Crate embedded_jsonrpc

JSON-RPC for Embedded Systems

This crate provides a simple JSON-RPC server implementation for embedded systems.

Features

• no_std Support: Compatible with #![no_std] environments.
• Zero Alloc: Uses statically allocated buffers and heapless containers for predictable memory usage.
• Async: Non-blocking IO with embedded-io-async.
• Varint Framing: Efficient message framing and length-prefix encoding using protobuf style varints.
• Error Handling: Includes comprehensive error codes and descriptions based on the JSON-RPC specification.

Core Components

JSON-RPC Data Structures

• RpcRequest: Represents a JSON-RPC request, including the method and optional parameters.
• RpcResponse: Represents a JSON-RPC response, including the result or error information.
• RpcError and RpcErrorCode: Encapsulate errors with standard codes and descriptions.

RPC Server

• RpcServer: Core server to manage method registration and handle incoming requests.
• Handlers: Define functions for specific RPC methods using a type-safe RpcHandler.
• serve: Processes incoming requests and sends responses over an embedded-io-async stream.

Example Usage

Create an RPC Server

use embedded_jsonrpc::{RpcServer, RpcResponse, RpcError, RpcErrorCode, JSONRPC_VERSION};

const MAX_HANDLERS: usize = 4;
const MAX_REQUEST_LEN: usize = 256;
const MAX_RESPONSE_LEN: usize = 256;

let mut server: RpcServer<'_, MAX_HANDLERS, MAX_RESPONSE_LEN> = RpcServer::new();
server.register_method("echo", |id, _request_json, response_json| {
   let response = RpcResponse {
       jsonrpc: JSONRPC_VERSION,
       id,
       error: None,
   };
   serde_json_core::to_slice(&response, response_json).unwrap()
});

Serve Requests

let mut stream: YourAsyncStream = YourAsyncStream::new();
let mut rpc_buffer = [0u8; MAX_REQUEST_LEN];
server.serve(&mut stream, &mut rpc_buffer).await.unwrap();

License

This crate is licensed under the Mozilla Public License 2.0 (MPL-2.0). See the LICENSE file for more details.

References

• JSON-RPC 2.0 Specification
• Protocol Buffers Varint Encoding
• Embedded IO Async

Modules

• varint
  Varint Encoding and Decoding Library

Structs

• RpcError
  JSON-RPC Error structure
• RpcRequest
  JSON-RPC Request structure
• RpcResponse
  JSON-RPC Response structure
• RpcServer
  RPC server

Enums

• RpcErrorCode
  JSON-RPC Standard Error Codes

Constants

• JSONRPC_VERSION
  JSON-RPC Version Currently only supports version 2.0 https://www.jsonrpc.org/specification

Type Aliases

• RpcHandler
  Type for RPC handler functions