I have a basic chat app set up like so:
$(function () {
// Set up references for other functions to call
chatConnection = $.connection.chatHub;
// Set up callbacks before starting server connection
chatConnection.client.addNewMessageToPage = function (name, message) {
var prettyMessage = name + ':' + message;
$('#chatHistory').append(prettyMessage);
$("#chatHistory").animate({ scrollTop: $('#chatHistory').prop("scrollHeight") }, 10);
};
// Start up connection to server, set up events
$.connection.hub.start().done(function () {
$('#sendChatButton').click(function () {
// Call the Send method on the hub.
chatConnection.server.sendMessage($('#displayName').val(), $('#chatBox').val());
// Clear text box and reset focus for next comment.
$('#chatBox').val('').focus();
});
});
});
This calls into my ChatHub.cs server side and I am getting and passing back messages as you would expect.
public void SendMessage(string name, string message)
{
Clients.All.addNewMessageToPage(name, message);
}
Now I want to add functionality. I Have a new class almost identical to my ChatHub called "GameHub" and it's job is to process moves instead of processing chat. So far I have something like this:
$(function () {
// Set up references for other functions to call
chatConnection = $.connection.chatHub;
gameConnection = $.connection.gameHub;
// Set up callbacks before starting server connection
chatConnection.client.addNewMessageToPage = function (name, message) {
var prettyMessage = name + ':' + message;
$('#chatHistory').append(prettyMessage);
$("#chatHistory").animate({ scrollTop: $('#chatHistory').prop("scrollHeight") }, 10);
};
gameConnection.client.receiveMove = function (name, move){
alert(name + ' played ' + move);
};
// Start up connection to server, set up events
$.connection.hub.start().done(function () {
$('#sendChatButton').click(function () {
// Call the Send method on the hub.
chatConnection.server.sendMessage($('#displayName').val(), $('#chatBox').val());
// Clear text box and reset focus for next comment.
$('#chatBox').val('').focus();
});
$('#sendMoveButton').click(function () {
gameConnection.server.sendMove(getMove());
});
});
});
but nothing is making it to the server. Is this because I don't have it set up correct? Can signalR even support 2 hubs or should it be a single hub and "spoke" out from there to my 2 different functional areas?
You can but given that there is no performance difference it's simpler to have those functions in one hub. All data will hit all hubs as they all share the same connection.
As documented here.
You can check, since it's not provided, your game hub and method to ensure you have them named and cased properly on the server side. Possible issues...
Related
Context : I am using a Collection Params to call method from the Server to a C app. The C app does its stuff and then calls the server by RPC to send me the results. With the result, I get the Params ID to delete the corresponding element.
With the deletion of the Element of Params, the C app gets a removed message. I want to prevent this behavior to avoid overloading the C app of messages.
I've thinked about implementing the removed event into the Publish method on the server to prevent the server from informing the C app. I just want the C app to be inform about added events.
On the Meteor Doc, there is an example of implementation of added and removed but I don't understand it. Can someone help me ?
I've tried this (don't work at all) :
Meteor.publish('expert_mode_parameters', function ()
{
var self = this;
var handle = Expert_Mode_Parameters.find().observeChanges({
added: function ()
{
return Expert_Mode_Parameters.find();
},
removed: function ()
{
return [];
}
});
self.ready();
self.onStop(function () {
handle.stop();
});
}
It looks like your goal is to subscribe to a data set but only receive added messages, not changed or removed.
The below code should do this:
Meteor.publish('expert_mode_parameters', function () {
var self = this;
var handle = Expert_Mode_Parameters.find().observe({
added: function (document) {
self.added("expert_mode_parameters", document._id, document);
}
});
self.ready();
self.onStop(function () {
handle.stop();
});
}
The concept is, you're watching the results of Expert_Mode_Parameters.find() and then calling self.added(document) when there is a new item. The same thing can easily be expanded to include changed.
I am building a realtime game with Meteor streams. I need to update only one client - send a room ID from server. Users are not logged in so Meteor.userId() is null and therefore I can't use this: http://arunoda.github.io/meteor-streams/communication-patterns.html#streaming_private_page
There is only one URL (homepage) where all things happen. So I don't use any URL parameters for room. Everything is on the server.
I have tried to use Meteor.uuid() instead of Meteor.userId() but uuid is changed after each emit (which is strange).
In socket.io I would do this:
//clients is an array of connected socket ids
var clientIndex = clients.indexOf(socket.id);
io.sockets.socket(clients[clientIndex]).emit('message', 'hi client');
Is there any way to do this in Meteor streams or Meteor itself?
Well, this can be easily done if you decided to use database, but I guess it is not the best option if you have a large number of clients.
So another way to achieve this - without database - is to make a good use of the Meteor's publish/subscribe mechanism. Basically the way it could work is the following:
1. client asks server for a communication token (use Meteor.methods)
2. client subscribes to some (abstract) data set using that token
3. server publishes the required data based on the received token
So you will need to define a method - say getToken - on the server that generates tokens for new users (since you don't want to use accounts). This could be something more or less like this:
var clients = {}
Meteor.methods({
getToken: function () {
var token;
do {
token = Random.id();
} while (clients[token]);
clients[token] = {
dependency: new Deps.Dependency(),
messages: [],
};
return token;
},
});
A new client will need to ask for token and subscribe to the data stream:
Meteor.startup(function () {
Meteor.call('getToken', function (error, myToken) {
// possibly use local storage to save the token for further use
if (!error) {
Meteor.subscribe('messages', myToken);
}
});
});
On the server you will need to define a custom publish method:
Meteor.publish('messages', function (token) {
var self = this;
if (!clients[token]) {
throw new Meteor.Error(403, 'Access deniend.');
}
send(token, 'hello my new client');
var handle = Deps.autorun(function () {
clients[token].dependency.depend();
while (clients[token].messages.length) {
self.added('messages', Random.id(), {
message: clients[token].messages.shift()
});
}
});
self.ready();
self.onStop(function () {
handle.stop();
});
});
and the send function could defined as follows:
var send = function (token, message) {
if (clients[token]) {
clients[token].messages.push(message);
clients[token].dependency.changed();
}
}
That's a method I would use. Please check if it works for you.
I think using Meteor.onConnection() like a login would enable you to do what you want pretty easily in a publish function.
Something like this:
Messages = new Meteor.Collection( 'messages' );
if ( Meteor.isServer ){
var Connections = new Meteor.Collection( 'connections' );
Meteor.onConnection( function( connection ){
var connectionMongoId = Connections.insert( connection );
//example Message
Message.insert( {connectionId: connection.id, msg: "Welcome"});
//remove users when they disconnect
connection.onClose = function(){
Connections.remove( connectionMongoId );
};
});
Meteor.publish( 'messages', function(){
var self = this;
var connectionId = self.connection.id;
return Messages.find( {connectionId: connectionId});
});
}
if ( Meteor.isClient ){
Meteor.subscribe('messages');
Template.myTemplate.messages = function(){
//show all user messages in template
return Messages.find();
};
}
I have used database backed collections here since they are the default but the database is not necessary. Making Messages a collection makes the reactive publishing easy whenever a new message is inserted.
One way that this is different from streams is that all the messages sent to all clients will end up being kept in server memory as it tries to keeps track of all data sent. If that is really undesirable then you could use a Meteor.method so send data instead and just use publish to notify a user a new message is available so call the method and get it.
Anyway this is how I would start.
is there a way to simulate lag with Meteor? Perhaps something that would delay all calls by say, 300ms?
You can do it in publish using:
Meteor._sleepForMs(5000); // sleeps for 5 seconds
I guess I'm a bit late for the party, but here's a better solution:
There are basically two parts to this question. One is, how to delay Meteor WebSocket (SockJS) writes and one is how to delay HTTP traffic (connect). You'll need to add both of the following snippets to your server-side code in order to delay all traffic sent from the Meteor server.
WebSocket
The hard part was overwriting the WebSocket write to delay it with a setTimeout:
(function () {
// Set the delay you want
var timeout = 3000
// stream_server abstracts sockJS the DDP-Server talks to it.
var streamServer = Meteor.server.stream_server
// The connect event listener
var standardConnect = streamServer.server._events.connection
// Overwrite the default event-handler
streamServer.server._events.connection = function (socket) {
// Overwrite the writes to the socket
var write = socket.write
socket.write = function () {
var self = this
var args = arguments
// Add a delay
setTimeout(function () {
// Call the normal write methods with the arguments passed to this call
write.apply(self, args)
}, timeout)
}
// Call the normal handler after overwritting the socket.write function
standardConnect.apply(this, arguments)
}
})()
HTTP
With connect it's pretty straight forward:
// Add a simple connect handler, wich calls the next handler after a delay
WebApp.rawConnectHandlers.use(function (req, res, next) {
return setTimeout(next, timeout)
})
Not sure about all calls, but you can use Futures to add a lag on the server, that way you can see latency compensation in action.
In a meteor method for example, you can
Meteor.methods({
post: function(post) {
post.title = post.title + (this.isSimulation ? '(client)' : '(server)');
// wait for 5 seconds
if (! this.isSimulation) {
var Future = Npm.require('fibers/future');
var future = new Future();
Meteor.setTimeout(function() {
future.ret();
}, 5 * 1000); // 5 seconds
future.wait();
}
var postId = Posts.insert(post);
return postId;
}
});
This will show the post being inserted with (client) appended to the end, and then 5 seconds later will get the update from the server and post's title will end with (server)
If you want simulate the lag in the subscriptions you can do the next:
Meteor.publish('collection', function(params) {
Meteor._sleepForMs(2000); // Sleep for 2 seconds
return CollectionX.find(params.query,params.projection);
});
I have a form that was created on it's own UI thread running in the system tray which I need to manipulate with a signalR connection from the server which I believe to be running on a background thread. I'm aware of the need to invoke controls when not accessing them from their UI thread. I am able to manipulate (make popup in my case) using the following code that is called on form load but would like a sanity check as I'm fairly new to async:
private void WireUpTransport()
{
// connect up to the signalR server
var connection = new HubConnection("http://localhost:32957/");
var messageHub = connection.CreateProxy("message");
var uiThreadScheduler = TaskScheduler.FromCurrentSynchronizationContext();
var backgroundTask = connection.Start().ContinueWith(task =>
{
if (task.IsFaulted)
{
Console.WriteLine("There was an error opening the connection: {0}", task.Exception.GetBaseException());
}
else
{
Console.WriteLine("The connection was opened successfully");
}
});
// subscribe to the servers Broadcast method
messageHub.On<Domain.Message>("Broadcast", message =>
{
// do our work on the UI thread
var uiTask = backgroundTask.ContinueWith(t =>
{
popupNotifier.TitleText = message.Title + ", Priority: " + message.Priority.ToString();
popupNotifier.ContentText = message.Body;
popupNotifier.Popup();
}, uiThreadScheduler);
});
}
Does this look OK? It's working on my local machine but this has the potential to be rolled out on every user machine in our business and I need to get it right.
Technically you should hook up to all notifications (using On<T>) before you Start listening. As far as your async work I'm not quite sure what you were trying to do, but for some reason your chaining the notification to your UI in On<T> to the backgroundTask variable which is the Task that was returned to you by the call to Start. There's no reason for that to be involved there.
So this is probably what you want:
private void WireUpTransport()
{
// connect up to the signalR server
var connection = new HubConnection("http://localhost:32957/");
var messageHub = connection.CreateProxy("message");
var uiTaskScheduler = TaskScheduler.FromCurrentSynchronizationContext();
// subscribe to the servers Broadcast method
messageHub.On<Domain.Message>("Broadcast", message =>
{
// do our work on the UI thread
Task.Factory.StartNew(
() =>
{
popupNotifier.TitleText = message.Title + ", Priority: " + message.Priority.ToString();
popupNotifier.ContentText = message.Body;
popupNotifier.Popup();
},
CancellationToken.None,
TaskCreationOptions.None,
uiTaskScheduler);
});
connection.Start().ContinueWith(task =>
{
if (task.IsFaulted)
{
Console.WriteLine("There was an error opening the connection: {0}", task.Exception.GetBaseException());
}
else
{
Console.WriteLine("The connection was opened successfully");
}
});
}
Finding it hard to describe this issue - so please edit if you know more relevant terms.
I'm building a web application which essentially uses Redis (PubSub) + Node.js + Socket.IO as a distribution server.
I have two-way communication working with no issues - but I need to be able to make a request to the server from the client (asynchronously) and deal with the response while still processing other irrelevant responses that might come in before it.
This is what I have so far, but I'm not particularly happy with this approach:
Server
// Lots of other code
redis.psubscribe('*');
redis.on("pmessage", function(pattern, channel, message) {
// broadcast
});
io.on('connection', function(client) {
client.on('message', function(message) {
switch(message.method) {
// call relevant function
}
});
});
function object_exists(object_id) {
// do stuff to check object exists
client.send({method: 'object_exists', value: object_exists});
}
Client
var call = Array();
$(document).ready(function() {
socket.connect();
socket.on("message", function(obj){
console.log(obj);
call[obj.method](obj.value);
});
});
function object_exists(object_id) {
socket.send({method: 'object_exists', value: object_id});
// Set a function to be called when the next server message with the 'object_exists' method is received.
call['object_exists'] = function(value) {
if(value) {
// object does exist
}
}
}
tl;dr: I need to 'ask' the server something and then deal with the response using Socket.IO.
You don't specifically say why you are unhappy with your approach, but it looks to me like you are almost there. I am not really sure what you are trying to do with the call array, so I just took it out for clarity.
Basically, you just need to set up a switch statement to act as a message router on each side of the socket connection and fire off the appropriate methods based in incoming messages. Send enough state with the message itself so you can handle the work without any additional context. In your reworked code, I send the object_id to the server and back again to the client.
///SERVER
// Lots of other code
redis.psubscribe('*');
redis.on("pmessage", function(pattern, channel, message) {
// broadcast
});
io.on('connection', function(client) {
client.on('message', function(message) {
switch(message.method) {
case 'object_exists':
object_exists(message.objectId);
break;
}
});
});
//Takes an id an returns true if the object exists
function object_exists(object_id) {
// do stuff to check object exists
client.send({method: 'object_exists', objectId: object_id, value: object_exists});
}
///CLIENT
$(document).ready(function() {
//setup the message event handler for any messages coming back from the server
//This won't fire right away
socket.on("message", function(message){
switch(message.method) {
case 'object_exists':
object_exists(message.objectId, message.value);
break;
}
});
//When we connect, send the server the message asking if object_exists
socket.on("connect", function() {
socket.send({method: 'object_exists', objectId: object_id});
});
//Initiate the connection
socket.connect();
});
//Get's called with with objectId and a true if it exists, false if it does not
function object_exists(objectId, value) {
if(value) {
// object does exist, do something with objectId
}
else {
// object does not exist
}
}
If you want to see a bunch more code in the same stack doing work similar to what you are trying to accomplish, check out my nodechat.js project.