I succeded to make a webserver (access point ) which is showing an HTML code, using an esp32 and an stm32 which is sending the at commands to it. How I can do if I want to show on a webpage in real-time data from a sensor? I heard that I need to use WebSocket but I didn't find so much.
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I have a java/j2ee application deployed in tomcat container on a windows server. The application is a training portal where the training files such as pdf/ppt/flash/mp4 files are read from a share path. When the user clicks a training link, the associated file from the share folder is read downloaded from the share path to the client machine and start running.
If the user clicks mp4/flash/pdf files, it is taking too much time to get opened.
Is there anything in the application level, we need to configure? or it is a configuration for load in the server? or is it something needs attention from a WAN settings?
I am unable to find out a solution for this issue?
Please post your thoughts.
I'm not 100% sure because there is not so much details, but I'm 90% sure that the application code is not the main problem.
For example:
If the user clicks mp4/flash/pdf files, it is taking too much time to get opened.
A PDF is basically just a string. Flash is a client-side technology. And I'm pretty sure that you just send a stream to a video player in order to play a MP4. So the server is supposed to just take the file and send it. The server is probably not the source of your problem if we assume that he can handle the number of requests.
So it's about your network: it is too slow for some reasons. And it's difficult to be more specific without more details.
Regards.
I have been trying to make multiplayer applications on a website for a while. I wanted to start with a basic chat system. I made one but it is really slow. On the HTML page it send the message through AJAX to a PHP application which saves it to a text file. Then back on the HTML file, it is constantly checking the text file every 3 seconds. This is very slow and unreliable. So i looked up better ways of doing this. I found Node.js and used it along with Socket.io and express to create a faster chat application. But it only works on local host and i have no idea how to implement it on a website. So I kept looking and discovered WebSockets. Which are so confusing and seem to have very little support. I am confused how websites out there have applications that can be real time with so few options. How is this done? Am i missing a way of doing this? If you can help me that would be great.
Socket.io is using websockets under the hood already. Using raw websockets isn't necessary for your chat app.
You're on the right track using socket.io and node.js server-side.
Building a multi-player game in the browser will be a very difficult task for a beginner. But that's why it's good to learn! I suggest using a library for graphics (a quick google gave me this: http://www.pixijs.com/ ).
The over all architecture should be something like:
Users go to your server and receive a web page (.html) which contains the javascript and a canvas they need to play the game. This is the "client-side" because it's all running on each users' web browser on their computer.
The web page runs the javascript which talks to the node.js server using socket.io. This is the "server-side". The job of the server is to coordinate player data (who is who, where are they in the game, who's doing what etc) and keep track of the game state. Basically, this is where the game actually is, kind of like having the Monopoly board on the server, while the client-side is really just responsible for showing the board to the players (drawing it on the HTML5 canvas) and sending player input to the server.
Tutorials:
USE GOOGLE. Try just literally searching for "javascript game tutorial". Try every tutorial that comes up. If something is taking a while to get up and running then ditch it and move to another one.
Do simple little things at first 'till you start to grok what the overall process is like. For example: https://developer.mozilla.org/en-US/docs/Games/Workflows/2D_Breakout_game_pure_JavaScript
Remember playing ultra-simple games like Pong? Try writing games like this first. Your chat system is a great start, by the way, because it covers the basics of how to get a server up and running, how to get a page, how to send data around.
As for getting something up and running on a server where others can connect to it... Check this out: have your buddies come to your house and bring their laptops, start your node.js chat server, tell them what your IP address is, and have them go to "http://YOURIPADDRESS:8000" in their browser-- they'll connect to your node.js server!
Getting it running on a hosting provider is a little more involved and probably not worth the trouble at this stage. You'll learn more about this later just by keeping on the way you're going.
Socket.IO does not only work on localhost. You will need to get a server to run your application on. I highly recommend not worrying about this piece of the puzzle just yet, as it is somewhat complicated if you are brand new at this. Come back to this part when you are ready.
As for the game development, I recommend using Phaser. It has everything you need to get started and great documentation.
http://phaser.io
I am working with Google Tango to extract data from the tablet and use it at the same time in another device. I am trying to record the data and use it with another laptop via live streaming.
I've looked at various topics about it and I found the Paraview topic. However the App records the data, save as ZIP file and send it via bluetooth(which is fine for me). I do not want to save the file as ZIP format and send it to another device. I want to record and use the data via live streaming(bluetooth or Wi-Fi).
Is that possible? How can I do it?
Paraview shared the source code so I think I can change it make it work for me. However I am not really used to programming.
Thank you very much for your help. I really appreciate it.
You might want to use sockets: setting a socket server on your computer and connecting to it via your tablet. It is a way to transfer information via what is called, for example, a TCP protocol.
However, there might be a more efficient way to do what you want to achieve with USB debugging. I did not got able to make USB debugging work yet on the tablet and computer I worked with.
You could use TangoAnywhere, I developed it so you can broadcast Google Tango position and orientation data to any device.
https://play.google.com/store/apps/details?id=de.grauonline.tangoanywhere
You connect using a TCP client on your PC/Mac (simple TCP client written Python or something) to port 8080 of your Tango device and will get the position data in realtime.
I recommend the Tango ROS Streamer app which enables you to choose which data (position, point cloud, RGB image) to stream or not.
You will need ROS to retrieve the data. On Linux ROS is easy to install, otherwise use a docker image of ROS.
Caution: the theorical WiFi bandwidth does not enable to stream all the RGB frames at full resolution without dropping some.
I'm not really sure how to search this over the internet, I tried some searches but never got the help I needed, so I'll just ask here. (sry if it's already answered!)
I'm building a embedded system that runs on windows. I'll gather some data and send over the internet to read at home. I'm most probably using a 3G connection to connect my system (that will keep moving) to the internet and send the data over. I planned to use a ftp server with a hamachi connection to send the files to another pc. And it'll be automated, so the only person action will be to read the data at home. I tested and this all works fine when I use a reliable connection, like when I'm home.
My question is, will it work when my 3G connection drops and how can I make this system reliable?
I want to keep storing the data if the connection is down and send it all when it's back online, but i don't know if the system will automatically connect (i can't have a person manually clicking 'connect') to hamachi or to the ftp server (my first time using this technologies).
Also, is there a better, more reliable or simpler way than hamachi+ftp to send the data?
Thx,
EDIT: Adding more info. I'm gathering data with a LabView VI. The plan was to save this data into a file (txt, csv or whatever), send the file over and have another VI reading the file and display some graphs and etc. There is a DataSocket in Labview to send some data over the internet, but I'm not familiar with these internet protocols, it says I can use FTP, HTTP and others. What is paid and what can i do for free?
Also, is there a better, more reliable or simpler way than hamachi+ftp to send the data?
Might it be simpler to use e-mail (SMTP)? That has the advantage that the sender and receiver need not be up at the same time.
I need a simple way to use XMLHttpRequest as a way for a web client to access applications in an embedded device. I'm getting confused trying to figure out how to make something thin and light that handles the XMLHttpRequests coming to the web server and can translate those to application calls.
The situation:
The web client using Ajax (ExtJS specifically) needs to send and receive asynchronously to an existing embedded application. This isn't just to have a thick client/thin server, the client needs to run background checking on the application status.
The application can expose a socket interface, with a known set of commands, events, and configuration values. Configuration could probably be transmitted as XML since it comes from a SQLite database.
In between the client and app is a lighttpd web server running something that somehow handles the translation. This something is the problem.
What I think I want:
Lighttpd can use FastCGI to route all XMLHttpRequest to an external process. This process will understand HTML/XML, and translate between that and the application's language. It will have custom logic to simulate pushing notifications to the client (receive XMLHttpRequest, don't respond until the next notification is available).
C/C++. I'd really like to avoid installing Java/PHP/Perl on an embedded device. So I'll need more low level understanding.
How do I do this?
Are there good C++ libraries for interpreting the CGI headers and HTML so that I don't have to do any syntax processing, I can just deal with the request/response contents?
Are there any good references to exactly what goes on, server side, when handling the XMLHttpRequest and CGI interfaces?
Is there any package that does most of this job already, or will I have to build the non-HTTP/CGI stuff from scratch?
If I understand correctly, the way I approach this problem would be a 3-tier (Don't get hang up so much on the 3-tier buzz words that we all have heard about):
JavaScript (ExtJs) on browsers talks HTTP, Ajax using XmlHttpRequest, raw (naked) or wrapper doesn't really matter, to the web server (Lighttpd, Apache, ...).
Since the app on the embedded device can talk by socket, the web server would use socket to talk to the embedded device.
You can decide to put more business logic on the JavaScript, and keep the Apache/Lighttpd code really thin so it wont timeout.
In this way, you can leverage all technologies that you're already familiar with. Ajax between tier 1 and 2 is nothing new, and use socket between 2 and 3.
I did not mean that you did not know socket. I just proposed a way to take a desc of a problem where I hear a lots of words: XML/HTML/Ajax/XmlHttpRequest/Java/PHP/Perl/C++/CGI and more and offer a way to simplify into smaller, better understood problem. Let me clarify:
If you want to ultimately retrieve data from the embedded devices and render on the browsers, then have the browsers making a request to the web server, the web server uses socket to talk to the embedded device. How the data is passed between browser and server, that's normal HTTP, no more, no less. Same thing between web server and embedded device, except socket instead of HTTP.
So if just you take a simple problem, like doing an addition of 2 numbers. Except these 2 input numbers would get passed to the web server, and then the web server passes to the embedded device, where the addition is carried out. The result gets passed back to the web server, back to the browser for rendering. If you can do that much, you can already make the data flow everywhere you want to.
How to parse the data depends on how you design the structure of the data that might include container which wraps around a payload.
"... whatever HTTP is coming to the server into usable bits of information, and generate the proper HTTP response"
...but that's not any different than how you handle the HTTP request on the server using your server-side language.
...how to implement a backend process in C/C++, instead of installing a package like PHP
If the embedded device is programmed in C/C++, you are required to know how to do socket programming in C/C++. On your web server, you also have to know how to socket programming, except that will be in that server-side language.
Hope this helps.