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How to send notification from one android device to another android device in same wifi network

I want to send notification from one android device (android tv without bluetooth, telephony) to another android device (phone/tablet). Both are on same wifi network. Through the notification, I want to launch an app or open a page in phone/tablet browser.
I went through GCM messaging and also saw some options where we can have a kind of http server on the phone running but could not understand implementation.
Can someone help with idea and if possible, some piece of code as well.
As I need it for demo, so even any hack solution is fine for me :-)
Thanks for any help or reading.

Your best bet as a hacky solution is to do simple Socket connection between two devices. Since they are on same Wifi, it will be simpler and won't have any firewall restrictions.
Avoid GCM, it requires setting up a GCM Server and then complex registration. It also makes your solution dependent upon Internet connectivity & Google ofcourse.
See an example here:
http://android-er.blogspot.in/2014/02/android-sercerclient-example-client.html
Basically one device such as TV can be a socket listener. The phone/tablet can connect to that socket and then you can initiate a notification on either device based on your requirements and data exchange.

how to send notification from one device to another

Currently I am trying to implement a feature where if I do some action in my app on one android device (changing channel on android tv), it should trigger my another android device in close proximity to launch one of its application.
I was just wondering which could be the easiest way to prototype it? Should I need to send some kind of push notification or another simple solution is possible? I just need it for prototyping as of now.
Thanks

You can use GCM with XMPP protocol that allows device-to-cloud connection. In the documentation you will find examples, just read it through.
This technique is very often called device to device but it's actually about upstreaming to the server and telling the server to push notification.
Requirement for both apps would be to use the same GCM sender ID.
Since this is a prototype you don't actually need to check if device is close to you or not. Otherwise, you could frequently update device's location on the server.

I think you want to develop a application like airdroid
https://play.google.com/store/apps/details?id=com.sand.airdroid&hl=en
As i know it set up small http server in one phone. And Send request from an another device. As you want. This sample help you to create such kind of http server. There is one restriction both device must be in same network.
https://github.com/NanoHttpd/nanohttpd.

Enable data connection on android system app

I'm trying to make a android system app (for me and friends), to let me control my android phone over my server.
Actually I've problem to enable/disable data connection. When I search, I found topic that said there is no possibility, or giving a no longer supported way (by using breach). This was exactly the same for GPS controle, but I found a way because my app is a system app.
So I want to know if someone know a way to enable and disable data connection without user consent on a system app. I didn't find anything on the api.
Thanks !

Is it possible to lock the bluetooth in android device for a specific time period

I am able to disable Bluetooth using Bluetooth API`s Disable method .but my requirement is also to prevent the user interaction for Bluetooth when my apps is running.Is there any way to prevent the user interaction i.e when the user try to enable Bluetooth the app will block it.
Thanks in advance.

This is a small piece of code that needs to be written to disable/block bluetooth access. However, if you want to modify the functionality lagely, rooting is the solution. However, this post is already having relevance to the one noted ast : How to enable/disable bluetooth programmatically in android

Is there a way for automatic/programatic pairing of 2 bluetooth devices in android?

I am developing an application which connects devices over bluetooth and exchanges messages. It works fine for paired devices, but I would also like it to automatically pair devices that are not paired. Like for example it could store and use the same PIN for pairing requests, I just dont know how to manage this request programatically in my applciation, how to automatically set and send the PIN when you get a pairing request and how to initiate such a request with the predefined PIN code.
Any snippets or thoughts would be highly appreciated! :)
EDIT:
I know its risky, I am developing this app for emergency situations only where no other means but bluetooth is available. Also is there maybe a way of premature pairing with devices without even connecting to them? Like lets say there is a list of MAC Addresses of those devices and I can use them to generate a bond with that devices so that they appear paired on my device?

You can't do this. To do what you want to do would create a huge security risk. Think about it, my device just comes anywhere in bluetooth range of yours and now I can send you anything I want without you knowing? You can't really do this and I highly recommend not trying to subvert it.

Reflecting the setPin method allowed me to send the pin automatically to the other device. I had to implement it in a broadcast receiver that is listening for pairing requests. Although I cant get rid of the dialog it just stucks there on the screen and I dont know how to close it (programatically) and continue the bonding procedure since this dialog is called from inside connect() which is a blocking method. I am not giving up on it yet though :)

With Bluetooth version 2.1 and above there is a method of pairing called the 'just works' association model. This is the lowest security method of pairing and has no protection against man-in-the-middle attacks.
However, this will provide a secure, encrypted link without the need to exchange pin numbers or verify device ID.
The API on different platforms may differ but the underlying HCI messages require that you indicate that your device (or one of the devices) has the following IO capabilities:
No Keyboard, No Display.
As you might have guessed, this is a mode for very
simple devices that use Bluetooth, such as a speaker or headphones.
If you can find the API to configure that, then the 'just works' association mode of Secure Simple Pairing will be used for pairing.
The next step is to store the link keys e.g. bonding. Many devices e.g. mobile phones, will still create a dialogue box to the user to ask if they want to 'remember this device', as user authorisation is specified by the BT specifications... but that's another problem.