> **Experimental** > > `@aws-cdk/aws-iotevents-alpha` is an [**experimental**](/stability) (alpha) package: its API may change in any release, without a major version bump. # DetectorModel Defines an AWS IoT Events detector model in this stack. Extends: Construct › Resource › DetectorModel Implements: IDetectorModel, IResource, IEnvironmentAware, IConstruct, IDependable - Stability: [Experimental](/cdk/api/stability.html) - Source: [`lib/detector-model.ts`](https://github.com/aws/aws-cdk/blob/v2.275.0-alpha.0/packages/@aws-cdk/aws-iotevents-alpha/lib/detector-model.ts#L99) ## Example ```ts import * as iotevents from '@aws-cdk/aws-iotevents-alpha'; import * as actions from '@aws-cdk/aws-iotevents-actions-alpha'; import * as lambda from 'aws-cdk-lib/aws-lambda'; declare const func: lambda.IFunction; const input = new iotevents.Input(this, 'MyInput', { inputName: 'my_input', // optional attributeJsonPaths: ['payload.deviceId', 'payload.temperature'], }); const warmState = new iotevents.State({ stateName: 'warm', onEnter: [{ eventName: 'test-enter-event', condition: iotevents.Expression.currentInput(input), actions: [new actions.LambdaInvokeAction(func)], // optional }], onInput: [{ // optional eventName: 'test-input-event', actions: [new actions.LambdaInvokeAction(func)], }], onExit: [{ // optional eventName: 'test-exit-event', actions: [new actions.LambdaInvokeAction(func)], }], }); const coldState = new iotevents.State({ stateName: 'cold', }); // transit to coldState when temperature is less than 15 warmState.transitionTo(coldState, { eventName: 'to_coldState', // optional property, default by combining the names of the States when: iotevents.Expression.lt( iotevents.Expression.inputAttribute(input, 'payload.temperature'), iotevents.Expression.fromString('15'), ), executing: [new actions.LambdaInvokeAction(func)], // optional }); // transit to warmState when temperature is greater than or equal to 15 coldState.transitionTo(warmState, { when: iotevents.Expression.gte( iotevents.Expression.inputAttribute(input, 'payload.temperature'), iotevents.Expression.fromString('15'), ), }); new iotevents.DetectorModel(this, 'MyDetectorModel', { detectorModelName: 'test-detector-model', // optional description: 'test-detector-model-description', // optional property, default is none evaluationMethod: iotevents.EventEvaluation.SERIAL, // optional property, default is iotevents.EventEvaluation.BATCH detectorKey: 'payload.deviceId', // optional property, default is none and single detector instance will be created and all inputs will be routed to it initialState: warmState, }); ``` ## Initializer ```ts new DetectorModel(scope: Construct, id: string, props: DetectorModelProps) ``` ## Construct Props - `description`: string = none — A brief description of the detector model. - `detectorKey`: string — The value used to identify a detector instance. **Default:** none (single detector instance will be created and all inputs will be routed to it) When a device or system sends input, a new detector instance with a unique key value is created. AWS IoT Events can continue to route input to its corresponding detector instance based on this identifying information. This parameter uses a JSON-path expression to select the attribute-value pair in the message payload that is used for identification. To route the message to the correct detector instance, the device must send a message payload that contains the same attribute-value. - `detectorModelName`: string — The name of the detector model. **Default:** CloudFormation will generate a unique name of the detector model - `evaluationMethod`: [EventEvaluation](/cdk/api/v2/docs/@aws-cdk_aws-iotevents-alpha.EventEvaluation.html) = EventEvaluation.BATCH — Information about the order in which events are evaluated and how actions are executed. When setting to SERIAL, variables are updated and event conditions are evaluated in the order that the events are defined. When setting to BATCH, variables within a state are updated and events within a state are performed only after all event conditions are evaluated. - `initialState`: [State](/cdk/api/v2/docs/@aws-cdk_aws-iotevents-alpha.State.html) (required) — The state that is entered at the creation of each detector. - `role`: [IRole](/cdk/api/v2/docs/aws-cdk-lib.aws_iam.IRole.html) — The role that grants permission to AWS IoT Events to perform its operations. **Default:** a role will be created with default permissions ## Properties - `detectorModelName`: string — The name of the detector model. - `env`: [ResourceEnvironment](/cdk/api/v2/docs/aws-cdk-lib.interfaces.ResourceEnvironment.html) — The environment this resource belongs to. For resources that are created and managed in a Stack (those created by creating new class instances like `new Role()`, `new Bucket()`, etc.), this is always the same as the environment of the stack they belong to. For referenced resources (those obtained from referencing methods like `Role.fromRoleArn()`, `Bucket.fromBucketName()`, etc.), they might be different than the stack they were imported into. - `node`: [Node](/cdk/api/v2/docs/constructs.Node.html) — The tree node. - `PROPERTY_INJECTION_ID`: string (static) — Uniquely identifies this class. - `stack`: [Stack](/cdk/api/v2/docs/aws-cdk-lib.Stack.html) — The stack in which this resource is defined. ## Methods - `applyCrossStackReferenceStrength(strength: ReferenceStrength): void` — Override the cross-stack reference strength for this resource. When set, any cross-stack reference to this resource will use the specified mechanism instead of the global default determined by the `@aws-cdk/core:defaultCrossStackReferences` context key. This is useful for selectively weakening specific references to avoid the "deadly embrace" problem without changing the app-wide default. **Parameters** - `strength` — - The reference strength to use for this resource. - `applyRemovalPolicy(policy: RemovalPolicy): void` — Apply the given removal policy to this resource. The Removal Policy controls what happens to this resource when it stops being managed by CloudFormation, either because you've removed it from the CDK application or because you've made a change that requires the resource to be replaced. The resource can be deleted (`RemovalPolicy.DESTROY`), or left in your AWS account for data recovery and cleanup later (`RemovalPolicy.RETAIN`). - `fromDetectorModelName(scope: Construct, id: string, detectorModelName: string): IDetectorModel` (static) — Import an existing detector model. - `isConstruct(x: any): boolean` (static) — Checks if `x` is a construct. Use this method instead of `instanceof` to properly detect `Construct` instances, even when the construct library is symlinked. Explanation: in JavaScript, multiple copies of the `constructs` library on disk are seen as independent, completely different libraries. As a consequence, the class `Construct` in each copy of the `constructs` library is seen as a different class, and an instance of one class will not test as `instanceof` the other class. `npm install` will not create installations like this, but users may manually symlink construct libraries together or use a monorepo tool: in those cases, multiple copies of the `constructs` library can be accidentally installed, and `instanceof` will behave unpredictably. It is safest to avoid using `instanceof`, and using this type-testing method instead. **Parameters** - `x` — Any object. **Returns:** true if `x` is an object created from a class which extends `Construct`. - `isOwnedResource(construct: IConstruct): boolean` (static) — Returns true if the construct was created by CDK, and false otherwise. - `isResource(construct: IConstruct): boolean` (static) — Check whether the given construct is a Resource. - `toString(): string` — Returns a string representation of this construct. - `with(...mixins: IMixin[]): IConstruct` — Applies one or more mixins to this construct. Mixins are applied in order. The list of constructs is captured at the start of the call, so constructs added by a mixin will not be visited. Use multiple `with()` calls if subsequent mixins should apply to added constructs.