IGUANA Gateway Services:

As denoted above, the IGUANA gateway implements several services. The key to these services is an event processor, which triggers so-called ``actions'' if certain ``criteria'' are met. Criteria and actions are defined with a special language, called ``Event Language''. If a certain event is triggered, for instance by the gateway boot, or when a certain time has elapsed, the event processor checks if user defined conditions are met, such as if a datapoint value has changed, or is greater or less than another datapoint value. If the condition is met, an action is executed, such as logging, or sending an asynchronous notifications via SMTP or SNMP. This procedure is depicted in figure 41. Further references can be found in [PRA01] and [LOB02].

Figure 41: IGUANA Event Processor

The following actions are currently implemented:

Logging:

This action logs a datapoint value in a specified encoding with an according timestamp and a text message. The number of log entries are defined when the event is created. In case the log is full, oldest entries are discarded. Log entries are always associated to events and may be retrieved from the ESD.

Datapoint Write:

The Datapoint Write action may be used to write predefined values to certain datapoints.

Asynchronous Notifications:

In the case of this action, an asynchronous notification, such as an E-Mail or an SNMP-Trap can be sent to a previously specified destination.