Moving Towards Embedded Android Moving Towards Embedded modify the platform in a non- invasive built with exactly this particular feature manner. By giving basic advice for in mind. Naturally, taking advantage of a Android: Things you need porting and upgrading Android, this high level programming language is not a article addresses common issues often sole interest of the mobile software to know arising during the process of migration. industry but also of embedded system application developers. It is features like Java Exceptions, Threading and access to These are the benefits of Android the Networking Stack and the excellent Manuel Di Cerbo and Andreas Rudolf toolset coming with it, that draw the Nexus-Computing GmbH Switzerland 1. User Interface attention to the platform. Furthermore, it offers tools in order to support creating While there might be some occasions UI and localisation for applications, During recent developments, the where it even makes sense to use which are two features often requested embedded industry is starting to offer Android without UI - so called headless in embedded applications. Android as an option to run on their Android - the key reason to choose hardware products. The demand for Android over other solutions is in many 3. Stability and Prosperity Android on embedded systems has been cases the ability to build high quality in moderation for some time with steady user interfaces. The Android User Although controversially discussed in the ascent during the past few years. Interface resembles a profound pillar of press, the state of Android's stability and the platform with the goal to deliver security is benefiting from being one of This article discusses benefits and deeply immersive UI concepts by the most well tested Operating Systems in challenges when considering to offer incorporating the Android’s numerous existence. Android for an embedded system APIs into applications. Opposed to the platform, taking into account recent desktop experience, users of mobile Android runs daily on millions of developments in both embedded Linux phones and tablets are very alert by devices, accumulating testing time and embedded Android. By discussing the disruptive UI design choices. These beyond the scope of any embedded requirements of Android hardware and include delayed responsiveness or non system application in the field. Bug shedding light into the process of porting intuitive interaction. While creating reports are filed on a regular basis and Android to a new platform, this custom design patterns for an embedded most important of all, Android is under document aims to clarify the current application make sense in selected cases, nonstop development and progression. state of Android in the embedded the user values recognising UI patterns Driven by the industry's motivation of systems' industry. across all their devices. offering Android systems to the consumer, it is a major concern of Google While some suppliers are already 2. Java and Android Development Tools and their partners to account for offering a version of Android for their Android's quality and continuous hardware, the question arises if and how Due to the nature of the Android iteration. to update to a more recent version of the internals, it is possible to run Java code system. Taking into account benefits and very efficiently even on low resource challenges, it demonstrates how to ARM systems. Android’s core system is April 2014, Nexus-Computing GmbH Switzerland - www. nexus-computing.ch - [email protected] Moving Towards Embedded Android When comparing Android's software 5. Linux access to this new stack is given by the stack to a typical embedded Linux setup, "ndc" tool, which is only partially a significantly higher level of complexity Android is based on the Linux kernel. documented and remains for the moment is apparent. Arguably Android’s overall Although the system stack of Android is not very intuitive. stability might suffer from the inherent significantly more complex than a complexity of the middleware. classical embedded Linux approach, it init: Android uses its own init language Countering this claim is the fact that still features the ability to run Linux (see init.rc) and provides system very hard requirements are set for applications in parallel. Particularly, this initialization via rc scripts. With version Android’s operability by Google and their is a way to incorporate already available Kitkat, init.rc is now universal for all partners since non optimal user middleware into Android. The often Android systems, and platform specific experience will directly impact sales found IPC through socket daemons are initialization is done exclusively in other figures of devices. therefore portable to the Android files such as init.${platform}.rc or init. platform with little effort. Certainly, ${platform}.usb.rc. Although rc files 4. Ahead of time bindings to the UI still need to be appear similar to shell scripts, only a addressed with proper implementation. small subset of Linux commands are Provided, Android's propagation in the However, depending on the architecture, available at their disposal. embedded industry is still in early it might not even be necessary to write stages. Yet, the demand sources in the JNI bindings for existing applications, as toolbox: embedded Linux engineers are foresight of market trends. There are long as the middleware offers accessible used to have access to busybox’s firm believers who take the risk to invest communication such as UNIX sockets. extensive utilities. Android does not into Android at this time, in order to be feature a built-in busybox but instead one step ahead of competition in the The common pitfalls when moving from offers the toolbox, which is a rather future. Linux to Android limited utility. Early versions did not even include a “cp” command and many In general, clients intend to develop 1. Different tools compared to Linux other tools familiar to Linux engineers modular and extendable software are still absent or handled by other applications for their customers in order There are numerous user space tools utilities not present in standard to simplify the development process. which are absent in Android (current embedded Linux distributions. With tools such as the ADT Bundle or the version Kitkat). Parts of the system will Fortunately, it is not very difficult to Android Studio, this demand can be also throw the most experienced Linux install a fully functional busybox in covered in an elegant manner. While not engineer off the rails. parallel on a target Android platform. necessarily a technical advantage of the platform, these arguments rest on ifconfig, route, dhcpcd: Android recently user, group: Android heavily relies on features such as extensibility and introduced a very distinct system for Linux permissions for the filesystem. Yet maintainability of Android applications handling network interfaces, routes, dns, one of the most helpful tools in order to in general. gateways, etc. The OS has built an entire modify access rights is missing. There is stack around the IP tools which is no groupadd nor useradd. Some written in Java and accessed by the functionality is exposed by the package Android framework. As a developer, the manager (pm) tool, yet it is very limited. April 2014, Nexus-Computing GmbH Switzerland - www. nexus-computing.ch - [email protected] Moving Towards Embedded Android For adding a specific user to Android, the runtime. A large portion is set during Generally Android treats the underlying header file android_filesystem_config.h Android compile time. file system as distinctly partitioned for needs to be adjusted and fundamental its purpose. By default it expects two parts of Android need to be recompiled. => make symbols: By setting make partitions at least: system (readonly) and variables in the various *.mk files of the data (rw) and additionally expects a system, switches in the make process are cache partition, a recovery partition and 2. Unorthodox settings and build time set. an external partition. It is however flags. possible to deploy Android into only one => CFLAGS: usually flags are not set by physical partition as well. env: Android has a rather controversial hand, but by checking make variables behaviour with system preferences. ifneq(...). ifdefs are found in various One of the most common mistakes made There are multiple systems in place to do segments of Android and usually have a when deploying Android, is exporting the the same thing: tell Android what to do large impact on system behaviour. file systems with wrong user and group at runtime. Almost all of their switches permissions or wrong file stats. Due to are poorly documented, if at all. => config.xml: the fact that a lot of thought went into the resource file found under making Android secure, not only will => getprop,setprop: these are the tools to frameworks/base/core/res/res/values Android refuse to boot if stats and set system wide properties. Like found in defines many switches for the Java based permissions are not set accordingly, but default.prop or system/build.prop they Android middleware. Loaded only at also since recently SELinux is in place to define how Android behaves. They are runtime but not directly editable after determine if access to the file system closely tied to init and some of them deployment. breaks the predefined rules. trigger actions which can be controlled by the "on property" instruction of the rc In general there is a large amount of Android ARM Platforms for Embedded init files. system options that get set during Systems compile time. While understandable for => sql settings: many settings on the reasons of easing software architecture, Although there is quite an amount of application level are extracted during this is certainly a downside to other chipset manufacturers offering Android runtime from an sql database. The operating systems.