I have created one POC for alerts using WebSockets. Where I am using AWS Socket API gateway for server side implementation and WebSocket JS API in client side.
Now I need to integrate WebSockets with a multipage application and need to get alerts. But I can't use same websocket instance in all the web pages, I have to open different web sockets for each page. Now I want to set some unique identifier for all the open sockets such that all the web pages for the logged in user in a particular browser have the same socket id, So that it will reduce the overhead of storing so many socket ids against one user sessionid.
So I want to know if it is possible with WebSocket API in JS or any other API is available which I can use to achieve this MultiSocket with same socket id kind of implementation.
For my job, I am doing research on finding a means on how a web application running locally from file:\ in IE11, created with either HTML5 or Javascript, can access the raw data or listen to a computer's serial port being sent out from a windows service or proxy. The situation is that We have a proxy designed to collect data from a computer's serial port and it will send that data outward on our network to the local host.
What we want our web application to do is to catch that data the proxy is sending out directly from the service on the computer, removing the need to have the proxy send the data to a server and having the web application collect the data from a server. So far googling the solution has been difficult. Does anyone know the solution to our problem or knows where to find the solution?
Lazy people, why don't you use Google search bar (!?!)...
Here: https://github.com/garrows/browser-serialport
Note: You cannot use this in a Web page, i.e. cannot put it on a Web server. And it is supported only by Chrome.
I am building a java chatting web application.(Server and Client in one project)
follow is my condition
Springframework 4.2.3
JSP
Maven Project which converted from a Dynamic Web Project
Unable to use node.js
So User scenario in my head is
User enters some text and press Send
Ajax call to deliver messages to server
Server checks the users who are currently connected(from Session maybe)
Server calls other users script to append new message
I am quite confusing with step4. Is it possible that Java calls DOM event trigger?
How could a client get a new message event from server?
Thanks. :D
P.S.
These days majority of chatting servers are event-driven. Is it possible to build an event driven chatting server with Java?
Your solution is formed as if there is no WebSocket technology available to you. WebSocket is implemented to solve real time messaging issues. It pushes message to the destination.
But if to stick wih your method following is meaningful.
You need someplace to keep incoming messages such as database or session.setAttribute [bad idea]. Then use some ajax call loop on the clients machine to ask for a new incoming message from server.
Probably your server will slow down due to incoming flood of GET requests from multiple users.
to Your last question in post scriptum: yes, I use tomcat websocket api.jar in my projects. There is well written documentation on apache.org
As I mentioned, learn WebSocket if your users are not using old internet explorer browsers. There are bunch of tutorials on it...
I'm creating an app where the server and the clients will run on the same local network. Is it possible to use web sockets, or rather more specifically, socket.io to have one central server and many clients that are running native apps
? The way I understand socket.io to work is that the clients read the web-pages that are served from the server but what happens when your clients become tablet devices running native apps instead of web pages in a browser?
The scenario I'm working with at the minute will have one central server containing a MEAN app and the clients (iPads) will make GET requests to the data available on the server. However, I'd also like there to be real-time functionality so if someone triggers a POST request on their iPad, the server acknowledges it and displays it in the server's client-side. The iPad apps will (ideally) be running native phonegap applications rather than accessing 192.168.1.1:9000 from their browser.
Is this technically possible to connect to the socket server from the native apps or would the devices have to send POST requests to a central server that's constantly listening for new 'messages'? I'm totally new to the whole real-time stuff so I'm just trying to wrap my head around it all.
Apologies if this isn't totally clear, it's a bit hard to describe with just text but I think you get the idea?
Correct me if I am wrong.
You have multiple iPads running native app. They send a POST request to your node JS server which is running in a computer in the same local network. Whenever the server receives a request from app, you want to display that a request has been received in your computer screen.
If my assumptions about the scenario is correct, then it is fairly easy to do. Here are the steps to do it.
Create a small webpage (front end). Load socket IO in the front end page like this -
<script type="text/javascript" src="YOUR_SERVER_IP/socket.io/socket.io.js"></script>
Then connect to server using var socket = io(). This should trigger connection event in your backend.
Handle all POST request from apps normally. Nothing special. Just add a small snippet in between. socket.emit('new_request', request_data). This sends new_request event to front end.
Handle the new_request in your front end using socket.on('new_request', function(request_data) { ... });. That's it. No need to add anything to your native app for realtime update.
The second step would be a little complicated as it is necessary to make socket variable available inside all POST requests. Since you chose node.js, I don't think you need any help with that.
Not totally clear on your project, but I'll try to give you some pointers.
An effective way to send data between native apps and a server is using a REST server. REST is based on HTTP requests and allows you to modify data on the server, which can connect to your database. The data returned is typically either JSON or XML formatted. See here for a brief intro: http://www.infoq.com/articles/rest-introduction
Android/iOS/etc have built in APIs for making HTTP requests. Your native app would send a request to the server, parse the response, and update your native UI accordingly. The same server can be used from a website using jQuery ajax HTTP requests.
Express.js is more suited to serving web pages and includes things like templating. Look into "restify" (see here: mcavage.me/node-restify/) if you just want to have a REST server that handles requests. Both run on top of node.js (nodejs.org).
As far as real-time communication, if you're developing for iOS look into APNS (Apple Push Notification Service). Apple maintains a persistent connection, and by going through their servers you can easily send messages to your app. The equivalent of this on Android is GCM (Google Cloud Messaging).
You can also do sockets directly if that's easier for you. Be careful with maintaining an open socket on a mobile device though, it can be a huge battery drain. Here's a library for connecting ObjC to Socket.IO using websockets, it may be useful for you: https://github.com/pkyeck/socket.IO-objc
Hope that helps!
To answer your question, it is definitely possible. Socket.io would serve as the central server that can essentially emit messages to all of the client. You can also make Socket.io listen for the messages from any of the clients and serve the emitted message to the rest of the clients.
Here's an example of how socket.io can be used. Simply clone, npm install, and run using 'node app.js'
All you have to do is to provide a valid server address when you connect your socket from the iPad clients:
var socket = io.connect( 'http://my.external.nodejs.server' );
Let us know if you need help with actual sending/receiving of socket events.
It is possible to connect to Websockets from your apps.
If you are using PhoneGap then you need a pluging that gives support to websockets in your app (the client) and then use websocket like normal way using Javascript see this.
If your app is native iOS look into this it could help you.
The primary use of the Sockets in your case is to be a bidirectional "pipe" between an app and server. There is no need of server sending the whole web-page to the native app. All what you need is to send some data from server to the client(app) in response to POST (or GET) request and then using this data on client side to update client's UI in real-time. If you are going to use moderate amount of devices (say tens of them), you may have connected all of them to the server permanently keeping individual socket connection open for every individual link server-to-app. Thus you may deliver data and update client's state in real time.
In fact web browsers also employ sockets to communicate to web servers. However as in general case there is no control on amount of concurrent clients in Internet, for the sake of limited networking resources conservation, servers do not keep sockets open for a long time, closing it just after the web-page was sent to client (or timeout has expired). That's how HTTP protocol works on the low level. The server waiting for the HTTP clients (browsers) by listening the 80 port, responding them by sending the whole web page content, then closing the connection and keep waiting for another requests on the same port.
In your case it's basically a good idea to use socket.io as it's a uniform implementation of sockets (ok WebSockets) on both client and server side. The good starting point is here
Hi I was wondering how one would go about setting up a delphi server that can interact with a javascript client. I am developing a game with this tool : www.scirra.com
It is called construct 2 and it uses javascript. It has a plugin to use socket.io and websockets so either one would be great.
So basicly I want to develop a delphi server that would receive messages from the one javascript client and broadcast it to the other javascript client. If the user wanted to host a game he would run the delphi application and then join the game and wait for other players to join.
To sum up;
(A) Is it possible to use websockets in delphi to communicate with javascript.
(B) if so would someone please make a simple demo.
Thanks for your time
There are some WebSocket client and server implementations available (see WebSocket server implementations for Delphi).
By design, client-side JavaScript (in the browser) can use the WebSocket protocol to communicate with the server. The Delphi WebSocket server implementations then can handle the requests and push data back to the client just like any other WebSocket server library. However, I do not know anything about the code quality or Delphi version compatibility of all these libraries so some additional research is required.
Regarding the Demo: most libraries surely include some demo HTML with JavaScript / WebSocket communication. Simply download it and open it in your favorite text editor ;)
p.s. as I can see socket.io not only supports WebSocket but also long polling so basically you can use any HTTP server library for Delphi to write the server side logic. See:
How can I update HTML pages dynamically with Indy HTTP server using jQuery and "Long Polling"?
How to: update HTML pages dynamically using jQuery and “Long Polling”