@metamask/json-rpc-middleware-stream

What is @metamask/json-rpc-middleware-stream?

@metamask/json-rpc-middleware-stream is a package that provides middleware for JSON-RPC communication over streams. It is particularly useful for building applications that need to handle JSON-RPC requests and responses in a streaming context, such as browser extensions or other environments where communication between different contexts is required.

What are @metamask/json-rpc-middleware-stream's main functionalities?

Creating a JSON-RPC Stream

This feature allows you to create a JSON-RPC stream middleware and integrate it with a JSON-RPC engine. The stream can then be used to send and receive JSON-RPC messages.

const { createStreamMiddleware } = require('@metamask/json-rpc-middleware-stream');
const { createEngineStream } = require('json-rpc-engine');
const { JsonRpcEngine } = require('json-rpc-engine');

const engine = new JsonRpcEngine();
const streamMiddleware = createStreamMiddleware();

engine.push(streamMiddleware.middleware);
const stream = createEngineStream({ engine });

// Now you can use the stream for communication
stream.on('data', (data) => {
  console.log('Received data:', data);
});

stream.write({ id: 1, jsonrpc: '2.0', method: 'eth_blockNumber', params: [] });

Handling JSON-RPC Requests

This feature demonstrates how to handle JSON-RPC requests using the middleware. In this example, the middleware responds to the 'eth_blockNumber' method with a mock block number.

const { createStreamMiddleware } = require('@metamask/json-rpc-middleware-stream');
const { JsonRpcEngine } = require('json-rpc-engine');

const engine = new JsonRpcEngine();
const streamMiddleware = createStreamMiddleware();

engine.push(streamMiddleware.middleware);

engine.push((req, res, next, end) => {
  if (req.method === 'eth_blockNumber') {
    res.result = '0x10'; // Example block number
    end();
  } else {
    next();
  }
});

const stream = streamMiddleware.stream;

stream.on('data', (data) => {
  console.log('Received data:', data);
});

stream.write({ id: 1, jsonrpc: '2.0', method: 'eth_blockNumber', params: [] });

Other packages similar to @metamask/json-rpc-middleware-stream

json-rpc-engine

json-rpc-engine is a framework for building JSON-RPC middleware stacks. It allows you to create a series of middleware functions that can process JSON-RPC requests and responses. Compared to @metamask/json-rpc-middleware-stream, json-rpc-engine focuses more on the middleware stack itself rather than the streaming aspect.

web3-provider-engine

web3-provider-engine is a tool for composing Ethereum provider middleware using a JSON-RPC engine. It is commonly used in Ethereum dApps to handle various provider-related tasks. While it also deals with JSON-RPC, it is more specialized for Ethereum and includes additional features for managing provider connections and caching.

README

@metamask/json-rpc-middleware-stream

A small toolset for streaming JSON RPC data and matching requests and responses. Made to be used with @metamask/json-rpc-engine.

Installation

yarn add @metamask/json-rpc-middleware-stream

or

npm install @metamask/json-rpc-middleware-stream

Contributing

This package is part of a monorepo. Instructions for contributing can be found in the monorepo README.