问题
Does anyone know the current and correct way to invoke Amazon AWS Lambda functions asynchronously instead of synchronously?
The InvokeAsync API in the AWS Java SDK is still available but marked as deprecated and they suggest you use use the Invoke API. I can't figure out why they would be forcing us to using sync. I have a web frontend that dispatches some batch jobs. I can't expect the frontend to keep a connection open for several minutes while it waits for the response (which is actually e-mailed to them after about 4-5 minutes of processing).
Ideally I'm trying to figure out how to do this with their API Endpoints rather than the Java SDK because the environment (GAE) that I'm running my backend in doesn't support AWS's use of HttpClient.
回答1:
I'm looking at the latest API docs here, and it looks like only AWSLambdaAsyncClient.invokeAsyncAsync() is deprecated. The AWSLambdaAsyncClient.invokeAsync() method is not marked as deprecated. It looks like they are just doing some code cleanup by removing the need for the InvokeAsyncRequest and InvokeAsyncResult classes and the extra invokeAsyncAsync() methods.
You should be able to use the AWSLambdaAsyncClient.invokeAsync() method which uses InvokeRequest and returns InvokeResult. You might have to set the InvocationType on the InvokeRequest to InvocationType.Event. It's not clear if that's needed if you are using the Async client.
Regarding your second question about calling Lambda functions asynchronously without using the SDK, I would look into using API Gateway as a service proxy. This is the recommended way to expose Lambda functions for asynchronous calls.
回答2:
The below code can be used to invoke the Lambda asynchronously from another Lambda
AWSLambdaAsyncClient client = new AWSLambdaAsyncClient();
client.withRegion(Regions.fromName(region));
InvokeRequest request = new InvokeRequest();
request.setInvocationType("Event");
request.withFunctionName(functionName).withPayload(payload);
InvokeResult invoke = client.invoke(request);
回答3:
Approach given in the accepted answer is now deprecated. Answer given by the user @dassum is the approach to be followed, but the answer lacks a bit of explanation.
When creating the InvokeRequest, set the InvocationType as "Event" for asynchronous invocation and "RequestResponse" for synchronous invocation.
AWSLambda lambda = //create your lambda client here
lambda.invoke(new InvokeRequest()
.withFunctionName(LAMBDA_FUNCTION_NAME)
.withInvocationType(InvocationType.Event) //asynchronous
.withPayload(payload))
Reference to docs:
https://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/com/amazonaws/services/lambda/AWSLambda.html#invoke-com.amazonaws.services.lambda.model.InvokeRequest-
来源：https://stackoverflow.com/questions/37365009/how-to-invoke-an-aws-lambda-function-asynchronously