Reference

Table of Contents

• Installation
  • As browser client
  • As Node.js client
• Socket
  • Event
  • Life Cycle
  • Sending and Receiving Event
  • Getting and Setting Result of Event Processing
  • Heartbeat
  • Connection Sharing
  • Reconnection
  • Transport
• Transport
  • Implementation
  • Compatibility
    • Browser
    • Node.js
• Quirks
  • The browser limits the number of simultaneous connections
  • Pressing ESC key aborts the connection
  • Sending an event emits a clicking sound
  • A blank page pops up when using connection sharing

Installation

As browser client

Download vibe.js the way you want.

• The compressed for production
• The uncompressed for development
• bower install vibe

Then load or link it by using either script tag or Asynchronous Module Definition loader.

<script src="/vibe/vibe.min.js"></script>
<script>
var socket = vibe.open("/vibe");
</script>

require(["vibe"], function(vibe) {
    var socket = vibe.open("/vibe");
});

As Node.js client

vibe.js is available on npm under the name of vibe-client. Install the module.

npm install vibe-client --save

It will install the latest version adding it to dependencies entry in package.json in the current project folder. If you are on Windows, you may have trouble in installing Contextify. See a installation guide from jsdom.

Then load it as a Node.js module.

var vibe = require("vibe-client");
var socket = vibe.open("http://localhost:8080/vibe");

Socket

The feature-rich and flexible interface for two-way communication.

Event

From the semantic point of view, the unit of data to be sent and be received is the event, like the interaction between user and browser. The socket object's events can be classified like the following:

• Pseudo event: connecting and waiting

  They only exist in the client and have nothing to do with the server. Event handlers belong to those events

• Network event: open and close

  They are fired in process of connecting and disconnecting by the transport object.

• Message event: message and everything else

  They are sent and received via the connection effectively. Only this type of event can be extended. All the custom event used by the socket or the user belong to custom message event.

Life Cycle

Socket always is in a specific state that can be accessed by state method. According to the status of connection to the server, transition between states occurs and this circulating transition makes a life cycle. The following list is a list of state which a socket can be in. A word in parentheses in closed state means close reason.

• preparing

  As an initial state of life cycle, it's internally used during reinitializing socket state and handshaking.

  State transition occurs to

  • connecting: if transport is selected.
  • closed(notransport): if there is no available transport in transports option in runtime environment.

• connecting

  The selected transport starts connecting to the server and the connecting event is fired. Timer for time-out is activated if timeout option is a positive number, environment for connection sharing is constructed and the socket starts to share its connection if sharing option is true. The connecting event is an initial event which the socket fires so you can handle it.

  State transition occurs to

  • opened: if transport succeeds in establishing a connection.
  • closed(error): if transport fails to connect.
  • closed(done): if sse transport fails to connect.
  • closed(timeout): if it's timed out.
  • closed(aborted): if close method is called.

• opened

  The connection is established successfully and communication is possible. The open event is fired. Heartbeat communication starts if heartbeat option is number greater than 5000. Only in this state, the socket can send and receive events via connection to the server.

  State transition occurs to

  • closed(error): if heartbeat fails.
  • closed(error): if connection is disconnected due to some error.
  • closed(done): if connection is closed cleanly.
  • closed(done): if connection established by sse transport is disconnected due to some error.
  • closed(aborted): if close method is called.

• closed

  The connection has been closed, has been regarded as closed or could not be opened. The close event is fired with the close reason. If the reconnect handler is set to or returns false, the socket's life cycle ends here.

  State transition occurs to

  • waiting: if the reconnect handler returns a positive number.

• waiting

  The socket waits out the reconnection delay. The waiting event is fired with the reconnection delay in milliseconds and the total number of reconnection attempts.

  State transition occurs to

  • preparing: after the reconnection delay.
  • closed(aborted): if close method is called.

Sending and Receiving Event

You can send event using send(event: string, data?: any) and receive event using on(event: string, onEvent: (data?: any) => void). Any event name can be used, except connecting, open, close and waiting and any data can be sent and received but it should be able to be marshalled/unmarshalled to JSON.

Note

• Socket must be in opened state.
• To manage a lot of events easily, use URI as event name format like /account/update.

The client sends events and the server echoes back to the client.

vibe.open("http://localhost:8080/vibe", {reconnect: false})
.on("open", function() {
    this.send("echo", Math.PI)
    .send("echo", "pi")
    .send("echo", {"p": "i"})
    .send("echo", ["p", "i"]);
})
.on("echo", function(data) {
    console.log(data);
});

server.on("socket", function(socket) {
    socket.on("echo", function(data) {
        console.log(data);
        this.send("echo", data);
    });
});

The server sends events and the client echoes back to the server.

vibe.open("http://localhost:8080/vibe", {reconnect: false})
.on("echo", function(data) {
    console.log(data);
    this.send("echo", data);
})

server.on("socket", function(socket) {
    socket.on("echo", function(data) {
      console.log(data);
    })
    .send("echo", Math.PI)
    .send("echo", "pi")
    .send("echo", {"p": "i"})
    .send("echo", ["p", "i"]);
});

Getting and Setting Result of Event Processing

You can get the result of event processing from the server in sending event using send(event: string, data?: any, onResolved?: (data?: any) => void, onRejected?: (data?: any) => void), and set the result of event processing to the server in receiving event using on(event: string, handler:(data?: any, reply?: {resolve: (data?: any) => void; reject: (data?: any) => void}) => void). Either resolved or rejected callback is executed once when the counterpart executes it.

You can apply this functionality to sending events in order, Acknowledgements, Remote Procedure Call and so on. It looks nothing new to traditional Ajax, but comparing to Ajax, WebSocket can reduce unnecessary traffic like HTTP headers and the result can be shared by multiple tabs and windows. To write a low-latency webapp, you can utilize reply in place of Ajax.

Note

• Socket must be in opened state.
• Beforehand determine whether to use rejected callback or not to avoid writing unnecessary rejected callbacks.

The client sends events attaching callbacks and the server executes one of them with the result of event processing.

vibe.open("http://localhost:8080/vibe", {reconnect: false})
.on("open", function(data) {
    this.send("/account/find", "flowersinthesand", function(data) {
        console.log("resolved with " + data);
    }, function(data) {
        console.log("rejected with " + data);
    })
    .send("/account/find", "flowersits", function(data) {
        console.log("resolved with " + data);
    }, function(data) {
        console.log("rejected with " + data);
    });
});

server.on("socket", function(socket) {
    socket.on("/account/find", function(id, reply) {
      console.log(id);
      if (id === "flowersinthesand") {
          reply.resolve({name: "Donghwan Kim"});
      } else {
          reply.reject("¯\(°_o)/¯");
      }
    });
});

The server sends events attaching callbacks and the client executes one of them with the result of event processing.

vibe.open("http://localhost:8080/vibe", {reconnect: false})
.on("/account/find", function(id, reply) {
    console.log(id);
    if (id === "flowersinthesand") {
        reply.resolve({name: "Donghwan Kim"});
    } else {
        reply.reject("¯\(°_o)/¯");
    }
});

server.on("socket", function(socket) {
    socket.send("/account/find", "flowersinthesand", function(data) {
        console.log("resolved with " + data);
    }, function(data) {
        console.log("rejected with " + data);
    })
    .send("/account/find", "flowersits", function(data) {
        console.log("resolved with " + data);
    }, function(data) {
        console.log("rejected with " + data);
    });
});

Heartbeat

Considering a multitude of browsers, transports, servers, networks and their combination, heartbeat is essential to maintain stable connection. For that reason, a socket starts heartbeat communication every 20 seconds on the open event by default. It can be configured only through the server.

Eavesdropping heartbeat of client and server.

vibe.open("http://localhost:8080/vibe", {reconnect: false})
.on("heartbeat", function() {
    console.log("heartbeat at " + Date.now());
});

server.on("socket", function(socket) {
    socket.on("heartbeat", function() {
        console.log("heartbeat at " + Date.now());
    });
});

Connection Sharing

It's common case that user opens multiple tabs of same website and each tab have its persistent connection like vibe. In the case of a web portal consisting of many portlets, if portlet has a persistent connection, it may not be able to send any request, receive and display anything in violation of the simultaneous connection limit. By sharing a connection, it can be avoided.

To enalbe, set sharing:boolean option to true. As long as the cookie is enabled, socket will automatically find and use a shared connection if it exists within the cookie's scope and share its connection if there is no corresponding one. Note that if the web page or computer becomes horribly busy, a newly created socket might establish a physical connection but still it doesn't break anything.

Note

• Applies to only browser.
• In the current implementation, the server can't see socket using shared connection apart from one which possesses a real physical connection. Sockets using shared connection are a kind of mirror of socket having shared the connection but there is no restriction in functionalities. In the future, it will be enhanced or replaced with new implementation to allow for the server to recognize a socket using shared connection as a indipendent socket.
• Reply can't be used together with the current implementation but with new implementation, it will be available.

Sending and reciving event via shared connection.

vibe.open("http://localhost:8080/vibe", {
    reconnect: false, 
    sharing: true
})
.on("open", function() {
    this.send("echo", "purple night");
})
.on("echo", function(data) {
    console.log(data);
});

vibe.open("http://localhost:8080/vibe", {
    reconnect: false, 
    sharing: true
})
.on("open", function() {
    this.send("echo", "purple night");
})
.on("echo", function(data) {
    console.log(data);
});

server.on("socket", function(socket) {
    socket.on("echo", function(data) {
        this.send("echo", data);
    });
});

Reconnection

Reconnection has been disabled in the above code snippets for convenience of test, but it's essential for production so that it's enabled by default. The default strategy generates a geometric progression with initial delay 500 and ratio 2 (500, 1000, 2000, 4000 ...). To change it, set reconnect (delay: number, attempts: number): number function which receives the last delay in ms or null at first and the total number of reconnection attempts and should return a delay in ms or false not to reconnect.

Note

• Don't add event handler during dispatch including open event. Because reconnection doesn't remove event handlers, it will be duplicated in next life cycle.

Transport

WebSocket is clearly a best transport but in the real world, many coporate proxies, firewalls, antivirus softwares and cloud application platforms block it for some reason. Of course, many users still use browsers not supporting WebSocket, which we can't compel to upgrade it.

Such transport is configurable through transports:string[] option. The default value is null, which means following the server's configuration. Therefore, you don't need to use that option unless you try to test something. Specific details about transport are introduced in Transport section.

Note

• Transport availability is calculated by feature detection in runtime environment. It doesn't mean that selected transport will work with the given network and server.
• Whatever transport is selected, it doesn't affect socket's functionalities.

Transport

The private interface that used to establish a connection, send data, receive data and close the connection.

Implementation

According to the technology, available transport implementations can be sorted into three groups like the following:

• WebSocket

  WebSocket is a protocol designed for a full-duplex communications over a TCP connection. However, many coporate proxies, firewalls and antivirus softwares blocks it for some reason.

  • ws: works if browser supports WebSocket.

• HTTP Streaming

  The client performs a HTTP persistent connection and watches changes in response text and the server prints chunk as data over the connection.

  • sse: works if browser supports EventSource. If the browser is Safari 5 or 6, only same origin connection works. By reason of the spec's ambiguity, there is no way to determine whether a connection closed normally or not so that the close event's reason will be always done even though the connection closed due to an error.
  • streamxhr: in case of same origin connection, works without qualification. In case of cross origin, works if XMLHttpRequest supports CORS. However for both cases, if the browser is Internet Explorer, the version should be equal to or higher than 10 and if the browser is Opera, the version should be equal to or higher than 13.
  • streamxdr: works if browser supports XDomainRequest and xdrURL option is set.
  • streamiframe: works if it's same origin connection and browser supports ActiveXObject. This transport differs from the traditional Hidden Iframe in terms of fetching a response text. The traditional transport expects script tags, whereas this transport periodically polls the response text.

  For convenience, a special transport, stream, is provided, which represents the above implementation with order.

• HTTP Long polling

  The client performs a HTTP persistent connection and the server ends the connection with data. Then, the client receives it and performs a request again.

  • longpollajax: in case of same origin connection, works without qualification. In case of cross origin, works if XMLHttpRequest supports CORS.
  • longpollxdr: works if browser supports XDomainRequest and xdrURL option is set.
  • longpolljsonp: works always.

  For convenience, a special transport, longpoll, is provided, which represents the above implementation with order.

As specified in the protocol, in case of HTTP Streaming and HTTP Long polling, they establishes read-only connection using GET method. To simulate a full-duplex connection over HTTP, POST is used to write data and the following ways are used in HTTP transports to perform POST request.

• XMLHttpRequest: in case of same origin, works without qualification. In case of cross origin, works if browser supports CORS.
• XDomainRequest: works if browser supports XDomainRequest and xdrURL option is set.
• Form tag: works alwayas but makes a clicking sound.

Compatibility

The compatiblity of vibe.js depends on transport compatibility.

Browser

The policy for browser support is the same with the one of jQuery 1.x.

Transport list in each cell is ordered by recommendation. As to ws, a word in parentheses means WebSocket protocol. So in order to use ws, the server has to be able to support that protocol.

Note

• 1: only availabe in same origin connection
• 2: not available in Metro.
• 3: xdrURL option is required.

Node.js

Node.js lower than 0.10 may work.

Quirks

The vibe.js always has tried to deal with any quirks in non-invasive way. However, it is not possible sometimes.

The browser limits the number of simultaneous connections

Applies to: HTTP transport

According to the HTTP/1.1 spec, a single-user client should not maintain more than 2 connections. This restriction actually varies with the browser. If you consider multiple topics to subscribe and publish, utilize the custom event in a single connection.

Pressing ESC key aborts the connection

Applies to: Firefox less than 20

One of default behaviors of pressing ESC key in Firefox is to cancel all open networking requests fired by XMLHttpRequest, EventSource, WebSocket and so on. The workaround is to prevent that behavior, and its drawback is that the user can't expect the default behavior of pressing ESC key. Fixed in Firefox 20.

// With jQuery
$(window).keydown(function(event) {
    if (event.which === 27) {
        event.preventDefault();
    }
});

Sending an event emits a clicking sound

Applies to: cross-origin HTTP connection on browsers not supporting CORS

If a given url is cross-origin and the browser doesn't support CORS such as Internet Explorer 6, an invisible form tag is used to send data to the server. Here, a clicking sound occurs every time the form is submitted. There is no workaround. Sorry...

A blank page pops up when using connection sharing

Applies to: Internet Explorer whose version is higher than 8.0.7601.17514 and lower than 9.0

When sharing option is true, if there is trace of a shared connection, new sockets try to utilize it. In doing this, some Internet Explorer versions don't allow to access other windows so that a blank page pops up instead of getting a reference to targeted window. No workaround. Sorry...