Javascript - Interacting with the OS - javascript

I'm implementing a specialized cloud storage solution. As part of the deal, I supply a client app similar to "Google Drive"/Dropbox. This app is quite good because it not only keeps everything synced but also, when uploading a file, it can significantly increase upload speed.
My problem here is that a lot of times, the users HAVE the client app installed, but forget to use it, and upload new files via browser. So I was wondering if there's a way to make the browser report back to my app if my client app is installed.
I know that I can't run a app via javascript, but I was thinking can I ask if "there is someone who knows how to read the extension .XPTO" using javascript? because I can bind the extension to my app, and if there's no responder, I could proceed with regular browser upload...

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Possible to remotely access files on mobile devices using HTML5/JS?

I have a file sharing web app online where I want people to be able to remotely access and upload files from their mobile devices without a client, but clientless via HTML5/JS, to our servers.
I have seem remote support companies log in to client devices just using browser with clients permission.
Thank you for your time
Robert
I have a file sharing web app online where I want people to be able to remotely access and upload files from their mobile devices without a client, but clientless via HTML5/JS, to our servers.
This isn't possible.
Web applications cannot access files that haven't been explicitly selected by the user. Additionally, they cannot store files on the user's system without a download, and they cannot do anything at all unless they are active in a browser -- they cannot run in the background.
Web applications running on mobile (i.e, Android or iOS) devices are even more limited. They typically cannot interact with most files on the system. For instance, web applications running on iOS can only upload photos from the user's photo library, not arbitrary files.
I have seem remote support companies log in to client devices just using browser with clients permission.
Either you were mistaken, or something else was going on. For instance, a client application may have been previously installed.
I'm not following exactly what you mean. If you already have the service, that means that you can just create a form with a filefield to upload whatever you want, the size limit is only imposed by your web server (apache/nginx/whatever) and your backend service.
You can complicate things a little bit using HTML5 web storage (that's what MEGA uses) but I can't give you any specifics if you don't explain a bit more in depth what you want to achieve.

Alternative for java applet which needs to communicate with browser via javascript

In our web application, we using a Java applet to invoke MS.Word application by jacob jar e.g. Word to open, edit, and when it saves automatically it uploaded to the server.
Google Chrome will no longer support NPAPI, so soon we can not run our applet in Chrome anymore.
So, any suggestions for an alternative for the Java applet. We want to make the same experience for the user, just like before.
We have the same problem. With Webstart is not longer possible to do that communication. We are going to use Websockets between webstart application and browser. Our first attempt is to start a websockets server in the webstart and make browser connect to localhosts. If this is not possible for security limitations in the browsers then we are going to do it through the webserver, browser and webstart application connecting to the webserver and exchanging messages.
I can see 2 distinct possibilities.
Create a standalone application that "wraps" your web application using a technology such as electron. You can then do your browser to desktop integration as you like. This will require an install on the client.
Launch a webstart application (or it could really be any installation that happens on the client). It will need to start a webserver, or connect to a webserver and communicate via http.
I'm saddened by the loss of the Applet. It is a technology not easily replaced. And another methods seem somewhat like 'workarounds'. There is no easy, cross-browser way to break out of the browser sandbox and access the system.
For myself, the loss of the Applet has simply meant that automating some of these processes has become too difficult and it is just better to find an alternative way of achieving a similar end result.
A small note: If you are starting a local webserver, be mindful of security. It can be accessed by other processes on the system. Wouldn't it be fun to open word on anyone's system by sending a request to a port!

android app with apache cordova

I'm developing a web app using HTML5,CSS3 and JavaScript.
Then I want to use the Apache ordova platform to generate a native android app from my web app but I still don't understand what do I need for this,specially do I need a server-side development with php for example??
First off i suggest you read this
Pretty much your app will be able to accomplish a little bit more than what you would be able to do in a browser if all you had available was the ability to write html/js*.
*by this i mean that you have access to device-specific hardware which is not available in a browser and a few more things but pretty much that's it.
You will need to install node.js (or io.js), then install cordova through npm, and make sure you have the Android SDK installed. Once you create your project, your html/css/js will be wrapped into a native webview component, you do not need any server to render it, effectively your app is a native app that can be installed from google play.
You will need a server, typically a RESTful API, if your app needs to query data remotely or persist to some third party. If you are thinking through a classic MVC mindset (render a page through some php code) then you probably need to read about cordova and how it works. A cordova app is a client-side only app, no server-side processing is possible unless through a network communication to a server you have access to on the internet. You can do persistence locally (to the android device) and even use a local database, but remember that this db exists on the device, so you won't be able to share information between users unless you somehow coordinate that through your app (and most likely a server-side app / rest api).
It is unlikely that your existing web app can be wrapped into a cordova app straight away, cordova apps are single page apps mostly.

How to use the browser as the GUI for an offline application?

I want to be able to create an offline program that can use the browser as GUI. I'm not particularly good at GUI programming in general, and overall it seems that using HTML and CSS to structure a GUI would be the easiest.
Cross browser method is preferred, but I will most likely use Google Chrome
I need to be able to open an external program, possibly with command line arguments
Javascript seems like the best language for this, however as far as I know it isn't possible to launch programs with it.
This is on Windows 7.
That's a good idea and is done by a several popular softwares.
The best way is to make your offline program run a web server that the browser will be able to access.
ie: Your program starts a web server on localhost:5555 and then you'll be able to request http://localhost:5555/users in Javascript, from your browser.
Another approach could be using a UI framework like AngularJS + local storage. I'm working on an app right now that will be used online (connected to the web), online locally (connected to a local server that is not connected to the web), and offline.
You could build a single-page web app and let Angular manage all the "urls".

What is the best way for a website to check if a user has installed a client app?

Let's say I've got a website that works better if a client has installed and logged into a desktop application. I'd like to be able to do 2 things:
Alter the website if they haven't installed the app (to make it easy for them to find a link to the installer)
If they've installed the app on a couple of machines, determine which machine they are browsing from
I'd like something that works on Windows and OSX, on any of the major browsers. Linux is a bonus.
A few thoughts:
Websites can detect if you've got Flash installed. How does that work and could it be used for both of my goals?
Could I just let the client serve HTTP on localhost and do some javascript requests to fetch a local ID? I know google desktop search did something like this at one point. Is this a standard practice?
Thanks!
You can register a protocol from your desktop application (see this). This can be used, for example, to open your desktop application with arbitrary data from the website. You could then have your desktop app send a HTTP request to your webserver, telling it what machine you are on.
You can have a browser plugin (activex for IE or Netscape plugin for the rest of the browsers) that can communicate with the application. When the webpage is loaded, it can try to instantiate the plugin and if it succeeded, it can use it as a proxy to the application. If it fails, then either the app is not installed or the plugin was explictly disabled by the user. Either way, your website should degrade its functionality accordingly.
Update: Forgot to answer your questions:
Flash does it exactly this way. Flash is a browser plugin that is created by the web pages.
You can have a machine ID generated at the application/plugin install time and your plugin can pass that machine ID to the webpage when it is created.
On the topic of using local webserver:
I would stay away from having a local webserver, mainly because of security considerations. It takes quite a lot of work to make sure your local webserver is locked down sufficiently and there are no XSS vulnerabilities that other malicious websites can exploit to make it do stuff on their behalf.
Plus, having a webserver means that either it has to run as a system-wide process, or if it runs as the user, you can have the website interact with only one user's instance of the application, even though multiple users can be logged on and running it at the same time.
Google Desktop Search suffered from both the XSS security vulnerability (though they fixed it) and the limitation of only one user being able to use it on a machine (I don't know if they fixed this one yet, though chances are they did).
Websites can detect if you've got Flash installed.
Actually, I believe a browser can detect if you have the Flash plugin for the browser installed, and webpages can offer "installed" and "uninstalled" option that the browser can choose.
Otherwise, you are asking for a means, by putting some code in a webpage, of being able to analyze a user's home computer, and report what it learned to you website.
Can you say Major Security Hole?
If you can pick a development environment for the desktop app, then check out AIR from Adobe. It lets you develop desktop applications using either html/javascript, Flash, or Flex.
It has API calls you can use from a browser based flash app to see if the desktop based AIR app is installed, what version, etc. You can even launch it and pass parameters from the web app to the desktop app.
http://www.rogue-development.com/blog2/2008/03/interacting-with-an-air-app-from-a-browser-based-app/
Websites can detect if you've got Flash installed. How does that work and could it be used for both of my goals?
it's quite a bit simple, your browser tries to render some additional files, with some specific formats such as flash .swf and I the browser doesn't find installation, then will be start downloading, or you will get the option to download that program.
Flash also uses AC_RunActiveContent.js please take a look at this js, people usually put this on their webpages
if (AC_FL_RunContent == 0) {
alert("This page requires AC_RunActiveContent.js.");
} else {
AC_FL_RunContent( 'codebase','http://download.macromedia.com/pub/shockwave cabs/flash swflash.cab#version=8,0,0,0','width','981','height','635','id','build5','align','middle','src','build5','quality','high','bgcolor','#ffffff','name','build5','allowscriptaccess','sameDomain','allowfullscreen','false','pluginspage','http://www.macromedia.com/go/getflashplayer','movie','build5' ); //end AC code
}

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