This topic explains different types of rules and how they trigger Location Awareness Services for WebSphere® Sensor Events events.
Rules define conditions and policies that need to be met. For example, rules can be used to restrict access to certain zones or to limit the amount of time an item stays in a zone. Business rules are implemented based on a generic Complex Event Processing (CEP) engine which facilitates the development of additional rule types. Events (alerts) occur when rules are violated. Events are published and saved in the event database. Subscriber programs can subscribe to Location Awareness Services for WebSphere Sensor Events events. Violations of rules related to items can also be displayed in the Spatial Management Client.
Location Awareness Services for WebSphere Sensor Events rules typically refer to the aspects of the real world as it is modeled in Location Awareness Services for WebSphere Sensor Events - items and persons equipped with tags and the topology of the location to be monitored. Some basic rule types are supported by Location Awareness Services for WebSphere Sensor Events and you can use portlet-based user interfaces to create instances of these rule types. An example of a rule type is "must not enter" whereas an example of a related rule instance is "members of the Visitor class must not enter protected zones".
When you define a rule, you can check for future events, but not for events that have already happened. This means that you cannot define an rule for conditions that have already occurred.
The following rules are related to zones and can be set and maintained in the Business Rules portlet in the WebSphere Application Server administrative console:
When a tag is considered to have entered or exited a zone is also affected by the MaxUnrecognizedMovement system property. See System Properties.
These rules check whether a visitor is accompanied in specified zones by an escort. An alert is triggered if the visitor is away from the escort for a specified amount of time. The visitor must belong to a container class, the escort must not contain a container class, and the DynamicContainerSupportOn system property must be selected. See System Properties.
When an item is in a zone longer than specified by the rule, an alert is triggered for the tag.
When a defined threshold of items in a zone is exceeded, an alert is triggered.
This rule type triggers an alert when a tag is near a base item, which must be a container item, for longer than a specified period of time.
This type of rule is called the Man Down Detection and is typically associated with a tag on a person. When a tag does not move or blink for more than a specified time interval, an alert is triggered.
The following global rule types do not have different instances, but can be customized in the System Properties portlet in the Location Awareness Services for WebSphere Sensor Events Administrative Console:
When a tag is no longer detected by the event provider, an alert is triggered. See MaxUnrecognizedMovement and TagNotResponsiveAlertAction in System Properties for more information. In addition, the tag icon fades on the Spatial Management Client.
When a tag has a low or empty battery, a BatteryLowAlert is issued. See BatteryLowAlertAction or BatteryExhaustedAlertAction in System Properties for more information. In addition, the Spatial Management Client displays a small battery icon.
When a tag is detected that is not related to a defined item, an UnknownTagAlert is generated. See UnknownTagalertAction in System Properties for more information. In addition, the Spatial Management Client displays an unknown tag icon.
If a tag that belongs to a class that is defined as stationary moves, an alert is generated. The movement must exceed the value specified in the MaxUnrecognizedMovement system property.
To avoid a flooding condition of stationary alerts, if the tag moves twice the amount of units defined in MaxToleratedMovement, then a stationary alert will be generated once every 5 minutes.