分析和比較開(kāi)放和封閉的移動(dòng)平臺(tái)畢業(yè)論文文獻(xiàn)翻譯

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1、 ESEP 2011: 9-10 December 2011, Singapore An Analysis and Comparison of Open and Closed Mobile Platforms Android vs. iPhone Yinglu ZOUa,?, Hao WU b, Jianxin HUANG a,b a Information Engineering College,7 JianXue Road, JinShui District, ZhengZhou, 450001, China Abstract With the release of An

2、droid 2.2 Froyo and iPhone 4, the war between open and closed mobile platforms tends to befiercer. Being the representatives of the two parties, Froyo and iOS 4 are quite different at system framework, newfeature, application market and integration model. According to the company spirits of Google a

3、nd Apple, we do some analyses and comparisons of the above points, explain the differences of Android and iPhone from the shallower to the deeper, then conclude the characteristics of open and closed mobile platforms, aiming at providing an objective reference for researchers of mobile platforms, he

4、lping them see clearer into mobile industry. As a result,both Froyo and iOS 4 have their advantages and disadvantages, still they are far from being perfect, there’s room forfurther improvement. Keywords: Android；iPhone；Froyo；iOS 4；smart phone；mobile platform 1. Introduction In recent years, the

5、popularity of smart phone kept going up. More and more smart phones are sold anda lot of people are embracing them. Smart phones brought great convenience to users, as well created opportunities for smart phone researchers. That’s to say, the wide spread of smart phones benefited both sides. At the

6、same time, developing of smart phone OS becomes one of the smartest industry. To be a smart phone OS, the system should: 1. Provide services like a PC. 2. Work with a GPU for better visual effects. 3. Allow the user to surf on Internet freely. And apparently, there’re also some weaknesses:1.Limited

7、battery. 2. Poor CPU performance against PC CPU. 3. Small storage. 4. The use of RAM may leads to loss of data when the phone runs out of battery Now the 2 giants of smart phone OS are Android and iPhone OS. On one side, Android is based on Linux kernel and Dalvik virtual machine, and it is open so

8、urced. The upper layer of Android is Java based,allowing developers to develop Android applications with Google SDK and sell their software in Android Market. On the other side, iPhone OS, which bases on Unix kernel and Darwin model but is closed sourced,evolves from Mac OS X and is the default OS o

9、f iPhone, iPod Touch and iPad. Objective C based software can run in iPhone OS, and just like Android, you can develop your own iPhone applications and upload them onto Apple’s ‘App Store’ for sale [1] [2] [3] [4]. By comparing the latest Android and iPhone OS, Android 2.2 Froyo and iOS 4, we can t

10、ake a glimpse at the main feature of open and closed smart phone OSs. While the 2 OSs are designed in rather different mentality and functionality, it’s a little early to tell which one is better. 2. Smart Phone OS 2.1. Android The system architecture of Android consists of 5 layers, which are Li

11、nux Kernel, Android Runtime, Libraries, Application Framework and Applications, from bottom to top. Android provides core services like security, memory management, process management, network stack and drivers, basing on Linux 2.6. Being the abstract layer between software and hardware, the layer

12、 of Linux Kernel hides the implementing details of hardware and provides integrated services for upper layer. Dalvik virtual machine and Java core libraries are included in the layer of Android Runtime, providing most functions in Java core libraries. The layer of Libraries contains a class of C/C

13、++ libraries for Android components. Those libraries are integrated by the layer of Application Framework and then provided to developers. The layer of Application Framework provides all kinds of modules for program initialization to simplify the use of components, allowing developers do whatever t

14、hey want and provide services for other softwares, under the limitation of security, of course. Mainstream applications are located in the layer of Application, including e-mail, SMS, calendar, Google map, Web browser and contacts. Users interact directly with this layer [1] [2]. The latest versio

15、n of Android, Android 2.2 Froyo, puts on some new features. They are: 1. Support Flash 10.1, enables user to watch flash on the phone. 2. V8 JavaScript engine in web browser leads to faster Internet data transportation. 3. Big advance in network sharing. You can use the phone as a 3G NIC,or convert

16、3G signal to Wi-Fi. 4. Automatically software update. 5. Softwares can be setup in SD card to extend file storages. 2.2. iPhone iPhone OS is consist of 4 abstract layers: Core OS, Core Service, Media and Cocoa Touch respectively. Layers of Core OS and Core Service are designed in C language to ha

17、ndle core system services, enabling developers to perform file access, sockets calling and data handling. CFNetwork and SQLite are also parts of these 2 layers. The layer of Media, according to its name, this layer is used to control video and audio, as well handle 2D and 3D images. The Open GL-ES

18、 Quratz part of the layer is coded with C language, while the part of Core-Audio and Core-Animation is Objective C based. The layer of Cocoa Touch builds a basic framework for all kinds of programs in iPhone. Most programs run in Cocoa Touch layer, and it’s surely Objective C based [3] [4]. The la

19、test iPhone OS is iOS 4. It includes the following new features: 1.Software classification. This feature enables user to place sorted softwares into different documents, making it clearer to manage. 2. Email integration. One account is for all e-mails from different providers. 3. iBook, originally

20、from iPad, is built in iOS. 4. A brand new Apple Game Center makes iPhone a tremendous entertainment platform. 2.3. Android vs. iPhone Being the top 2 smart phone OSs, we’re sure that both Android and iPhone have their own advantages and disadvantages. Now let’s take a look at each of them, and se

21、e what unique feature they have. Android 2.2 Froyo fully support multitask, which means you can listen to music while writing blog. And iOS 4, officially announced to be ‘multitasked’, is in fact a play of concept. Only a few of softwares which are authorized by Apple can run ‘simultaneously’, who

22、se principle is much easier that multitask:when an application is switched out, its current state is saved and then the system just closes it. And when it’s switched in, we’re back to the previous snapshot [5] [6] [7]. During the publication of Android 2.2 Froyo, Google announced it has ‘the most f

23、luent web browser’,because the use of V8 JavaScript engine. V8 is a brand new engine, designed for running big size JavaScript application. In some kind of tests, V8 is much faster than JScript from Internet Explorer, SpiderMonkey from Firefox and JavaScriptCore from Safari. It all owe to 3 key part

24、s of V8, they’re fast attribute access, dynamic code generation, effective trash cleaning. 2.3.1. Fast Attribute Access JavaScript is a kind of dynamic language, which means attributes can be added or deleted at runtime, and they’re frequently changed. Most JavaScript engines use a dictionary s

25、tyle structure to store the attributes of an object, so it requires a whole dictionary search to find the position of attributes in memory.It’s quite inefficient and it’s slower than Java and Smalltalk. To solve this problem, V8 discarded dynamic search and realized it in a different way: Create hi

26、dden classes for objects dynamically. In JavaScript, every time when we’re adding a new attribute to an object,we create a subclass with the new attribute from a hidden class as the super class. It’s a recursive course and the above performance happens only once when we first do this. Later we just

27、use the previous hidden subclass when we’re in the same situation. So there’s no need to repeat operation and create a dictionary. This leads to the save of time and energy, as well make it easier for the implementation of class optimization and inner cache [4]. 2.3.2. Dynamic Code Generation When

28、 JavaScript is running for the very first time, V8 translate it directly into local machine code, rather than explain it to bytecode. Attribute access is done by inner cache, which is often translated into instructions by V8 at runtime. When it comes to the code where certain object is accessed, V8

29、 tries to find the current hidden class. Meanwhile, V8 assumes that all objects in the snippet are described by the same hidden class, so V8 willmodify corresponding inner cache to make the direct use of the hidden class more convenient. If thisassumption is correct, the access of attributes can be

30、 all done in only 1 instruction. Even if the predictionfails, inner cache is modified again by V8, which won’t take too much time and resource. When one hidden class is shared by a lot of objects, the access speed can be close to most dynamic language access speed. Inner cache and hidden class, mix

31、ed with dynamic code and class optimization, improve the efficiency of JavaScript at a large scale [4]. 2.3.3. Effective Trash Cleaning V8 does memory recycles automatically. To guarantee the speed of object distribution, as well cut the time of trash cleaning and clear fragment up, V8 will inter

32、rupt the running application when performing trash cleaning. Mostly, only a small part of object stack is involved in trash cleaning cycle, so the interruption caused little. All location of objects and pointers are logged by V8, so the system won’t take object for pointer and memory overflow is avo

33、ided [4]. Besides ‘the most fluent web browser’, Google collaborated with Adobe and Android 2.2 Froyo fully supports Flash. That’s to say, not only flash media, but all flash web pages can display perfectly on Android. To the contrary, Apple turned down Adobe and take HTML5 as iPhone’s web protocol

34、, making it unable to show some flash based animation. Android 2.2 Froyo also leads the way in network sharing. Smart phone with Froyo can be connected toa PC as a 3G NIC, and can also conveniently convert 3G signal to Wi-Fi. iOS 4 can do the first too, butfailed to convert 3G to Wi-Fi. Video conf

35、erence is both supported by Froyo and iOS 4, but the conditions are different. You can see aFroyo user via camera as long as you get a camera also. However, iOS 4 user can only do video talk toanother iOS 4 user, which is a big limitation. While Android is ascendant in network interaction, Apple is

36、 unique in its friendship and entertainment.The added feature of ‘software classification’ enables user to place sorted softwares into differentdocuments, making it clearer to manage. What’s more, there’re hundreds of thousands applications inApp Store, meaning that iPhone can have up to hundreds of

37、 thousands functions. This is a ratherremarkable feature that Apple publicizes. And the most convincing point given by Apple, is that ‘Android looks exactly familiar with iPhone.’ Although it’s just a subjective sense, the born of iPhone really brought big revolution to the phone industry, and the

38、 name ‘Apple’ itself is a world famous brand [7] [8]. 3. Open and Closed platforms 3.1. SDK The most important part of every developing platform is SDK, enable 3rd party developers to make software for the platform. Usually, libraries, debug tools and emulators are included in SDK. Different plat

39、forms distribute their SDKs differently. Some SDK is complete free and open, while others are strictly limited. Developers of open platforms can get and modify part or all of the source code. Google and Linux are leaders of open platforms; they publicized the whole source code of Android and Linux.

40、 The good point is that, platform owners can save a great amount of time and energy developing and maintaining the platform, because 3rd party developers will do this for them. With less money spent on development and maintenance, a relatively low price can attract more and more phone users. Contra

41、rily, closed platforms lock their source code in the safety and forbid 3rd party accesses. Apple and Microsoft are the representatives of them, they are both closed sourced, but some differences do exists. 3rd party iPhone applications are restricted within narrow limits, for that Apple will look th

42、rough every application which is uploaded onto ‘App Store’, and a lot of applications are turned down.Microsoft don’t check Windows applications at all, it all depends on the users themselves. You installed the mareware, you suffer the loss. 3.2. Application Market Market is the medium between dev

43、elopers and users, hence it’s very important. Some predicted that there will be more and more application markets while some don’t think so. In current markets, both do exist. Some specify only one market for their products, while others sell their softwares in various markets. Softwares from Nokia

44、, Microsoft and Linux Mobile are sold in every market. Developers of these platforms can release their own application in whatever markets, so markets have to compete with each other for a living. This is good for users. However, the lack of universal management may lead to mess and chaos, softwares

45、 that have the same functionality exist in different markets, which confuses users a lot. Correspondingly, sole markets claim that most applications should be sold in them. This kind of monopolization leads to no competitor. ‘App Store’ and ’Android Market’ are deputy of sole markets. Normally, iPh

46、one applications can only be found in ‘App Store’, and Apple will check every one of them by itself. Good news is that every application in ‘App Store’ is officially tested, it’s safe; Bad news is that a lot of pretty good softwares are rejected for various reasons. And a big unofficial mechanism is

47、 built by hackers, that is ‘jailbreak’ and ‘SIM unlock’. ‘Jailbreak’ is a process that allows iPad, iPhone and iPod Touch users to gain root access and unlock the operating system thus removing any limitations imposed upon them by Apple. Once jailbroken, iPhone users are able to download many exten

48、sions and themes previously unavailable through the App Store via installers such as Cydia. A jailbroken iPad, iPhone or iPod Touch is still able to use the App Store and iTunes [9]. And a ‘SIM lock’ is a capability built into GSM phones by mobile phone manufacturers. Network providers use this ca

49、pability to restrict the use of these phones to specific countries and network providers.Generally, phones can be locked to accept only SIM cards based on the International Mobile Subscriber Identity. ‘SIM unlock’ make it possible to use a mobile phone without considering countries and networks spec

50、ified by mobile phone manufacturers. However in Android, Google doesn’t test every application at all, so although there’s an official market for Android applications, you can still release your product anywhere you want. Considering security problems, Google banned the use of some components. Like

51、 ‘jailbreak’ and ‘SIM unlock’ in iPhone, ‘root’ in Android gives users 100% control of their devices, along with some security risks. ‘Root’ is a process that allows users of cellphones running the Android operating system to attain privileged control (known as "root access") within Androids Linux s

52、ubsystem, similar to jailbreaking on Apple devices running the iOS operating system, overcoming limitations that the carriers and manufacturers put on such phones. Rooting makes it possible to use custom versions of the Android system such as CyanogenMod, supporting features unavailable in stock ROM

53、s. It also allows for newer versions of Android not supplied by the original device manufacturer. In contrast to iOS jailbreaking, rooting is not needed to run applications not distributed by the official Android Market. It is needed however, when trying to access paid Android applications from coun

54、tries which are not part of the paid applications market. 3.3. Integration Some companies focus only on their core industry, i.e. develop an operating system and provide an environment for 3rd party development. Others not only do these, but manage the process of developing a software to publicizi

55、ng it. Depending on the integration of platforms, we sort them to 4 kinds: full integration platform, market integration platform, device integration platform and no integration platform. The publicizing model of full integration platform is very strict. Its management ranges from device manufactur

56、ing to application release, whose representative is Apple. Apple’s factory produces iPhone, Apple’s ‘App Store’ sells application, Apple’s ‘iTunes’ is the channel of Apple’s resources. The whole process is under Apple’s control. Market integration platforms commit themselves to developing and selli

57、ng softwares. Google is one of them. Unlike apple, Google don’t have a factory to manufacture its own handsets, but only developed Android and set up ‘Android Market’ for Android applications. However, companies like Google definitely have the capability to produce its own devices. Google is in good

58、 relationship with HTC, who is the OEM of T-Mobile, O2 and Orange, etc. Device integration platforms produce their own handsets, but don’t set up application markets. Forexample, RIM makes Blackberry, but there’s no official application market for Blackberry. No integration platforms do few things.

59、 Microsoft neither makes mobile phones, nor sets up a market.What they do is only developing the operating system: Windows Phone 7. 4. Conclusion Representatives of open and closed platforms, Android 2.2 Froyo and iOS 4 are both loved and hated.Great browsers are built into them, and their produce

60、rs are both world famous revolutionary. Android leans to Internet experience, which comes down in one continuous line with Google. But currently, various versions of Android fill the market, and most companies in Open Handset Alliance tend to customize their own Android systems. These facts make And

61、roid lack of a general brand image, so people may feel confused and say ‘No’ to Android. iPhone OS focuses more on entertainment and it’s very friendly. But Apple is too cool to attract more customers: Diehard fans of Steve Jobs buy every product made by Apple, and people who dislike the style Apple

62、 do things may just sniffed at Apple. Besides, Android 2.2 Froyo succeeds the features of open platforms well. It’s a ‘users only’ platform, because users of Froyo can almost customize everything they want. And members of Open Handset Alliance tend to provide more choices for users. And iOS 4, typ

63、ically closed platform member, manages everything ranging from OS development to device manufacturing. It’s a ‘consider for users’ platform.To some extent, users of Android canonizes ‘free’ and ‘open’, what they care is if they have 100% management of their handsets, no matter whether the OS is call

64、ed ‘Android’ or ‘Another’. Apple users are loyal to the brand; they would like to authorize Apple to make decisions for them. So although some iPhone users love physical keyboards, they bought iPhone. In other words, Android users think a lot of ‘open platform’ rather than the brand Google; most iPh

65、one users are follower of Apple, they love the ‘closed platforms’ created by Steve Jobs. Both Android and iPhone have their unique IDE, SDK and other characteristics. Believe it or not, no perfection exists in the world, so none of today’s mobile platforms fully meets the needs of users and researc

66、hers. The choice of platform boils down to the needs of users and researchers, this article should make the decision easier. Of course the content of this article is time sensitive; platforms will gradually meet the demands of consumers as new technologies emerging. References [1] Dave Mark, Jeff LaMarche. “Beginning iPhone 3 Development: Exploring the iPhone SDK”. 2009. [2] Erica Sadun. “The iPhone Developer’s Cookbook: Building Application with the iPhone SDK”, 2009. [3] Ed Burnette. “Hel