The Chromecast device is a "receiver device [that] runs a scaled-down Chrome browser with a receiver application". Can I download and install this receiver app on a chrome browser for example on my Windows notebook?
I have implemented a complete chromecast v2 receiver, called YouMap ChromeCast Receiver, available in Google play store and Amazon store, xda-developer thread here: http://forum.xda-developers.com/android-tv/chromecast/app-youmap-chromecast-receiver-android-t3161851
The current Chromecast protocol is a completely different one from the original DIAL based protocol. Right now, only YouTube still uses the old protocol, which chromecast maintains its backward compatibility.
The discovery is mDNS, exactly same as Apple TV bonjour protocol.
The most difficult part is device authentication, the sender and the receiver perform handshakes by exchanging keys and certificates in a way extremely difficult to crack. AppleTV does the same using FairPlay encryption.
The next difficult part is the mirroring protocol, which is also very complicated, need to deal with packet splits, packet retransmissions. Overall, chromecast mirroring protocol is well designed, better than miracast, better than AirPlay mirroring (I have also implemented both of them, so I know what I am talking about).
When I get chances, will write more here.
The chromecast device works using the DIAL protocol. It is completely possible to emulate this protocol using some simple code to listen on the multicast group for discovery and then handle the HTTP requests to launch applications. It is then the launched application that communicates with the casting device, I believe using the RAMP protocol.
Luckily for us the applications that the chromecast device uses are mostly web applications meaning our device emulator just needs to launch a web browser and point it to a specific url when it receives an application request.
For example the youtube app, after device discovery and establishing where the applications are located (part of DIAL). Will send a HTTP POST request containing a pairing key to /<apps url>/YouTube. All the emulating device needs to do now is open https://www.youtube.com/tv?<pairing key> in a browser window. From here, I believe, communication for controlling the youtube app is not sent through the casting device but through the open tabs on the casting device and the emulator.
This is my understanding of how the chromecast device works and specifically the youtube app from looking at https://github.com/dz0ny/leapcast which is a python emulator that has youtube and google music working.
Google is in progress of open sourcing some part of the chrome cast.
https://code.google.com/p/chromium/codesearch#chromium/src/chromecast/
https://code.google.com/p/chromium/issues/list?q=label:Chromecast
So theoretically you can build a similar device.
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I am a newbie dev trying to build a web application that can read and write to an RFID Card through the browser.
I am currently using an ACR122U Card Reader and have gotten it reading directly to my server in NodeJS with the nfc-pcsc node package.
Of course, I don't want to have my users have to run their own server and install a ton of libraries to read a card.
Ideally, they can just plug a card reader into their USB port and communicate from USB>Browser>Node Server and back again.
Can anyone recommend a good way to communicate with a USB RFID reader through the browser (and send to backend server?). Thanks
As far as I know, at the moment (Mar.2021) there is only experimental support for USB in browsers (WebUSB API). Please refer to https://developer.mozilla.org/en-US/docs/Web/API/USB
As this API is experimental, you may not want to rely on it for production. In this case, a component running on end users machine will be needed (e.g. a more or less simple service that responds via https at 'localhost'. This approach opens several usability/security concerns (such as supplying a trusted certificate for localhost, properly managing CORS headers etc).
You may want to refer to this question for additional suggestion: Architectures to access Smart Card from a generic browser? Or: How to bridge the gap from browser to PC/SC stack?
Since we need to have a UDP socket to discover the device, and since javascript seems not supporting UDP, is it possible to connect to Sony Camera Remote API with a javascript based mobile app (non native).
As said in the comments, you can use Cordova to do the SSDP discovery.
However, as far as I can see, the API is HTTP-based. So if you don't need discover (can write in the IP address and port manually), then this should be possible to do.
Did you ever get anywhere with this project? I'd be interested in getting some LiveView and controlling a camera using Javascript.
For example, if I have a friend over and he wants to show me a video using a given app that runs both on my device and his device. Could that app display a QR code on the screen or something that he could scan and instantly be granted access to my Chromecast device?
As Ali mentioned, Chromecast devices are discovered and apps launched via local network applications. One an app is started, it could easily connect with a cloud service that allows other (non-local) devices to talk w/ your Chromecast via the cloud service. A Chromecast Receiver application is just a HTML5 application (HTML, CSS, and JavaScript). You can really do what ever you want once your application gets launched.
If displaying a QR code that allows some kind of rendezvous with your cloud application is what you want to do, you can certainly do that.
I presume your friend's mobile device is on the same wifi network, right? Currently, a chromecast device has no identity outside of its local wifi network, so if the sender is not on the same network as the receiver, there is no way they can exchange messages. Back to your question, if your friend is on your network, then he could see your device except from those applications for which your device is not whitelisted for. Is that the case you want to handle through, say, a QR code? If so, that is currently not doable either since whitelisting is not just a local setup. Maybe I misunderstood your question?
Based on your questions, you are saying that both you and your friend have the same app. If so, and if your friend connects to your wifi network, then he will see your chromecast (you do not whitelist a device for a phone, you whitelist a device for an app id and as long as your friend has the same app (hence the same app id I resume), your whitelisted device will be discoverable by his phone. On the other hand, if you do not want to give him credentials to get on your network, then you need a cloud backend and a lot of work, since although your chromecast device can send a message to cloud and your cloud service can notify the other user's phone (using, say notification or some other mechanism that you employ in your app), the reverse (i.e. sending a message from your friend's phone to your chromecast (through your cloud service)) is much harder. Your friend's phone can send your phone a message (again via a back end service, a bluetooth communication, NFC, etc and then your phone using your app can send that to the chromecast receiver but I am sure you are getting the idea that it is a lot of work. Signing up on your wifi network can be made easier with a QR code or something so at this pint, that would be the easiest solution.
I wanted to know if it is possible to program one chromecast device to send video to another chromecast device acting like a receiver. I have browsed the API reference on the Google developer website and it doesn't seem to be supported, but also doesn't say it isn't supported.
This is not currently possible, and probably never will be. Chromecast devices don't "source' video, they only transfer from wifi to an HDMI output. it is possible to play the same stream on two different chromecast devices, but there is no way to synchronize them at the moment. In theory this is something the devices could support.
Can anyone tell me how to send receive data between two applications over an ActiveSync connection?
In my scenario there will be one application running on a desktop and another on a windows mobile device, both these applications need to communicate among them. The connection between the desktop and the mobile device can be ActiveSync over USB or Bluetooth. I need the applications to exchange a continuous stream of data, more like a chat application. Ideally, the mobile device application will be sending out data 10-15 times a second (maybe more) and the desktop application will receive the data and display it.
For e.g., let’s consider the ‘Notes’ application for mobile device. Basically it allows user to save small textual notes. Now my application would be something similar, with the exception that it will send out all input it receives to the desktop application. The desktop app will receive the ‘inputs’ and process it.
Finally, I'm open to using any other option then ActiveSync, provided it supports Bluetooth.
You should check out ActiveSync api documentation for informations.
There is also an alternative solution, which I use.
Windows Mobile activates a temporary LAN when the device is connected on the USB.
You can use Window Sockets for the communication and avoid ActiveSync,
if it's not too much trouble for you.
Usually, the device gets IP 169.254.2.1 and the PC the 169.254.2.2.