In my application, I want to send some data(say, "Hello") from my app to my PC over WIFI network. In PC, a service will listen to that data. But i don't have any idea of sending data over WIFI. I didn't get any proper references too. can someone help me.
Thanks in advance.
What you need is a propper protocol which both, your server and your phone can easily deal with.
If you don't send sensitive data, I think easiest would be HTTP
This depends on what you want the service on the PC to do with the received data, really. For all I know, you might find some off-the-shelf software that can help you set up this service. However, as others mention here, http is definetely the easiest way to do this. If you cannot find any existing software for the "listening pc", you'll need to write a program that listens at a predetermined port for http traffic (I wouldn't use the standard http port, 80, since you might run into conflicts with existing http software). You can do this quite easily in java, using Serversocket and/or Socket (as Tobias Rizau mentions above). Personally, I'd write a C/C++ program, since imo. that makes a better service, but that's absolutely not necessary (especially if you only know Java).
Related
I need some help in terms of choosing a design option for my problem.
I currently managed to implement a RaspberryPi acting as a Server and my local machine to act as the client. This client send JSON-Data to the Server which processes these. Everything is working as expected and I am using TCP-Sockets for the communication.
My problem:
The next step of my project will be, that I will use instead of a PC an Android-Device as client. What I want to achieve is, to send data to the server on the go. What I mean by that is, I do not want to restrict the server to be in a special network neither the client. What can be expected, is that server and client are next to each other, like in the range of a bluetooth connection. My question is, is there a relatively simple way to implement this communication? Is TCP a possible solution for this (even working in mobile networks?) or do I need to use Bluetooth, or is the way to go, to create some kind of network the client/server connects to and communicate here?
Sorry for propably stupid questions, but I am new to all this network stuff.
EDIT:
Since there were no respones, maybe I can do a more precise question. Is there a proper way to scan a network for a device name?
The only way I currently can imagine is to do a bruteforce like check on every IP-Address and resolve the names?
I first tried to let the Pi host an ad-hoc network, but it seems that non-rooted android smartphones do not have the possibility to access ad-hoc networks.
Therefore I made the Pi acting as an access point.
The communication now is very simple realized by a tcp server-client system.
I'm having the following scenario:
On the PC i will have a program running: java or .net, haven't decided yet.
When a certain event happens on PC i want to notify the android device.
I want a solution as independent and reliable as possible.
Opening a server on the PC/Android i think is out of the question because the user might be behind a router or on GSM internet (as far as i know it can't open ports as server)
The solution i have at this moment is to have a web server on the internet and have it handle the job, but i'd like not to use this because the delay between checks should be around 5 seconds, and i expect to have about 2-3k users simultaneously, and that will probably know down a regular web server.
So, any ideas how this communication can be made?
You may consider the option of Bluetooth client server application since PC and Android device usually have Bluetooth. You will have a Java server running on the PC and an Android client on the device. Check out this post: Send text through Bluetooth from Java Server to Android Client
You can handle the situation where Bluetooth is not available by creating a failover mechanism using REST API & JSON.
If you're already a web developer, I think creating a light HTTP based REST or JSON service would be a great solution. You've already said you don't want to do that which leaves the option of rolling your own client/server set up.
On the Android side of things, one way to do it would be to use TCP sockets. You can learn more about them here: http://developer.android.com/reference/java/net/Socket.html
For my Android app, users need to connect to a server that will be hosted somewhere on the same LAN. There can be multiple servers hosted on the same LAN. To make it easy for the user, I was going to scan the current LAN that the Android device is connected to and then list all of the network devices that have the server running on it, rather than having the user input the IP to the computer manually.
I'm fairly new to networking, and after some searching I found out that I would have to use a multi-cast DNS search or UDP broadcast to detect the other devices. I also found a nice library called jmDNS, although I've found very few documentation and sample code on it. Could somebody point me in the right direction for what I'm trying to do to save me wasted time (mostly if I'm on the right track)? I'm assuming that I'll have to modify my server a bit to broadcast it's there? It works completely as intended if I input the IP manually into the configuration page on my app. Also, this only needs to discover Windows computers, not sure if that matters. Thanks in advance.
Well, jmDNS is a complete Java library that you could use for your setup. It can be used to braodcast your services which other clients can search for.
Bounjour service on windows is a bit tricky, although it's definitely possible. The easier way, I would say is to use jmDNS for broadcast and discovery for both your servers and clients.
You would run the jDMs or other service on your local area network as a background service or a dameon.
Here's the scenario:
I need to write an application for Android to create a RFCOMM socket to a PC with a Bluetooth dongle (I'm going to write the server too).
My requirement is that the user doesn't have to pair device manually.
Actually, with a big hack, I'm using the createInsecureRfcommSocket.
A little scenario: I've an Android application which exchanges information with a Linux box with a RFCOMM socket opened. I can manually set the PIN on the devices (hard coding it IS an option)
I'm looking for different roads:
Write a JNI wrapper
As has been done here by Max Kellermann, I can write a JNI layer to make all the pairing phase. This should be a good option, but there's a problem:
The NDK 4b does not provide libbluetooth libraries, so -lbluetooth fails, as well as the NDK v.3.
Options:
Find the NDK 1.5 (which includes lib bluetooth). After days of web search I've been not able to find out. Anyone has or knows where I can find it?
Compile libbluetooth for Android by myself and use them for -lbluetooth. No lucky there, I'm not able to build them. Any hint?
Use something exposed by the APIs
Any one know how can I use createRfcommSocketToServiceRecord and have the user not to manually pair the device? Is it possible? How should I write the server?
Something I do not know
Maybe (sure!) there is something I do not know. Maybe I can use something else? Not RFCOMM? SDP?
Maybe I can manually pair with the Android API?
I hope to have been clear enough, if not just ask. And again, as it's not the first time, I'm in your hands :)
Thanks for all the support guys!
At the end, I can say that you can't.
Even if you find a way, using wrappers, writing C modules and so on, android evolution will probably change the thing you're using.
And so, there's no option. Sadly.
Let's see how Android Bluetooth API will change in the future.
Yes we can create it Rfcomsocket and listen the socket without user concerns and also without pairing devices.
https://code.tutsplus.com/tutorials/create-a-bluetooth-scanner-with-androids-bluetooth-api--cms-24084
Follow this !!
The Android Bluetooth API is not finalized, and will change. Use at your own risk. This class implements an API to the Bluetooth RFCOMM layer. An RFCOMM socket is similar to a normal socket in that it takes an address and a port number. The difference is of course that the address is a Bluetooth-device address, and the port number is an RFCOMM channel. The API allows for the establishment of listening sockets via methods bind, listen, and accept, as well as for the making of outgoing connections with connect, connectAsync, and waitForAsyncConnect. After constructing a socket, you need to create it and then destroy it when you are done using it. Both create and accept return a FileDescriptor for the actual data. Alternatively, you may call getInputStream and getOutputStream to retrieve the respective streams without going through the FileDescriptor.
I was wondering what the simplest program for sending an object from my Android phone to my computer wirelessly (via LAN) would be. I have created Java RMI programs with a server and multiple clients, so I have a grasp of the concept. However with android I'm just not sure where to start.
What I am aiming to do is send some sort of information (could simply be text) to my computer and my computer will do an action. I have the GUI interface's and the actions to be carried out all worked out, just the sending of some sort of information is getting me.
Could anyone help me out?
I would say it's not much different from sending data between regular computers. Basically you have the same options. Unless you have some special requirements, the most straight forward solution would be to just set up a ordinary server / socket.
A tutorial on the basics (including example code): http://www.ryerson.ca/~dgrimsha/courses/cps841/serverSockets.html