Event

The Event tab has the following fields.

Field

Description

Candidate Event Key

Expression built from the data of the incoming file change event. This expression should evaluate to a string and it is compared to the "key" field of the activity’s input. If the Candidate Event Key and the activity’s key match, then the process accepts the incoming file change event.

For example, you may have created a file earlier in the process and you may want to wait for an external application to modify the file. When the external application modifies the file, it appends the word "Changed" to the filename to signify the file is ready for processing.

You should specify the $fileInfo/fileName for the Candidate Event Key field, and you should specify concat("$CreateFile/fileName", "Changed") for the "key" field on the Input tab. $CreateFile/filename is the name of the file created earlier in the process. This expression is specified in XPath, and only data from the incoming event is available for use in this XPath expression. For more information about XPath expressions, see TIBCO ActiveMatrix BusinessWorks™ Process Design.

Event Timeout (msec)

A file change may occur before this activity is executed. This field specifies the amount of time (in milliseconds) to wait if the file change occurs before this activity is executed in the process instance. If the event timeout expires, an error is logged and the event is discarded.

If no value is specified in this field, the message waits indefinitely. If zero is specified, the event is discarded immediately, unless this activity has already been executed.

Note: When building an expression in the Candidate Event Key field, only data from the incoming event is available. This is because you want to place an expression containing incoming event data in the Candidate Event Key field. When the results of this expression match the results of the expression in the "key" item on the Input tab, the Wait For File Change activity proceeds.