Recommended way to handle REST parameters in Spring cloud function

Question

I really like the way Spring cloud function decouples the business logic from the runtime target (local or cloud) and makes it easy to integrate with serverless providers.

I plan to use SCF with AWS Lambda behind an API gateway to design the backend of a system.

However, I am not completely clear on what is the recommended way to handle REST related parameters such as Query params, headers, path etc. inside the Spring cloud functions. As per our initial analysis, we could derive two possible approaches:

When enabling “Lambda proxy integration” in API Gateway, Query params and other information are available as Message headers inside the SCF.
We can use “Mapping templates” in API Gateway to map all the required information into a JSON body and deserialize as a POJO to take input directly into the SCF. This way, the SCF does not need to bother about how the required data is passed to the API.

What is the recommended way to achieve this? Are we missing something that enables to do this in a better way?

Hey Saikat, I am on the same boat and wondering if you have managed to build REST API with SCF and it would be super helpful if you have a reference repo/article in order to build in this approach — Rakesh Mothukuri, Mar 19 '21 at 07:32
@RakeshMothukuri I did not find a suitable article. But I implemented what Dave Syer suggested as an answer. Works pretty well. — Saikat Gupta, Mar 19 '21 at 15:20

score 0 · Answer 1 · answered Sep 01 '20 at 15:38

I don't think you are missing anything featurewise, except perhaps that it might also be convenient to work with composite functions - e.g. marshal|transform, where marshal is a Function<Message<?>, ?> and transform is the business logic. The marshal function could be generic (and convert to some sort of canonical form), and be provided as an autoconfiguration in a shared library (for instance).

Recommended way to handle REST parameters in Spring cloud function

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