I have javascript (client - executed through node.js) and C++ (server) code running on Ubuntu (Linux) and I want this client-server to communicate with each other. Can somebody tell me how I can make C++ code work like a server or client using web socket? Basically, I want javascript code to send some data to C++ code, the C++ code will process on the data and return the result back to javascript code. I'm not sure if I this communication between javascript and C++ code can happen with out web socket. Any pointers in this direction would be of great help!
Thanks,
pats
I very recently started working on a C++ websocket library: https://github.com/szmoore/foxbox
An example of a websocket server is: https://github.com/szmoore/foxbox/blob/master/examples/wsserver.cpp
I also have an example of a JavaScript client.
Warnings: The library doesn't support TLS, is based around POSIX sockets, and is still in development and probably horribly insecure.
So, whilst shamelessly promoting my own library I will also point you at libwebsockets, a C library suggested in answer to this question: https://stackoverflow.com/questions/3916217/standalone-c-or-c-websocket-server-library?lq=1
You have several choices. I am assuming your C++ server already has a websocket server running on it but if not, get Mongoose or the non-GPL fork Civetweb. Both are tiny bits of c code you build into your C++ program to add webserver,including websockets, functionality.
In fact, civetweb comes with a websocket example.
However, you do not need a websocket, just an ordinary socket should do. You'll probably want to send the data in JSON format to makeit easy to consume by the javascript code.
I know this question was asked a LOOONG time ago, but here is a gist of my set up that allows to have a communication between my c++ and Javascript apps; if anyone stumbles on this question:
I use TCP/IP connections to set up communication between a C++ app and a Javascript (Typescript) app. ZeroMQ (0mq) library is perfect for that. On c++ side you have libs like zmqpp and on the JS side you have zeromq.js.
After the data is received in JS land, you can use Socket.IO if you would like to have that streaming data available in a browser. Generally, you would have to forward the data stream off 0mq through Socket.IO and then access it on the browser side.
Bonus: make the data format using Protobuf.
On the Javascript side you will probably want to use an XmlHttpRequest. This will cause the javascript to post an HTTP(s) request to your server. For the C++ server side, you can look at something like Pion for an embeddable HTTP server or if you want to link into a full web server like Apache, you can use Fast CGI to plug your server code into Apache.
Related
I'm having some troubles finding a good way to stablish a communication between my frontend and my backend.
I have a C++ app that deals with the communication with some device, I'd like that my webpage gets the request from the user, then send that request to my always running C++ app, process that request, and then send a response back to my webpage, is there any way to make this happen?
You could use Boost Asio to build a REST server into your C++ app see:
https://www.boost.org/doc/libs/1_55_0/doc/html/boost_asio/examples/cpp11_examples.html
Or you could use a C++ REST framework see:
https://github.com/Microsoft/cpprestsdk
There are a few others as well.
Finally you could build your REST/Web server using some other language such as Java or C# and use a messaging protocol to communicate to your C++ server. You could use sockets or ZeroMQ for example:
http://zeromq.org
i want to send one array from my Desktop application (c++) to another Web application(browser-based) which is written in javascript.
What is the standard approach to do this ?
my purpose just is to try send array through websocket to a simple web application.
i am a little familiar with node.js but i dont know is it possible to use it inside c++ application or not.
I want to send one array from my Desktop application (c++) to another Web application(browser-based) which is written in javascript. What is the standard approach to do this ?
Your question is too broad, or shows some misconceptions about desktop applications and web applications.
Be sure to understand (in details) HTTP and reason in terms of HTTP requests and responses (including those initiating a websocket connection). Remember that a websocket is above some HTTP connection.... Understand the role of HTTP cookies.
You could change your desktop application into a web application (perhaps running on http://localhost/ ...), but that requires some significant work and redesign. You probably then want to use some HTTP server library, like Wt or libonion (it supports Websockets).
Perhaps you might improve your web application to make AJAX requests (e.g. to some http://localhost:34567 ...) to you local application transformed into a specialized web sever running locally (and also using websockets, if you need that).
Perhaps you want your Desktop application to also become an HTTP client. You then need some HTTP client library (like libcurl or QtNetwork).
I'm building a C++ application that produces data that I want to pipe to a web browser. If I send all of the data to the server, and then out to clients, there will be too much traffic. Is there a way I can use my server to establish a direct socket connection between my C++ application and a remote browser?
I'm writing my server using node.js for what it's worth
Yes: you can embed a web server inside your C++ application. If you can poll for the data using simple HTTP GET, you can use the simple C web server library "mongoose" for example. Or you may need to use WebSockets which probably requires a fancier library in C or C++. Then your Node.js server can simply give the URL of your C++ server to the clients, who will connect to the C++ server directly.
All that being said, it's likely that Node.js can support the load, so if you haven't actually run into scaling problems, you might want to just skip this whole project.
Is it possible to communicate from a web browser(Loaded an HTM page from server) to an application running in the same server using AJAX. Need to send the request from browser using a button click and update the page with responses received from one another application running in the same server machine?
I am using HTML pages to create website and not using any PHP or ASP like server side scripting. In server machine data are manipulated using a C++ application.
I think you can use any sort of Javascript functions to do that. But you might need to use jQuery or similar frameworks to make your live easier. You might need to search for "Comet Programming" to know exactly how to do 2-way communication between client and server
Updated:
Well, this kind of stuff requires you to read a lot (if you have not already known). Basically, what you need is a server that can do long-polling (or eventsource, websockets). There are many open-source ones that might help you to get started. I can list a several good ones here. There are a lot more
http://www.ape-project.org/
http://cometd.org/
http://socket.io/
http://code.google.com/p/erlycomet/
http://faye.jcoglan.com/
So after you have the comet server up and running you will need to setup the client side (probably Javascript). For those listed projects, most of them come with the client side code to interact with the server (Except for erlycomet). Therefore, you can just use the examples provided and run a quick prototype. If you want to use your raspberry pi, you can use nodejs which provide a lot of ease for dealing with real-time communication (socket.io, faye). And lately, http://www.meteor.com/
I would think of the problem this way: you want to provide a web front end to an existing c++ application. To achieve this you need to think about how your web server communicates with your c++ application. Communication between the browser and web server can be thought of as a separate problem - as you say AJAX calls can be used, or maybe have a look at websockets.
Once you have your request in the web server you need to communicate it to the C++ application (and/or visa versa). This can be done a number of ways, e.g. sockets or RPC. I found this question here which has some good advice.
I need to build a lightweight http server for my application basically it's a server which listen to a port and outputs a status information on requests, https, other functionality. But I would like to know first if something like this existe in C++, for linux and open source.
Does anyone know a program like that?
Thanks.
EDIT: It should be able to support high load.
If you can use boost, the asio library provides an http example. It does not use SSL, but asio can use OpenSSL very easily.
If you want to handle high loads I would suggest following:
Use proper web server with all goodies it comes with like Lighttpd, Nginx or Apache (in that order).
It would do great job in serving static files and handle your application. And they are very lightweight.
Write an Application in C++ using proper web framework - CppCMS - that is designed for high loads
Connect Web Application to the server via FastCGI or SCGI protocol (in this order).
Disclaimer: I'm the author of CppCMS
A quick google search for "C++ web application framework" shows things called CppCMS and something else called WT. That might get you started.
Or, as Sam already answered: boost.asio comes with a HTTP example that may be sufficient if your needs are simple. (Real HTTP request handling is actually surprisingly complex: http://webmachine.basho.com/diagram.html )
See thttpd. Supposibly the fastest open source file server on all machines with a single CPU.
If not using HTTPS, it's about a two hour exercise to write a static file server.