Rule Logic - Custom Logic Blocks
This page describes the Custom Logic Blocks in more detail
Last updated
This page describes the Custom Logic Blocks in more detail
Last updated
Custom Logic Blocks allow the implementation of more complex business logic with the akenza Rule Engine. They enable simple stateless and stateful operations upon rule trigger using custom scripts in Javascript. Custom Logic Blocks are created on organization-level and are therefore available in all workspaces and can be selected when creating a rule.
This webinar explains how to create Custom Rules:
A set of examples for logic blocks can be found here:
A Custom Logic Block consists of a definition of:
Inputs: the dynamic data that is evaluated during script execution (sensor data)
Parameters: constant values like thresholds
A script used to run the logic
In order to keep its usage consistent, it is not possible to edit custom logic inputs and parameters if the Custom Logic Block is assigned to an active rule.
Inputs specify the input data sources for a Custom Logic Block and contain the dynamic data of a device. At least one input needs to be defined in order to create a Custom Logic Block.
Parameters represent static properties that are available during script runtime.
The Rule logic script defines the custom logic that is evaluated during rule runs.
Once a Custom Logic Block is saved, it can be selected as a logic block when creating a rule. Inputs need to be linked to an input device or tag and parameters need to be set.
Further, one or more actions need to be defined. The templating syntax can be used to access the results of a Custom Logic Block {{result.*}}. For example, {{result.message}} for the script shown above.
There is also the possibility to emit a timer inside the custom logic block.
When emitting the timer event, two params can be specified
runAt
required, a date which needs to be at least 15 seconds in the future
meta
optional, object which can contain any values
The meta object will be available when the rule is triggered by that timer and can be accessed at timer.meta
during script run. This can provide useful information for the next timed run or help uniquely identify timers when running them.
Refer to Stateful Operations for more information on how to share data between runs of a rule.
The Custom Logic Block script is invoked with the event object as param. It contains the following properties & strucutre:
inputs
object, contains the values of the specified variables
state
object, contains the user defined rule state
type
string, indicates how the rule was invoked (either timer
or uplink
)
dataSources
object, see data source properties
device
object, see device properties
properties
object, contains the user defined properties of the custom logic block
Note: if type
has the value of timer
certain properties will behave differently:
the variable values of the inputs
object will be null
dataSources
will be an empty object
device
will be undefined
The following properties of a device can be accessed when using template syntax.
Note: The prefix device.
is always required in order to access sub properties.
name
the device name
description
the device description
integrationId
the integrationId of the device (only for LoRaWAN devices)
workspaceId
the workspaceId of the device
dataFlowId
the data flow id of the device
connectivity
the connectivity of the device
id
the akenza device id
deviceId
the unique device id
The following properties of a data source can be accessed when using template syntax.
To access a specific data source, use dataSources.X
where X
is the number of the data source as specified in the rule (starting at 1).
Some properties can be null in certain circumstances (e.g. the correlationId
or the device
) if e.g. the rule was triggered by a timer event or the data source is set to access the last sample.
Note: The prefix dataSources.X.
is always required in order to access sub properties.
correlationId
the correlation id of the data source (only available if the data source was triggering the flow)
device
the complete device object. See Device Properties for sub properties
deviceId
the unique device id
akenzaDeviceId
the akenza device id
topic
the topic of the sample
timestamp
the timestamp of the sample
data.*
access any values of the sample.
meta.*
access any values of the meta object
uplinkMeta
the complete uplink meta object
trigger
boolean, indicates whether the data source has triggered the uplink
deviceInput
boolean, indicates if the data source is a device
tagInput
boolean, indicates if the data source is a tag
The values related to the sample (namely correlationId
, topic
, timestamp
, data
, meta
and uplinkMeta
) are resolved based on which data source triggered the rule evalution. If the data source is triggering (trigger = true
) the rule, the values will be the one from the triggering uplink. Otherwise the values will correlate the most recent stored sample.
The following properties of uplink meta data can be accessed when using template syntax
Note: The prefix uplinkMeta.
is always required in order to access sub properties.
dataReceived
the ISO-8601 timestamp when the data was recieved
bytesReceived
the number of bytes received in the uplink request
processingStart
the ISO-8601 timestamp when the processing was started
scriptRunUplinkStart
the ISO-8601 timestamp when script run was started
scriptRunUplinkEnd
the ISO-8601 timestamp when script run ended
processingEnd
the ISO-8601 timestamp when the processing ended
outputProduced
the ISO-8601 timestamp when all output were produced
uplinkDuration
the ISO-8601 duration of the whole uplink flow
processingDuration
the IOS-8601 duration of the processing
scriptRunningDuration
the ISO-8601 duration of the script run
Field
Description
Input display/ label name
The input name
Input description
An optional description
Input variable name
A variable name used to access the value inside the script
Default topic
An optional default topic that is preselected when using the logic block
Default data key
An optional default data key that is preselected when using the logic block
Field
Description
Parameter display/label name
The parameter name
Parameter variable name
A variable name used to access the parameter inside the script
Parameter Type
The data type of the parameter; Numerical, String, or Boolean
Default value
A default value for the parameter