Managing Collection of Events
In addition to performance metrics, webMethods API Gateway can also log event data. Event data supplies information about activities or conditions that occur on API Gateway.
API Gateway logs two basic kinds of events: 1) data relating to the operation of API Gateway itself and 2) data relating to the execution of virtual services.
The event data that API Gateway collects about itself are referred to as lifecycle events. These events represent activities or conditions that occur during the general operation of API Gateway. Lifecycle events are reported for the completion of significant processes (for example, API Gateway server start-up and shut down). API Gateway logs lifecycle events if you configure it to do so.
API Gateway collects the following types of event data relating to the execution of virtual services. Be aware that API Gateway does not collect this type of information automatically. If you want to capture these types of events, you must deploy run-time policies to do so:
Transaction Events report information about the requests that the
API Gateway processes. This type of event is produced by the execution of a logging action in a run-time policy. For example, you might configure a run-time policy to log all of the request and response messages submitted to a particular virtual service.
Monitoring Events report transgressions relating to performance metrics. This type of event is produced by the execution of a monitoring action in a run-time policy. For example, you might configure a run-time policy to report occasions when the response time for a virtual service exceeds a specified threshold.
API Gateway publishes event data as Simple Network Management Protocol (SNMP) traps. When you install API Gateway, you can configure it to publish this data to CentraSite, to another third-party SNMP server or to both. If you select to log event data to CentraSite, you can view the events using CentraSite Business UI.
Like the performance log, the event log grows larger over time. If it becomes very large, queries to the log causes performance issues with CentraSite. To manage the size of the event log, we suggest that you occasionally purge old entries from it. As a general guideline, consider maintaining only three months of event data in the log. (Adjust this recommendation as necessary to accommodate your particular needs. If you routinely log request and response messages, for example, you might need to purge more often.)
You can configure CentraSite's log-purging utility to purge the event log on a scheduled basis. When you configure the purging facility, you can specify whether you want to delete the purged entries or export them to an archive file (in case you want to retain them for future reference).