B4J Tutorial [IoT] Raspberry 2 & B4J from the scratch...

Madhav Tenneti

Member
Licensed User
Nice Step by Step instructions.

Having problems uploading Applications using b4j-bridge, during the upload the screen goes blank, looks like display driver gets effected, moving mouse slowly brings back the display on PI2, opening Tempjars folder is a Zip file, upon extracting this several folders are created however the Application jar file is missing, my RasPi Os is the current Jessie build.
 

Erel

Administrator
Staff member
Licensed User
Why don't you use Putty or a similar SSH client to connect to the device?
 

derez

Expert
Licensed User
Managed to run a server app in my OrangePi, just followed the instructions.
Would be a good hint to remind that the public directory is in tempjars directory, not the application's.
In orange Pi the home directory is called root and you can run programs without sudo.
How do I close putty and not close the pi ? I want to start an app and keep it running after closing the putty interface (without having to connect it to real display).
Thanks
 

derez

Expert
Licensed User
I updated java jdk to 8 from the board using this
B4X:
sudo apt-get update && sudo apt-get install oracle-java8-jdk
I couldn't find the path_to_java so I wrote (with my app's name)
B4X:
nohup java -jar somejar.jar > nohup.out &
and it works, the program runs after closing putty.
Thank you !
 

derez

Expert
Licensed User
Strange - after I have my orangepi work with wifi, connect putty and winSCP, I see that the b4j servers I installed are not working. If I change to net by cable - they all work.
I have added to the /etc/wpa_supplicant/wpa_supplicant.conf file only these parameters (with my network names):
B4X:
network={
    ssid="testing"
    psk="testingPassword"
}
I have found that if I add more parameters like written here http://www.howtogeek.com/167425/how-to-setup-wi-fi-on-your-raspberry-pi-via-the-command-line/ it does not work at all.
It does not work also after connecting bridge (bridge is connected but the server does not react)
any hint ?
 
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derez

Expert
Licensed User
Yes. I can run the server by the bridge but it does not get calls.
Loading the browser page does not reach the public folder to load index.html.
 
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derez

Expert
Licensed User
Even stranger than that - if I connect the cable in addition and then remove it - it works, but never starts without the cable.
It is probably a problem with the dongle's driver.
 
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