# AWS::IoTEvents Construct Library
<!--BEGIN STABILITY BANNER-->---
![cdk-constructs: Experimental](https://img.shields.io/badge/cdk--constructs-experimental-important.svg?style=for-the-badge)
> The APIs of higher level constructs in this module are experimental and under active development.
> They are subject to non-backward compatible changes or removal in any future version. These are
> not subject to the [Semantic Versioning](https://semver.org/) model and breaking changes will be
> announced in the release notes. This means that while you may use them, you may need to update
> your source code when upgrading to a newer version of this package.
---
<!--END STABILITY BANNER-->
AWS IoT Events enables you to monitor your equipment or device fleets for
failures or changes in operation, and to trigger actions when such events
occur.
## `DetectorModel`
The following example creates an AWS IoT Events detector model to your stack.
The detector model need a reference to at least one AWS IoT Events input.
AWS IoT Events inputs enable the detector to get MQTT payload values from IoT Core rules.
You can define built-in actions to use a timer or set a variable, or send data to other AWS resources.
See also [@aws-cdk/aws-iotevents-actions](https://docs.aws.amazon.com/cdk/api/v1/docs/aws-iotevents-actions-readme.html) for other actions.
```python
import aws_cdk.aws_iotevents_alpha as iotevents
import aws_cdk.aws_iotevents_actions_alpha as actions
import aws_cdk.aws_lambda as lambda_
# func: lambda.IFunction
input = iotevents.Input(self, "MyInput",
input_name="my_input", # optional
attribute_json_paths=["payload.deviceId", "payload.temperature"]
)
warm_state = iotevents.State(
state_name="warm",
on_enter=[iotevents.Event(
event_name="test-enter-event",
condition=iotevents.Expression.current_input(input),
actions=[actions.LambdaInvokeAction(func)]
)],
on_input=[iotevents.Event( # optional
event_name="test-input-event",
actions=[actions.LambdaInvokeAction(func)])],
on_exit=[iotevents.Event( # optional
event_name="test-exit-event",
actions=[actions.LambdaInvokeAction(func)])]
)
cold_state = iotevents.State(
state_name="cold"
)
# transit to coldState when temperature is less than 15
warm_state.transition_to(cold_state,
event_name="to_coldState", # optional property, default by combining the names of the States
when=iotevents.Expression.lt(
iotevents.Expression.input_attribute(input, "payload.temperature"),
iotevents.Expression.from_string("15")),
executing=[actions.LambdaInvokeAction(func)]
)
# transit to warmState when temperature is greater than or equal to 15
cold_state.transition_to(warm_state,
when=iotevents.Expression.gte(
iotevents.Expression.input_attribute(input, "payload.temperature"),
iotevents.Expression.from_string("15"))
)
iotevents.DetectorModel(self, "MyDetectorModel",
detector_model_name="test-detector-model", # optional
description="test-detector-model-description", # optional property, default is none
evaluation_method=iotevents.EventEvaluation.SERIAL, # optional property, default is iotevents.EventEvaluation.BATCH
detector_key="payload.deviceId", # optional property, default is none and single detector instance will be created and all inputs will be routed to it
initial_state=warm_state
)
```
To grant permissions to put messages in the input,
you can use the `grantWrite()` method:
```python
import aws_cdk.aws_iam as iam
import aws_cdk.aws_iotevents_alpha as iotevents
# grantable: iam.IGrantable
input = iotevents.Input.from_input_name(self, "MyInput", "my_input")
input.grant_write(grantable)
```