Introducing the Open Hands set Alliance

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The Open Handset Alliance (OHA) is a collection of more than 30 technology companies including hardware manufacturers, mobile carriers, and software developers. Of particular note are the prominent mobile technology companies Motorola, HTC, T-Mobile, and Qualcomm. In their own words, the OHA represents:

A commitment to openness, a shared vision for the future, and concrete plans to make the vision a reality. To accelerate innovation in mobile and offer consumers a richer, less expensive, and better mobile experience.

http://www.openhandsetalliance.com/oha_faq.html

The OHA hopes to deliver a better mobile software experience for consumers by providing the platform needed for innovative mobile development at a faster rate and a higher quality without licensing fees for software developers or handset manufacturers.

Ultimately the success of Android as a mobile platform will depend largely on the success of OHA partners in releasing desirable handsets and mobile services that encourage the widespread adoption of Android phones. Developers meanwhile have the opportunity to create innovative new mobile applications for Android to encourage more mobile technology companies to become part of the OHA.

What Does Android Run On ?

The first Android mobile handset, the T-Mobile G1, was released in the US in October 2008 and in the UK in November 2008. The Open Handset Alliance has further committed to deploying additional handsets and services that support Android early in 2009.

Rather than a mobile OS created for a single hardware implementation, Android is designed to support a large variety of hardware platforms, from touch-screen phones to devices with no screens at all.

Beyond that, with no licensing fees or proprietary software, the cost to handset manufacturers for providing Android-compatible variations of their handsets is comparatively low. It’s hoped that once demand for hardware capable of running popular Android applications reaches a critical mass, more device manufacturers will produce increasingly tailored hardware to meet that demand.

Why Develop for Android?

If you have a background in mobile application development, this is meaningless to ask:

• A lot of what you can do with Android is already possible.
• But doing it is painful.

Android represents a clean break, a mobile framework based on the reality of modern mobile devices.

With a simple and powerful SDK, no licensing fees, excellent documentation, and a thriving developer community, Android is an excellent opportunity to create software that changes how and why people use their mobile phones.

Android is backed by more than 30 OHA members and is surrounded by significant industry buzz.

In market terms, the growth in portable devices is a worldwide phenomenon, with mobile-phone ownership outstripping computer ownership in many countries. The increasing popularity of smartphones — multifunction devices including a phone but featuring cameras, Internet access, media players, Wi-Fi, and GPS services — combined with the increasing availability of mobile broadband and Wi-Fi has created a growth market for advanced mobile applications.

What Will Drive Android Adoption?

Android is targeted primarily at developers, with Google and the OHA betting that the way to deliver better mobile software to consumers is by making it easier for developers to write it themselves.

As a development platform, Android is powerful and intuitive, letting developers who have never programmed for mobile devices create useful applications quickly and easily. It’s easy to see how innovative Android applications could create demand for the devices necessary to run them, particularly if developers write applications for Android because they can’t write them for other platforms.

Open access to the nuts and bolts of the underlying system is what’s always driven software development and platform adoption. The Internet’s inherent openness and neutrality have seen it become the platform for a multi-billion-dollar industry within 10 years of its inception. Before that, it was open systems like Linux and the powerful APIs provided as part of the Windows operating system that enabled the explosion in personal computers and the movement of computer programming from the arcane to the mainstream.

This openness and power ensure that anyone with the inclination can bring a vision to life at minimal cost. So far, that’s not been the case for mobile phones, and that’s why there are so few good mobile phone applications and fewer still available for free.

Corporations will also be attracted to Android for the level of control it offers. By using a popular enterprise programming language in Java, no licensing fees, and offering the level of access and control users demand, Android offers an excellent enterprise platform.

What Does It Have That Others Don’t?

Many of the features listed previously, such as 3D graphics and native database support, are also available in other mobile SDKs. Here are some of the unique features that set Android apart:

• Google Map Applications: Google Maps for Mobile has been hugely popular, and Android offers a Google Map as an atomic, reusable control for use in your applications. The MapView widget lets you display, manipulate, and annotate a Google Map within your Activities to build map-based applications using the familiar Google Maps interface.

• Background Services and Applications: Background services let you create applications that use an event-driven model, working silently while other applications are being used or while your mobile sits ignored until it rings, flashes, or vibrates to get your attention. Maybe it’s an application that tracks the stock market, alerting you to significant changes in your portfolio, or a service that changes your ring tone or volume depending on your current location, the time of day, and the identity of the caller.

• Shared Data and Interprocess Communication: Using Intents and Content Providers, Android lets your applications exchange messages, perform processing, and share data. You can also use these mechanisms to leverage the data and functionality provided by the native Android applications. To mitigate the risks of such an open strategy, each application’s process, data storage, and files are private unless explicitly shared with other applications using a full permission-based security mechanism.

• All Applications Are Created Equal Android doesn’t differentiate between native applications and those developed by third parties. This gives consumers unprecedented power to change the look and feel of their devices by letting them completely replace every native application with a third-party alternative that has access to the same underlying data and hardware. Every rule needs an exception and this one has two. The “unlock” and “in-call experience” screens can not be replaced in the initial SDK release.

• P2P Interdevice Application Messaging: Android offers peer-to-peer messaging that supports presence, instant messaging, and interdevice/interapplication communication.

Changing the Mobile Development Landscape

Existing mobile development platforms have created an aura of exclusivity around mobile development. Whether by design or as a side-effect of the cost or complexity involved in developing native applications, most mobile phones will remain nearly identical to what they were when first unwrapped.

In contrast, Android allows, even encourages, radical change. As consumer devices, Android handsets ship with a core set of standard applications that consumers demand on a new phone, but the real power lies in the ability for users to completely change how their device looks, feels, and functions.

Android gives developers a great opportunity. All Android applications are a native part of the phone, not just software that’s run in a sandbox on top of it. Rather than writing small-screen versions of software that can be run on low-power devices, you can now write mobile applications that change the way people use their phones.

While Android will still have to compete with existing and future mobile development platforms as an open source developer framework, the strength of use of the development environment is strongly in its favor. Certainly its free and open approach to mobile application development, with total access to the phone’s resources, is a giant step in the right direction.

Introducing the Development Framework

With the PR job done, it’s time to look at how you can start developing applications for Android. Android applications are written using Java as a programming language but are executed using a custom virtual machine called Dalvik rather than a traditional Java VM.

Each Android application runs in a separate process within its own Dalvik instance, relinquishing all responsibility for memory and process management to the Android run time, which stops and kills processes as necessary to manage resources.

Dalvik and the Android run time sit on top of a Linux kernel that handles low-level hardware interaction including drivers and memory management, while a set of APIs provides access to all of the underlying services, features, and hardware.

What Comes in the Box

The Android software development kit (SDK) includes everything you need to start developing, testing, and debugging Android applications. Included in the SDK download are:

• The Android APIs: The core of the SDK is the Android API libraries that provide developer access to the Android stack. These are the same libraries used at Google to create native Android applications.

• Development Tools: To turn Android source code into executable Android applications, the SDK includes several development tools that let you compile and debug your applications.

• The Android Emulator: The Android Emulator is a fully interactive Android device emulator featuring several alternative skins. Using the emulator, you can see how your applications will look and behave on a real Android device. All Android applications run within the Dalvik VM so that the software emulator is an excellent environment — in fact, as it is hardware-neutral, it provides a better independent test environment than any single hardware implementation.

• Full Documentation: The SDK includes extensive code-level reference information detailing exactly what’s included in each package and class and how to use them. In addition to the code documentation, Android’s reference documentation explains how to get started and gives detailed explanations of the fundamentals behind Android development.

• Sample Code: The Android SDK includes a selection of sample applications that demonstrate some of the possibilities available using Android, as well as simple programs that highlight how to use individual API features.

• Online Support Despite its relative youth, Android has generated a vibrant developer community. The Google Groups at http://code.google.com/android/groups are active forums of Android developers with regular input from the Android development team at Google.

For those using the popular Eclipse IDE, Android has released a special plug-in that simplifies project creation and tightly integrates Eclipse with the Android Emulator and debugging tools.

Understanding the Android Software Stack

The Android software stack is composed of the elements shown in Figure 1-1 and described in further detail below it. Put simply, a Linux kernel and a collection of C/C++ libraries are exposed through an application framework that provides services for, and management of, the run time and applications.

• Linux Kernel: Core services (including hardware drivers, process and memory management, security, network, and power management) are handled by a Linux 2.6 kernel. The kernel also provides an abstraction layer between the hardware and the remainder of the stack.

• Libraries: Running on top of the kernel, Android includes various C/C++ core libraries such as libc and SSL, as well as:

• A media library for playback of audio and video media

• A Surface manager to provide display management

• Graphics libraries that include SGL and OpenGL for 2D and 3D graphics

• SQLite for native database support

• SSL and WebKit for integrated web browser and Internet security

• Android Run Time: What makes an Android phone an Android phone rather than a mobile Linux implementation is the Android run time. Including the core libraries and the Dalvik virtual machine, the Android run time is the engine that powers your applications and, along with the libraries, forms the basis for the application framework.

• Core Libraries: While Android development is done in Java, Dalvik is not a Java VM. The core Android libraries provide most of the functionality available in the core Java libraries as well as the Android-specific libraries.

• Dalvik Virtual Machine: Dalvik is a register-based virtual machine that’s been optimized to ensure that a device can run multiple instances efficiently. It relies on the Linux kernel for threading and low-level memory management.

• Application Framework: The application framework provides the classes used to create Android applications. It also provides a generic abstraction for hardware access and manages the user interface and application resources.

• Application Layer: All applications, both native and third party, are built on the application layer using the same API libraries. The application layer runs within the Android run time using the classes and services made available from the application framework.

next The Dalvik Virtual Machine