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3 Triggers
Vis?o geral
As triggers s?o express?es l¨®gicas que analisam os dados coletados pelos itens e representam o estado do sistema em rela??o aos mesmos.
Enquanto os itens s?o utilizados para coletar dados, ¨¦ impens¨¢vel esperar que algu¨¦m tenha tempo para analisar manualmente todos os valores coletados para alertar sobre desvios e limites. O trabalho de analisar os dados deve ser deixado a cargo das express?es das trigger.
Uma express?o de trigger permite definir um limite aceit¨¢vel de dados. Logo, quando o dado recebido fugir do limite aceit¨¢vel a trigger ser¨¢ acionada, mudando seu estado para "INCIDENTE".
Uma trigger pode ter os seguintes estados:
| Valor | Descri??o |
|---|---|
| OK | Este ¨¦ o estado normal de uma trigger. Em vers?es anteriores do Áú»¢¶Ä²© era chamado de "FALSE/FALSO". |
| INCIDENTE | Normalmente indica que algo ocorreu. Por exemplo, o "load de CPU" est¨¢ muito alto. Em vers?es anteriores do Áú»¢¶Ä²© era chamado de "TRUE/VERDADEIRO". |
O estado de uma trigger (a express?o) ¨¦ recalculada toda vez que o Áú»¢¶Ä²© Server recebe um novo valor que afete a express?o.
Se fun??es baseadas em tempo (nodata(), date(), dayofmonth(), dayofweek(), time(), now()) forem utilizadas na express?o, o estado da trigger ser¨¢ recalculado a cada 30 segundos pelo processo de timer do Áú»¢¶Ä²©. Se forem utilizadas fun??es baseadas em tempo e fun??es normais, a trigger ser¨¢ recalculada quando receber um novo valour E a cada 30 segundos.
Voc¨º pode obter maiores detalhes atrav¨¦s do manual de constru??o de express?es de trigger.
Calculation time
A trigger is recalculated every time Áú»¢¶Ä²© server receives a new value that is part of the expression. When a new value is received, each function that is included in the expression is recalculated (not just the one that received the new value).
Additionally, a trigger is recalculated each time when a new value is received and every 30 seconds if time-based functions are used in the expression.
Time-based functions are nodata(), date(), dayofmonth(), dayofweek(), time(), now()); they are recalculated every 30 seconds by the Áú»¢¶Ä²© history syncer process.
Evaluation period
An evaluation period is used in functions referencing the item history. It allows to specify the interval we are interested in. It can be specified as time period (30s, 10m, 1h) or as a value range (#5 - for five latest values).
The evaluation period is measured up to "now" - where "now" is the latest recalculation time of the trigger (see Calculation time above); "now" is not the "now" time of the server.
The evaluation period specifies either:
- To consider all values between "now-time period" and "now" (or, with time shift, between "now-time shift-time period" and "now-time_shift")
- To consider no more than the num count of values from the past, up to "now"
- If there are 0 available values for the time period or num count specified - then the trigger or calculated item that uses this function becomes unsupported
Note that:
- If only a single function (referencing data history) is used in the trigger, "now" is always the latest received value. For example, if the last value was received an hour ago, the evaluation period will be regarded as up to the latest value an hour ago.
- A new trigger is calculated as soon as the first value is received (history functions); it will be calculated within 30 seconds for time-based functions. Thus the trigger will be calculated even though perhaps the set evaluation period (for example, one hour) has not yet passed since the trigger was created. The trigger will also be calculated after the first value, even though the evaluation range was set, for example, to ten latest values.