Rule

As introduced in general concepts, a rule is a tool that you can use to monitor your assets and be notified of abnormal situations or events. Senfi can send you email, SMS or notify your operators in the dashboard when, for example, a Fire is detected in a building, a Lift has broken down, or when a Machine is overdue for maintenance. Rule is the tool you can use to configure these notifications.

A rule in Senfi comprises of:

• Inputs - Metric & Tag values
• Conditions
• Output - True or False, a Boolean value
• Actions - Do something when Output changs. e.g. email
• Rule execution options - Configures when a Rule is evaluated

Inputs are evaluated by Conditions to generate a single boolean Output. When value of Output changes, Actions, such as email and dashboard alerts, are executed. Rule execution options allows you to configure how the Rule is executed. e.g: how often the Rule is evaluated, when to execute Actions etc.

 Inputs --> Conditions --> Output

 Output Changed --> Actions

Example

• Input: iot_weighingscale_v1.battery_level
• Condition: < 20
• Action: Email reminder to replace battery
• Rule execution option: Immediately (means evaluate this rule whenever there is any incoming measurement)

Inputs, Conditions and Output

Before adding a Rule, you should already have an event or situation that you wish to be notified about. The event or situation should be one that can be detected by monitoring data received by Senfi.

Select, as Inputs, the Metrics and Measurements from which the event or situation can be detected from. Then, construct the set of Conditions that will evaluate to true when event or situation occurs. The result of said Conditions is the Output of the Rule.

Actions

Whenever Output changes (from true to false and vice versa), Actions may be executed. Actions includes sending an email, sms, request to a webhook or triggering an alert in the dashboard.

Content of Actions

Depending on the Action, different content options are available. Some examples is the title & body of an email, message text for SMS, and body content for webhook request. You will be able to describe the event or situation that has happened to the recipient of the notification in the content of an Action

To further aid you in describing the event, you can embed the value of an Input in the content of an Action. To learn how to embed, take a look at this example

Rule execution options

By setting Evaluate Type to Immediate or Polling, you can choose to execute a Rule when new values are received for any Input Measurements, or periodically, regardless of whether any Input Measurements have changed.

If Rule is set to run periodically (Polling), you must specify how often a Rule is executed by setting Intervals in seconds.

Detailed Example

The event that you would like to be notified about is potential fire in a building. There are temperature sensors throughout the building. When a reading from any temperature sensor exceeds 60°C, a fire has probably broken out near the sensor. You would like to be notified by email of such an occurrence.

• The Input in this example would be the metric and measurement that readings from temperature sensor is sent to. e.g: iot_temperature_sensor_v1.temperature
• Condition is iot_temperature_sensor_v1.temperature > 60
• Action is email, with body text:

"Potential fire detected in room: ${iot_temperature_sensor_v1.room}. Temperature in the room is ${iot_temperature_sensor_v1.temperature}°C"

With the above Rule configured, when iot_temperature_sensor.temperature goes from 59 to 61, an email will be sent with the body text:

"Potential fire detected in room: #03-00. Temperature in the room is 61°C"

Note: "room" is a Tag of the iot_temperature_sensor_v1 measurement that indicates which room the sensor is in.

Constructing Condition

This section will guide you to construct a condition using the Editor when adding/editing a Rule in the CMS. The objective here is to tell Senfi how to detect the event or situation that you wish to be notified of.

Rule Editor

The Rule Editor is a graph based "Drag and Drop" editor. Each node in the Editor represents either an Input, Data Transformation, Logic, or an Action. Arrows are used to link the nodes and control the flow of data between nodes.

Input & Output of a node

Arrows coming into the left of a node indicates the node's input,
and arrows going out the right of a node indicates the node's output.

The graph must always start from Input nodes and ends in the Output or Action nodes (Data originates from Input nodes, is transformed by Data Transformation, Logic nodes, and is consumed by Output & Action nodes).

Input nodes

Constant - outputs a constant value. e.g: 0, 1, true, false

Metric - outputs the latest value of a metric

Input modifier nodes

Range - modifies output of "Metric" node from latest to historical values

Logic Nodes

Operator - comparison operators. e.g. <, >=, ==, !=

Logic - perform "AND" or "OR" between 2 or more boolean values

Data Transformation nodes

Filter - to be used with "Range" node. Filters input values to output a subset number of values.

Aggregate - to be used with "Range" node. Aggregates input values into a single value. E.g. sum, average, median.

Function - value-wise transformation. Transform each value, e.g ABS, Floor, Round etc. Can be used directly with a "Metric" node, or with "Range" node. Outputs the same number of values as its input.

Output node

Output - Output node. Must have 1 and only 1 node. Specifies the Output of a Rule

Action nodes

Action - Action node. Input must always be from the "Output" node. Can have 0 or more "Action" nodes. Instructs Senfi to do something when Output changes.

Basic Steps

1. Drag a node above working area into the working area to create a node.
2. Create "Metric" nodes, one for each Input metric.
3. Select the correct measurement and metric for each "Metric" node. Read: how to configure a node
4. (Optional) If you need to compare metric value against a constant value, use the "Constant" node.
5. Create "Operator" and "Logic" nodes to construct necessary logic
   • logic graph should output a single boolean (true or false) value
   • output from "Metric" node must go to input of a "Operator" node.
   • "Operator" and "Logic" nodes can be nested.
   • You can attach more than 2 inputs to a "Logic" node
6. Create a "Output" node and attach output of logic graph as its input
7. Create "Action" nodes, one for each desired Action and attach output of "Output" node as its input
8. Save when done

Example

Example 1

Example 1: A simple Rule detecting when a Lift has tripped (safetyTrip == 1).

Example 2

Example 2: Detects when a Lift tripped (safetyTrip == 1), AND passengers are trapped in the Lift (load > 0)

Working with historical values

When historical values is required to detect an event, the "Range", "Filter" and "Aggregate" nodes is needed.

By default, a "Metric" node will output the Last Known value of the metric. To obtain historical values of a metric, attach the output of "Metric" node to the input of a "Range" node. The output of the "Range" node will be historical values from the metric.

The configuration options of the "Range" node allows you to change the range of historical values to output. You can configure it to output metric values from 1 hour ago till now, or the last 10 received metric values.

After obtaining the list of historical values, you can:

• Filter the list using the "Filter" node.
• Transform each value in the list using the "Function" node.

The "Filter" and "Function" nodes can be nested.

Finally, the list of historical values must be aggregated using the "Aggregate" node before its output can be used by a "Logic" or "Operator" node.

Example using historical values

Historical Example 1

The example above detects when a Lift is stopped at Level 2 for over a minute.

Configuring Nodes

Each node contains attributes & options which you can modify. To modify the attributes of a node, move your mouse over the node and click on the "Gear" button that appears near the top right corner of the node (Beside the "X" button). A window will popup to allow you to configure the node.

Aggregate node

This section explains what each of the options for "Aggregate" node does.

sum

the sum of all input values

count

the number of input values

average

the average of input values

median

the median value of input values

max

the largest value

min

the smallest value

mode

the value that appears most often

range

the difference between the largest and smallest value (max - min)

stddev

standard deviation

percentile

percentile. This option accepts an additional "Percentile Value" parameter.

every

outputs true if every value fulfills the condition. This option accepts an addition "Condition" parameter.

any

outputs true if at least 1 value fulfills the condition. This option accepts an addition "Condition" parameter.

Function node

This section explains what each of the options in "Function" node does.

abs

absolute value

round

round to nearest integer

ceil

round up

floor

round down

map

This option accepts an additional "function" parameter. Using the custom "function" parameter, transforms each input value