Thread Architecture

Part 1: Illustrate in a state diagram the workings of a community exit gate with its software in place as described below. Add states and events to those mentioned, as necessary. (A diagram with more states is often much clearer than one with complicated guard conditions.) Use superstates if you wish.

The gate works as follows:

The gate is normally in state Closed.
It can be opened by the event click from a remote controller.
In response to click, the software issues the command start-open to the gate hardware.
The gate is in state Opening while it swings fully open.
When the gate is fully open, the software starts a timer and the gate enters state Opened.
After t seconds in Opened, the software attempts to close the gate.
If no obstacle is detected above a roadway sensor, the software issues the command start-close, and the gate enters state Closing.
In Closing, in response to click, the software issues the commands stop and start-open; the gate enters the state Opening.
If an obstacle is detected, the software restarts the timer; the gate remains open.
After t seconds, another attempt is made, and so forth.
When the gate is fully closed, it enters state Closed.
Unless the gate is already fully open, a power cut event causes it to open fully on back-up power.
For this, the software issues the command start-bkp-open and the gate enters Emergency Opening.
If power is restored—the event power up—in Emergency Opening, the gate reverts to how it behaves as when being opened normally.
Once the gate is fully open after a power cut, it enters state Emergency Opened.
The gate remains in Emergency Opened until the main power is restored.
When power is restored, the software closes the gate as usual unless there is an obstacle above the roadway sensor.
If an obstacle is detected, the software makes another attempt at closing after t seconds, and so forth, in the same manner as when the gate has been opened normally.
Part 2: Using the state diagram below and the event series: list the state entered and any actions taken for each of the event occurrences in the series. Event #1 occurs in state S0 and causes a transition to a different state. Event #2 occurs in that new state and so on. States can be visited more than once.

Instructions

Deliverable Length: One state diagram for Part 1 and one table for Part 2

In an essay, describe entity-life modeling in your own words.

Cover at least the following:

event sequences
event-sequence models
combining event sequences
optimal even-sequence models
building a thread architecture based on an event-sequence model
(optionally) event sequence models of subproblems

Use examples from the Chapter 4 and 5 … in the Study Guide, or come up with your own