Entity Life History
Event
- Special events that need to be shown on ELH's include
- Abnormal Death events (special use of quit/resume)
- Special checks on effects of death of master (cascade effects)
Effect
- Result of the occurrence of an event
- May be non-updating depending on the state of the entity
- Can use Effect qualifiers
Entity Role
- An event can affect two occurrences of an entity in two different ways, depending on their state. E.g. rescheduling of a course run. Causes deletion of existing course run and creation of new one. This is a simultaneous effect on a ELH. The role of the entity when it happens is shown in square brackets.
State Indicator
- A single byte attribute changed every time an entity is updated.
- They appear under leaves on ELH's
- Each leaf has a before end after value, starting at 1 for creation and increasing with new events.
- First and last values are null -/1
- On an iteration the valid previous indicators include the new valid indicator
- If a value is not to be changed it is an asterisk
- Quit and resume sets state value before quit
- They are the last thing to be done to an ELH.
- Why bother ?
- It can be very useful to know the state of an entity from a processing viewpoint. It explains where the entity is in its Life History and also a little of where it has been.
Please see Weaver chapter 11 for example diagrams.