I am looking to implement a cloud application that allows one to save contacts and if the contact also has the app on, see on a map where the contact is (if in close proximity to you).
I've been looking around towards how to do so and the first step is to establish a connection.
For my purposes, a centralized server to which apps connect and fetch repeatedly updated database information about other users is unsatisfactory as this is too "centralized" for a cloud app.
I've some experience with Bluetooth but in my opinion and experience, bluetooth is not practical as the two devices must then be in very very close proximity with each other.
Thus my question is this, how do android phones connect p2p without the use of local wifi? If that is even possible?
Thank you for your time
Thus my question is this, how do android phones connect p2p without the use of local wifi? If that is even possible?
Yes, via Bluetooth where available, but it will probably not meet your needs. So, in practice, the answer to your question is no. You will need the local wifi.
That being said, you could attempt multicast on the LAN to detect other connected devices enabled with your application. If you want more than LAN, you will need a fully fledge solution including super peers and a P2P framework, like JXTA
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We found multiple ways to connect two device with a Peer-to-Peer connection using things like Bluetooth and Wifi direct. Problem is, each device need the user to accept or confirm the connection.
We would like to make a One to Many system where everyone can connect to one device. This device need to manage all the connections incoming without any user interaction (really independant) and then display in our activity some informations receive from all the connected device.
We're looking for some good examples on how we can do this. Thanks
Cant you just use basic TCP Server?
EDIT/Answer to comment:
Yes it is possible, here is one of my sample apps, tho servers can be created on ports above 1024
My question is that is it possible to send and receive data between multiple android devices via broadcasting over wifi without establishing p2p connection?
Our professor asked us to design a wireless network system in which you broadcast a message within your android phone, and the other android phones nearby receive it and broadcast it again so that the other phones can receive it and it continues like that. In this way, for example, when someone writes a message in a classroom or café everyone will be able to receive it and broadcast it again. (like an adhoc network system). And although my professor believes it can be achievable, I didn't find anything online like this kind of android network system. So my question is again is it possible to do something like that?
Any helpful leads and references will be appreciated.
Edit: I had to change the title of the question.
I couldn't find a proper solution so I tried the following method so far: I set up a UDP messaging app using Wifi hotspot (it works perfectly for multi clients). The phone who turns on the hotspot is the server and others who connect to it are the clients. Then, I decided to turn this system into an adhoc-like system where there would be more than one hotspot and the clients would connect to them in cycling order and serve as a bridge among these servers.(every second, they will switch to other hotspot and vice versa.) So, they will carry the messages from one network to another. (I know it is very inefficient and prone to time delays; but it is the only idea I have come up with so far.)
When I told this system to my professor, he said that it is too complicated and I just need to broadcast a message from a device to a common channel(without setting up a network connection), and other devices will listen to this broadcast channel(without connecting to a network system), receive the message and broadcast their own messages along with received ones to this channel again as I described in the question body. (he never mentions hotspot, Wifi direct, and etc.) He even told me that the only thing I need to do was to think simpler and use the properties of 802.11. But, I do not think it is that easy to set up such a wireless system, at least for Android where ad hoc systems are not supported yet. So any help will be greatly appreciated. Thanks!
The Nearby Connections API in Google Play Services released last week uses WiFi multicast: https://developers.google.com/games/services/android/nearby
It works for devices already on the same WiFi network. However, it uses a host/clients model, and doesn't work with WiFi direct or a tethered hotspot connection.
You could also use the WiFi direct APIs from ICS: https://developer.android.com/guide/topics/connectivity/wifip2p.html
You can have multiple devices connected together via WiFi direct, so firing UDP packets as #willis suggests would seem the way to go
It is implementable. Do you know the aircrack? similarly, you can receive all packets even not sent to you, and you can send any kinds of packets even not sent by you.
I am working on one project in which two android devices which are in different network need to transfer some data. Both device will have internet connection. It will be either Wifi or GSM provider.
Consider the following cases:
If one Android device has GSM network and
another device in some other place which has Wifi network
If one Android device has GSM network and another device has GSM network
How to transfer data in such cases?
I don't want to use server in between.
Please let me know how do I solve this issue. Any clue or any links which will help me. So far I didn't find any such things. Please help me...
Short Answer: You're going to have to use a server.
Long Answer: You could use bluetooth if the location is close enough or maybe Wifi Direct although I haven't personally used the latter. Although, ultimately a server will be the best option. If you don't know a lot about backend development I could recommend parse.com as a good service that makes creating backends very easy and has fairly high usage limits before you have to pay.
Unless a device has been configured with an external IP address, which is very unlikely (impossible?) on a cellular network, there won't be a way to directly contact it from an external device. Even on WiFi, most devices will never have an externally defined address.
If you had administrative control over a directly connected and externally addressed router, you could port-forward traffic to a single device, but that's likely not the solution you're after.
A much easier approach is to use one of the services that let you define a back-end w/o a lot of setup or costs. The most popular one is probably Parse.
So I am developing an APP and I need to connect multiple android and multiple Iphone to send text data without any internet connection or service provider data network.
So one of the phone will have to act as a server to relay information between them. But the app will have to decide which phone will be the server and if a phone that is the server leaves the conversation then another phone will pickup as the server this will all be done with some smart programming but before I get there.
I know Android WiFi direct can do a one to many connection setup which makes it easy to connect android phone and accomplish the task between android phone only. But the problems comes when I need to connect Iphone with the android phones. Since the Iphone must be able to act as a server as well.
I would like to know a few things:
Can I connect Android and Iphone via WiFi Direct?
Can I connect Android and Iphone using Multipeer connectivity feature on Iphone?
Is there anyway to create a soft access point using Iphone? I know android can do this via WiFi direct feature.
If non of these can work can you suggest something.
From the discussion here it doesn't look possible
I wonder though if both OS allow enough control over the WiFi transceiver if you couldn't just write an app that could what you are asking and just bypassing the built in software architecture all together. I would think Bluetooth would be too weak except in extremely dense device saturation environments, but just for proof of concept that could be another route to take. My guess though is that you just wouldn't get that level of control over any of the radios inside a phone through the current OS.
I have an android app, it does the following:
Connects with a server to read and update a database at the same time as others.
I want to convert this to an app that does not need an internet connection. Therefore i would like to know if its possible to have an android device acting as the server with the database, whilst multiple phones connect to it via bluetooth getting and updating the information in the database?
Thanks
Yes. It possible.
However all of your devices will have to be located nearby, so they can connect to each other through bluetooth.
You can take a look at Android Bluetooth API.
However, my recommendation would be to use Wifi instead of Bluetooth. YOu will need additional WiFi router. However, you won't need to deal with Bluetooth API in such case.
You will only need to write a server on one of Android device and the rest of devices will work the same (as now)
There are a few options to doing so, that don't involve a server. Both of them require a slightly different approach than both devices connecting to a server.
Wi-fi Direct- Only available with Android 4.0+.
Bluetooth
Personally, I have been using the Bluetooth option, and not found it terribly difficult. Essentially, you have to do the following to make it work.
Have one of the devices listen for a connection. If it is unpaired, you will have to make the device discoverable.
The second device needs to initiate a connection. It can do this by looking at the known devices and trying to connect to one, or listening for a new device
After the two devices connect, they must initiate some kind of a communication protocol. The communication is essential a serial connection.
Blue-tooth requires that the devices be within about 10 m of each other. Wi-fi direct will allow somewhat further, but as mentioned, is less supported. It is possible to allow for both communication methods, but is somewhat challenging.