Provided is a way of evaluating rules/conditions that span different domain entities against a set of disparate events from multiple sources that have occurred within a specific window or interval of time from the current time back to a specific time in the past. Events are stored in dedicated storage to enable an extended window of time to be used for multiple event evaluation. Only relevant event/rule pairs are evaluated. The system will record when an event relevant to a rule happens. When a second event that is relevant to the rule happens, the system checks the records to see if a previous relevant event had happened in the past that would cause the rule to trigger an alert. A mechanism is also provided for evaluating static state in combination with changed properties.