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Send data to Matlab from Android/Java

I spent some time searching for a way to send data from a android application to Matlab - with no approach. I would prefer to do it with JSON via a Restful webservice.
I probably have the wrong concept in mind how this is going to work.
Matlab should be running/waiting for POST requests from my android device to receive the data, bring it into matlab form from json , progress it and send it back - than wait again for new requests.
The "RESTful web service" like "webread" seems not to wait for incoming data and go active for them.
How to let Matlab listen for incoming data with json ?
or how to let Matlab receive data from Android/java based programms ?
Do i need another frameworks, api's or even a server with Database to get that done ?
Can anyone give me some hints ?

Approach 1:
Matlab also provides Matlab Mobile https://de.mathworks.com/products/matlab-mobile.html, which is capable of executing Matlab code from your device, however, it is not possible to send images to Matlab.
However, you can use WebCam https://play.google.com/store/apps/details?id=com.pas.webcam&hl=en and open up a Server, which is pretty straightforward. You can run the app in the background and then connect to Matlab via Matlab-Mobile, and access it via your IP address and usually Port 8080.
Approach 2:
You can use a WebSocket -Server which is implemented here:
https://de.mathworks.com/matlabcentral/fileexchange/50040-jebej-matlabwebsocket
For more information on how to get it to run you can follow the directions given on the GitHub readme, here: https://github.com/jebej/MatlabWebSocket
A WebSocket Server is on the highest layer of the 7th layer (application layer) of the OSI model https://en.wikipedia.org/wiki/OSI_model and builds op on the 4th layer (TCP). However, you do not need to specify such things as buffer size etc.
The following example code is directly taken from the example code from the GitHub project. To fulfill the desired outcome in the Android application it is the best approach to rebuild the client application on Android.
Echo Server:
classdef EchoServer < WebSocketServer
%ECHOSERVER Summary of this class goes here
% Detailed explanation goes here
properties
end
methods
function obj = EchoServer(varargin)
%Constructor
obj#WebSocketServer(varargin{:});
end
end
methods (Access = protected)
function onOpen(obj,conn,message)
fprintf('%s\n',message)
end
function onTextMessage(obj,conn,message)
% This function sends an echo back to the client
conn.send(message); % Echo
end
function onBinaryMessage(obj,conn,bytearray)
% This function sends an echo back to the client
conn.send(bytearray); % Echo
end
function onError(obj,conn,message)
fprintf('%s\n',message)
end
function onClose(obj,conn,message)
fprintf('%s\n',message)
end
end
end
To run it in MATLAB type:
s = EchoServer(30000);
This will then utilize the port 30000 on your local machine.
On Android simply create a WebSocket-Client and use your URI, which you can find out by using ipconfig (windows) or ifconig (Linux). In Android the uri should like the following:
ws://192.168.1.102:30000
Where the IP address may change according to your IP address

Here are my 2 cents.
Your approach seems right.
Step 1: You need to run a web server using MATLAB on your device. By going through Web Server, it looks like you can use it to run webserver, and execute a .m file when a POST or GET request is made to your server.
Step 2: Lets say that your server is accepting requests on port 8080. From your Android device, if you are on same network then you can make a HTTP POST request to http://your.ip.address:8080 and extract the data and execute your code in .m file.
Note: You can also get a public URL for your local server running on the device using ngrok utility. Then make a POST request to that public URL. You need not be on the same network then in order to make a request. Here is some explanation: Accessing localhost from android over wifi.
Edit:
Additional question says:
Matlab is possible of receiving data via TCP/IP client, but how does the android site need to do the POST/GET algorithm and how can response Matlab responsible to it?
Let me rephrase what I understand. Firstly, you want to know how from Android code, one can do a POST/GET request and secondly how will Matlab respond to the request?
In Android you can make a POST request in background thread either using AsyncTask (Android HttpURLConnection with AsyncTask Tutorial) or if you want to do it properly, you can use Retrofit library to do POST/GET calls (Using Retrofit 2.x as REST client - Tutorial
).
When using WebServer as mentioned in the link previously, when the .m file gets executed on the POST call, you can send the response to the POST request from there. On Android, where you initiated the call, you can receive the callback.
Hope this helps a bit.

Have you tried the Android Support Package for MATLAB?
While it doesn't allow access to the camera, when used with MATLAB Mobile it does provide access to:
Acceleration on 3-axes
Magnetic field on 3-axes
Angular velocity on 3-axes
Azimuth, roll, pitch
Latitude, longitude, altitude, horizontal accuracy, speed, and course
Here's a link with more detailed information on how to get started.

What is the established way to request data from an android device

I currently have an small application that I have been using to learn java/android programming. Right now I have a setup were the app on one phone sends a request (via sms) to another phone running the same app. The remote phone receives the request and sends back some info. Next I would like to try this from the web. Is there an established "best" way to to this?
I was thinking I would have a web server send requests to the device via google cloud messaging and then have the device return the data directly to the web server. (Not that I really know how to do any of that just yet).
I see that there is a google cloud messaging return path (send messages from the device to the google cloud server, but it seems very new, do I need something like that? The main thing I want is to be able to ask the phone to do something when I want, not have it poll to see if there is a request, or just periodically update some status.
UPDATE:
Thanks to the answers below for confirming to me that I was on the right track.
I now have some basic functionality.
I started out using this gcm android demo code
https://code.google.com/p/gcm/source/browse/#git%2Fgcm-client%2Fsrc%2Fcom%2Fgoogle%2Fandroid%2Fgcm%2Fdemo%2Fapp%253Fstate%253Dclosed
and this ruby gem
https://github.com/spacialdb/gcm/blob/master/README.md
between the above two I was able to send a message to my phone pretty easily.
To get the round trip working, I setup a very simple rails app on heroku.
I included a modified version of the sample code in the gcm gem in a controller and then used
HttpPatch (needed for rails 4) to send a post/patch from my phone to my web app, the controller then echoes the message back to my phone.
I guess it would be nice to get the two way gcm stuff to work, but I am not sure there are any gems that handle that, and I am not qualified to handle a task like that :)

I would say it's the right call: Google Cloud Messaging for Android
From the site Android Developer:
This could be a lightweight message telling your app there is new data
to be fetched from the server (for instance, a movie uploaded by a
friend), or it could be a message containing up to 4kb of payload data
(so apps like instant messaging can consume the message directly).
In this case you don't want to fetch data from the server but you want to send them.
You can send them in different ways. I would suggest, since you are learning, to try a RESTful solution using one of the implementation of JAX-RS.

As a short and direct answer for beginner : GCM (Google Cloud Messaging) would solve your issue. However, if your app turned out to be something bigger, other more technical and complicated solutions are present too.
see this link.

Sending SMS through PC using java via android mobile

I would like to connect my mobile phone in USB debugging mode and then send sms through some java code, so that the text is actually send through my cellphone using my provider sms plan. I am without any idea. I googled but could not get anything useful. Any idea, approach or link to some tutorial would be very helpful.

I'd suggest SMS lib for sending SMSs via your cell phone using Java code.
But if you are open to other ideas, I'd suggest to use a public webservice that sends in your place your SMSs, you can use for example nexmo, they have very good api and charges very cheap SMS. You have an initial credit for starting.

how to receive data from server to android

I am trying to make an Android application about cars tracking using GPS.
Like this "the system is having GPS and send a data (Longitude and Latitude) to Web Server GPS, and then Web Server will send it (Latitude and Longitude) to client (android)"
My question is how the client (android) to receive packet data from server that include (longitude and latitude) to display position car in google maps (android).

You could just write a web service that returns the data you need, and poll it at regular intervals. This is the easier solution.
A better one would be to use push notifications by utilizing Google's C2DM, but it's still in beta as far as I know (which is a shame, truly...). But still, it might be good enough for your needs, check it out here.

Try to use web service which serves location of cars or use http.

Send sms from java servlet to cell phone

I want to create an application which send sms from java servlet to mobile device, it's my first time to make like this application.
I found many APIs that supports this feature, actually they confuse me, so I choose one tutorial and follow it,
here's the link of the tutorial http://www.visualgsm.com/tutorial010_send_sms_java.htm
I download VisualGSM Enterprise Server (SMS Gateway) and run it, try to make the steps as mentioned, step 3 in example 2 doesn't work.
I want to know, whether I can make real testing for sending sms? Can I receive an sms on my own cell phone??
what is the best way to send sms? I really confused :(

There's 2 ways to do this: via modem or via API service.
There are various services which provide a gateway to the carriers as a service. They are called aggregators. A few industrial grade ones are mobile messenger and ericsson other consumer grade aggregators are http://www.twilio.com/sms/.