The 'jayson' npm package is a JSON-RPC 2.0/1.0 compliant server and client library for Node.js. It allows you to create JSON-RPC servers and clients, making it easy to implement remote procedure calls (RPC) in a standardized way.
Creating a JSON-RPC Server
This code creates a JSON-RPC server with a single method 'add' that takes two arguments and returns their sum. The server listens on port 3000.
const jayson = require('jayson');
const server = jayson.server({
add: function(args, callback) {
callback(null, args[0] + args[1]);
}
});
server.http().listen(3000);Creating a JSON-RPC Client
This code creates a JSON-RPC client that connects to a server running on 'http://localhost:3000'. It makes a request to the 'add' method with arguments [1, 1] and logs the result.
const jayson = require('jayson');
const client = jayson.client.http('http://localhost:3000');
client.request('add', [1, 1], function(err, response) {
if(err) throw err;
console.log(response.result); // 2
});Batch Requests
This code demonstrates how to make batch requests using the JSON-RPC client. It sends two 'add' requests in a single batch and logs the responses.
const jayson = require('jayson');
const client = jayson.client.http('http://localhost:3000');
const batch = [
client.request('add', [1, 1], null, false),
client.request('add', [2, 2], null, false)
];
client.request(batch, function(err, responses) {
if(err) throw err;
console.log(responses); // [{jsonrpc: '2.0', result: 2, id: 1}, {jsonrpc: '2.0', result: 4, id: 2}]
});The 'jsonrpc-lite' package is a lightweight JSON-RPC 2.0 library for Node.js. It provides a simple and minimalistic approach to creating JSON-RPC servers and clients. Compared to 'jayson', 'jsonrpc-lite' is more lightweight but may lack some of the advanced features and flexibility that 'jayson' offers.
The 'node-json-rpc' package is another JSON-RPC 2.0 library for Node.js. It provides a straightforward way to create JSON-RPC servers and clients. While it offers similar functionalities to 'jayson', it may have a different API design and might not be as feature-rich.
The 'json-rpc2' package is a JSON-RPC 2.0 library for Node.js that supports both client and server implementations. It is similar to 'jayson' in terms of functionality but may have different design choices and API conventions.
Jayson is a JSON-RPC 2.0 compliant server and client written in JavaScript for node.js that aims to be as simple as possible to use.
A basic JSON-RPC 2.0 server via HTTP:
Server in examples/simple_example/server.js:
var jayson = require(__dirname + '/../..');
// create a server
var server = jayson.server({
add: function(a, b, callback) {
callback(null, a + b);
}
});
// Bind a http interface to the server and let it listen to localhost:3000
server.http().listen(3000);
Client in examples/simple_example/client.js invoking add on the above server:
var jayson = require(__dirname + '/../..');
// create a client
var client = jayson.client.http({
port: 3000,
hostname: 'localhost'
});
// invoke "add"
client.request('add', [1, 1], function(err, error, response) {
if(err) throw err;
console.log(response); // 2!
});
Install the latest version of jayson from npm by executing npm install jayson in your shell. Do a global install with npm install --global jayson if you want the jayson client CLI in your PATH.
There is a CLI client in bin/jayson.js and it should be available as jayson in your shell if you installed the package with the --global switch. Run jayson --help to see how it works.
Jayson does not have any special dependencies that cannot be resolved with a simple npm install. It has been tested with the following node.js versions:
In addition to this document, a comprehensive class documentation made with jsdoc is available at jayson.tedeh.net.
npm install --devmake test or npm testThe client is available as the Client or client property of require('jayson').
Client Base class for interfacing with a server.Client.tcp TCP interfaceClient.http HTTP interface.Client.fork Node.js child_process/fork interface.Client.jquery Wrapper around jQuery.ajax.Notification requests are for cases where the reply from the server is not important and should be ignored. This is accomplished by setting the id property of a request object to null.
Client in examples/notifications/client.js doing a notification request:
var jayson = require(__dirname + '/../..');
var client = jayson.client.http({
host: 'localhost',
port: 3000
});
// the third parameter is set to "null" to indicate a notification
client.request('ping', [], null, function(err) {
if(err) throw err;
// request was received successfully
});
A server in examples/notifications/server.js:
var jayson = require(__dirname + '/../..');
var server = jayson.server({
ping: function(callback) {
// do something
callback();
}
});
server.http().listen(3000);
null to Client.prototype.request does not generate a notification request. This argument has to be set explicitly to null for this to happen.A batch request is an array of individual requests that are sent to the server as one. Doing a batch request is very simple in Jayson and consists of constructing an Array of individual requests (created by not passing a callback to Client.prototype.request) that is then itself passed to Client.prototype.request.
Client example in examples/batch_request/client.js:
var jayson = require(__dirname + '/../..');
var client = jayson.client.http({
host: 'localhost',
port: 3000
});
var batch = [
client.request('does_not_exist', [10, 5]),
client.request('add', [1, 1]),
client.request('add', [0, 0], null) // a notification
];
// callback takes two arguments (first type of callback)
client.request(batch, function(err, responses) {
if(err) throw err;
// responses is an array of errors and successes together
console.log('responses', responses);
});
// callback takes three arguments (second type of callback)
client.request(batch, function(err, errors, successes) {
if(err) throw err;
// errors is an array of the requests that errored
console.log('errors', errors);
// successes is an array of requests that succeded
console.log('successes', successes);
});
Server example in examples/batch_request/server.js:
var jayson = require(__dirname + '/../..');
var server = jayson.server({
add: function(a, b, callback) {
callback(null, a + b);
}
});
server.http().listen(3000);
request. To find the right result, compare the ID from the request with the ID in the result yourself.When the length (number of arguments) of a client callback function is either 2 or 3 it receives slightly different values when invoked.
null, second argument is the response object as returned (containing either a result or a error property) or null for notifications.error property or null (if success), third argument is a JSON-RPC result property or null (if error).When doing a batch request with a 3-length callback, the second argument will be an array of requests with a error property and the third argument will be an array of requests with a result property.
A client will emit the following events (in addition to any special ones emitted by a specific interface):
request Emitted when a client is just about to dispatch a request. First argument is the request object.response Emitted when a client has just received a reponse. First argument is the request object, second argument is the response as received.Every client supports these options:
reviver -> Function to use as a JSON reviverreplacer -> Function to use as a JSON replacergenerator -> Function to generate request ids with. If omitted, Jayson will just generate a "random" number that is [RFC4122] compliant and looks like this: 3d4be346-b5bb-4e28-bc4a-0b721d4f9ef9version -> Can be either 1 or 2 depending on which specification should be followed in communicating with the server. Defaults to 2 for JSON-RPC 2.0Uses the same options as http.request (which also enables the use of https) in addition to these options:
encoding -> String that determines the encoding to use and defaults to utf8It is possible to pass a string URL as the first argument. The URL will be run through url.parse. Example:
var jayson = require(__dirname + '/../..');
var client = jayson.client.http('http://localhost:3000');
// client.options is now the result of url.parse
Uses the same options as the base class.
Uses the same options as the base class.
The jQuery Client is stand-alone from the other classes and should preferably be compiled with make compile which outputs different flavors into the build directory. Supports inclusion via AMD. Uses the same options as jQuery.ajax and exposes itself as $.jayson with the same arguments as Client.prototype.request.
The server classes are available as the Server or server property of require('jayson').
The server also sports several interfaces that can be accessed as properties of an instance of Server.
Server - Base interface for a server that supports receiving JSON-RPC 2.0 requests.Server.tcp - TCP server that inherits from net.Server.Server.http - HTTP server that inherits from http.Server.Server.https - HTTPS server that inherits from https.Server.Server.middleware - Method that returns a Connect/Express compatible middleware function.Server.fork Creates a child process that can take requests via client.forkEvery server supports these options:
reviver -> Function to use as a JSON reviverreplacer -> Function to use as a JSON replacerversion -> Can be either 1 or 2 depending on which specification clients are expected to follow. Defaults to 2 for JSON-RPC 2.0A Jayson server can use many interfaces at the same time.
Server in examples/many_interfaces/server.js that listens to both http and a https requests:
var jayson = require(__dirname + '/../..');
var server = jayson.server({
add: function(a, b, callback) {
return callback(null, a + b);
}
});
// "http" will be an instance of require('http').Server
var http = server.http();
// "https" will be an instance of require('https').Server
var https = server.https({
//cert: require('fs').readFileSync('cert.pem'),
//key require('fs').readFileSync('key.pem')
});
http.listen(80, function() {
console.log('Listening on *:80')
});
https.listen(443, function() {
console.log('Listening on *:443')
});
Passing an instance of a client as a method to the server makes the server relay incoming requests to wherever the client is pointing to. This might be used to delegate computationally expensive functions into a separate fork/server or to abstract a cluster of servers behind a common interface.
Public server in examples/relay/server_public.js listening on *:3000:
var jayson = require(__dirname + '/../..');
// create a server where "add" will relay a localhost-only server
var server = jayson.server({
add: jayson.client.http({
hostname: 'localhost',
port: 3001
})
});
// let the server listen to *:3000
server.http().listen(3000, function() {
console.log('Listening on *:3000');
});
Private server in examples/relay/server_private.js listening on localhost:3001:
var jayson = require(__dirname + '/../..');
var server = jayson.server({
add: function(a, b, callback) {
callback(null, a + b);
}
});
// let the private server listen to localhost:3001
server.http().listen(3001, '127.0.0.1', function() {
console.log('Listening on 127.0.0.1:3001');
});
Every request to add on the public server will now relay the request to the private server. See the client example in examples/relay/client.js.
In addition to events that are specific to certain interfaces, all servers will emit the following events:
request Emitted when the server receives an interpretable (non-batch) request. First argument is the request object.response Emitted when the server is returning a response. First argument is the request object, the second is the response object.batch Emitted when the server receives a batch request. First argument is an array of requests. Will emit request for each interpretable request in the batch.If you should like to return an error from an method request to indicate a failure, remember that the JSON-RPC 2.0 specification requires the error to be an Object with a code (Integer/Number) to be regarded as valid. You can also provide a message (String) and a data (Object) with additional information. Example:
var jayson = require(__dirname + '/../..');
var server = jayson.server({
i_cant_find_anything: function(id, callback) {
var error = {code: 404, message: 'Cannot find ' + id};
callback(error); // will return the error object as given
},
i_cant_return_a_valid_error: function(callback) {
callback({message: 'I forgot to enter a code'}); // will return a pre-defined "Internal Error"
}
});
It is also possible to cause a method to return one of the predefined JSON-RPC 2.0 error codes using the server helper function Server.prototype.error inside of a server method. Example:
var jayson = require(__dirname + '/../..');
var server = jayson.server({
invalid_params: function(id, callback) {
var error = this.error(-32602); // returns an error with the default properties set
callback(error);
}
});
You can even override the default messages:
var jayson = require(__dirname + '/../..');
var server = jayson.server({
error_giver_of_doom: function(callback) {
callback(true) // invalid error format, which causes an Internal Error to be returned instead
}
});
// Override the default message
server.errorMessages[Server.errors.INTERNAL_ERROR] = 'I has a sad. I cant do anything right';
JSON lacks support for representing types other than the simple ones defined in the JSON specification. Fortunately the JSON methods in JavaScript (JSON.parse and JSON.stringify) provide options for custom serialization/deserialization routines. Jayson allows you to pass your own routines as options to both clients and servers.
Simple example transferring the state of an object between a client and a server:
Shared code between the server and the client in examples/reviving_and_replacing/shared.js:
var Counter = exports.Counter = function(value) {
this.count = value || 0;
};
Counter.prototype.increment = function() {
this.count += 1;
};
exports.replacer = function(key, value) {
if(value instanceof Counter) {
return {$class: 'counter', $props: {count: value.count}};
}
return value;
};
exports.reviver = function(key, value) {
if(value && value.$class === 'counter') {
var obj = new Counter;
for(var prop in value.$props) obj[prop] = value.$props[prop];
return obj;
}
return value;
};
Server in examples/reviving_and_replacing/server.js:
var jayson = require(__dirname + '/../..');
var shared = require('./shared');
// Set the reviver/replacer options
var options = {
reviver: shared.reviver,
replacer: shared.replacer
};
// create a server
var server = jayson.server({
increment: function(counter, callback) {
counter.increment();
callback(null, counter);
}
}, options);
// let the server listen to for http connections on localhost:3000
server.http().listen(3000);
A client in examples/reviving_and_replacing/client.js invoking "increment" on the server:
var jayson = require(__dirname + '/../..');
var shared = require('./shared');
// create a client with the shared reviver and replacer
var client = jayson.client.http({
port: 3000,
hostname: 'localhost',
reviver: shared.reviver,
replacer: shared.replacer
});
// create the object
var instance = new shared.Counter(2);
// invoke "increment"
client.request('increment', [instance], function(err, error, result) {
if(err) throw err;
console.log(result instanceof shared.Counter); // true
console.log(result.count); // 3!
console.log(instance === result); // false - it won't be the same object, naturally
});
toJSON method for any JavaScript object. Unfortunately there is no corresponding method for reviving objects (that would not work, obviously), so the reviver always has to be set up manually.It is possible (and simple) to create automatic forks with jayson using the node.js child_process core library. This might be used for expensive or blocking calculations and to provide some separation from the main server thread.
The forking server class is available as jayson.Server.Fork and takes a file as the first option. This file will be require'd by jayson and should export any methods that are to be made available to clients.
The main server in examples/forking/server.js
var jayson = require(__dirname + '/../..');
// creates a fork
var fork = jayson.server.fork(__dirname + '/fork');
var front = jayson.server({
fib: jayson.client.fork(fork) // connects "fib" to the fork
});
// let the front server listen to localhost:3000
front.http().listen(3000);
The forked server in examples/forking/fork.js
// export "fib" for forking
exports.fib = function(n, callback) {
function fib(n) {
if(n < 2) return n;
return fib(n - 1) + fib(n - 2);
};
var result = fib(n);
callback(null, fib(n));
};
A client doing a fibonacci request in examples/forking/client.js
var jayson = require(__dirname + '/../..');
var client = jayson.client.http({
port: 3000,
hostname: 'localhost'
});
// request "fib" on the server
client.request('fib', [15], function(err, response) {
console.log(response);
});
module.exports an instance of jayson.Server instead of exporting plain methods.Highlighting issues or submitting pull requests on Github is most welcome.
FAQs
JSON-RPC 1.0/2.0 compliant server and client
The npm package jayson receives a total of 283,008 weekly downloads. As such, jayson popularity was classified as popular.
We found that jayson demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
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