AF TagEventListener

The AF TagEventListener activity publishes notification messages each time values of the tags that you listen to are changed. Therefore, by using this activity, you can listen to tag updates and fetch the changed entries.

General

In the General tab, you can specify the name of the activity in the process, establish a connection to the PI AF server, select the tags to listen to, and define how often the tag updates are to be checked.

The following table lists the fields in the General tab of the AF TagEventListener activity:
Field Module Property? Description
Name No A unique name of the activity in a process.
Server Connection Yes The PI AF shared resource selected to connect to a PI AF server.

Click the icon to select an OSIsoft PI System AF connection resource. If no matching OSIsoft PI System AF connection resource is found, click Create Shared Resource to create one.

Polling Interval (milliseconds) Yes The polling interval of publishing, which specifies how often in milliseconds the tags in the Tag List are checked for value updates.
Tag List No The list of tags that you listen to:
  • Add: inserts a new row at the bottom of the list, in which you can type the name of the tag to listen to.
  • Remove: deletes a selected row in the list. When the table is empty, this button is disabled.
  • Add Tags From File: quickly adds multiple tags into the list at a time by loading a .txt or .csv file encoded in ASCII with one tag name per row.

If the tags you listen to do not exist in the PI server, warning messages are displayed in the Console view at run time.

Description

In the Description tab, you can type a short description for the AF TagEventListener activity.

Advanced

In the Advanced tab, you can specify the object class of the entry that you want to search for.

The following table lists the fields in the Advanced tab of the AF TagEventListener activity:
Field Module Property? Description
Sequence Key No This field contains an XPath expression that specifies the order in which the process runs. Process instances with sequencing keys that have the same value are executed sequentially in the order in which the process instances were created.
Custom Job Id No This field contains an XPath expression that specifies a custom job ID for the process instance. This ID is displayed in the TIBCO Administrator View Service dialog, and it is also available in the $_processContext process variable.

Conversations

A conversation represents two or more related message exchanges in the same process that are correlated by the BusinessWorks engine. In the Conversations tab, you can initiate a conversation by clicking the Add New Conversation icon .

For more information about how to use conversations, see TIBCO ActiveMatrix BusinessWorks Application Development.

Output

In the Output tab, you can find the published changes of the tag values.

Note: All the time is in UTC time zone.
The changes of the tag values are displayed under the following output items:
Output Item Data Type Description
header Complex The response message header.
serverName String The name of the PI server that stores the tag.
tagList Complex The tag value that is changed.

For descriptions of all the attributes in the previous three items, see Attributes in the Output Items.