android_introduce

1 Enea is a global software and services company focused on solutions for communication-driven products. With 40 years of experience Enea is a world leader in the development of software platforms with extreme demands on high-availability and performance. Enea’s expertise in real-time operating systems and high availability middleware shortens development cycles, brings down product costs and increases system reliability. Enea’s vertical solutions cover telecom handsets and infrastructure, medtech, automotive and mil/aero. Enea is listed on Nasdaq OMX Nordic Exchange Stockholm AB. For more information please visit enea.com or contact us at info@enea.com. www.enea.com white paper the emergence of android paves the way for new opportunities for the world’s mobile phone manufacturers to take advantage of the trend created by apple with its iphone, moving the user back to the center. the only problem is that android is a work in progress. ANdrOid: Opportunities and Challenges The Emergence of Android What is Android? Android is a Linux-based platform for mobile and small form factor devices. There are two things that distinguish Android from other Linux distributions – it is a single-user system and it is adapted for use on mobile platforms. The Open Handset Alliance organization and its members are behind the concept, and its main sponsor, which has also adopted a significant role, is Google. Perhaps Android’s most important characteristic is openness. Not only is most of the platform code open source; but also, all applications are of equal value. if, for example, users don’t like the browser supplied, they’re free to replace it with another browser of their choice. There are already thousands of applications which add or replace inbuilt functionality. despite the new opportunities for mobile phone manufacturers, a tricky balancing act is ensuing. Manufacturers are on one hand trying to rush Android devices to market as quickly as possible, while at the same time managing their legacy phone platform investments. Android-based mobile phones belong to the “smart-phones” segment. While traditional “feature phones” will often be based on a real-time operating system with all of the functionality provided by the manufacturer, smart- phones are based on an application operating system such as Linux, Symbian or Windows CE and only base applications written by the manufacturer. Other applications can be purchased and downloaded by users as they need the functionality. in this regard, smart- phones are more like ordinary PCs. But Android is significantly different from other smart-phones. All interfaces are open to anyone who wants to write applications. The manufacturer is unable to maintain their own proprietary interfaces to specific functionality with - out countering the entire Android concept. Quite the opposite, in fact; all functionality is accessible to all and manufacturers are encouraged to publish any extensions. Inside Android All Android applications are written in the Java programming language. They are then compiled in two stages, first using an ordinary Java compiler and then using a dex compiler. dex stands for dalvik executable format. The finished code is then executed in a virtual machine known as dalvik. dalvik is often referred to as a Java machine. However, this is not quite correct since dalvik doesn’t run Java bytecode at all; it runs its own variant, known as dex code. The internal layout also differs in a number of respects. dalvik is a register-based machine – i.e. like most modern CPUs – while Java machines are stack-based. More- over, every application is run in its own instance of the virtual machine, while Java machines traditionally run in separate threads in the same instance, at least for mobile platforms. The main instance of dalvik is known as Zygote and is started on system launch. As soon as an application is to start, a copy of the Zygote process is created by means of a fork() call and the application then runs in the new instance. This particular layout, which involves every application having its own instance – or its own process in the operating system – paves the way for a very specific solution in order to achieve a robust system. By combining this with the fact that Android is a single-user system, separate user and group identities are used for every application. Furthermore, 2 white paper very restrictive rights are set and appli- cations are unable to access anything automatically other than their own resources. However, it is possible to share resources. This is controlled by asking the user when installing the application whether – for example – their own phonebook should be accessible, or whether the application should be permitted to access anything via the network. inter Process Communication (iPC) is another area where Android differs from other Linux-based systems. While the classic iPC functions are accessible, the preferred iPC is a technology called Binder. in many respects, Binder is an object-oriented communication channel like COM or COrBA. However, in Android’s version Binder is a lot less generic, and instead is specially adapted for precisely this platform. One subsystem in Android that has received a lot of publicity is the C library, which is used for all native code. To avoid the typical license problems which normally affects companies when they develop products based on Linux, the Android team developed their own version of the standard C library. This library is called the Bionic C library and is protected by a BSd licence instead of the GPL licence which protects many of the other C libraries used in Linux. This means that mobile phone manufacturers can add functionality to the C library without having to publish their source code. A lot of other code that is included in the Android concept is protected by the Apache licence, but there are also parts protected by GPL or LGPL and other common open source licenses. The wide range of licences used in the platform poses a risk for manufacturers. The Bionic C library is by no means revolutionary, but it has some inte- resting properties besides the license stated above. While the library can be linked statically or dynamically to the C application, each process will get its own copy of the entire library, placed in the process’ address space. This means that the code has to be really compact. To meet this requirement, a number of special cases have been removed and only necessary functionality has been implemented. For instance, C++ support is very limited. Quite simply, native services and system functionality have to be written in C. The Android team does not view this as a big problem since they do not really recommend anyone to write native code. Telephone manufacturers and application developers will be sticking to Java. The Android team has however recently released an NdK, or native development toolkit, so their view on native code may have changed somewhat. Another of the classical problems for developers of more advanced embedded systems is file systems performance. The best file systems for Linux require the block device to be of hard disk type. But this is not the case in smart-phones and other small form factor devices. instead, a file system customised for a block device of flash memory type is required. The most common flash file systems for Linux at the moment have problems with either performance or stability. The recom- mended file system for Android is called Yaffs2, and with this some success has been achieved in resolving many problems, but others have been added. For instance, it will not be possible to use Yaffs2 on modern flash memory types without some major development work. in the long run, mobile manu- facturers may have look for other file systems even though there are no clear open source alternatives at present. Another challenge faced by smart- phone manufacturers involves the actual system layout. These are often based on a System-On-Chip (SoC), where several CPUs – which are often running several different operating systems – have to be able to communicate efficiently. Android does not include any clear directives for the hardware, other than minimum requirements for the memory and CPU speed. A typical smart-phone layout includes a power- ful application processor running – for example – Linux and a radio processor running a robust, real-time operating system such as Enea OSE. This combi- nation often includes one or more dSPs that offloads the radio cpu by executing the more complex algorithms. The dSP often runs another operating system such as Enea OSEck. To achieve a reliable telephone, communication paths between the various processors have to be robust and effective. Enea’s LiNX product can be used to resolve these problems. LiNX simply links together the application operating system with other operating systems. LiNX for Linux has been released with open source code. There are also other solutions available. Opportunities, but Many Challenges The biggest problem with Android is that it is not a complete platform, despite the fact that Android phones are already on the market. For instance, there is still not full support for blue- tooth, functionality which a lot of users think should obviously be included these days. Nor is it entirely clear how manufacturers are supposed to extend the platform for their own requirements without breaching the public interfaces. Enea®, Enea OSE®, Netbricks®, Polyhedra® and Zealcore® are registered trademarks of Enea AB and its subsidiaries. Enea OSE®ck, Enea OSE® Epsilon, Enea® Element, Enea® Optima, Enea® Optima Log Analyzer, Enea® Black Box recorder, Enea® LiNX, Enea® Accelerator, Polyhedra® Flashlite, Enea® dSPEEd Platform, Enea® System Manager, Accelerating Network Convergence™, device Software Optimized™ and Embedded for Leaders™ are unregistered trademarks of Enea AB or its subsidiaries. Any other company, product or service names mentioned above are the registered or unregistered trademarks of their respective owner. WP52 082009. © Enea AB 2009. 3 white paper At present, it is not possible to add refinements such as a more advanced camera APi without first acquiring approval from the Android alliance. The fact that the platform is not complete yet is quite obvious from the limited documentation available. The application layer, with all its Java inter- faces, is very well documented; but for anyone who is interested in the rest of the platform, there is only document- ation in the form of source code, as well as forums and blogs. Of course, it is great to have a large community with a great deal of commitment, but everyone who looks more in depth at Android has to form their own opinions of whether the information they find is reliable. The hardware requirements are also too modest. According to the specifi- cation, you need at least 128 MB rAM, 256 MB flash and a CPU operating at a minimum of 200 MHz. However, Android is intended primarily as a platform for the high end segment, which will surely mean that most manufacturers will feel obliged to exceed the minimum requirements by a good margin. Another problem area is how the income for the third party applications will be handled. Android has its own software store, known as Android Market, which is fully controlled by Google. it is not known whether the income from Android market is distributed between members of the Open Handset Alliance, but this is highly likely to be a matter for dispute. And finally, there is the question of security. As mobile phones become more open and resemble PCs more, the risks of viruses and other malware increase. When installing applications, users have to approve the rights given to each application, but then it is up to the developer of that application not to abuse these rights. Conclusions despite its problems, Android is the hottest thing to have happened in the mobile industry in a long time, and most mobile manufacturers have major projects in the pipeline. it also creates some exciting new challenges and opportunities for service companies and operators. For more information: www.enea.com/android The Android logo is reproduced from work created and shared by Google and used according to terms described in the Creative Commons 3.0 Attribution License.