Detect Gaps
The Detect Gaps tool monitors incoming observations and reports whenever any track or tracks have exceeded the specified gap duration. Gap detection can be set to a specified interval and a gap notification is created as an output event.
Example
The following is an example use case for the tool:
In a real-time analytic, a network of smart pressure gauges reports the level of pressure every 10 seconds. A maintenance crew wants to know when any of the pressure gauges are offline and failing to report pressure information. The Detect Gaps tool can be configured with a gap duration of 30 seconds and a gap detection interval of 5 seconds. With this configuration, the Detect Gaps tool checks all known gauges every 5 seconds to determine whether any have gone more than 30 seconds without reporting pressure information.
Usage notes
Keep the following in mind when working with the tool:
A Gap duration parameter value equal to or greater than the expected interval between observations is recommended. If the gap duration is set to less than the normal expected interval, it frequently detects false gaps.
This tool only processes events with a unique track ID. A key field must be specified in the input dataset Track ID option to use this tool.
Gap detection interval-specific usage notes:
The Detect Gaps tool runs at the rate specified by the Gap detection interval parameter. This means that if the gap detection interval is set to 20 minutes, the Detect Gaps tool reviews all known tracks every 20 minutes to determine whether any have exceeded the gap duration.
The Detect Gaps tool provides Continuous or On Change notification modes for when a gap is detected.
Continuous—A gap event is created when a gap is first detected for a given track ID. An additional gap event is created at the rate specified in the Gap detection interval parameter for as long as there is an ongoing gap. A final gap event is issued when the same track ID has been observed again.
On Change—A gap event is created when a gap is first detected for a given track ID. A second and final gap event is issued when the same track ID has been observed again.
Gap duration and Gap detection interval values must be specified to identify gaps. Features missing for equal to or greater than the specified gap duration are identified as gaps. Gap detection occurs at the rate specified by the Gap detection interval parameter.
The Detect Gaps tool maintains a state store of the current observation for each track ID. When a new observation is received, it is compared to the current observation of the same track ID, if present, to determine if a gap has occurred. If the new observation has a more recent timestamp than the current observation in the state store, the current observation is replaced. If it has an identical timestamp to the current observation for the same track ID, the tool does not distinguish between the two observations. This means the tool does not replace the current observation in the state store with the new observation, the new observation is not added to the state store and future observations for this track ID are compared to the current observation that remained in the state store until a new observation arrives with a more recent timestamp. A warning is logged by the tool when this occurs.
This tool does not require geometry.
Parameters
The following are the parameters for the tool:
|
Parameter |
Description |
Data type |
|---|---|---|
|
Input layer |
The tracks that are being watched for gaps in a data stream. |
Features |
|
Gap duration |
Specifies the time window in which an observation must be received for a track. |
String |
|
Notification mode |
Specifies gap notification or gap detection methods.
|
String |
|
Gap detection interval |
Specifies how frequently events should be checked for exceeding the value specified in the Gap duration parameter. |
String |
|
Track ID fields |
Choose the field or fields to uniquely identify features to be processed. The parameter is automatically populated if a key field is set for the Track ID option on the input. |
Fields |
Output layer
The output layer from this tool has the fields and values of the incoming feature and also contains three more fields including lastReceived, IsGap, and GapDuration.
|
Field name |
Description |
Field type |
|---|---|---|
|
|
The time stamp of the most recent observation received for the track |
Date |
|
|
The current gap status: true if a gap condition exists and false if not |
Boolean |
|
|
The total elapsed time of the ongoing gap |
Integer |
Considerations and limitations
Consider the following when working with the tool:
The Gap duration parameter cannot exceed 24 hours.
The Detect Gaps tool maintains the state of a gap for a maximum of seven days.