A feature rich and persistent jsonrpc client and server library


Keywords
jsonrpc, json-rpc, rpc, json, jsonrpc-2.0, jsonrpc-1.0, middleware, connect, http, tcp, api, library, ws, websocket, web, socket, sockets, node, javascript, js, browser, promise, promises, batch, notifications, server, client, handler
License
MIT
Install
npm install jaysonic@2.0.1

Documentation

Jaysonic - A persistent JSON-RPC client and server


A TCP, HTTP and WebSocket server and client that implement the JSON-RPC 2.0 Specification.

List of features

  • Promise based
  • Persistent connections
  • Notification subscriptions
  • Batching
  • TCP server/client
  • HTTP server/client
  • WebSocket server/client
  • WebSocket client supported in the browser
  • Automatic increment of request ID
  • Associate response ID with request

Download & Installation

$ npm install jaysonic

Initialization

All clients and servers are instantiated with the same syntax, just change the type

// TCP
const server = new Jaysonic.server.tcp();
const client = new Jaysonic.client.tcp();
// HTTP
const server = new Jaysonic.server.http();
const client = new Jaysonic.client.http();
// WS
const wss = new Jaysonic.server.ws();

Note that there are two web socket clients
One can only be run in the browser, and the other can run in a NodeJS environment.

WS Client for browser

The browser ws client is based on the window.WebSocket class.

const Jaysonic = require("jaysonic/lib/client-ws");
const ws = new Jaysonic.wsclient();

WS Client for Node

The Node ws client is based on the ws library (same as the server).

const Jaysonic = require("jaysonic");
const ws = new Jaysonic.client.ws();

Options

The client and server support changing the JSON-RPC version and the delimiter used. Just pass them in the same object as the host and port to override the defaults.

host: The host IP to serve from for the server, or to connect to by the client. Default is 127.0.0.1. Note this is only available for the HTTP and TCP server/client.
port: The host port to serve from for the server, or to connect to by the client. Default is 8100.
delimiter: Delimiter to break requests by. Defaults to \n.
version: RPC version to use. Defaults to 2.0.
retries: The number of retry attempts for the client to connect to the server. Default is 2.
timeout: The amount of time before a request times out. Will return a -32000 error code. The default value is 30 (in seconds).

The TCP and HTTP server have an additional option specified by the NodeJS Docs.

exclusive: If exclusive is false (default), then cluster workers will use the same underlying handle, allowing connection handling duties to be shared. When exclusive is true, the handle is not shared, and attempted port sharing results in an error.

The HTTP client supports additional options for the HTTP request.

method: The method to make the request with. Default is POST. path: The path to send the request to. Default is /. encoding: How to encode the HTTP request. Will factor into content-length calculation. Default is utf-8. headers: Headers to include in the request. Defaults provided by the spec are:

  • "Content-Length"
    • calculated by request message, this is not configurable
  • "Content-Type"
    • defaults to "application/json
  • Accept
    • defaults to "application/json"

The WebSocket client supports an additional option in place of the host property.

url: The web socket url to connect to. Default is ws://127.0.0.1:8100.

The WebSocket server is based on the ws library (https://github.com/websockets/ws).

It supports all of the options listed in their README. Typically changing the port is enough.

Code Demos

The default host and port for the server is 127.0.0.1:8100. Based on the node net.Server() module.

The default host and port for the TCP client is 127.0.0.1:8100. Based on the node net.Socket() module.

The default request URL for the HTTP client is http://127.0.0.1:8100/. Based on the node http.ClientRequest module.

The default url for the WS client is ws://127.0.0.1:8100. Based on the WebSocket module from JavaScript.

The default port for the WS Server is 8100. Based on the ws library.

The default options will be used when instantiating the client or the server. Overrides can be provided by passing an object with the modifications.

Initialization

TCP
const Jaysonic = require("jaysonic");

// server with overrides
const server = new Jaysonic.server.tcp({
  host: "127.0.0.1",
  port: 8100,
  delimiter: "\n",
  version: 1
});
HTTP
const Jaysonic = require("jaysonic");

// client with overrides
const client = new Jaysonic.client.http({
    method: "POST",
    headers: {
      "Content-Type": "application/json; charset=utf-8",
      Accept: "application/json"
    },
    path: "/"
  };
});
WS

wsclient class can only be used in the browser. client.ws cannot be used in the browser.

const Jaysonic = require("jaysonic");
const socket = require("jaysonic/lib/client-ws");

// client and server with overrides

// client in the browser
const ws = new socket.wsclient({
  url: "ws://127.0.0.1:8100"
});
// or to work in node
const ws = new Jaysonic.client.ws({
  url: "ws://127.0.0.1:8100"
});

const wss = new Jaysonic.server.ws({
  port: 8100
});

Server side

Instantiation and Listening
const Jaysonic = require("jaysonic");

const server = new Jaysonic.server.tcp();

server
  .listen()
  .then(({ host, port }) => {
    console.log(`Server listening on ${host}:${port}`);
  })
  .catch((error) => {
    console.log(`Unable to start server, ${error}`);
  });
Closing the connection
server
  .close()
  .then(() => {
    // do something
  })
  .catch((error) => {
    // error when trying to close the connection
  });
Adding Methods
server.method("add", ([a, b]) => a + b);

// can also add named
const add = ([a, b]) => a + b;

server.method("add", add);

// or promises
const add = ([a, b]) =>
  new Promise((resolve, reject) => {
    resolve(a + b);
  });

server.method("add", add);

Note: The same syntax for all the above methods is used for the HTTP and WS server

Listening for client connections

The clientConnected and clientDisconnected methods return the host and port of the client in the callback. These methods are not available for the HTTP server.

server.clientConnected(({ host, port }) => {
  console.log("client connected");
});

server.clientDisconnected(({ host, port }) => {
  console.log("client disconnected");
});

Client Side

Connecting
const Jaysonic = require("jaysonic");
const client = new Jaysonic.client.tcp();

client
  .connect()
  .then(({ host, port }) => {
    console.log(`Client connected on ${host}:${port}`);
  })
  .catch((error) => {
    console.log(`Client unable to connect, ${error}`);
  });

Note that the HTTP client does not have a connect() method and can just begin making requests to the server.

Listening for server disconnect

The serverDisconnected method fires a callback when the server is disconnected.

client.serverDisconnected(() => {
  // do something
});
Making requests

Requests can only be made once connection is established.

client
  .connect()
  .then(({ host, port }) => {
    add();
  })
  .catch((error) => {
    console.log(`Client unable to connect, ${error}`);
  });

const add = () => {
  client
    .request()
    .send("add", [1, 2])
    .then((result) => {
      console.log(result);
      // {jsonrpc: "2.0", result: 3, id: 1}
    })
    .catch((error) => {
      console.log(error);
    });
};
Subscriptions

Clients can subscribe to notifications from the server.

Note: Subscriptions are not supported by the HTTP server/client
Notifications no longer return an error as the first parameter in the callback as of v2.0.0

client.subscribe("notification", (message) => {
  console.log(message);
  // {jsonrpc: "2.0", method: "notification", params: []}
});
server.notify([["notification", []]]);

The websocket browser client returns an object with a 'detail' key which contains the notification as of v2.0.0

wsclient.subscribe("notification", ({ detail }) => {
  console.log(detail);
  // {jsonrpc: "2.0", method: "notification", params: []}
});
wsserver.notify([["notification", []]]);

A client can also unsubscribe a method from a notification, or unsubscribe all methods from a notification. This requires the callback function to be named, else it wont be able to remove it.

client.unsubscribe("notification", callback);
client.unsubscribeAll("notification");
Batch Requests
client
  .connect()
  .then(({ host, port }) => {
    add();
  })
  .catch((error) => {
    console.log(`Client unable to connect, ${error}`);
  });

const add = () =>
  client
    .batch([
      // access the message object on the request
      client.request().message("add", [1, 2]),
      client.request().message("add", [3, 4])
    ])
    .then((result) => {
      // [
      //   {jsonrpc: "2.0", result: 3, id: 1},
      //   {jsonrpc: "2.0", result: 7, id: 2}
      // ]
    })
    .catch((error) => {
      console.log(error);
    });

The same syntax is used for the HTTP client

HTTP Client Requests

The HTTP Client will include additional information about the response, as per nodes http.IncomingMessage method. See more here.

The HTTP client response and error are objects with a body property, which contains the json response from the server, as well as the http.IncomingMessage instance. Which contains things like the header and statusCode. All methods can be found here.

Additionally, the error object contains a response property that provides the body of the erroneous response.

client
  .request()
  .send("add", [1, 2])
  .then((result) => {
    console.log(result.body);
    // 3
    console.log(result.statusCode);
    // 200
  })
  .catch((error) => {
    console.log(error);
  });

Notifications

Client

Clients can send notifications to the server.

The server can also listen for all notifications not tied to methods and handle accordingly.

Note as of v2.0.0 server.onNotify no longer returns an error as the fist parameter to the callback

// optionally returns a promise indicating success or failure for sending message
client.request().notify("notify", []);

server.onNotify("notify", (message) => {
  console.log(message);
  // {jsonrpc: "2.0", method: "notify", params: []}
});

A server can also unsubscribe a method from a notification, or unsubscribe all methods from a notification. This requires the callback function to be named, else it wont be able to remove it.

server.unsubscribeOnNotify("notification", callback);
server.unsubscribeAllOnNotify("notification");
Server

The server can send notifications to the client. This can be done individually or in a batch.

Note: As of v2.0.0 notifications from the server are sent as a list of lists, instead of just supplying the method and params. This was done to handle batch notifications.

server.notify will return a list of error objects if there was a problem sending the notification out to any client, or if no clients are connected. The error of one client will not affect the notification being sent out to the rest of the clients.

// optionally returns a promise indicating success or failure for sending message
client.subscribe("notify", callback);

// send a single notification
server.notify([["notify", []]]);

// send a batch of notifications
server.notify([
  ["notify", []],
  ["test", [1, 2, 3]]
]);

As of v2.0.0, notifications sent and recieved in batches are now supported

Batches
// send from the client by setting the 3rd parameter in the request().message() method to false
client.batch([client.request().message("test", [], false)]);

// send from server by providing a list of arrays containing
// a method and optional params value
server.notify([["notification", ["a", 1]], ["browser"]]);

As per the JSON-RPC spec for HTTP, a notification response must include a 204 status code, with an empty response body. The HTTP Client will resolve a response object if it receives this response, and reject it otherwise.

HTTP Client Notifications

// optionally returns a promise indicating success or failure for sending message
client
  .request()
  .notify("notify", [])
  .then((response) => {
    console.log(response.statusCode);
    // 204
  })
  .catch((error) => {
    console.log(error);
  });

server.onNotify("notify", (message) => {
  console.log(message);
  // {jsonrpc: "2.0", method: "notify", params: []}
});

Contributing

Definitely welcome. I tried to account for everything in the spec, but issues come up of course.

Keep it simple. Keep it minimal. Make sure all tests pass and no linting errors.

Authors or Acknowledgments

  • Isaac Rowell

License

This project is licensed under the MIT License