Run-Time Behavior
- Last UpdatedJul 05, 2023
- 2 minute read
Run-time behavior pertains to the running state of a deployed ViewEngine object. The most important function of the running ViewEngine is its scheduler. The ViewEngine has a scan-based scheduler that triggers at the configured scan period, specified in milliseconds. Each scan period interval, the ViewEngine executes every object on the engine, including itself.
Since the ViewEngine object will generally host only a few ViewApp objects, you may want to reduce the ScanPeriod to minimize the latency of tag and/or attribute value updates for the hosted ViewApps.
Once deployed and operating, the ViewEngine object can assume one of the following states:
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State Change |
Behavior |
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Startup |
In this transition state, the ViewEngine object starts as a new operating system process and starts all of the objects that it hosts. Objects hosted by the ViewEngine object are:
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Going onscan |
The ViewEngine object notifies all of the ViewApp objects that it hosts that the engine has been put OnScan. |
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Going offscan |
The ViewEngine object notifies all of the ViewApp objects that it hosts that the engine is offscan (inoperative). |
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Shutdown |
The ViewEngine object shuts down as an operating system process. Before doing so, one final checkpoint is performed after all ViewApp objects hosted by the ViewEngine object are:
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