ZMQ JSON-RPC Client

JSON-RPC 2.0 client implementation using a ZeroMQ socket as transport mechanism. More precisely a dealer socket is used for the client, in line with the asynchronous clients / servers pattern of ZeroMQ.

For corresponding server implementation, see zmq-json-rpc-server.

Installation

npm install zmq-json-rpc-client

Usage

Create a JSON RPC client with a ZeroMQ endpoint and emit requests or notifications.

client = zmqJsonRpcClient(endpoint, options)

This module exports a factory faction that accepts a ZeroMQ endpoint, eg. 'tcp:127.0.0.1:3030' and options.

Options

Options can be passed to the factory function as an object, specified by the following keys and values.

nextId

Value: Function that is called each time a new request is created. Defaults to a built-in incrementer starting at 1.

timeout

Value: The number of milliseconds the client will wait for a reply when sending a request, until returning a timeout error. Defaults to 30000 (30 seconds).

socketId

Value: Identity that will be used for the underlaying ZeroMQ socket. Defaults to five random bytes.

client.emit(method, params, callback)

Sends a JSON-RPC request or notification. Params and callback are optional. A notification is sent if callback is omitted. A request that expetct a reply will be sent if passing a callback. The callback will receive error and
result as arguments.

client.socket

Exposes the underlying ZeroMQ socket object.

Example

 
var zmqJsonRpcClient = require('zmq-json-rpc-client');
var client = zmqJsonRpcClient('tcp:127.0.0.1', { socketId: 'client' });
 
// Send a notification
client.emit('update', [1, 2, 3, 4, 5]);  
 
// Send a request
client.emit('subtract', {"subtrahend": 23, "minuend": 42}, function(err, result) {
  // ...
});
 

Test

Run unit tests:

$ npm test

License

MIT