The RPC subsystem is where the common framework for handling incoming JSON requests is implemented. Currently the NextGen RPC framework is a work in progress and the handlers are not yet implemented using the new common framework classes.

Integration plan

Implement base framework - done
Migrate handlers one by one, making them injectable, adding unit-tests - in progress
Integrate all new handlers into clio in one go
Cover the rest with unit-tests
Release first time with new subsystem active

Components

See common subfolder.

AnyHandler: The type-erased wrapper that allows for storing different handlers in one map/vector.
RpcSpec/FieldSpec: The RPC specification classes, used to specify how incoming JSON is to be validated before it's parsed and passed on to individual handler implementations.
Validators: A bunch of supported validators that can be specified as requirements for each FieldSpec to make up the final RpcSpec of any given RPC handler.

Implementing a (NextGen) handler

See unittests/rpc for exmaples.

Handlers need to fulfil the requirements specified by the Handler concept (see rpc/common/Concepts.h):

Expose types:
- Input - The POD struct which acts as input for the handler
- Output - The POD struct which acts as output of a valid handler invocation
Have a spec() member function returning a const reference to an RpcSpec describing the JSON input.
Have a process(Input) member function that operates on Input POD and returns HandlerReturnType<Output>
Implement value_from and value_to support using tag_invoke as per boost::json documentation for these functions.