Is there a way to go about getting 2 android phones to communicate to each other locally without going through a central server? Sort of like being on WLAN? I need these 2 phones to be able to sync themselves to each other when they are nearby and running the same app.
Maybe through bluetooth perhaps? Just a suggestion, I'm not sure how to go about this, but an idea might be to have each app broadcast through a certain port on LAN whilst searching for the other's broadcast through the same port. Once the other device has been identified, then transfer the data.
The only ways to do that with WLAN environment (and not included a AP i.e infrastructure mode)
Ad-Hoc mode (Google will help you more on this)
Wi-Fi direct - that is the future of peer-to-peer with WLAN. (Again am sure Google will be more than happy to help you!)
Related
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
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.
What is the best way for an Android app installed on two devices to communicate with each other? Can the devices connect directly without using text messaging?
You have several options, depending on your requirements and setup:
If your devices are very close to one another (up to about 10 meters), you can communicate using Bluetooth, as Derek suggested.
If your devices are somewhat further away, but within WiFi range of each other (up to about 100 meters), then they can communicate with each other using the Peer-to-Peer WiFi API, documented here (part of the Android Wireless API). This does not require a WiFi router to be present, and the devices will find each other and communicate directly. This does however require Android 4.1 or higher.
The Android Wireless API will also work if your devices are on the same local network (i.e., use the same WiFi router), even if they are not themselves within range of each other.
If none of these options are viable/guaranteed, then I agree with Derek that the easiest way would be to use ServerSocket and Socket to create a server/client interface through the Internet. Here is a sample application doing that. The main problem you might encounter is that if the server is sitting behind a NAT (such as a home internet router), you will have to configure the NAT to forward the incoming packets to your Android server.
You can connect them via bluetooth using BluetoothSockets. Android developer website has pretty good documentation on this.
http://developer.android.com/guide/topics/wireless/bluetooth.html
Or if you'd rather (and have internet on both devices), you can use regular Socket's.
http://developer.android.com/reference/java/net/ServerSocket.html for server side
http://developer.android.com/reference/java/net/Socket.html for client side
If you have a large amount of data to transfer, internet sockets have a greater data capacity and will be faster. The other advantage is that there is no such thing as "out of range". You can connect the two devices wherever internet is available, whereas with bluetooth they have to be within bluetooth range of each other
you can use PubNub. it handles all networking and you should only care about messages.
it has great API to work.
(Thanks to #Ian Jennings : Can we send data from an android device to another android device directly (p2p) without server in the middle?)
Depends on what you are doing. If you have a server, you may be able to send some message to it and have it pulled by the other device (assuming both clients have the app installed). I think this would be the most intuitive way (but it really depends on what you are communicating).
Text messaging and email might work, but you (or the user) needs to know the numbers/emails associated with a device to do that.
you should have a look at WifiDirect
Wi-Fi peer-to-peer (P2P) allows Android 4.0 (API level 14) or later
devices with the appropriate hardware to connect directly to each
other via Wi-Fi without an intermediate access point.
As was already suggested, sockets are the easiest way to accomplish this if your devices are all connected to a network.
There are things to accomplish here:
Use Network Service Discovery to find devices running your app
Connect to other instances of your app using a socket
For a complete tutorial you can check this out
ShortAnswer: Yes
Data can be sent directly.
In order of range:
1 Bluetooth
2 wifidirect
3 maybe.. GSM hardware direct?
After that, options again in range order:
4 tether or network
5 Internet
The android NSD API is meant to do the exact same thing you are trying to achieve! The example bundled with SDK is self explanatory!
please check:
Android NSD API example
I need a way to send messages between 2 android devices, 1 a phone and 1 a tablet. I'm using Java to create the app. I'm looking at servers but I can't figure out where to start. Thanks for any help :-)
P.s. Both devices would be using the same wifi connection so could I use a port to send messages
Beside the obvious solution from #dilix you could use a library like JGroups which provides automatic discovery of other devices.
The answer depends on how far away the devices are. Right next to each other (inches)? NFC. Within about 20 feet? Bluetooth. Within a hundred meters or so? Wifi Direct, which is peer to peer wireless connections. More than that? You're going to need a central server, because no carrier allows incoming TCP or UDP data- they all firewall it off. Of course all of the longer distance answers will also work for shorter distances. But different solutions here also have different security requirements.
I think you can try sockets to send\receive messages:
http://developer.android.com/reference/java/net/ServerSocket.html
http://developer.android.com/reference/java/net/Socket.html
Try to searh "android socket" and you can find some information even on the stackoverflow.
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.