In the first part of this series I looked into how to assemble a two-way mirror so that an Android phone behind it can be used as an information hub. Of course this is only one part of the story, cause we also need some software to display all this useful information on our Android device. Now, obviously there is already such software available, however I decided to write my own version from scratch for the following reasons:
- to learn more about Android application development
- it had to support Android Gingerbread (API level 10)
- have all the modules important to me here in the UK
Everybody know these words. You say it when you have to check a microphone which were plugged into some sound system. It’s just test if the microphone is working well and the spoken words are reflected by the amplifier. It’s a simple test to check the functionality of the microphone or the whole sound system. Why should I write about sound systems? No, I don’t try to learn playing a guitar or any other instrument, I like to share some thoughts about software testing. After writing a post about Valgrind, I had the feeling that I should try to show some ways of testing software. In the following post I will analyze what can be tested, what is useful and which tools are available. I don’t aim to make a full overview of software testing itself, I just like to highlight some tools (or thoughts) which are useful and every developer should know of.
Since the first 64-bit version of Windows Vista it is necessary to digital sign any kernel mode driver. Without a proper code signing the driver isn’t loaded by the system. Although it is also possible to sign drivers and applications for the 32-bit versions of Windows (as far as I know starting with Windows XP) it became mandatory in the 64-bit versions for any kernel mode driver. A serious software provider always sign its own software to make sure the user can rely on the authenticity of the package he e.g. downloaded from the Internet. It also prevent a question about installing a driver from an untrusted source which could be denied by the user and therefore makes the own software unusable. In any case the user has to confirm an installation of a driver, even if this driver is correctly signed, if the driver isn’t Windows Hardware Quality Labs (WHQL) certificated. In the following post I will not explain the basics of how to sign Windows drivers, there are many articles out there like the one from Microsoft itself, but I will look at changes which have to be made to correctly code sign drivers with a certificate signed by the VeriSign Class 3 Primary CA – G5 root certificate, which is in use by the end of 2010.
Mac OS X and the applications running on it are known for being sometimes unusual in the look and feel. For some reason developer on Mac OS X seems to be more creative than on other platforms. For an application developer which deals with user input it is important to make any user interaction as useful as possible and present this information in a way which is on the one side as much less annoying as possible but also attractive and informative on the other side. Lastly I was thinking about how to show the users they are using a beta version, which should remind them that this is not production ready software, but on the same time make it easy to respond to bugs they find in this pre-release. The solution, I came up with, was a badge in the toolbar which shows this is a release which is definitely in a testing phase, but also allows the user to double-click to give a respond to this particular version. In the following post I will show how to do this.
As you may know, developing for multiple platforms is one of my strengths. Strictly speaking, it’s a basic requirement if you are involved in such a product like VirtualBox, which runs on every major (and several minor) platform available today. Beside the GUI, which uses Qt and therewith is portable without any additional cost (which isn’t fully true if you want real native look and feel on every platform, especially on Mac OS X), all the rest of VirtualBox is written in a portable way. This is done by using only C/C++ and Assembler when necessary. Everything which needs a different approach, because of the design of the OS (and the API’s which are available there), is implemented in a platform dependent way. In the history of VirtualBox, several modules are created and grown by the time, which makes it really easy to deal with this differences. For stuff like file handling, paths, strings, semaphores or any other basic functionality, you can just use the modules which are available. On the other side it might be necessary, for a new feature we implement, to write it from the ground. In the following post I will show how to create a file shortcut for the three major operation systems available today.
Have you ever wondered how Mac OS X knows which file type belongs to which application? On Windows there is the registry. An installer writes the necessary info into it. Most applications on Mac OS X doesn’t come with an installer, they are just moved from the downloaded DMG file to the
/Applications folder. So a developer doesn’t have the ability to take action when the user “install” the application. Anyway there is no need to provide an installer for just this task, cause Mac OS X register file type associations on the first start of the application. In the following post, I will show how to do this, but furthermore I will show where this information is stored and how it could be reseted.
You may know the following situation. You arrive in the morning in the office, do what you always do and check out the latest changes of the software you are working on. After a little bit of compile time and the first coffee you start the just build application. Bumm, kernel panic. After rebooting and locking through the changes you may have an idea what the reason for this could be. A colleague of you is working on a fancy new feature which needed changes to a kernel module. As you almost know nothing about this code you seek for help and, as it of course not happen on his computer, he is asking for a backtrace of this panic. You have two problems now. First you need to see the panic yourself and second it would be nice to get a copy of the backtrace for sharing this info within a bugtracker. In the following post I will show how both aims could be easily archived.