I am developing currently an Android application that will communicate with other Android devices per Wifi. The Wifi will also provide the online connection. There is no server in this Wifi environment.
The idea was that the devices will discover each other with UDP multicast messages. But we noticed that UDP multicast often does not work on the devices. Sometimes it does, sometimes not.
To work around this issue we implemented a mechanism where the devices will store the local Ips online so that other devices will be able to retrieve them.
But this, of course, does only work if the Online State is available, which sometimes is not.
My question is, if there are other techniques with what the devices are able to connect per Wifi to the each other without knowing it´s Ip in the first place. Is there an easy way to forward the addresses per Bluetooth for example? Or could Wifi Direct be an option?
Every idea is welcome. Thanks for all of your help.
A zero configuration networking solution might work for you. There is a Nuget package called zeroconf that should work with Xamarin:
https://www.nuget.org/packages/Zeroconf/
Source code:
https://github.com/onovotny/Zeroconf
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
I wanted to know if WiFi P2P android API is ideal for use if we take lot of connections into consideration, tha app's users can be at time clients and servers they can share files and send messages and get them also as clients ? if no what is the best solution ( N.B : i'm opened to client/server architecture ).
I just wanted to know the limits of the API cited above and Thank you guys ...
Wifi direct as a technology is ideal for peer to peer communication.However talking about wifi direct for android , it works well only for a single connection that is only 1-1 use case .It is possible to create a one to many where every device connects to the group owner (Soft AP).But even if u build a one to one and try extend to multi use case you will have problems with certain devices that do no connect perfectly.
Checkout some of the problems listed under problems after downloading this application https://play.google.com/store/apps/details?id=com.budius.WiFiShoot&hl=en
If you want to go for multiple connection it is better to use hotspot .One device ends up being the hotspot and other clients connect to the hotspot .It is being used by plenty of application like xender, zapiya.
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.
I try to create an ad-hoc network between many Android devices, but I can't find documentation to do that.
I thought Wifi direct could work for what I want, but is it possible to have multiple connection on one device ? I saw that we could do a device acting like an access point and communicate with many devices, but can we communicate from one client device to two access point devices ?
I have for example 3 devices: A -> B -> C
The "A" device need to communicate with "C" device but he's too far away, so I want to have ad-hoc wifi direct connection between A&B and ad-hoc wifi direct connection between B&C, so A can communicate with C. It should also work with more than 3 devices.
Thanks !
Here is the link to the Wifi Direct Demo http://developer.android.com/resources/samples/WiFiDirectDemo/index.html
I have been working on establishing ad hoc communication over Android phones for a month. I am trying to create an app that could work without having 3G or access point. Main idea is to let the clients to be able transfer voice or data in a close range.
There are some guys implemented a basic system regarding almost the same topic. It basically works with Wi-Fi access point. So you need an access point in order to establish the connection. Although this is not what I am looking for, it might be helpful for others. You might need to contact them for more details.
https://sites.google.com/site/androidwalkietalkie/home
Android does not have support for ad-hoc WiFi at this time -- sorry!
Update (2019): Android has supported WiFi Direct for a while, and this answer has not been updated.
Your scenario would work. A would be able to connect with C as long as B (the group owner) is within range of both A and C.
See Android's developer documentation for more info:
https://developer.android.com/guide/topics/connectivity/wifip2p
At this time only Galaxy S 2 support Wi-Fi Direct
The wifi direct supports concurrent hosting and client capabilities on single interface. Which means, the device will act as an AP, allowing other devices to connect to it as clients, And also connect to another AP as a client. And can share internet connection by driving the internet traffic between the interfaces.
However, current implementations of wifi direct on android are specific to the phone and not part of andorid sdk. So there is not much clarity if they support concurrency. This capability is not limited by hardware.
Ad hoc wifi is disabled in Android. You need to ask Google why they have chosen to do so. If you have access to a device that allow you to install custom Android images, you will be able to patch Android to support it. Or you can root your device and reenable ad hoc Wifi, there are plenty of solutions on the web on how to enable ad hoc on rooted Android devices. This is a software issue, the hardware on every Android device that I know of has support for ad hoc Wifi.
The Serval Project, based in part on WiFi Tether, is the only place I've found this functionality. It's still alpha phase, but seems to be the forerunner in the field. The wiki is much more useful than the main project page linked above, with installation instructions and a bit of documentation.
Serval may or may not be right for your needs, but I felt it should be pointed out that ad-hoc networking is not impossible on Android. It might be better to wait until Google gets around to implementing it as standard API, though (if you believe they ever will :) ).
Well You might be interested in looking at AllJoyn. It is qualcoms SDK for android OS which includes wi-fi peer-to-peer implementations by creating adhoc connections. This is same as Wi-Fi Direct.