js/WebSocketTransport.js

/** 
 * @author: Wentao Shang
 * See COPYING for copyright and distribution information.
 */

/**
 * @constructor
 */
var WebSocketTransport = function WebSocketTransport() {    
    if (!WebSocket)
        throw new Error("WebSocket support is not available on this platform.");
    
	this.ws = null;
    this.connectedHost = null; // Read by NDN.
    this.connectedPort = null; // Read by NDN.
    this.elementReader = null;
    this.defaultGetHostAndPort = NDN.makeShuffledGetHostAndPort
        (["A.ws.ndn.ucla.edu", "B.ws.ndn.ucla.edu", "C.ws.ndn.ucla.edu", "D.ws.ndn.ucla.edu", 
          "E.ws.ndn.ucla.edu"],
         9696);
};

/**
 * Connect to the host and port in ndn.  This replaces a previous connection and sets connectedHost
 *   and connectedPort.  Once connected, call onopenCallback().
 * Listen on the port to read an entire binary XML encoded element and call
 *    ndn.onReceivedElement(element).
 */
WebSocketTransport.prototype.connect = function(ndn, onopenCallback) {
	if (this.ws != null)
		delete this.ws;
	
	this.ws = new WebSocket('ws://' + ndn.host + ':' + ndn.port);
	if (LOG > 0) console.log('ws connection created.');
    this.connectedHost = ndn.host;
    this.connectedPort = ndn.port;
	
	this.ws.binaryType = "arraybuffer";
	
    this.elementReader = new BinaryXmlElementReader(ndn);
	var self = this;
	this.ws.onmessage = function(ev) {
		var result = ev.data;
		//console.log('RecvHandle called.');
			
		if(result == null || result == undefined || result == "" ) {
			console.log('INVALID ANSWER');
		} else if (result instanceof ArrayBuffer) {
	        var bytearray = new Uint8Array(result);
	        
			if (LOG>3) console.log('BINARY RESPONSE IS ' + DataUtils.toHex(bytearray));
			
			try {
                // Find the end of the binary XML element and call ndn.onReceivedElement.
                self.elementReader.onReceivedData(bytearray);
			} catch (ex) {
				console.log("NDN.ws.onmessage exception: " + ex);
				return;
			}
		}
	}
	
	this.ws.onopen = function(ev) {
		if (LOG > 3) console.log(ev);
		if (LOG > 3) console.log('ws.onopen: WebSocket connection opened.');
		if (LOG > 3) console.log('ws.onopen: ReadyState: ' + this.readyState);
        // NDN.registerPrefix will fetch the ccndid when needed.
        
        onopenCallback();
	}
	
	this.ws.onerror = function(ev) {
		console.log('ws.onerror: ReadyState: ' + this.readyState);
		console.log(ev);
		console.log('ws.onerror: WebSocket error: ' + ev.data);
	}
	
	this.ws.onclose = function(ev) {
		console.log('ws.onclose: WebSocket connection closed.');
		self.ws = null;
		
		// Close NDN when WebSocket is closed
		ndn.readyStatus = NDN.CLOSED;
		ndn.onclose();
		//console.log("NDN.onclose event fired.");
	}
};

/**
 * Send the Uint8Array data.
 */
WebSocketTransport.prototype.send = function(data) {
	if (this.ws != null) {
        // If we directly use data.buffer to feed ws.send(), 
        // WebSocket may end up sending a packet with 10000 bytes of data.
        // That is, WebSocket will flush the entire buffer
        // regardless of the offset of the Uint8Array. So we have to create
        // a new Uint8Array buffer with just the right size and copy the 
        // content from binaryInterest to the new buffer.
        //    ---Wentao
        var bytearray = new Uint8Array(data.length);
        bytearray.set(data);
        this.ws.send(bytearray.buffer);
		if (LOG > 3) console.log('ws.send() returned.');
	}
	else
		console.log('WebSocket connection is not established.');
}