can somebody help me out a little? I am a little stuck.
I am trying to write a signaling process with ajax and a database involved (this is just for learning the basics of WebRTC for now).
I am receiving the SDP fine from the JSON-object as it seems, but then I always get an error "Cannot create answer in stable" when I try to create an answer in get_remote_offer() for pc_partner.
I am pretty sure it is something obvious, but I am pretty new to WebRTC and just can't see what.
I am using Firefox here and just trying to connect two instances of it (one in private mode, one in "normal" mode, but I am trying to make it work for remote users.
This is my code:
var opt;
var video_el_partner;
var video_el_local;
var pc_partner;
var pc_local;
var interval_gro;
var remote_offer_available = false;
var service_url = "https://xyz.de/webrtc";
var pwd = "xxx";
var signaling_url = "https://xyz.de/webrtc/sdp_transfer.php";
function init_stream(video_partner_id, video_local_id, allow_video, allow_audio){
if (location.protocol === 'https:') { // only possible for https!
pc_local = new RTCPeerConnection();
pc_partner = new RTCPeerConnection();
if(document.getElementById(video_partner_id) != null){
video_el_partner = document.getElementById(video_partner_id);
video_el_local = document.getElementById(video_local_id);
if(allow_video == null){
allow_video = true;
}
if(allow_audio == null){
allow_audio = true;
}
opt = { audio: allow_audio, video: allow_video };
if(typeof navigator != 'undefined' && typeof navigator.mediaDevices != 'undefined' && navigator.mediaDevices.getUserMedia != null){
navigator.mediaDevices.getUserMedia(opt).then (
function (this_stream){
// local video directly into video element:
video_el_local.srcObject = this_stream;
// remote one is more insteresting:
pc_local.addStream(this_stream);
pc_local.createOffer().then(
function (this_sdp) {
// sdp (session dependend protocol object) is now available... this would need to go to a server somehow now.
// they use socket.io for that... maybe I can use my own thing to do that?
pc_local.setLocalDescription(this_sdp);
var this_sdp_json = JSON.stringify(this_sdp)
var params_ins = "mode=insert_offer&sdp_con=" + this_sdp_json + "&pass=" + pwd + "&service_url=" + service_url;
ajax_request_simple (
signaling_url,
params_ins,
function (res_ins) {
// insert done. Lets read for another candidate.
console.log('Set Interval!');
interval_gro = window.setInterval('get_remote_offer();', 5000);
}
);
}
);
}
).catch(
function (error) {
console.log('Problem: ');
console.log(error);
}
);
} else {
console.log("navgiator or navigator.mediaDevices is not defined.");
}
}
} else {
console.log('init_stream(): We can only do anything like that on https-connections! Http is not supported by the browser!');
}
}
window.onload = function () {
document.getElementById('button_start_stream').onclick = function () {
init_stream('video_partner', 'video_local', true, false);
}
}
function is_json_str(str) {
try {
JSON.parse(str);
} catch (e) {
return false;
}
return true;
}
function get_remote_offer() {
var params_read = "mode=get_offer&pass=" + pwd + "&service_url=" + service_url;
ajax_request_simple (
signaling_url,
params_read,
function (res_read) {
// done.
if(is_json_str(res_read)){
// seems like we get one now.
// lets use that to connect and stream the video to the remote view.
var partner_offer = res_read;
partner_offer = JSON.parse(partner_offer);
// clear interval if found.
window.clearInterval(interval_gro);
console.log('Cleared Interval. Found!');
pc_local.setRemoteDescription(
new RTCSessionDescription(partner_offer), function(){
// video_el_partner.srcObject = event.stream;
pc_local.onicecandidate = function (e) {
if ( e.candidate != null ) {
pc_partner.addIceCandidate( new RTCIceCandidate(e.candidate) );
}
};
pc_partner.onicecandidate = function (e) {
if ( e.candidate != null ) {
pc_local.addIceCandidate( new RTCIceCandidate(e.candidate) );
}
};
pc_partner.createAnswer(
function (offer) {
pc_local.setRemoteDescription(offer);
pc_partner.setLocalDescription(offer);
}
);
// pc_local.ontrack = function (evt) {
// video_el_local.srcObject = evt.stream;
// };
pc_partner.ontrack = function (evt) {
video_el_partner.srcObject = evt.stream;
};
},
function(e) {
console.log("Problem while doing client-answer: ", e);
}
);
} else {
console.log("Can not parse: ");
console.log(res_read);
}
}
);
}
Sorry for the mix of promises and callbacks... I tried a couple of things out just in case... when it is working I will rewrite the callback parts.
Thank you very much in advance for any hint you can give me :).
Best regards and thanks for reading till now ;).
Fuchur
I have Ejabberd server hosted in remote location. And I am trying to register new accounts using Strophe.js register plugin I could not find why this is not working. Below is the code I have written
var connection = new Strophe.Connection("http://ip-address:5222/http-bind");
var callback = function (status) {
alert(Strophe.Status.REGISTER); // Returning me 10
if (status === Strophe.Status.REGISTER) {
alert("Entered");
connection.register.fields.username = "hello";
connection.register.fields.password = "hello";
connection.register.submit();
} else if (status === Strophe.Status.REGISTERED) {
alert("registered!");
connection.authenticate();
} else if (status === Strophe.Status.CONNECTED) {
alert("logged in!");
} else {
// Sometimes execution entering into this block.
document.body.innerHTML = (JSON.stringify(status));
}
};
connection.register.connect("localhost", callback);
Any extra code to be added to this or any fix I have to do make this work. Please help me on this. Strophe.js documentation is awful.
In strophe.register.js go to line no 215 and make change as per below code.
/*if (register.length === 0) {
that._changeConnectStatus(Strophe.Status.REGIFAIL, null);
return;
} else */
this.enabled = true;
Try above one.
var connection = new Strophe.Connection("http://ip-address:5222/http-bind/");
Trailing Slash is needed at the end.
I am trying to associate an XMLHttpRequest with a tab on the browser using the following code:
function getBrowserFromChannel(aChannel) {
var notificationCallbacks =
aChannel.notificationCallbacks ?
aChannel.notificationCallbacks :
aChannel.loadGroup.notificationCallbacks;
if (!notificationCallbacks) {
console.log("no callbacks");
return (0);
}
var loadContext = notificationCallbacks.getInterface(Ci.nsILoadContext);
getInterface(Ci.nsILoadContext) fails with: "Component does not have requested interface"
Any idea how else I can get the browser?
Thanks
Try this code (from Lightbeam):
function getLoadContext(aRequest) {
try {
// first try the notification callbacks
var loadContext = aRequest.QueryInterface(Ci.nsIChannel)
.notificationCallbacks.getInterface(Ci.nsILoadContext);
return loadContext;
} catch (ex) {
// fail over to trying the load group
try {
if (!aRequest.loadGroup) return null;
var loadContext = aRequest.loadGroup.notificationCallbacks.getInterface(Ci.nsILoadContext);
return loadContext;
} catch (ex) {
return null;
}
}
}
Note the license is MPL 1.1/GPL 2.0/LGPL 2.1
I need to work out the best way to read data that is being written to a file, using node.js, in real time. Trouble is, Node is a fast moving ship which makes finding the best method for addressing a problem difficult.
What I Want To Do
I have a java process that is doing something and then writing the results of this thing it does to a text file. It typically takes anything from 5 mins to 5 hours to run, with data being written the whole time, and can get up to some fairly hefty throughput rates (circa. 1000 lines/sec).
I would like to read this file, in real time, and then, using node aggregate the data and write it to a socket where it can be graphed on the client.
The client, graphs, sockets and aggregation logic are all done but I am confused about the best approach for reading the file.
What I Have Tried (or at least played with)
FIFO - I can tell my Java process to write to a fifo and read this using node, this is in fact how we have this currently implemted using Perl, but because everything else is running in node it makes sense to port the code over.
Unix Sockets - As above.
fs.watchFile - will this work for what we need?
fs.createReadStream - is this better than watchFile?
fs & tail -f - seems like a hack.
What, actually, is my Question
I am tending towards using Unix Sockets, this seems the fastest option. But does node have better built-in features for reading files from the fs in real time?
If you want to keep the file as a persistent store of your data to prevent a loss of stream in case of a system crash or one of the members in your network of running processes dies, you can still continue on writing to a file and reading from it.
If you do not need this file as a persistent storage of produced results from your Java process, then going with a Unix socket is much better for both the ease and also the performance.
fs.watchFile() is not what you need because it works on file stats as filesystem reports it and since you want to read the file as it is already being written, this is not what you want.
SHORT UPDATE: I am very sorry to realize that although I had accused fs.watchFile() for using file stats in previous paragraph, I had done the very same thing myself in my example code below! Although I had already warned readers to "take care!" because I had written it in just a few minutes without even testing well; still, it can be done better by using fs.watch() instead of watchFile or fstatSync if underlying system supports it.
For reading/writing from a file, I have just written below for fun in my break:
test-fs-writer.js: [You will not need this since you write file in your Java process]
var fs = require('fs'),
lineno=0;
var stream = fs.createWriteStream('test-read-write.txt', {flags:'a'});
stream.on('open', function() {
console.log('Stream opened, will start writing in 2 secs');
setInterval(function() { stream.write((++lineno)+' oi!\n'); }, 2000);
});
test-fs-reader.js: [Take care, this is just demonstration, check err objects!]
var fs = require('fs'),
bite_size = 256,
readbytes = 0,
file;
fs.open('test-read-write.txt', 'r', function(err, fd) { file = fd; readsome(); });
function readsome() {
var stats = fs.fstatSync(file); // yes sometimes async does not make sense!
if(stats.size<readbytes+1) {
console.log('Hehe I am much faster than your writer..! I will sleep for a while, I deserve it!');
setTimeout(readsome, 3000);
}
else {
fs.read(file, new Buffer(bite_size), 0, bite_size, readbytes, processsome);
}
}
function processsome(err, bytecount, buff) {
console.log('Read', bytecount, 'and will process it now.');
// Here we will process our incoming data:
// Do whatever you need. Just be careful about not using beyond the bytecount in buff.
console.log(buff.toString('utf-8', 0, bytecount));
// So we continue reading from where we left:
readbytes+=bytecount;
process.nextTick(readsome);
}
You can safely avoid using nextTick and call readsome() directly instead. Since we are still working sync here, it is not necessary in any sense. I just like it. :p
EDIT by Oliver Lloyd
Taking the example above but extending it to read CSV data gives:
var lastLineFeed,
lineArray;
function processsome(err, bytecount, buff) {
lastLineFeed = buff.toString('utf-8', 0, bytecount).lastIndexOf('\n');
if(lastLineFeed > -1){
// Split the buffer by line
lineArray = buff.toString('utf-8', 0, bytecount).slice(0,lastLineFeed).split('\n');
// Then split each line by comma
for(i=0;i<lineArray.length;i++){
// Add read rows to an array for use elsewhere
valueArray.push(lineArray[i].split(','));
}
// Set a new position to read from
readbytes+=lastLineFeed+1;
} else {
// No complete lines were read
readbytes+=bytecount;
}
process.nextTick(readFile);
}
Why do you think tail -f is a hack?
While figuring out I found a good example I would do something similar.
Real time online activity monitor example with node.js and WebSocket:
http://blog.new-bamboo.co.uk/2009/12/7/real-time-online-activity-monitor-example-with-node-js-and-websocket
Just to make this answer complete, I wrote you an example code which would run under 0.8.0 - (the http server is a hack maybe).
A child process is spawned running with tail, and since a child process is an EventEmitter with three streams (we use stdout in our case) you can just add the a listener with on
filename: tailServer.js
usage: node tailServer /var/log/filename.log
var http = require("http");
var filename = process.argv[2];
if (!filename)
return console.log("Usage: node tailServer filename");
var spawn = require('child_process').spawn;
var tail = spawn('tail', ['-f', filename]);
http.createServer(function (request, response) {
console.log('request starting...');
response.writeHead(200, {'Content-Type': 'text/plain' });
tail.stdout.on('data', function (data) {
response.write('' + data);
});
}).listen(8088);
console.log('Server running at http://127.0.0.1:8088/');
this module is an implementation of the principle #hasanyasin suggests:
https://github.com/felixge/node-growing-file
I took the answer from #hasanyasin and wrapped it up into a modular promise. The basic idea is that you pass a file and a handler function that does something with the stringified-buffer that is read from the file. If the handler function returns true, then the file will stop being read. You can also set a timeout that will kill reading if the handler doesn't return true fast enough.
The promiser will return true if the resolve() was called due to timeout, otherwise it will return false.
See the bottom for usage example.
// https://stackoverflow.com/a/11233045
var fs = require('fs');
var Promise = require('promise');
class liveReaderPromiseMe {
constructor(file, buffStringHandler, opts) {
/*
var opts = {
starting_position: 0,
byte_size: 256,
check_for_bytes_every_ms: 3000,
no_handler_resolution_timeout_ms: null
};
*/
if (file == null) {
throw new Error("file arg must be present");
} else {
this.file = file;
}
if (buffStringHandler == null) {
throw new Error("buffStringHandler arg must be present");
} else {
this.buffStringHandler = buffStringHandler;
}
if (opts == null) {
opts = {};
}
if (opts.starting_position == null) {
this.current_position = 0;
} else {
this.current_position = opts.starting_position;
}
if (opts.byte_size == null) {
this.byte_size = 256;
} else {
this.byte_size = opts.byte_size;
}
if (opts.check_for_bytes_every_ms == null) {
this.check_for_bytes_every_ms = 3000;
} else {
this.check_for_bytes_every_ms = opts.check_for_bytes_every_ms;
}
if (opts.no_handler_resolution_timeout_ms == null) {
this.no_handler_resolution_timeout_ms = null;
} else {
this.no_handler_resolution_timeout_ms = opts.no_handler_resolution_timeout_ms;
}
}
startHandlerTimeout() {
if (this.no_handler_resolution_timeout_ms && (this._handlerTimer == null)) {
var that = this;
this._handlerTimer = setTimeout(
function() {
that._is_handler_timed_out = true;
},
this.no_handler_resolution_timeout_ms
);
}
}
clearHandlerTimeout() {
if (this._handlerTimer != null) {
clearTimeout(this._handlerTimer);
this._handlerTimer = null;
}
this._is_handler_timed_out = false;
}
isHandlerTimedOut() {
return !!this._is_handler_timed_out;
}
fsReadCallback(err, bytecount, buff) {
try {
if (err) {
throw err;
} else {
this.current_position += bytecount;
var buff_str = buff.toString('utf-8', 0, bytecount);
var that = this;
Promise.resolve().then(function() {
return that.buffStringHandler(buff_str);
}).then(function(is_handler_resolved) {
if (is_handler_resolved) {
that.resolve(false);
} else {
process.nextTick(that.doReading.bind(that));
}
}).catch(function(err) {
that.reject(err);
});
}
} catch(err) {
this.reject(err);
}
}
fsRead(bytecount) {
fs.read(
this.file,
new Buffer(bytecount),
0,
bytecount,
this.current_position,
this.fsReadCallback.bind(this)
);
}
doReading() {
if (this.isHandlerTimedOut()) {
return this.resolve(true);
}
var max_next_bytes = fs.fstatSync(this.file).size - this.current_position;
if (max_next_bytes) {
this.fsRead( (this.byte_size > max_next_bytes) ? max_next_bytes : this.byte_size );
} else {
setTimeout(this.doReading.bind(this), this.check_for_bytes_every_ms);
}
}
promiser() {
var that = this;
return new Promise(function(resolve, reject) {
that.resolve = resolve;
that.reject = reject;
that.doReading();
that.startHandlerTimeout();
}).then(function(was_resolved_by_timeout) {
that.clearHandlerTimeout();
return was_resolved_by_timeout;
});
}
}
module.exports = function(file, buffStringHandler, opts) {
try {
var live_reader = new liveReaderPromiseMe(file, buffStringHandler, opts);
return live_reader.promiser();
} catch(err) {
return Promise.reject(err);
}
};
Then use the above code like this:
var fs = require('fs');
var path = require('path');
var Promise = require('promise');
var liveReadAppendingFilePromiser = require('./path/to/liveReadAppendingFilePromiser');
var ending_str = '_THIS_IS_THE_END_';
var test_path = path.join('E:/tmp/test.txt');
var s_list = [];
var buffStringHandler = function(s) {
s_list.push(s);
var tmp = s_list.join('');
if (-1 !== tmp.indexOf(ending_str)) {
// if this return never occurs, then the file will be read until no_handler_resolution_timeout_ms
// by default, no_handler_resolution_timeout_ms is null, so read will continue forever until this function returns something that evaluates to true
return true;
// you can also return a promise:
// return Promise.resolve().then(function() { return true; } );
}
};
var appender = fs.openSync(test_path, 'a');
try {
var reader = fs.openSync(test_path, 'r');
try {
var options = {
starting_position: 0,
byte_size: 256,
check_for_bytes_every_ms: 3000,
no_handler_resolution_timeout_ms: 10000,
};
liveReadAppendingFilePromiser(reader, buffStringHandler, options)
.then(function(did_reader_time_out) {
console.log('reader timed out: ', did_reader_time_out);
console.log(s_list.join(''));
}).catch(function(err) {
console.error('bad stuff: ', err);
}).then(function() {
fs.closeSync(appender);
fs.closeSync(reader);
});
fs.write(appender, '\ncheck it out, I am a string');
fs.write(appender, '\nwho killed kenny');
//fs.write(appender, ending_str);
} catch(err) {
fs.closeSync(reader);
console.log('err1');
throw err;
}
} catch(err) {
fs.closeSync(appender);
console.log('err2');
throw err;
}
Here is how the code is.
function AppAssistant() {
this.dbObj = new DatabaseAssistant();
this.schemaObj = new SchemaAssistant();
this.result = {};
}
AppAssistant.prototype.setup = function() {
}
AppAssistant.prototype.handleLaunch = function(launchParams) {
if (gConfigDatabase.engine == "sqllite") {
} else {
}
}
AppAssistant.prototype.processResult = function() {
}
AppAssistant.prototype.execMigrations = function(version) {
}
// Database error handler
// If the db does not exists, it will generate set of tables
AppAssistant.prototype.errorHandler = function() {
Mojo.Log.info("In app asst error handler.");
if (gConfigDatabase.engine == "sqllite") {
try {
// execute some queries to create tables and insert some values in the HTML Opendatabase.
// Show disclaimer Page
Mojo.Controller.stageController.pushScene('disclaimer');
} catch (e) {
Mojo.Log.error("In AppAssistant errorHandler : ", e);
}
} else {
Mojo.Log.info("db8 part of app asst error handler");
try {
// execute operations to create kinds for db8 analogous to tables
Mojo.Controller.stageController.pushScene("disclaimer");
} catch (e) {
Mojo.Log.info("Error in db8 appAsst error handler", e);
}
}
}
AppAssistant.prototype.handleCommand = function(event) {
}
All this was done to support both sqllite and db8 for an webOS app. The problem i am facing is that when i configure a variable (gConfigDatabase) as sqllite then the Mojo.Controller.stageController.pushScene` method which is there in the errorHandler function works. but when i change it so that db8 engine is used, then i get an error saying undefined method pushScene. Any clues or hints on debugging or solving this ?