All incoming data, i.e. data sent by devices the conditions defined with resource data event publication rules are checked.
If the condition is met, it is next checked if that condition was also met by the last received value of the resource on the same device if so no event will be raised. If not a condition-enter event will be raised.
If the condition is not met, it is next checked if that condition was met by the last received value of the resource on the same device; if so a condition-exit event will be raised. If not no event will be raised.
Due to caching e.g. in offline cases it can happen, that resource values with a timestamp t1 arrives on the Resource Data Observation Service later than resource values with a timestamp t2 (where t2 > t1). In this case the resource value for t1 will be ignored and will never trigger an enter or exit event.
