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Wait for File Change

Activity

The Wait for File Change activity waits for a file creation, modification, or deletion event to occur during process execution. When this activity is executed, the process instance suspends and waits for the specified change to occur before resuming.

See Scalability With Incoming Events in TIBCO ActiveMatrix BusinessWorks Process Design Guide for information on running the "Wait for..." activities in a multi-engine mode.

Configuration

The Configuration tab has the following fields.

Field	Global Var?	Description
Name	No	The name to appear as the label for the activity in the process definition.
Description	No	Short description of the activity.
File Name	Yes	The path and name of the file to poll for. You can use the Browse button to locate an existing file. You can also use wildcards to monitor a directory for files that match the given specification. For example, C:\files\*.log would match any change to a file in the files directory with an extension of .log.
Polling Interval (sec)	Yes	Polling interval (in seconds) to check for changes in the specified file.
Include Existing Files	Yes	Check for the file among the files that existed before the process engine started running. When this field is checked, if an existing file matches the specification in the File Name field when a process engine starts, then the Wait for File Change activity accepts that file as changed and proceeds to the next activity. If this field is not checked, any existing files that match the specification in the File Name field are ignored until there is some change in the file.
Exclude File Content	Yes	Specifies not to load the data from the file into this activity’s output. If this field is checked, the contents of the file are not available to subsequent activities in the process definition.
Content as	Yes	The type of content in the file. Can be either text or binary.
Encoding	Yes	The character encoding for the file.

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. See TIBCO ActiveMatrix BusinessWorks Process Design for more information about XPath expressions.
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.

 

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.

Input

See TIBCO ActiveMatrix BusinessWorks Process Design for more information about mapping and transforming input data.

The input for the activity is the following.

Input Item	Datatype	Description
key	string	The value that is compared to the Candidate Event Key field of the Event tab to determine if this message applies to this process. See Event for an example of using the Candidate Event Key field with the key input item.
processTimeout	integer	The time (in milliseconds) to wait for the incoming file change event. An error is returned if the event is not received in this time limit.

Output

The output for the activity is the following.

Output Item	Datatype	Description
action	string	The change in the file that occurred. The action is either the create, remove, or modify.
timeOccured	integer	The time that the Wait for File Change activity detected the change in the file. The time is expressed as the amount of time, in milliseconds since midnight, January 1, 1970, UTC.
fileInfo	complex	Element containing the fileName, location, type, readProtected, writeProtected, and size data.
fullName	string	The name of the file, including the path information.
fileName	string	The name of the file without the path information.
location	string	The path to the file.
configuredFileName	string	This element is not populated by this activity.
type	string	The file type.
readProtected	boolean	Whether the file is read-protected.
writeProtected	boolean	Whether the file is write-protected.
size	integer	Size of the file in bytes.
lastModified	string	Time stamp indicating when the file was last modified.
fileContent	complex	Element containing the textContent and binaryContent data.
textContent	string	Contents of the file (text files), if the Exclude File Contents field was not checked on the Configuration tab.
binaryContent	binary	Contents of the file (binary files), if the Exclude File Contents field was not checked on the Configuration tab.
encoding	string	The character encoding for the file.

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