I am developing an android application where i need to connect to a server socket from my application. The application works fine when i am at home and my android phone and the server using the same Wi-Fi. However, when I am at the university my application can not connect to the server socket. It always shows "The Operation has timed out Error".
Obviously I have changed the code to make sure if i am connecting using the right IP Address.
Can anyone give me some suggestions please.
thanks
kaisar
If it's working fine at home, but not other places, it would lead me to believe the wifi you're connected to at school may be blocking people from accessing other sites on certain ports. This isn't uncommon. If you're not using wifi, your wireless provider may be doing the same thing.
When you're at home, try turning off wifi and going through the cell network and see what results you get.
Related
I have small TFTP server running on port 8080. It is an Android application. When I try to connect it while being on Ethernet, it works seamlessly. However, when I switch from Ethernet to Wifi. I get 'Connection refuse' error. Or sometime it displays first page and then when I try to navigate, it crashes with same error. So, what do I need to do if the IP changes ? Do i need to restart the TFTP server ?
Thanks
This looks like a wifi network error due to some radio interference or to some problem with the hardware. The connection refused error is probably the effect to some timeout that get triggered on after a (partially) failed attempt to establish a communication channel. This is why you sometime can see a part of the requested document.
I'm almost sure you are using a wireless router to allow the two device to communicate each other. Did you try a different router and/or a totally different place (a friend's house, for example)?
I want to start a local network connection using the built-in Wi-Fi hotspot on Android devices.
Is there a way to accomplish it?
And how to communicate between two devices?
EDIT:
I want to do it programmatically. Then I can transfer my own data between devices.
I haven't done this before, so my answer is all theoretical.
I think what you need to do is declare one device the server and start its hotspot manually with a known name.
Start / stop built-in Wi-Fi / USB tethering from code? (According to this question, you can't start hotspot programatically).
Once you have the hotspot set up, you start up the server app and wait for incoming connections. The server app can show you the ip address or hostname.
On the clients, you can do a simple check and see if the hotspot name is around and automatically connect to it if you find it. See this link for connecting to a network:
Using WifiManager to connect to a network
As for your second question, how to communicate - you need to establish a connection between the devices. For this, you need the ip address of the server. The simplest thing to do would be to show the ip address on the server UI and then manually enter it on the clients and press connect. It would then establish a connection to the server on a known port and you can send messages between client and server.
For reference, I found NanoHttpd, which is a webserver for Android. It uses ServerSocket to listen for incoming connections.
Possible answers:
Before ICS and non rooted devices
There is no way you can connect to a device over wifi. There is no API to do. Bluetooth is your best option or user interaction.
Before ICS and rooted devices
I am not sure if someone hacked the code, but when I tried to do an automatic connection to a wifi spot I noticed:
The api is hidden inside the SDK.
The method that does the connection checks the thread who ask for it. If it's not the os thread, it throws an exception.
Using ICS
With ICS there is a new way to connect devices through wifi called Wi-Fi Direct.
Here is a link with some demos.
If you are going to develop your own application for each and every individual terminals(devices) then i think for you socket programming will do the trick .
Yes , android supports socket programming in the same was as java socket programming .
1st google java socket programming tutorials and then you can using the same knowledge in android .
Also do remember to include the uses internet permission in the manifest , actually thats something which ate my brains for a long time :)
You mean communication between wifi enabled devices without any server like p2p? if so its wifi direct which is supported in ICS check this out http://developer.android.com/reference/android/net/wifi/p2p/package-summary.html
Before ICS there is no standard android API for wifi direct, though Galaxy S2 has wifi direct it uses proprietary API's which 3rd party devs can't use.
i dont know programmically create wify LAN,but you can create wify LAN manually,then you can do java tcp/udp program as said by brianestey
"As for your second question, how to communicate - you need to establish a connection between the devices. For this, you need the ip address of the server. The simplest thing to do would be to show the ip address on the server UI and then manually enter it on the clients and press connect. It would then establish a connection to the server on a known port and you can send messages between client and server."
for manual connection follow the steps
take settings/wireless&networks/portable wi-fi hotspot settings from any one of the phone
create new hotspot and turn on wi-fi portable hotspot from there
connect all other device to that hotspot including your pc
you will get ip of each device programmically (includig pc,but i dont know)
I'm designing an Android app that will require the use of a web server on the local device. I've been trying out some different servers for this purpose. At present I haven't written any code or run anything in an emulator, just played around with the servers on my actual phone, and I'm observing some strange behaviour.
Whenever I try to connect to the local web server, and I have WIFI switched off, the HTTP request fails. If I switch WIFI on, it succeeds.
Depending on which address I use, I get different results: using localhost or 127.0.0.1, I get connection refused when WIFI is off; using the current 10.X.Y.Z address I get a timeout. Both addresses work when WIFI is on.
I have tried this with xWS, PAW and i-Jetty: the behaviour is consistent. WIFI on, I can connect to the local web server; WIFI off, I can't.
I am using the default "Internet" browser on Android 2.3.3 on a Samsung Galaxy S (GT-I9000).
Does anyone know why this is? Is it a simple question of a setting somewhere I need to change, or what's going on?
Cheers,
/Uffe
Can you change the network interface the web server is connected to?
The default setting is probably something like eth0 or wlan0, if you change it to lo it could work.
You are asking why when you turn off your wifi, there is no connection to the 10.0.0.2 (Your computer's localhost) and when you turn it on, there is a connection?
Very simple. Wifi off - NO INTERNET connection. The device emulator is a separate OS inside your computer's OS. When you turn off your WIFI there is no route to the host (your computer) - there is no internet
I have now tested with my own simple client, and with Opera - and it works.
So in fact this is an issue not with the IP stack but with the default Android browser, or possibly with the settings enforced by the manufacturer (Samsung) or carrier (Telenor Sweden). Either way there is a workaround: use Opera instead.
Still don't know why it doesn't work with the default browser, but I'll mark this question answered.
I have an android application that talks to a server app running on grails (Groovy on Grails).
Android app basically establishes a connection with this address:
url="http://192.168.2.53:8080/tma/majBtm/androidToDesktop";
It all works fine when both the server and the android phone are connected in the same lan network.
Now the problem arises when I want the phone to talk to the server while the phone is outside the local network (I need it to use edge).
I came across VPN networks which I think might help me out. (the server has dynamic IP)
So what i did was go to dyndns.com and created a new hostname and have the app successfully run on the server. The host I created was - tmagrails.dyndns.com
How do I make my phone connect to this network? What changes am I supposed to make in order to get things working?
Also, I really want to know if this is the right approach. If not, is there any way to get things going for me?
Please advice.
First you need to set up port forwarding so that port 8080 is forwarded to your 192.168.2.53 ip address. A google search on your router model should tell you how to do this. If you want to make your app more secure you will also need to look at SSL and TLS While this won't garantee your app is secure it will stop the network traffic to your app being easily read if you were to access it from an open wifi hotspot.
Iam connecting 3G phone for my Android device for internet connection and another Socket(SPP) for CAN signal receiving.Whenever I manually connect to the Bluetooth tethering via 3G phone, i can browse internet perfectly and speed is good.Whenever programmatically connect to the 3G connection, i couldn't browse internet.i checked in shell and observing that in my mobile 'device is connected' message displayed and E symbol appears.No problem for me to connect Socket.But I got problem to use 3G phone.For this iam using APN/DUN mode.I checked both but no use.Is there any performance issue here or anything wrong to connect different devices by using Bluetooth API in android.Why this happends while connecting Mobile programmatically.Please give me guidance.
Regards,
Rajendar
Yes, you can have several open connections at a time.
In fact, I've used my hands-free bluetooth on my phone, as it is connected to my ELM327 SPP device streaming at full speed. I didn't notice any hiccups.
As for losing connectivity when you are connected to multiple devices, it's most likely an issue with the DUN provider you're using.
Also it's worth stating that, on Verizon/3g phones, when you use the phone as a phone, it suspends all 3g data services until the call is terminated.
The way L2CAP defines the LT_ADDR allows connecting devices up to 7. Your connection problems is something else.