Android iphone OS Comparison

Transcription

1 Android iphone OS Comparison David Thomas April 12, History 1.1 Android Android OS started as a project from Android Inc., based out of California. Their ideas and work caught the attention of Google, who absorbed their company. The men behind Android, Andy Rubin, Nick Sears, Rich Miner, and Chris White headed up the team at Google to start an open source mobile phone operating system based on the Linux kernel.[8] In November of 2007, The Open Handset Alliance consisting of Google, Texas Instruments, Broadcom Corporation,HTC, Intel, LG, Marvell Technology Group, Motorola, Nvidia, Qualcomm, Samsung Electronics, Sprint Nextel and T-Mobile, released the first official public information regarding Android, including that it would use Linux kernel version 2.6. The Android source was released to the public on October 21, 2008 using the Apache license. The Apache license, created by the Apache Software Foundation in January of 2004, allows for the user of the software the ability to modify and distribute the software freely. It also does not require that any kind of modifications to the software use the Apache License. When a piece of software is redistributed with modifications, the original copyright, patent, trademark, and attribution notices must be included with notices of modification to them.[8] 1.2 iphone The iphone OS is a closed source operating system developed by Apple for use on the iphone, ipod Touch, and now to a modified extent, the ipad. It was initially released on June 29, 2007 and has received many updates since.[10] The OS consists of four layers. The Core OS, Core Services, Media and Cocoa Touch. The biggest 1

2 accomplishment of the iphone OS was wielding the forefront of technology, such as multitouch capabilities and internal accelerometers with an easy, friendly user interface. The interface is designed to make user of different interactions with the device, such as a switch in viewing mode from portrait to landscape. Another example is a common use of shaking the device to signify an backspace or deletion. The iphone uses versions of many Mac OSX applications modified for the mobile phone environment. For example, web browsing on the iphone OS is done through Safari. Mail and Calendar events are handled through scaled down versions of Apple Mail and Apple ical.[9] 2 Supported Devices 2.1 Android Android supports many innovative and industry standard features for mobile phones, as well as other platforms that Android could be adapted to in the future. For example, the graphics platform is expandable from traditional smart phone layouts to 2D and 3D graphics using OpenGL over VGA.[8] Android supports all of the major connectivity technologies from mobile phones using GSM/CDMA to more personal connections via Bluetooth and Wi-Fi. Android is equipped to use video and still camera modes, touch screens, GPS, accelerometers, accelerated 3D graphics, and digital compasses. Android has codecs built in to support most popular digital media formats, such as H.263, H.264 (in3gp or MP4 container), MPEG-4 SP, AMR, AMR-WB(in 3GP container),aac, HE-AAC (in MP4 or 3GP container), MP3, MIDI, OGG Vorbis, WAV,JPEG, PNG, GIF, and BMP.[8] Currently there are atleast 18 devices running Android available at retail currently. Many large hardware manufacturers such as HTC, Dell, Acer, Motorola, and Samsung all have devices running Android with more companies such as Creative and Sony Ericsson on about to join the list. As mentioned earlier, Android is not exclusive to mobile phones. Creative Labs is working on an MP3 player that uses Android for advanced functionality.[8] It is meant to enter the same entry-level market as the ipod touch. The Zii Egg is designed for OEM retailers to rebrand and resell. It comes with ZiiLabs Plaszma OS, but also supports Android. The Zii Egg is currently being offered for 399 dollars as a prerelease to developers and OEM retailers. 2

3 2.2 iphone The iphone OS runs exclusively on iphone, ipod Touch, and ipad. All previous versions of the iphone and ipod Touch are supported as well. This includes the iphone, iphone 3G, and iphone 3GS released June 29, 2007, July 11, 2008, and June 19, 2009 respectively. That is roughly one hardware update per year. The ipod Touch 1G, ipod Touch 2G, and ipod Touch 3G released September 13, 2007, September 9, 2008, and September 9, 2009 respectively. The ipod Touch follows a similiar one hardware update per year strategy as the iphone. Only one version of the ipad is currently available, having been released on April 3, The iphone and ipod Touch both start from 199 dollars the ipad starts from 499 dollars 3 Hardware 3.1 Android In regards to hardware and device support, Android supports many innovative and industry standard features for mobile phones, as well as other platforms that Android could be adapted to in the future. For example, the graphics platform is expandable from traditional smart phone layouts to 2D and 3D graphics using OpenGL over VGA.[8] Android supports all of the major connectivity technologies from mobile phones using GSM/CDMA to more personal connections via Bluetooth and Wi- Fi. Android is equipped to use video and still camera modes, touch screens, GPS, accelerometers, accelerated 3D graphics, and digital compasses. Iphone also supports these same features, with exception CDMA since the iphone is contractually bound to AT&T.[9] Some of the official product specifications for the Zii Egg still have yet to be released, but it is known that both the ipod Touch and the Zii Egg come in 8GB, 16GB, and 32GB models. The Zii egg sets itself apart by provided an expansion SD Card slot to allow up to another 32GB of flash storage. The screen size (3.5, 320x480 pixels) is the same between the two, as well as the multitouch user interface. The Zii Egg includes GPS, where the ipod Touch does not. GPS is only a feature on the iphone 3GS. The ipod Touch does not currently boast an onboard camera, but the Zii Egg contains two. One rear facing HD camera, presumably for capturing video and pictures, and one lower resolution, forward facing VGA camera used for video conferencing. The HD content captured by the rear facing camera, as well as any HD media from storage can be output to HDMI or component sources at resolutions up to 1080p. 3

4 3.2 iphone, ipod Touch, and ipad The iphone 3GS utilizes a 600 MHz ARM 11 processor and can support OpenGL ES 2.0 with 256MB of RAM. There is a 3.0 megapixel autofocus camera onboard capable of 30 f.p.s. VGA video camera. There is a 7.2Mbps HSDPA system for 3G, 4G and GSM connections. A Wifi chip as well as Bluetooth 2.1 are also included. The iphone 3GS is x 62.1 x 12.3mm and weighs 4.76 ounces. It comes in 16GB and 32GB models. The iphone is powered by a 3.7V 1219 mah Lithium Ion battery. The ipod Touch features the same 600 MHz ARM 11 processor capable of OpenGL ES 2.0 as well as the 256MB of RAM. There is no camera on the ipod Touch or 7.2Mbps HSDPA system, however the Wifi and Bluetooth are included. The ipod Touch is 110 x 61 x 8.4mm and weighs 4.1 ounces. Both the iphone and ipod Touch have a 3.5 touchscreen with a resolution of 320x480 pixels. The ipod Touch runs on a 3.7V 789 mah Lithium Ion battery. The ipad runs on a 1 GHz Apple A4 PowerVR SGX 535 GPU with 256MB of RAM built in. The ipad comes in 16GB, 32GB and 64GB models. There is an optional ipad model that comes with HSDPA system to connect over GSM/Edge networks. Wifi and Bluetooth 2.1 come standard on all ipad models. The ipad has a touch screen that measure 9.7 inches diagonally with a resolution of 1024 x 768 pixels. The ipad is 24.3 x 19.0 x 1.3 cm and comes in between lbs depending on if the 3G networking hardware is included. It runs on a 25 wh Lithium Ion polymer battery. Comparatively, the iphone gets 30 hours audio playback, 10 hours of video playback, the ipod Touch gets 30 hours audio playback, 6 hours of video playback and the ipad gets 140 hours of audio playback and 10 hours of video playback.[9] 4 SDK 4.1 Android Applications for the Android OS are developed in Java using the open source Eclipse development environment. A special add on for Eclipse is required in order to develop for Android. This addon can be obtained from Google. All of the components for developing on Android OS are free and open source, however, the programs do not need to be open source. This is due to the Apache license that Android is released under. Android applications are released under the Google-run Android Market. No special program is needed to download the applications or browse the Android market, like how iphone OS requires itunes. Android applications can be developed on any platform, since Eclipse is open source and available for all major operating 4

5 systems, including Windows, Linux, Mac OSX and Solaris.[2] 4.2 iphone For both the iphone OS and Android, a well known development tool is used as the basis of the SDK. For iphone, the Mac exclusive xcode Application is used for development. The applications must be written in ObjectiveC, an object-oriented version of C developed by Apple.[1] A free membership with Apple s website for iphone developers is required to download the necessary additions to xcode in order to develop the applications. The free membership utilizes an iphone virtual machine for testing, but does not permit the developer to upload the application to an actual device. For that purpose, a 100 dollar upgraded membership is required that allows beta testing access and Apple App Store privileges. The beta testing access allows the developer to upload the application to up to ten ipod Touch or iphone devices for field testing. The environment supported by xcode is Apple s own Mac OSX. Therefore owning a Mac is required for developing applications on the iphone.[1] 5 Thread Management System 5.1 Android Android s foundation comes from the linux kernel and its associated GNU, GPL, and LGNU libraries. The specific port of the linux kernel to the ARM architecture is not unique to Android however. It is very widely used in other embedded systems. A few of the open source libraries driving Android included, Webkit, SQLite, OpenSSL and OpenGL ES. Webkit is a very prominent and fast technology that powers many desktop web browsers, such as Apple s Safari, Konquerer for KDE, and some of the top of the line Nokia cell phone s utilizing Symbian technology. SQLite is a very lightweight version of SQL that has been trimmed down to fit in less than 500kb of memory and can utilize the vast majority of SQL-92 functions. OpenSSL brings the same top of the line security found in all Mozilla Foundation products, Apple Mac OSX, and Linux. OpenGL ES brings a subset of the OpenGL functions that powers many modern desktop computer games optimized for the mobile, embedded platform.[2] The Dalvik virtual machine is used instead of the much more widely used Java Virtual Machine. Dalvik differs from Java in that it does not use Just In Time compilation techniques. By forgoing the ability to read Java bytecode and instead utilizing a dex bytecode native to Dalvik, Android can achieve much longer battery life. A sacrifice with this decision came in that Android can not use standard 5

6 Java SE applications and environments. In the topmost Application layer, however invisible to the user, resides the service processes. Communication to them is handled over message buses. One notable example would be a contacts manager application placing a phone call by utilizing the telephony service.[3] There are four types applications or processes in the Android framework.[12] The types include User interface applications, intent listeners, services, and content providers. The user interface applications are self drawn visualizations of application, The intent listeners interface with the message bus to allow application and processes to communicate with each other. A service in Android functions similar to services in other operating systems. Services lack user interfaces, but provide integral background functionality to applications. Content providers allow for data to be passed between applications. Android is unique in that it does not allow data to be accessed by outside processes. This makes Android the most secure mobile operating system. In instances when data needs to be transferred, content providers spectrum data technologies regulate if it is secure.[12] 1.1 Google Android Figure 1: The structure of the Android OS Layers[12] Google Android is a new mobile handset platform based on Linux, Apache Harmony 1 and a proprietary, for the moment at least 2, custom virtual machine named Dalvik. Figure 1 Overview of the Android Application Stack The Red Layer The red layer from figure 1 represents the services offered 6 by the Linux kernel and associated GNU utility packages ported to the ARM 4 architecture. These components are licensed under the GNU General Public License, the GPL 5, or the GNU Lesser General Public License, the LGPL 6. Being subject to the GNU GPL and LGPL licenses, these components are licensed with all source code included. Furthermore, due to the viral nature of the GPL license, any modification to this layer or derived work must be distributed as source to any 3 rd parties using the same licensing terms. The GNU/Linux ARM port is mature, stable, and used in many embedded projects both in and outside of Google 7.

7 5.2 iphone Mulithreaded applications are supported on iphone OS because of the common roots with Mac OSX. Every process contains at least one thread from which the main() function runs. That main thread can spawn helper threads to assist in execution. Each thread contains its own execution stack, even if it was spawned from another thread. However, all threads share the same virtual memory space and have the same access rights. The operating system was designed this way so that Apple could maintain very close control on how overall performance of the devices.[4] 6 Memory Management 6.1 Android Memory management in the Android OS is slightly more complicated than its iphone OS equivalent. That is because the iphone OS does not allow third party applications to run in the background currently. Androids ability to multitask means that a complex memory management system is necessary. When an application is no longer in use, it is effectively put to sleep by the operating system. In this state, is consumes virtually no processing power. The Java foundation of Android brings garbage collection in to free up memory when needed. It functions similarly to its desktop counterpart in that it runs in the background and deletes unused objects when space is needed.[12] 6.2 iphone The iphones basis in Objective C means that it utilizes similar memory management functionality as it desktop counterpart.[1] Objective C utilizes reference counting as a way of determining if an object is eligible to be deleted. It is only eligible to be deleted if it is no longer needed by any other class. Each object maintains a reference count of how many classes are currently using it. Once that count reaches zero, the object can be safely deleted. This is very similar to garbage collection in Java. The main difference is that Java relies on code running in the background constantly to make these checks for the safety of deletion. Objective C has Java garbage collection built in to it, however it is not able to be used on the iphone. The reference count is not automatically maintained, the programmer must manually account for it. This is accomplished with object ownership. Object ownership is when a section of code declares that the specific object is necessary to its functionality.[1] An object can 7

8 have multiple owners. In additions to declaring ownership, owners must release their ownership of an object as well. Ownership is not required for object use, however it is recommended for any extended use. While using an object temporarily without ownership, there is a risk of the object being deleted while it is still needed. When adding an object to an array, ownership does not need to be explicitly taken; ownership is automatically given to the array.[1] 7 Networking Android supports all of the major connectivity technologies from mobile phones using GSM/CDMA to more personal connections via Bluetooth and Wi-Fi. A mobile phone carrier and contract, as well as a mobile phone running Android are required to utilize the GSM/CDMA connectivity. The non mobile phone devices, such as the Creative Zii Egg, running Android can only utilize Wi-Fi, Bluetooth and the direct I/O through data cable.[8] Tethering is not allowed using an Android device due to contractual agreements with T-Mobile. The Apple iphone only supports GSM because of the exclusive rights AT&T has over the iphone market. Tethering has only recently become available to the iphone as a result of much user protest. The iphone has Wi-Fi and limited Bluetooth capabilities.[9] Ipod Touch owners are unable to utilize GSM networking due to the lack of contract and lack of hardware on the non-mobile phone device. Ipod Touches are however capable of the same Wi-Fi and limited Bluetooth connectivity.[9] 8 Power Management 8.1 Android Android has its own specific power management frame work built on top the standard Linux power management framework. The ideaology underlying Android power management strategy is that the CPU should not consume power if there are no processes that require power. Android utilizes wake locks to request CPU resources. If there are no wake locks in an active state, the CPU gets shut down to avoid wasting power. Android has facilities similiar to the iphone for the user to manage power by allowing specific networking devices to be shut down to save power, as well as an additional task manager application to increase user control over power consumption.[12] 8

9 8.2 iphone Power management is left to the user on the iphone. Options to disable each of the five major connectivity networks are available to the user in the settings menu. The most power consuming is the mobile phone service, or 3G network device. This can be disabled separately from the the 2G network device, for when the user is in a rural area without 3G service. Using only 2G can save a significant amount of battery power. The next most power consuming device is Wi-Fi. Following Wi-Fi is 2G networking, Bluetooth then GPS. All of these can be individually disabled by the user to provide a custom power management solution.[11] 9 Comparison 9.1 Development Environment and Application Distribution For both the iphone OS and Android, a well known development tool is used as the basis of the SDK. For iphone, the Mac exclusive xcode Application is used for development. The applications must be written in ObjectiveC, an object-oriented version of C developed by Apple.[1] A free membership with Apple s website for iphone developers is required to download the necessary additions to xcode in order to develop the applications. The free membership utilizes an iphone virtual machine for testing, but does not permit the developer to upload the application to an actual device. For that purpose, a 100 dollar upgraded membership is required that allows beta testing access and Apple App Store privileges. The beta testing access allows the developer to upload the application to up to ten ipod Touch or iphone devices for field testing. The App Store privileges allows the developer the ability to submit the finished application to Apple for approval. Upon approval, the application will be made available for distribution on the Apple App Store by Apple. The developer is entitled to 70 percent of the profits from the sale of the application, with the remaining 30 percent going to Apple. The Apple itunes application is required to access the App Store.[9] Applications for the Android OS are developed in Java using the open source Eclipse development environment. A special add on for Eclipse is required in order to develop for Android.[2] This add on can be obtained from Google. All of the component for developing on Android OS are free and open source, however, the programs do not need to be open source. This is due to the Apache license that Android is released under. Android applications are released under the Google-run Android Market. This Developers of priced applications receive 70 percent of the application price, with the remaining 30 percent distributed between the various 9

10 carriers that offer Android OS mobile phones. Revenue earned from the Android Market is paid to developers via Google Checkout merchant accounts. 9.2 Ease to Port Applications Porting a fully fledged application to either Android and iphone OS will require a substantial amount of work regardless of which platform you choose. Much of the effort depends on the originating framework and platform of the application. For example, if the application was originally written for Mac OSX using Apples ObjectiveC, then porting it to iphone will be much easier than porting it to Android.[1] Since iphone OS applications are written in a variant of C, any application originally written in C will port to iphone much easier than the Java based Android. If the application was originally designed for Java, then it will be much easier to port to the Android OS with the Android plugin with Eclipse.[2] 9.3 Virtualization In Android, the Dalvik virtual machine is used instead of the much more widely used Java Virtual Machine. Dalvik differs from Java in that it does not use Just In Time compilation techniques. By forgoing the ability to read Java bytecode and instead utilizing a dex bytecode native to Dalvik, Android can achieve much longer battery life. A sacrifice with this decision came in that Android can not use standard Java SE applications and environments. In the topmost Application layer, however invisible to the user, resides the service processes. Communication to them is handled over message buses. One notable example would be a contacts manager application placing a phone call by utilizing the telephony service. 9.4 Reliability and Security Both Android and iphone OS have proven to be more secure than their full sized computer counterparts. Both mobile operating systems greatly benefit from the inherent security of their parent desktop operating systems. The Mac OSX elements in iphone OS provide much of the same platform specific security that Mac computer systems have.[10] The Linux kernel in Android yields its same security benefits to Android as well. IPhone OS does not allow for multiple processes to be run in the background, so this prevents many sleeper processes that could violate the integrity and privacy of a users data.[10] Also, in order to be released for the public on the Apple iphone App Store, applications must be approved by Apple. Their source is 10

11 examined for possible malicious content by the professionals at Apple.[1] Androids principles prevent the regulation of applications at the level of Apple, however the data protection services in the operating system prevent malicious software from being able to access important information. Android prevents one processes from access the data in another process. This is not fool proof though. There are methods to access the sensitive data once the target process has been terminated. If the memory blocks have not been zeroed out, a malicious process could access the sensitive data left behind by the originating process. 9.5 Future and Other Factors The future of both Android and iphone OS are very bright. The new version of Android coming out, Android 2.5 (Froyo) is expected to implement a new Portable App Engine, which would allow Android devices to run iphone and Palm Pre applications. There are only about 2000 Palm Pre applications available, but there are more than 150,000 iphone applications available. This would greatly bolster the application selection available to Android devices as well as bring unity to the mobile phone market. This feature came from the 20 percent project of two Google engineers. Google allows its employees to spend 20 percent of their time at work developing their own ideas. The groundwork for a new charging technology will be added to support charging via WiFi signals. This technology should be similar to the RCA AirPower technology. Some smaller bug fixes, such as calendar features as well as new Translation application from Google are also expected to be included.[7] The iphone 4.0 OS, announced on April 8, will include some much needed features to bring iphone to the same level of customization that Android users enjoy. The headline feature of iphone OS 4.0 is the addition of multitasking. This has been a feature of Android since its release. Home screen folder options, allowing users to organize applications more efficiently and store more applications on their devices has also been added. The mail application has received some upgrades, including a unified inbox for users with multiple account. A new advertising technology, known as iad will also be making its debut in the new version of the OS. The iad technology will allow location specific ads to be displayed for iphone users. This addition has been controversial due to the privacy issues it introduces.[6] 10 Conclusion In conclusion, the Android OS is a far more open ended system that is ahead of the iphone in all things technological. The iphone leads in market share primarily do to 11

12 its head start in the marketplace. I feel that the Android OS is a superior choice to the iphone OS, but by a slim margin. The innovation that is known to come from the open source community should not be overlooked by Apple. Apple is known for paving the way for many new markets of mobile computing, but the lack options for users in terms of customization, as well as background processing as put them in a position chasing the Android OS. The one major advantage Apple has over the rest of the market is the tight control it maintains by only allowing the iphone OS to run on its own device. With that control, all aspects of device performance can be controlled tightly. References [1] (2010, April 12) IPhone Dev Center. [Online]. Available: [2] (2010, April 10) Android Developers. [Online]. Available: [3] (2010, April 10) Simple Thread Management - Java - Android. [Online]. Available: [4] (2010, April 10) IPhone Thread Management. [Online]. Available: [5] (2010, April 8) Virtualization Coming to Android. [Online]. Available: [6] (2010, April 11) Apple Showcases IPhone 4.0 Features. [Online]. Available: [7] (2010, April 3) Froyo and Gingerbread to Bring Unity to Android. [Online]. Available: [8] (2010, March 8) Android (operating System). [Online]. Available: [9] (2010, March 7) List of IPhone OS Devices. [Online]. Available: [10] A. Hoog and K. G. (2010, March 14) IPhone Forensics 12

13 [11] C. Rubicon. (2010, March 14) The Apple IPhone: Successes and Challenges for the Mobile Industry [12] Spectrum Data Technologies. (2010, March 7) A Spectrum White Paper: Thoughts on Google Android 13