Communication with an external (hardware) pushbutton - language-agnostic

I would like to create an external pushbutton to use with one of my applications. My question does not focus on the hardware itself (that's why I'm asking it here), but on the software/communication side. What would be the best and most straightforward way to do? A good speed is important, so it should not differ too much from the latency of a normal keyboard.
The following solutions come to my mind:
let the hardware be a modified keyboard, or at least it should be recognized by the system as a keyboard. Pro: no extra work from software-side required. Con: what if I need to use a normal keyboard as well? Ok, not so bad, with today's USB keyboards...
Communicate through serial port. This would be the most straightforward approach, or better yet, it would have been like 10 years ago. Now most computers don't even have one, of course, there are plenty of serial-usb converters around.
Let it be a standard USB device. I don't like the idea, with installing drivers, and having to care about different OS, etc.
Does anything better come to your minds?

The USB keyboard class HID seems the best to me. You can use different scancodes than standard keyboards, or less often used like those used for app-specific buttons on some keyboards. (Note that current X.Org drivers are still limited to scancodes < 256.)
Probably it's not hard to find a reference HID keyboard implementation for your device, too.
Serial ports are rare in modern PCs and especially notebooks; even if the system board has RS232 circuitry it has no external connector.
Writing a custom driver for the PC side means much more work and more space for bugs. You're far safer using a time-proven standard driver.

Related

Launch a desktop application from a browser

I'm trying to find a way to launch a desktop application from a browser for os x. This application will be for customers only and should only be used for the hardware we provide.
I'd like to start off by saying I think this is a stupid idea. I'm being forced to use this approach by our CEO. I understand security policies could be an issue, as well as glaring vulnerabilities.
Since they can only run this on a single device I don't know that jws would be the right solution. I haven't used it but based on what I've read it doubles as a distribution method (which we don't want). If it were to be jws then it would have to some how have to recognize the device we provided them to ensure it is being placed on the appropriate hardware, possibly based on the serial # (which I don't believe you can get from the browser).
Additionally, the browser would call methods and pass arguments to the application.
Is this even possible? If so, what tool would you recommend? Again, I'm only the messenger for this terrible idea.
You probably have Chrome or Safari configured to handle http://<uri> URIs, but many other types exist. Have you ever seen custom URI schemes used like itunes://<uri>, steam://<uri>, or skype://<uri> ?
Just like for http, when your OS tries to fetch the resource, it will attempt to handle the request in the application that registered a handler for that scheme.
If that's the kind of thing you're looking for, this question has already been answered.
My suspicion is that you were unaware of the term. If that answer works for you, we can mark this question as a duplicate.
In complement to #naomik's answer (which I believe is the right one), there are projects like AppJS, Fluid or Electron which are pretty much willing to bring web based apps to the desktop.
For the matter of communicating the App and your browser (should I say your server?), you could use an approach of message queues and websockets to get there, surely, it is a huge effort of orchestration and workarounds but in the end it is possible to get you there.
(Posted on behalf of the OP).
This does not appear to be possible. If you are considering this please don't, there are better solutions. I have finally convinced my CEO to use Angular2 inside electron for example.

Interactive 3D visualization on browser

I am trying to create a website where users can view and interact with room-furnishings in a 3D environment in a browser. Now, I do not wish to create anything from scratch, if it is possible to build upon existing open source efforts. So far, my research shows that:
The most established open source project I could build upon, that allows me to show 3D scenes on the browser and have users interact with them, uses Java3D for browser view, encapsulated in a java applet (sweethome3Dviewer).
Java 3D itself seems to be out of vogue, with most people recommending HTML5+WebGL (where unfortunately, I can't find any solutions that are as developed).
So here are my questions for this forum:
1) Are there any serious drawbacks of using a Java3D based approach?
I am talking of ANY drawbacks here, for example: "it is too slow"; "it is not stable"; "is limited by the number of concurrent users", etc.
2) What would you suggest I start with and build upon, if not the one based on Java3D?
Please note my preference for not re-inventing the wheel!
Yes, there is a serious drawback to using Java applets today: they are likely to simply not work at all.
The biggest problem is that the Java security system, which is intended to prevent programs like applets from accessing other parts of your computer (modifying files, running additional unsandboxed programs, etc.), has a history of security holes. Because of this history, there is a general consensus that permitting Java applets is simply not an acceptable security policy for the current day. Therefore, many browsers omit the Java plug-in or disable it by default.
And there are also browsers which simply have never had a Java browser plug-in at all, such as those on Android and iOS devices. Besides the security risk, there is also the issue that Java is “heavyweight” as web content goes — it can be seen as a waste of limited resources, for portable devices.
Thus, using Java applets is not a good choice: your applet will never work for many users, and those it does work for are taking an unnecessary security risk.
WebGL, on the other hand, is “just” another JavaScript-based API, which only does graphics, not lots of other things that have to be turned off by a “security manager” element. There are risks inherent to WebGL (GPU drivers are not the most security-minded thing out there) but in the current state of things it's unlikely that WebGL will be simply shut off rather than being fixed, if a problem is found.

Shortcut directly to Voice Search in Chrome Browser

I am helping someone recovering from an accident that makes it difficult for her to type and control the mouse with much precision. I'm not familiar with scripting languages used within browsers but would like to know if the following is possible:
A keyboard shortcut or function key is pressed that will, 1) create a new tab and open google.com in it and then, 2) Automatically "select" the microphone to start Voice Search without the user having to either select it directly or use the "Shift-CMD-." shortcut so she can start talking in the search command with no further keyboard interaction.
The computer being used is a mac running OS X 10.8.x and the browser is Chrome. I've searched for chrome extensions that do this but haven't been able to find any that would help.
Any ideas are much appreciated.
Thank-you.
Have you considered programmable keypads? For someone with limited dexterity / precision these devices may offer the solution you require and simplify keyboarding by limiting the number of keys to a small subset mapped to specific functions.
This 24-key keypad offers complete programability, though some reviewers remarked it is complicated to program.
http://www.amazon.com/XK-24-USB-Programmable-Keypad-Windows/dp/B003MB780E/
A cheaper option, which may be simpler to program, is to look at keyboards with a few programmable hot keys. A benefit of this keyboard it that it can pair with 3 devices and works with Macs, iPad/ods, Win PCs, etc. So, if your friend is also having difficulty using a phone as well this could be a huge help.
http://www.amazon.com/Logitech-Bluetooth-Illuminated-Keyboard-Smartphones/dp/B0099SMFVQ/

Can HTML5 communicate with peripherals like scanners and credit card readers?

My company writes software that installs on client machines to perform point-of-sale transactions. The software interfaces with a variety of external peripherals (receipt printers, bar code scanners, credit-card readers, etc). We do this with a WinForms app that we created in Visual Studio using the Microsoft OPOS library, which in turn communicates with our cloud server.
There are obvious inefficiencies in this model, primarily with updates. I'm researching other ways to communicate with these peripherals over the web, preferably via web browser. So far as I can tell, Java is one of the only technologies out there that can do what we're looking for (via applet), and I assume Adobe Flash can as well (via the Air platform). These are viable, but not preferable because we want to run our software on web-enabled mobile devices.
Does anybody have suggestions for other ways to communicate with external peripherals over the web?
UPDATE (Jan 16th, 2019): The Credential Management API has been announced. It's currently only supported on Chrome and Opera but it's looking promising. Google Developers wrote an article elaborating on the spec.
UPDATE (Dec 28th, 2016): Another couple years gone, and another update. This one will be more focused on two new developments than anything else. See the new "WebUSB & Web BlueTooth" section under "Full Device API". But the answer remains the same.
UPDATE (Nov 3rd, 2014): It's been just over two years since the original post was made, but the answer remains mostly the same for now. We are, however, closer to your original goal in several areas.
ORIGINAL ANSWER:
There would be a number of ways to go about this.
Background
The HTML5 specification has entered into the "Recommendation" state. This means that HTML5 is pretty much set for what it looks like. However, I will be using HTML5 in the same way that every marketing person in the world has decided is best. That is, I will not be talking about HTML. Well, I will, in so far as you will utilize it from an HTML page, but not really. What I'll actually be discussing is JavaScript (JS) and that's a horse of a different color. But for all intents and purposes, we're putting it all under the same heading as HTML5, which has been decided to mean "shiny and new" now.
Also, the items which I am discussing will vary in support. Some are very browser dependent projects (like Chromium specific implementations), and some are more standards driven projects that may not have browsers implementing or experimenting with them yet. I'll try to distinguish between the two as I go along.
Full Device API
Status: Incoming, but not ready
Being able to access devices from the browser is making slow but steady progress. Right now, many modern browsers have access to some of the more common devices like the camera or gamepads, but they are all high level APIs. Browser vendors, the standards groups, and lots of companies involved with the web are all trying to make webapps just as powerful as your local applications.
But the APIs you are looking for are still in progress and a ways off. For your particular case, and for the more general case of connecting your webapp to most devices, we're still a few years away from something we can use. If you want to see what awesome things are coming up in that field, here are just a select few items that may help you directly:
Web Near Field Communication (NFC) API
This one unfortunately may be dead in the water for now. But it looks like originally some folks at the W3C (mostly Intel it looks like) were looking at adding a NFC API to the web.
Media Capture Streams
The WebRTC group is working on programmatic access to media streams like the camera which would allow to integrate things like barcode scanning or other features. This has reached CR status and is available in browsers, but is less helpful on its own.
Web Bluetooth
If you had bluetooth capable tools, this API would help you connect with them from computers and devices that were able to listen and connect. The primary driver for this at the moment seems like it is the Chrome team, including an experimental implementation, but I wouldn't consider it anywhere ready to use yet (See "WebUSB & Web BlueTooth" section).
WebUSB
This would allow full access to low level USB information including listing devices and interacting with them. Same as Web BlueTooth, this seems to be current Chrome pet project, but I also wouldn't rely on it (See "WebUSB & Web BlueTooth" section).
Network Service Discovery
If you have other devices or items on the network which broadcast and use HTTP, this API would allow you to discover and interact with these services. No browser implementation, but it is in a working draft for the W3C.
Originally, Mozilla was pushing a number of these forward because of Boot2Gecko (or Firefox OS). However, with that project officially cancelled, we aren't seeing much progress from them in these areas now.
Members of the Chrome team, however, seem to have decided to dive in and start not only working towards these, but putting them live in browsers. Which leads us to...
WebUSB & Web BlueTooth
Like sausages, it's better to not know how Web Standards are made
-Abraham Lincoln (probably)
There's been a little bit of buzz in this area as it looks like the Chrome team snuck in these as experimental features and developed their own specification for it. Which is great! Just maybe not in the way that you were hoping for.
Each browser vendor and W3C contributor group has their own style and makes contributions towards the specs in their own way. The result is usually a fairly decent specification that the browsers have agreed upon. But getting from nothing to something is... messy. Real messy. And is quite a process a lot of times. It doesn't always result in a good spec (yeah, I'm talking about you Florian compromise...) but even when it does, it takes a while.
However, It seems like Google developed this version of the spec all on their own. And, in my experience, Google's approach to the specs is always a little... well... setting my personal opinions aside we'll say "gung-ho". They tend to just dive right into the deep end. And that seems to be what they've done here.
I highly doubt these specs or implementations will look anything like this when they become standards. And there's nothing wrong with that. That's part of the process. But I wouldn't go relying on this implementation or developing any code or products against it. This is an unprecedented feature on the web and all the browser vendors are gonna want a big say in this.
That said, this is actually good. One of the things Google often does (for better or worse) with situations like this is forces the conversation and it can push things along. And having a feature shipped in the browser, even an experimental feature, can turn up the heat on the demand for it. So we may see more progress in this area soon.
PhoneGap Apache Cordova. You know, for your phone
Status: Not fully featured and phone only
Apache Cordova, previously Adobe PhoneGap, is a way to write your program in HTML, CSS, and JS that allows you to access lower level functionality on things like phones, and compile across devices. This would be a way to implement your program, but it would be a phone application, not necessarily a desktop one. An option to consider, and something I figured I would mention.
Cordova implements a few of the above features already, but doesn't have some of the more powerful ones like NFC or BlueTooth.
The Native-App solution (for Windows 8)
Status: Possible, but OS specific and desktop app
Windows 8 offers the ability to build applications in HTML and JS. This would allow you to easily access lower level functionality on the OS via their API. From the looks of it, it is pretty extensive and you can do a lot. You mentioned cross OS support, however, and this obviously limits you to one OS.
It's so Flash-y!
Status: Dying/Dead, not possible as a web app
Flash won't have direct access to the system through the web. You could create an AIR application, but that will sort of defeat the purpose of having it web based. In addition, Flash support on mobile, and on the web it would seem, is on the decline.
NodeJS
Status: Can be a bit of a pain and only possible as a desktop app
NodeJS and JS applications have sort of been a hot topic the last couple years. I didn't discuss it in my original post because I felt it wasn't quite there yet. However, things have progressed and it is much closer to being ready for this sort of thing, and has the support and power of a growing user base. That said, for your particular case, I wouldn't recommend using it. It would have to be local on the users machine, and because of how NodeJS (and similar engines) are at the moment, it would require a lot of extra configuration and setup that would complicate things a bit.
So you could build an app using HTML, CSS and JS with NodeJS or similar engines and have low level access to what you need, but it has to be local, and it would take more work than I'm sure you want to do every time you'd like to install it for a customer.
... Now where was I?
So where does that leave us? Well, simple: if you want a single language/set of code as your code base, HTML/CSS/JS aren't a great option... yet. But they could be some day. For now, your options are limited to what you feel is best for your customer. Java is a stable option you listed, but obviously comes with its own drawbacks. As the web develops, I think we'll see a lot of really cool things coming out of the new functionality, but we've got a ways to go still.
More reading:
Brian.IO: Beyond HTML5
HTML5 Apps on Windows 8
Wikipedia list of projects built using JS
This is possible, but it would have to be done indirectly. In theory, you could write a socket-server in a low level language, which gets I/O, and sends the I/O through the socket (relaying, I guess). HTML5 uses WebSockets, or some equivalent to communicate with this socket-server.
Now it can be achieved with WebUSB API.
It is available in Chrome since version 54.
It is a W3C editor's draft so we can expect (hope) that it will be adopted by other browser vendors...
I've been thinking about this a lot lately... have a POS app mostly written in VB6, considering what to do next. HTML5 is an option and I was thinking I'd use VSPE to get the serial stuff into the JS.
http://www.eterlogic.com/Products.VSPE.html
Love this product! Works very well for getting serial traffic where you need it, so I think it would work well, at least as a proof-of-concept to get you going. You'll want to use a combination of "connector" types along with the "tcpclient" and "tcpserver".
Just for the record, a method that works well in 2016 (since chrome 26), but is to be withdrawn over the next 2 years is to deploy your html5 as a chrome app and use chrome.usb (or chrome.serial or chrome.bluetooth).
I am currently using chrome.usb and planning to migrate to a web app using WebUSB API (see Supersharp's answer), which I hope will be adopted by the time Google discontinue chrome apps 🤞.

Change or override the behavior of a USB keyboard to a more generic controller

Changing the keystrokes of a USB keyboard
My question is very similar to the one above... (to which there was no clear answer)
I have a nice USB keyboard that I would like to use to control an audio/visual program I am writing. I can't have the USB keyboard input interfere with the regular operating system interface -
Therefore I need to have the OS recognize it as a generic HID device of some kind, or a MIDI device, or something that sends OSC messages.
I am writing the program on OSX but would like to figure out a cross platform solution that doesn't involve me hacking the hardware of the keyboard - hopefully some sort of program or script that I can use. The reason for this is I'd like to distribute this program for others to use easily.
Any ideas on where to start? I'm thinking I'll probably need to write a separate program for users to select a USB device and reroute that into my program...
Any language is fine - I write code in Python, sometimes C, and Java / Processing.
Unfortunately you're going to find this EXTREMELY difficult to do: most modern operating systems will automatically detect the HID profile and load the drivers for it, and generally speaking make it very difficult to override that default behavior.
Without hacking the hardware you would need to somehow override the OS's default behavior for that specific USB VID (vendor ID) and PID (product ID) and instruct the OS to load your own custom kernel extension? I'd suggest starting with source of the AppleUSBKeyboard drivers at http://www.opensource.apple.com/source/IOUSBFamily/IOUSBFamily-206.4.1/AppleUSBKeyboard/ and then figuring out how to install your custom build as the preferred USB driver for your specific keyboard's VID and PID. After that it should be the messy messy messy issue of only sending the keys to your app and not to anything else.
Would it be possible to write a
function that disables regular
operating system keyboard input for
all keys except something like ESC if
my program is in focus? – jeffrey May
24 at 21:59
Yes this should be quite possible, I dont know about Mac but on Win32 you want a global keyboard hook (look up SetWindowsHookEx)