT?

This model is a simulation of Enterprise JavaBean (EJB) creation and execution on WebLogic.

HOW IT WORKS

The model starts with cluster-size servers and initial-beans and initial-threads on each server. For each iteration tx-volume transactions are simulated using the following algorithm:

* Select the next server (round robin).
* Calculate a random transaction duration between 1 and max-duration.
* If more than 90% of the threads are active, create threads-increase threads (overflow).
* Activate a thread that will live for the transaction duration.
* If no beans are idle, create a bean.
* Activate a bean that will live for the transaction duration.

After the transactions are run:

* Beans and threads that have been active for their transaction durations are deactivated.
* Beans that have been idle for more than 600 ticks are killed.

HOW TO USE IT

Set the initial conditions using the sliders. Press "go" to run the model continually. Press "step" to run one iteration.

World & View:

* Shapes: circles = servers, small triangles = threads, dots = beans (EJBs)
* Colors: red = active, green = idle, orange = thread overflow
* Server Labels: <beans>:<active>,<idle>|<threads>:<active>,<idle>|<threads-added>

Sliders:

* tx-volume - transaction volume (rate)
* max-duration - maximum transaction duration
* initial-beans - initial beans to create on each server
* initial-threads - initial threads to create on each server
* cluster-size - number of servers

Buttons:

* setup - Create servers, initial threads, and initial beans.
* go - Run tx-volume transactions forever.
* step - Run tx-volume transactions for one iteration (tick).

Monitors:

* tx-count - number of transactions run
* ticks - simulated seconds

CREDITS AND REFERENCES

Model created by Thornton Rose (thornton@rosesquared.org)

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