Herald-client NPM

herald-client

v1 is not backward compatible with v0

Client lib for herald server

Install with:

npm install herald-client

Dependencies:

crypt-maker

Documentation by jsDuck. Also in RUS.

Usage

Simple example:

    var hc = new (require('herald-client'))();
        hc.on('error', function(error){
            console.log('HC error:', error);
        });
    
        setTimeout(function() {
            hc.subscribe("channel1", function (sendedBy, obj) {
                console.error('chan1:', obj);
            });
            hc.subscribe("channel2", function (sendedBy, obj) {
                console.log('chan2:', sendedBy, obj);
            });
    
    
            setTimeout(function () {
                hc.unsubscribe("channel1", function(err){
                    if (err) console.error('Error in unsubscribing', err);
                });
                setInterval(function(){
                    hc.publish('channel1', 'C1: '+Math.random());
                    hc.publish('channel2', 'C2: '+Math.random());
                },10);
            }, 1000);
        }, 1000);
        process.on('SIGINT', function(){
            hc.close();
            process.exit();
        });
        process.on('SIGTERM', function(){
            hc.close();
            process.exit();
        });

In this example hc will try connect to 127.0.0.1:8765.

Methods

new HeraldClient(options, [algorithm, key])

options is an Object. May be {}. Contains properties:

.logger - Logger object - to log inner events
.name - String|Numeric - your application class identified. Default: Math.floor(Math.random()*1000000)
.uid - String|Numeric - your application unique identified. Default: name + '_' + Math.floor(Math.random()*1000000)
.messageMaker - Object. Some module, that make and parse messages. See below. Default: crypt-maker
.connect - Object. Options for new.Socket.connect. Default: {port: 8765}

See https://nodejs.org/api/net.html#net_net_connect_options_connectionlistener. Default: {port:8765}

If use crypt-maker and if algorithm && algorithm !== 'no' and no key passed to constructor - throws error.

hc.connect(options)

Connect to server. If options aren't passed, connect with last options. If already connected - do nothing. Options are:

options {Object} optional

Supports the following properties:

port {Number} optional
host {String} optional
backlog {Number} optional
path {String} optional
exclusive {Boolean} optional

For all info about this see: See https://nodejs.org/api/net.html#net_net_connect_options_connectionlistener.

hc.close(callback)

Stops the client and close connect from accepting new connections and keeps existing connections.

callback {Function} optional

hc.subscribe(eventName, callback)

Create subscribing on server. Then event emitted - call callback(senderIdentifier, bodyOfMessage). If error on subscribe hc will emit 'error' event.

eventName {String} - name of event
callback {Function}

hc.unsubscribe(eventName, callback)

Unsubscribe from event with name. If no callback and error on unsubscribe hc will emit 'error' event.

eventName {String} - name of event
callback {Function} optional

hc.publish(eventName, body, callback)

Publish event on server. If no callback and error on publish hc will emit 'error' event.

whom {String} - application name to send.
eventName {String} - name of event
eventBody {String | Object} - body of event
callback {Function} optional

hc.whisper(whom, body, header) removed

hc.whisp(whom, eventName, eventBody, callback)

Send event message to one application with name. (Will send to one instance, but not for all application with name).

whom {String} - application name to send.
eventName {String} - name of event
eventBody {String | Object} - body of event
callback {Function}

hc.whispUid(whomUid, eventName, eventBody, callback)

Send event message to one application with uid.

whomUid {String} - application name to send.
eventName {String} - name of event
eventBody {String | Object} - body of event
callback {Function}

hc.rpc(whom, action, options)

Try call procedure on application with name. (Will send to one instance, but not for all application with name).

whom {String} - application name to send.
action {Object} - action object, that you want to call at application.
action.name {String} - action name, that you want to call at application.
action.args {Object | String | Number | Array} - arguments for action. !!action.args should return true.
options {Object} optional Options for rpc. not ready yet.
callback {Function} optional

hc.rpcUid(whomUid, action, options)

Try call procedure on application with uid.

whomUid {String} - application name to send.
action {Object} - action object, that you want to call at application.
action.name {String} - action name, that you want to call at application.
action.args {Object | String | Number | Array} - arguments for action. !!action.args should return true.
options {Object} optional Options for rpc. not ready yet.
callback {Function} optional

hc.write(header, body, options)

Send some message to server. At now ignored by server

header {Object} - header of message to send.
body {Object|string} - body of message yo send.
options {Object} optional Options for rpc. not ready yet.
callback {Function} optional

hc.addRpcWorker(actionName, callback)

Add function to work with rpc calls.

actionName {String} - action name.
callback {Function} - function to call. See doc

Returns true if added or false if there was function with such name.

hc.removeRpcWorker(actionName)

Remove function from work with rpc calls.

actionName {String} - action name.

Returns true if was such function else returns false.

hc.unref()

Calling unref on a client will allow the program to exit if this is the only active client in the event system. If the server is already unrefd calling unref again will have no effect. Every success .connect() create new connection. That's why you should call unref again.

hc.ref()

Opposite of unref, calling ref on a previously unrefd server will not let the program exit if it's the only server left (the default behavior). If the server is refd calling ref again will have no effect.

Events

'ping'

Emitted when a server send 'ping' event.

'connect'

Emitted when the socket has been connected to server.

'close'

Emitted when the socket closes. Note that if connections exist, this event is not emitted until all connections are ended.

'error'

{Error Object}

Emitted when an error occurs. The 'close' event will be called directly following this event.

Message format

Every message should has header and body. If there is no header or body - message will not sent.

Authorize

Be careful by default without any encrypt algorithm any can connect to your server if he know format.

Example of message to authorize (without encrypt):

    '{"rpc":"herald-server","action":"authorize","actionId":7,"name":"156512",
    "uid":"156512_86835","messId":76688,"retry":5,"timeout":15000}\r\n
     {"args":{"wellKnown":"pHrAsE","name":"156512","uid":"156512_86835","rand":459}}\r\n\r\n'

If there is some connection with same uid - will not authorize new connection and close it.

Message header format

Fields:

messId Number - id of message. Client set it automaticaly.
name String - connection name. Used for whispering and rpc. Client set it to HeraldClient.name.
uid String - connection uid. Used for whispering and rpc. Unique for every connect. Client set it to HeraldClient.uid.
retry Number optional - Count of retries of sending this message. If no field - will not retry. Now it is ignored by server. Will work soon.
timeout Number optional - Duration in ms to wait answer from client. If no field - will not retry. Now it is ignored by server. Will work soon.

Event:

whisp String optional - name of connection to send event message.
whispUid String optional - uid of connection to send event message.
event String - event name. If no whisp or whispUid sends to all subscribers.

RPC:

actionId Number - id of action. Client set it automaticaly.
action String - name of action.
rpc String optional - name of connection to send rpc message.
rpcUid String optional - uid of connection to send rpc message.
rpcRegExp String|RegExp optional - regexp to find connections by name to send rpc message.

Message body format

Body can by plain string, json, number or something else, except functions.

Message examples

Examples shown without any encryption.

RPC by client name message:

     '{"rpc":"applicationToCall","action":"actionToCall","actionId":numberActionIdFromSender,
     "name":"nameOfSender","uid":"uidOfSender","messId":numberMessageId}\r\n
         {"args":{argsObject}}\r\n\r\n'

RPC by client UID message:

     '{"rpcUid":"applicationToCall","action":"actionToCall","actionId":numberActionIdFromSender,
     "name":"nameOfSender","uid":"uidOfSender","messId":numberMessageId}\r\n
         {"args":{argsObject}}\r\n\r\n'

Whispering message:

    '{"whisp":"nameOfAppToWhisp","event":"someSecretEvent","name":"nameOfSender","uid":"uidOfSender",
    "messId":numberMessageId}\r\n"eventBody"\r\n\r\n'

Event message:

    '{"event":"someEvent","name":"nameOfSender","uid":"uidOfSender","messId":numberMessageId}\r\n"eventBody"\r\n\r\n'

LICENSE - "MIT License"

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.