http-jsonrpc-server

• http-jsonrpc-server
  • Install
  • Usage
    • Specifying a Path
    • Optional Callbacks
    • Adding/Updating Methods
    • Closing the Server
    • Basic Authentication
    • Native HTTP Server
    • Exposed Constants
  • API Documentation
  • RpcServer
    • new RpcServer(options)
    • rpcServer.setMethod(name, method)
    • rpcServer.listen(port, host) ⇒ Promise.<number>
    • rpcServer.close() ⇒ Promise.<void>
  • Sample Requests
    • Sum
    • Sum (Batched)
    • Wait

A simple and lightweight library for creating a JSON-RPC 2.0 compliant HTTP server.

This package complies with the JSON-RPC 2.0 and JSON-RPC 2.0 Transport: HTTP specifications.

Install

To install http-jsonrpc-server in the current directory, run:

npm install http-jsonrpc-server --save

Usage

Below is code to create a server with two exposed methods and begin listening on a given port.

const RpcServer = require('http-jsonrpc-server');

function sum(arr) {
  let total = 0;
  for (let n = 0; n < arr.length; n += 1) {
    total += arr[n];
  }
  return total;
}

async function wait(params) {
  return new Promise((resolve) => {
    setTimeout(() => {
      resolve(true);
    }, params.ms);
  });
}

const rpcServer = new RpcServer({
  methods: {
    sum,
    wait,
  }
});
rpcServer.setMethod('sum', sum);
rpcServer.setMethod('wait', wait);
rpcServer.listen(9090, '127.0.0.1').then(() => {
  console.log('server is listening at http://127.0.0.1:9090/');
}

Specifying a Path

const rpcServer = new RpcServer({
  path: '/api'
});
rpcServer.listen(9090, '127.0.0.1').then(() => {
  console.log('server is listening at http://127.0.0.1:9090/api');
}

Optional Callbacks

onServerError will be called if the server emits an error. onRequest, and onRequestError, and onResult will be called each time a method is called, throws an error, or returns a result respectively.

const rpcServer = new RpcServer({
  onRequest: (request) => {
    console.log(JSON.stringify(request));
    // sample output: {"jsonrpc":"2.0","id":1,"method":"sum","params":[1,2,3]}
  },
  onRequestError: (err, id) => {
    console.error('request ' + id + ' threw an error: ' + err);
  },
  onResult: (result, id) => {
    console.log(result); // sample output: 6
  },
  onServerError: (err) => {
    console.error('the server threw an error: ' + err)
  },
});

Adding/Updating Methods

You can register new methods or update existing ones after the server has been created.

rpcServer.setMethod('sum', sum);

Closing the Server

rpcServer.close().then(() => {
  console.log('server stopped listening');
}

Basic Authentication

You can optionally enable Basic Authentication by specifying credentials when creating the server. Any requests will then require an Authorization header with [username]:[password] encoded in Base64. Note that TLS is not currently supported, therefore all traffic is unencrypted and these credentials can be stolen by anyone relaying or listening to requests. This authentication alone should not be considered secure over public networks.

const rpcServer = new RpcServer({
  username: 'johndoe',
  password: 'wasspord', // ignored unless username is specified
  realm: 'rpc' // realm defaults to "Restricted" if not specified
});

Native HTTP Server

You can access the underlying http.Server object with rpcServer.server.

if (rpcServer.server.listening) {
  console.log('server is listening');
}

Exposed Constants

console.log(rpcServer.PARSE_ERROR); // -32700
console.log(rpcServer.INVALID_REQUEST); // -32600
console.log(rpcServer.METHOD_NOT_FOUND); // -32601
console.log(rpcServer.INVALID_PARAMS); // -32602
console.log(rpcServer.SERVER_ERROR); // -32000
console.log(rpcServer.SERVER_ERROR_MAX); // -32099

API Documentation

RpcServer

Class representing a HTTP JSON-RPC server

Kind: global class

• RpcServer
  • new RpcServer(options)
  • .setMethod(name, method)
  • .listen(port, host) ⇒ Promise.<number>
  • .close() ⇒ Promise.<void>

new RpcServer(options)

Param	Type	Description
options	Object	Optional parameters for the server
options.methods	Object	A map of method names to functions. Method functions are passed one parameter which will either be an Object or a string array
options.context		Context to be used as this for method functions.
options.path	string	The path for the server
options.onRequest	function	Callback for when requests are received, it is passed an Object representing the request
options.onRequestError	function	Callback for when requested methods throw errors, it is passed an error and request id
options.onResult	function	Callback for when requests are successfully returned a result. It is passed the response object and request id
options.onServerError	function	Callback for server errors, it is passed an Error
options.username	string	Username for authentication. If provided, Basic Authentication will be enabled and required for all requests.
options.password	string	Password for authentication, ignored unless a username is also specified.
options.realm	string	Realm for authentication, ignored unless a username is also specified, defaults to Restricted if not specified.

rpcServer.setMethod(name, method)

Sets a method.

Kind: instance method of RpcServer

Param	Type	Description
name	string	The name of the method
method	function	The function to be called for this method. Method functions are passed one parameter which will either be an Object or a string array.

rpcServer.listen(port, host) ⇒ Promise.<number>

Begins listening on a given port and host.

Kind: instance method of RpcServer Returns: Promise.<number> - A promise that resolves to the assigned port once the server is listening. On error the promise will be rejected with an Error.

Param	Type	Description
port	number	The port number to listen on - an arbitrary available port is used if no port is specified
host	string	The host name or ip address to listen on - the unspecified IP address (0.0.0.0 or (::)) is used if no host is specified

rpcServer.close() ⇒ Promise.<void>

Stops listening on all ports.

Kind: instance method of RpcServer Returns: Promise.<void> - A promise that resolves once the server stops listening. On error the promise will be rejected with an Error.

Sample Requests

Here are some sample requests made against the server created in the first usage example.

Sum

POST / HTTP/1.1
Host: 127.0.0.1:9090
Content-Type: application/json
Accept: application/json
Content-Length: 56

{"jsonrpc":"2.0","id":1,"method":"sum","params":[1,2,3]}

connection: close
content-type: application/json
content-length: 35

 {"jsonrpc":"2.0","id":1,"result":6}

Sum (Batched)

POST / HTTP/1.1
Host: 127.0.0.1:9090
Content-Type: application/json
Accept: application/json
Content-Length: 115

[{"jsonrpc":"2.0","id":1,"method":"sum","params":[1,2,3]},{"jsonrpc":"2.0","id":2,"method":"sum","params":[4,5,6]}]

connection: close
content-type: application/json
content-length: 74

[{"jsonrpc":"2.0","id":1,"result":6},{"jsonrpc":"2.0","id":2,"result":15}]

Wait

POST / HTTP/1.1
Host: 127.0.0.1:9090
Content-Type: application/json
Accept: application/json
Content-Length: 59

{"jsonrpc":"2.0","id":1,"method":"wait","params":{"ms":50}}

connection: close
content-type: application/json
content-length: 38

{"jsonrpc":"2.0","id":1,"result":true}