I have a little problem. I have developed a midlet application that call some webservices through internet. I'm using cell phones with GPRS connection. For some time it runs as I wanted, run the apps, call the webservices through the GPRS, it returns the result, call the webservices again, and so on.
But say, I call the webservices and after the apps return the result I needed, I left it for a while. The next time I continue to access the webservices, the apps takes a while to connect through the GPRS. In nokia, it is marked with a G in a box. In SE it is marked with a glowing globe. This 'G' in the box or the glowing globe will appear after a while or won't appear at all, but the apps is still trying to connect to the internet.
Does it come from my apps or it come from the cell phone? And could I know [or the apps knows] that at the moment the apps tries to connect the GPRS is ready?
Thanks a lot for your responses...
There is nothing in Java ME (i.e. J2ME) that can control whether or not the device is connected, unfortunately. All you can do is try to connect.
Make sure you are properly closing all your connections, though. Including the HttpConnection object, not just the input/output streams.
Related
I'm trying to establish a connection between my PC running Ubuntu and my iPhone via Bluetooth automatically when it becomes available, after being manually paired beforehand. I've seen this to be possible with certain peripherals, mainly audio. For example, my phone will automatically connect to a Bluetooth speaker when it is turned on and Bluetooth is active on my phone; another example is my phone automatically connects to my car's radio system via Bluetooth when I turn the car on.
I'm not able to connect my phone to my PC without first initiating the connection from the smartphone's Bluetooth menu. I'm thinking that I could possibly write an application for the PC to attempt to connect to the device every few minutes or something, but it seems that the phone needs to be the device to initiate the connection.
The only information that I need for what I'm trying to do ultimately is that the devices can pair successfully. Essentially I'm trying to build a sort of proximity trigger between my phone and my PC without using Wi-Fi and GPS - I can't use these for some specific reasons.
Is there any way to make this happen?
Yes this should be doable as long as you use the Background Processing feature for iOS apps. In the example I'll give below, we'll have the PC be the peripheral and the phone be the central, but you can really have it working either way. You will need to do the following:-
First initial connection needs to be performed in the foreground (this is due to iOS's background limitations).
On the iOS side, you need an application that acts as a central that scans and connects to the remove device (check this example as a starting point).
Upon connection, you need to bond with the PC. Bonding is important as it will prevent you from having to do the pairing again in the future. However, pairing/bonding is managed by the iPhone's OS so you cannot write it in your application, so the workaround is to have an encrypted characteristic on the PC side that will force the iPhone to bond (this is covered later).
On the PC side, you need to have a BlueZ script that acts as a peripheral that is always advertising. You can do this using bluetoothctl (check the examples here and here).
Before you start advertising, you need to have a GATT server on the PC side (to do this, check this example).
When registering characteristics, ensure that one of them has the encrypt-read property (you can find a full list of the properties here).
Now when you attempt to read this characteristic from the iOS side, the two devices should bond (make sure that your PC is bondable which you can do this via these commands).
Once the devices are paired, your iOS app needs to be working in the background constantly scanning and attempting to connect to the same peripheral (have a look at this and this example).
You can find more useful information at the links below:-
Getting started with Bluetooth Low Energy
The Ultimate Guide to CoreBluetooth Development
How to manage Bluetooth devices on Linux using bluetoothctl
I am new to arduino, however I have experience in web development, lately I have been using, meteor js and the mean stack for different projects. I am open to trying any language though.
What I am trying to do is build a simple application to control the led on the arduino over the web.
I am working with another person and the arduino will be behind a firewall so I am not sure how to access it via the internet. I do have access to a arduino yun that I can use for testing at home which does have linio connected via bridge, which I dont quite understand what that does.
Ive also heard of this, https://www.yaler.net/ but would like to stay away from third party builds as much as possible if I can do it myself.
Whats the common way to do this with a arduino behind a firewall. and how do i do this with a arduino yun, is it easier with a yun?
So this is kind of a vague question, because we don't know exactly what your setup is and what's up with your firewall. But I'll try to help you out.
What I am trying to do is build a simple application to control the
led on the arduino over the web.
So this means you will need a web server running on the Arduino with a REST http client perhaps. You can easily find a dozen ways to do this by googling Arduino and REST, but here is one way you might go about it. Honestly though, I really wouldn't want to set up a REST server without a library.
From there, you simply set up a REST endpoint that when called, turns on the LED.
Whats the common way to do this with an Arduino behind a firewall.
This isn't remotely constrained to Arduinos. All (?) servers are behind a firewall. You will need to talk with your network administrator and have them open up the 80 port (for instance) and have it forward the call on the public port to the local Arduino server.
is it easier with a yun?
It doesn't matter what Arduino board you're running. It obviously has to have an ethernet or wireless port/shield but otherwise it doesn't matter.
I shouldn't even bring up the fact that googling "arduino rest controlled led" brought this link up... Besides the firewall, that appears to be exactly what you're looking for or will at least get you going.
I am from Bangalore-India. I have developed few J2ME applications that involves client/server interaction through HTTP connection.
I am testing my application on both the leading operators of the country- Airtel and Vodafone. My Midlet works fine with S60rd edition and S40 2nd edition(6030) phone. but as soon as i switch to S40 3rd edition phones like 6233, I am not able to acces the GPRS through my MIDLET. Though the GPRS is working fine with the native phone browser.
Even the MIDLET is not able to access GPRS on currently released phones such as 5310 Xpress Music and 3110 classic.
I have done some packet captures as weel at my server end but the observation is that my request is not reaching upto the server.
I have gone through tons of web references that talk abt APN settings, but no solution has worked for me :(
Is there anyone who can help me out so solve this S40 specific problem.
Thanks in advance.
Can you access GPRS from any MIDlets other than yours? If not, then it sounds very much like a GPRS settings problem.
If I remember correctly, S40 handsets have a Streaming settings option in the settings menu. Ensure you've created a GPRS access point which is referenced in the streaming settings option.
Can anyone tell me how to send receive data between two applications over an ActiveSync connection?
In my scenario there will be one application running on a desktop and another on a windows mobile device, both these applications need to communicate among them. The connection between the desktop and the mobile device can be ActiveSync over USB or Bluetooth. I need the applications to exchange a continuous stream of data, more like a chat application. Ideally, the mobile device application will be sending out data 10-15 times a second (maybe more) and the desktop application will receive the data and display it.
For e.g., let’s consider the ‘Notes’ application for mobile device. Basically it allows user to save small textual notes. Now my application would be something similar, with the exception that it will send out all input it receives to the desktop application. The desktop app will receive the ‘inputs’ and process it.
Finally, I'm open to using any other option then ActiveSync, provided it supports Bluetooth.
You should check out ActiveSync api documentation for informations.
There is also an alternative solution, which I use.
Windows Mobile activates a temporary LAN when the device is connected on the USB.
You can use Window Sockets for the communication and avoid ActiveSync,
if it's not too much trouble for you.
Usually, the device gets IP 169.254.2.1 and the PC the 169.254.2.2.
I am writing a windows application (written entirely in C++) which reads files from a storage card on a mobile phone running Windows Mobile. The tough part is, I don't know how to make my application detect the event that a user has connected the mobile phone to the USB of laptop. I did some reading on MSDN and have written a small code using RegisterDeviceNotification, which detects whenever a USB disk is attached/removed from the laptop. However, I am unable to tweak this to make it work for phone type devices. Please help me out through any links/tutroials which explains this(preferrably C++, as I don't know .NET or C#).
Thanks
Alok
According to this article you can use RegisterDeviceNotification to get notifications when activesync detects a device has been plugged/unplugged. (See option 3 at the end of the article)
It may just be a matter of setting up the correct notification filter.
Windows Mobile devices use RNDIS, a network interface protocol behind the scenes. Hence, the RegisterDeviceNotification method still works, but you're looking for a DEV_BROADCAST_DEVICEINTERFACE, not DEV_BROADCAST_VOLUME. (i.e. dbch_devicetype==DBT_DEVTYP_DEVICEINTERFACE)
You can use RAPI or RAPI2 to detect when a Windows Mobile device connects to a PC via Active Sync or Windows Mobile Device Center. RAPI can also be used to read the files on the storage card and much more.
RAPI is simpler to program because it is a C based API. RAPI2 has more functionality than RAPI, but is an object oriented COM API. If your needs are simple and you only care about one device/connection at a time then RAPI is good enough. There are two RAPI functions used to detect connections: CeRapiInit (blocking), and CeRapiInitEx (signals an event upon connection).