What data is sent to the target?

After you configure when a message is sent, then specify what type of data is sent. For each property, you can select from a list of Value Options.

Note: For the key-based scenarios, the type of data that triggers the message (archive or snapshot) is separate from the data that actually gets sent to the target. For example, you can specify that a change to the snapshot data of a key triggers the message. However, you can specify that the archive value of the key (not the snapshot value) is sent to the target. In the screen shot below, Value is selected for the Zone1.Capacity property.

The following scenarios describe the conditions under which a message is triggered.

• Scenario 1: Interval data

• Scenario 2: Any key change of archive data triggers a message

• Scenario 3: Any key change of snapshot data triggers a message

In each situation, the properties can be configured with a different value choice. The scenarios describe the effect of configuring the properties with the Value, Last Recorded Value, and Snapshot choices.

Scenario 1: Interval data

Interval data is sent at specified intervals. In the following example, t1 and t4 mark the beginning and end of the time interval. The message time stamp is the time at t4. The data that is sent depends on the value choice selected for the property:

• If the property is configured for Snapshot Value, then the snapshot value at t3 is sent with the t4 time stamp. (1)

• If the property is configured for Last Recorded Value, then the last recorded value before the message time stamp is sent, in this example, the archive value at t2 is sent with the t4 message time stamp. (2)

• If the property is configured for Value, then the archive and snapshot values in the time interval are used to calculate the interpolated value at t4. (3)

Scenario 2: Any key change of archive data triggers a message

When a snapshot value comes in at t3, it triggers the snapshot value at t2 to be archived (at t2). The archive value at t2 triggers the message and the time stamp is t2. The following illustration shows what data is sent to the target depending on the value choice selected:

• If A is configured for Last Recorded Value data, then the archive value at t2 is sent (1).

• If A is configured for Value data, then the interpolated value at t2 is sent (1).

Similarly, the data that is sent for property B depends on how it is configured:

• The Last Recorded Value is the first value in the PI Data Archive prior to or at the message time stamp (t2). In this example, if B is configured for Last Recorded Value, then the archive value which is the first value prior to t2 is sent (2).

• If B is configured for Value data, then the data is interpolated at t2 using the archive value at t1 and the snapshot value at t3 (3).

Scenario 3: Any key change of snapshot data triggers a message

A change to the snapshot value of any of the keys triggers a message. In this example, the message is triggered off of Key A. Snapshot data for Key A triggers a message at t3 and the message time stamp is t3. The snapshot value at t3 is returned for Key A (1).

Key B is not selected as a triggering key. The values for a second key, Key B, are determined by its configuration:

• If Key B is configured for Last recorded value, then the archive value at t1 with the t3 message time stamp is sent. (2)

• If Key B is configured for Snapshot value, then the snapshot value at t2 is sent with the t3 message time stamp. (3)

• If Key B is configured for Value, then the interpolated value at t3 is sent with the t3 timestamp. (4)

If you select the option, Trigger a message when all of the selected key values have changed, then there must be a change to all keys before a message is triggered. Snapshot values are returned for all selected keys, and the time stamp of the last key to return a snapshot value is the message time stamp.

Previews of streaming view data

Previews of the data always show archive values. Therefore, if the result of the message trigger settings is that snapshot data is sent to the target, this snapshot data does not appear in the preview. You will see archive values.

Out-of-order data

Key-triggered streaming views will not trigger a message on an event that has a time stamp prior to the last event's time stamp.