Question 18345 in Amazon Web Sevices Question posted in
The official Amazon Web Services documentation can be found here.

AWS CDK: Find out what exact type a parsed apigateway integration is (mock, http, lambda, awsservice) – Amazon Web Sevices

I am reading existing cloudformation and want to read method integrations. The return type of CfnMethod.getIntegration() is "class software.amazon.jsii.JsiiObject". I understand there are 3 different types of Integrations, all extending Integration class. I tried to first cast it to Integration, thinking I would be later able to check if the type of it really is http,aws or lambda integration. But the first step failed:
class software.amazon.jsii.JsiiObject cannot be cast to class software.amazon.awscdk.services.apigateway.Integration
Where is my thinking flawed? How do I get the info about what kind of an integration it is? To make it weirder this is in the apigateway integration in the docs:

    software.amazon.awscdk.services.apigateway
        Class HttpIntegration
            java.lang.Object
                 software.amazon.jsii.JsiiObject
                     software.amazon.awscdk.services.apigateway.Integration
                         software.amazon.awscdk.services.apigateway.HttpIntegration

I expected to be able to cast the JsiiObject into an Integration. Result: unable to cast (fails at "Integration" line).

public static void execute(HolderForAWSState holderForAWSState){
        List<CfnMethod> work = new ArrayList<>();
        for (IConstruct worker : holderForAWSState.getOrderedConstructs().get(CfnMethod.class)) {
            work.add((CfnMethod) worker);
        }
        for(CfnMethod worker: work){
        System.out.println("Integration class: ");
        System.out.println(worker.getIntegration().getClass());
        Integration integration = (Integration) worker.getIntegration();
        System.out.println(integration.getClass());
        }
    }
Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    One colleague of mine decided 2 hours with me on this problem is worth it.

    We played using an existing CfnMethod worker:

    JsiiObject jsiiObject = (JsiiObject) worker.getIntegration(); System.out.println(jsiiObject.$jsii$toJson());

    outcome:

    {"$jsii.byref":"Object@10049","$jsii.interfaces":["aws-cdk-lib.aws_apigateway.CfnMethod.IntegrationProperty"]}

    How come? So why isn't this method called "getIntegrationProperty()"? Maybe if I cast to it? IntegrationProperty intProp = (IntegrationProperty) worker.getIntegration();

    outcome:

    class software.amazon.jsii.JsiiObject cannot be cast to class software.amazon.awscdk.services.apigateway.CfnMethod$IntegrationProperty

    ????????

    After 1 more hour of fumbling around we found out, that the cast is not a direct one, but for whatever reason considered "unsafe" and requires a special static method from a special class, that of course is nowhere documented: IntegrationProperty integrationProp = UnsafeCast.unsafeCast(jsiiObject, IntegrationProperty.class);

    Worked like a charm. All Integration Property methods are accessible. Example:

    System.out.println(integrationProp.getClass()); System.out.println(integrationProp.getType());

    outcome:

    class software.amazon.awscdk.services.apigateway.CfnMethod$IntegrationProperty$Jsii$Proxy AWS_PROXY

    Thanks Simun!


  2. 0

    CDK is not implemented in Java and doesn’t follow any class hierarchies for that matter. CDK is implemented in Typescript and a Java Wrapper provides the interface for it. The core is still running typescript even when running from Java.

    A JsiiObject is a proxy for the corresponding Typescript object and as far as I can see CDK doesn’t provide support for investigating the type hierarchy comfortably from Java.

    I assume that the Integration is created by the CDK itself and not by user code.

    Unfortunately I don’t see a valid, non-hacky way to achieve this and you might need a completely different solution.

    For example use the AWS API to inspect the deployed CDK stack or extract the necessary information from the proxy yourself.

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