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NanoPack

RPC with NanoPack

NanoPack has built-in support for performing RPC. This is an overview of how to define an RPC service in NanoPack.

Defining a Service

Let’s define a service that performs basic arithmetic. First, create a schema file called MathService.np.yml, then add the following:

MathService.np.yml
service Math:

This declares a new service called Math. Inside this block is where you declare remote functions that can be called through the Math service. Let’s define an add function that takes in two 32-bit integers and returns a 32-bit integer:

MathService.np.yml
service Math:
  # adds a and b together
  fn add(a int32, b int32): int32

Now, we can do the same for subtraction:

MathService.np.yml
service Math:
  # adds a and b together
  fn add(a int32, b int32): int32


  # subtracts b from a (a - b)
  fn subtract(a int32, b int32): int32

Pretty straightforward, right? To run codegen on this schema, run nanoc like how you would for regular message schemas:

Terminal window
nanoc --language=swift MathService.np.yml

This will create a MathService.np.swift, which will contain two classes:

  • MathSerivceServer acts as an RPC server, handling and responding to incoming RPC requests.
  • MathServiceClient acts as an RPC client, providing callable functions that you defined in the schema that makes RPC requests to the server behind the scene.

Parameter and Return Types

You can use any valid NanoPack type as parameter type as well as return type, including messages that you define, as long as their schemas are processed together.

Void Functions

To declare a function that returns nothing, omit the return type:

fn myVoidFunction(param string, param2 MyMessage):