Annex B (informative) Examples ToC Previous Next

B.1 Examples for Event sequences from Condition instances ToC Previous Next

B.1.3 Server maintains previous states ToC Previous Next

This example is for Servers that are able to maintain previous states of a Condition and therefore create and maintain Branches of a single Condition.

Figure B.2 illustrates the use of branches by a Server requiring acknowledgement of all transitions into Active state, not just the most recent transition. In this example no acknowledgement is required on a transition into an inactive state. Table B.2 lists the values of the state Variables. All Events are coming from the same Condition instance and have therefore the same ConditionId.

readme_files/image031.png Figure B.2 – Previous state example

Table B.2 – Example of a Condition that maintains previous states via branches

EventId BranchId Active Acked Confirmed Retain Description
a) NULL False True True False Initial state of Condition.
1 NULL True False True True Alarm goes active.
2 NULL True True True True Condition acknowledged requires Confirm
3 NULL False True False True Alarm   goes inactive.
4 NULL False True True False Confirmed
5 NULL True False True True Alarm   goes active.
6 NULL False True True True Alarm   goes inactive.
7 1 True False True True b) Prior state needs acknowledgment. Branch #1 created.
8 NULL True False True True Alarm   goes active again.
9 1 True True False True Prior state acknowledged, Confirm required.
10 NULL False True True True b) Alarm   goes inactive again.
11 2 True False True True Prior state needs acknowledgment. Branch #2 created.
12 1 True True True False Prior state confirmed. Branch #1 deleted.
13 2 True True True False Prior state acknowledged, Auto Confirmed by system Branch #2 deleted.
14 NULL False True True False No longer of interest.
a) The first row is included to illustrate the initial state of the Condition. This state will not be reported by an Event.
Notes on specific situations shown with this example:
If the current state of the Condition is acknowledged then the Acked flag is set and the new state is reported (Event #2). If the Condition state changes before it can be acknowledged (Event #6) then a branch state is reported (Event #7). Timestamps for the Events #6 and #7 is identical.
The branch state can be updated several times (Events #9) before it is cleared (Event #12).
A single Condition can have many branch states active (Events #11)
b) It is recommended as in this table to leave Retain=True as long as there exist previous states (branches).
           

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