Sending websocket ping pong frame from browser

Question

I keep reading about ping pong messages in websockets to keep the connection alive  but I m not sure what they are   Is it a distinct frame type   I don t see any methods on a javascript WebSocket object in chrome related to ping-pong    Or is it just a design pattern  e g  I literally send  ping  or any other string to the server and have it respond    Is ping-pong at all related to continuation frames   The reason I ask is I m using a python framework that runs behind Mongrel2  so I m wondering if there s a way to send Mongrel2 a specific ping pong message that would tell it to keep the connection alive without my python app needing to worry about it   Analogous to a having a separate HTTP method for it  I guess   And I imagine a dedicated ping pong message frame could be simpler  less load on server and network  than the string  ping   though that probably wouldn t matter too much   EDIT  I just looked at RFC 6455 and it looks like Ping and Pong are definitely control frame types with their own opcodes   So how do I send a Ping frame from javascript in Chrome

User · Answer

a possible solution in js

In case the WebSocket server initiative disconnects the ws link after a few minutes there no messages sent between the server and client.

client sends a custom ping message, to keep alive by using the keepAlive function
server ignore the ping message and response a custom pong message

var timerID = 0; 
function keepAlive() { 
    var timeout = 20000;  
    if (webSocket.readyState == webSocket.OPEN) {  
        webSocket.send('');  
    }  
    timerId = setTimeout(keepAlive, timeout);  
}  
function cancelKeepAlive() {  
    if (timerId) {  
        clearTimeout(timerId);  
    }  
}

User · Answer

Ping is meant to be sent only from server to client  and browser should answer as soon as possible with Pong OpCode  automatically  So you have not to worry about that on higher level   Although that not all browsers support standard as they suppose to  they might have some differences in implementing such mechanism  and it might even means there is no Pong response functionality  But personally I am using Ping   Pong  and never saw client that does not implement this type of OpCode and automatic response on low level client side implementation

User · Answer

There is no Javascript API to send ping frames or receive pong frames  This is either supported by your browser  or not  There is also no API to enable  configure or detect whether the browser supports and is using ping pong frames  There was discussion about creating a Javascript ping pong API for this  There is a possibility that pings may be configurable detectable in the future  but it is unlikely that Javascript will be able to directly send and receive ping pong frames   However  if you control both the client and server code  then you can easily add ping pong support at a higher level  You will need some sort of message type header metadata in your message if you don t have that already  but that s pretty simple  Unless you are planning on sending pings hundreds of times per second or have thousands of simultaneous clients  the overhead is going to be pretty minimal to do it yourself

[javascript] Sending websocket ping/pong frame from browser

a possible solution in js

Examples related to javascript

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Examples related to mongrel2