KivaKit 1.2 adds seamless support for AWS Lambda. Lambdas for REST and GRPC can be added to a KivaKit Microservice without alteration (which will make this a short article).
Creating a Lambda
We have already seen a KivaKit request handler for REST in the Microservices article. We will simply reuse this code as our Lambda request handler. As a reminder the code from that article looks like this:
@OpenApiIncludeType(description = "Request for divisive action")
public class DivisionRequest extends BaseMicroservletRequest
{
@OpenApiIncludeType(description = "Response to a divide request")
public class DivisionResponse extends BaseMicroservletResponse
{
@Tag(1)
@Expose
@OpenApiIncludeMember(description = "The result of dividing",
example = "42")
int quotient;
public DivisionResponse()
{
this.quotient = dividend / divisor;
}
public String toString()
{
return Integer.toString(quotient);
}
}
@Tag(1)
@Expose
@OpenApiIncludeMember(description = "The number to be divided",
example = "84")
private int dividend;
@Tag(2)
@Expose
@OpenApiIncludeMember(description = "The number to divide the dividend by",
example = "2")
private int divisor;
public DivisionRequest(int dividend, int divisor)
{
this.dividend = dividend;
this.divisor = divisor;
}
public DivisionRequest()
{
}
@Override
@OpenApiRequestHandler(summary = "Divides two numbers")
public DivisionResponse onRequest()
{
return listenTo(new DivisionResponse());
}
@Override
public Class<DivisionResponse> responseType()
{
return DivisionResponse.class;
}
@Override
public Validator validator(ValidationType type)
{
return new BaseValidator()
{
@Override
protected void onValidate()
{
problemIf(divisor == 0, "Cannot divide by zero");
}
};
}
}Adding a Lambda Service
In a similar fashion to adding a REST service, a Lambda service is added like this:
public class DivisionMicroservice extends Microservice
{
[...]
@Override
public MicroserviceLambdaService onNewLambdaService()
{
return new DivisionLambdaService(this);
}
}The onNewLambdaService() method returns an instance of DivisionLambdaService, which extends MicroserviceLambdaService:
public class DivisionLambdaService extends MicroserviceLambdaService
{
[...]
@Override
public void onInitialize()
{
mount("division", "1.0", DivisionRequest.class);
}
}When the service is initialized, a call to the mount() method in onInitialize() is used to associate the name of our lambda and its version with the handler DivisionRequest. Nothing more is required.
Code
The code discussed above is available on GitHub:
The KivaKit Microservice API, including support for AWS Lambda, is available on Maven Central at these coordinates:
<dependency>
<groupId>com.telenav.kivakit</groupId>
<artifactId>kivakit-microservice</artifactId>
<version>1.2.0</version>
</dependency>Published on Java Code Geeks with permission by Jonathan Locke, partner at our JCG program. See the original article here: KivaKit and AWS Lambda Opinions expressed by Java Code Geeks contributors are their own. |
