Nexus 5 OTA after rooted and TWRP installed

I have been using Nexus 5 for quite a long time, and it's great to frequently receive update notification from google to get me the latest version of Android OS. We often joke that as a Nexus user, we paid for the system and get the device for free.

The update is called OTA (Over The Air). But since google changed its policy of verifying whether an OTA can perform or not, our lives become hard. In short, most of Nexus users will root the device, unlock bootloader and flash third party recovery for instance TWRP. (With this, you have most of controls of the Android OS and install lots of applications.) After done these, the system files will be changed. Google now changed the OTA policy to not only check some of the files are original version but check the whole system partition, which means in our case the OTA check will definitely fail and cannot run the update.

Below is a sample error:
expects build fingerprint of google/hammerhead/hammerhead 5.0.1/LRX22C/160258:user/release-keys or google/hammerhead/hammerhead 5.1 LMY47D/1743759   user/release-keys 
this device has Android/omni_hammerhead/hammerhead:4.4.4/KTU84P/4ef4c299f5:eng/test-keys

When what to do?

I had a lot of pain trying different methods, each time failed by the phone cannot boot and I have to reinstall the whole factory image, which means I have a complete fresh OS and have to install all the applications! So each update I need to spend days to get my phone ready, this is really hard.

During this Labors' Day vacation, I decide to study this problem and luckily I found a solution.

First of all,
Don't try the sideload, don't try to use TWRP to install... I have tried all these and they failed. :)

Solution:

1. Download Nexus Root Toolkit and update it to the latest version
2. click

 3. Very importantly, very importantly, very importantly CHECK don't flash userdata

Then follow all the instructions to flash, after this is done, phone will boot and updates all the application. Last but not least, flash the latest custom recovery and the latest Super

Enjoy the latest Android!

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Apache Commons CLI not working? No, it's a junk character problem

I am using Apache command line interface to accept run time parameters.

While in my code, I am using -t to specify run time topology name.
But to my surprise, it didn't work. I took 2 hours to debug this problem and finally by chance I compare the result and find our that

It's complaining about the - character. What is wrong with it?

I used Notepad++ and there is good plugin called HexEditor and it gives our the answer

This is causing strange problem.

You may ask why. This is because when someone sent me the command from Outlook, it was already junked. 

OK. the lesson and learn here is to be careful of the characters you pasted from Outlook, especially when it's in Chinese environment. We may try to type the command again to avoid problems.

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Strange Supervisorctl Problem: unix:///tmp/supervisor.sock no such file

I am using supevisord which is a great tool to spawn processes

http://supervisord.org/running.html

When I get things configured, I run supervisor with the command below:

supervisord -c /etc/supervisord.conf

Supervisor runs successfully and I can see programs got started, but when I check processes using

supervisorctl status

I got an strange error as below:

I tried several solutions for example change supervisord.conf ot use http socket

It even reported an refuse connection error.
supervisorctl status http://127.0.0.1:9001 refused connection.

I searched a lot and finally got the solution.

Problem:
I was using a old version of supervisord.conf file, people who work on clusters and do maintenance work often do this. But the problem happend because I did a fresh install of supervisord, and copied a supervisord.conf from another machine. The install is the latest version, and the copied one is old, which caused the problem.

The solution is very simple:

echo_supervisord_conf > /etc/supervisord.conf
#modify supervisord.conf, after it's done
sudo supervisord -c /etc/supervisord.conf
sudo supervisorctl status

The first line generates a new supervisord.conf which is a template, and then you can modify with the programs you want to start. And then start supervisord and check status. The result is good.

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Storm slf4j multiple binding problem

We are using Storm 0.9.3 and when we try to start supervisor node we found it reported the error below:

Clearly this is a slf4j multiple binding problem. Basically this famous library is used in different jars, when there are multiple slf4j find in the path only one will be picked up so that some jars called in a different version of slf4j will cause these compatibility problems. 

For the log above it clear states that there are 3 slf4j bindings under lib

• slf4j-jdk14-1.5.6.jar
• slf4j-nop-1.5.3.jar
• logback-classic-1.0.13.jar

And it needs 1.6 above as it said

SLF4J: slf4j-api 1.6.x (or later) is incompatible with this binding.

SLF4J: Your binding is version 1.5.5 or earlier.

SLF4J: Upgrade your binding to version 1.6.x.

Storm is compiled and tested, why it will have multiple slf4j* jars? The actual result is Storm vanilla package is good, but we add some jars to its lib folder:

So that when we package our Storm jar, we don't need each time to include all the packages it required, this is to save time: we develop on windows and upload developed package jar into cluster, if we can have a smaller generated jar file we save our time. 

Let's not judge whether this method is good or not, but the problem here is to solve the binding problem.

The solution is simple: 

From eclipse dependency 

Let's remove these two jars which are  slf4j 1.5.*

• slf4j-jdk14-1.5.6.jar
• slf4j-nop-1.5.3.jar

It can successfully launch now.

Then here comes another question: when we package Storm application, we want solve the slf4j multiple binding problem?

There is a nice pom.xml for you to reference (partial of pom.xml), this is what I searched and copied from internet, honor and thanks go to the original author.

 org.codehaus.gmaven
 gmaven-plugin
 1.5
 
  
   package
   
    execute
   
   
    
    File targetDir = new
    File("${project.basedir.path}/target".toString())
    println "dir is ${targetDir.path}"
    String jarBaseName = "${project.artifactId}-${project.version}"
    File jarWithUnwantedStuff = new File(targetDir,
    "${jarBaseName}-jar-with-dependencies.jar".toString())

    def explodedJarDir = new File(targetDir, "explodedJar".toString())
    def ant = new AntBuilder() // create an antbuilder
    ant.unzip(src: "${jarWithUnwantedStuff.path}",
    dest: explodedJarDir.path,
    overwrite: "false")
    File finalJar = new File(targetDir, "${jarBaseName}-deployable.jar")
    unwantedClassesDir = new File(explodedJarDir,
    "/org/slf4j/impl".toString())
    unwantedClassesDir.deleteDir()
    ant.zip(basedir: explodedJarDir.path, destFile: finalJar.path)
   
  
 

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Anroid Emulator Genymotion Connect to Internet

We have attended an Android training class and the lecturer told us that Genymotion is so far the best Android emulator.


https://www.genymotion.com/

I have setup a device as shown above: Nexus 5 and it can successfully run. But the problem is, when I am in company, I cannot access the network. But you can see on the top the WiFi icon shows connection is successful.

I searched and finally found out a solution.

1. Click and hold the Connected WiFi (typically the name is WiredSSID) for 2 or 3 seconds.

2. Choose modify network

3. Specify the proxy hostname and port, then click Save

4. Now you can web surf!

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