新一代J2ME终端标准MSAfor CLDC
——解读JSR-248
2006-1-8
摘要
MSA（Mobile Service Architecture，即移动服务架构） for CLDC定义在JSR-248中。本文根据该规范2005年9月6号的PublicReview v0.8版来解读它的内容，并结合ME EC对Public Review版的投票结果，来看它的应用前景。
摘要
MSA for CLDC的目的
JSR-248规范过程
MSA for CLDC的内容
应用前景分析
1 EC的投票情况
2 分析
总结
参考资料
关于作者
术语缩写表
MSA for CLDC的目的
MSA[1] for CLDC[2]定义了具有J2ME[3]功能的移动终端平台所应具有的功能。以前不同移动运营商各自为政，产生了多种不尽相同的自主标准，MSA for CLDC的目的是为了减小这种标准不同而产生各种移动Java之间的隔阂，为开发者提供一个具有高互操作性的应用程序和服务环境。该标准在JTWI[4]（JSR[5] 185）标准之上，在考虑向后兼容和兼顾未来的发展的基础上，定义了实现该标准的API集。
JSR-248规范过程
JSR的标准化的一般过程是：
－JSR发起人提交最初草案（INITIATION）；
－领域内的执行委员会（EC[6] /Executive Committee）Review这个草案并对此投票；
－如果投票通过，则成立制定该规范的专家组（EG[7] /Expert Group）；
－EG提交早期草案（EARLYDRAFT）。公众可以阅读此草案并提出自己的意见，同时EG根据这些反馈修正和改进该草案。
－EG提交Public草案（PUBLIC DRAFT）。公众再次Review并反馈，EG根据反馈进一步修正该草案。Review过程的后期，EC投票决定标准化过程是否继续；
－如果投票通过，并且其参考实现（RI[8] /Reference Implementation）和相应的TCK[9]（Technology Compatibility Kit）都已经准备完毕，提交EC做最终版本的批准投票；
－EC对Spec，RIs和TCKs做最终投票决定是否批准；
－如果投票通过，则最终发布（FINAL RELEASE）；
－后期版本的维护与升级......
JSR 248定义的是消费和嵌入式领域的内容，属于J2ME的范畴，所以这里的EC是ME EC。目前JSR 248标准化的进程是EC 对Public Review的投票已经通过。
JSR 248规范的EG由16家公司的代表组成，该专家组的组长（Leader）由Vodafone和Nokia的代表担当。专家组的16家公司分别是：BEA，BenQ，Cingular Wireless，Motorola，Nokia，NTT DoCoMo，Orange，RIM，Samsung，Siemens，Sony Ericsson，Sprint，Sun，T-Mobile和Vodafone。他们以移动运营商和终端厂商为主，还有其他相关厂商的参加，基本代表了相关涉众（Stakeholder）的权益。
MSA for CLDC的内容
从目前Public Review v0.8的版本来看，MSA for CLDC在JTWI所定义的统一的Java应用程序环境的基础上，加入了对Java新技术和feature的支持，兼容旧JTWI环境的同时又考虑未来向MSA for CDC[10]（定义在JSR 249规范中）环境的发展趋势。JSR 248规范是对Java的架构的一个定义，该架构规定了端到端的无线环境中具有Java功能的终端所必需具有的客户端的组件（Component），还定义了如何把这些组件集成在一起来构建一个最佳的移动Java平台。
为此，JSR 248采用了以往其他JSR规范的定义，把他们以Component JSR纳入自身体系。JSR 248所采用的Component JSR如下，他们基本都是JSR 248的强制（Mandatory，按照该规范必须实现）的，或是条件强制（Conditionally Mandatory，如果条件满足，按照该规范必须实现）的组成部分。
JSR 75 –PDA Optional Packages for the J2ME Platform Version 1.0
JSR 82 – Java APIs for Bluetooth Version1.1
JSR 118 – Mobile Information Device Profile2.0 Version 2.0.1
JSR 135 – Mobile Media API Version 1.1
JSR 139 – Connected Limited DeviceConfiguration 1.1 Version 1.1
JSR 172 - J2ME Web Services SpecificationVersion 1.0
JSR 177 – Security and Trust Services APIfor J2ME Version 1.0
JSR 179 – Location API for J2ME Version1.0.1
JSR 180 – SIP API for J2ME Version 1.0.1
JSR 184 - Mobile 3D Graphics API for J2MEVersion 1.1
JSR 185 – Java Technology for the WirelessIndustry Version 1.0
JSR 205 – Wireless Messaging API 2.0Version 2.0
JSR 211 – Content Handler API Version 1.0
JSR 226 - Scalable 2D Vector Graphics APIfor J2ME Version 1.0
JSR 229 – Payment API Version 1.0
JSR 234 – Advanced Multimedia SupplementsVersion 1.0
JSR 238 – MobileInternationalization API Version 1.0
JSR 248对各个Component JSR有可能有不明确的地方加以澄清，并对把他们集成在一起带来的兼容性和不明确性的问题对每个Component JSR都分别加以说明。在已有JSR之外，JSR 248还另外定义了其他的需求，这最主要的是安全方面的。JSR 248甚至还对硬件提出了最小需求和推荐配置，比如屏幕尺寸，色彩和内存容量等。
应用前景分析
看MSA for CLDC的前景，不能光凭一家之言，看看ME EC对JSR 248Public Review的投票情况就能看出些端倪，这些代表不同立场的EC们的备注就表明了他们对MSAfor CLDC目前情况的观点。
1 EC的投票情况
EC（ExecutiveCommittee）for J2ME由16家公司组成，他们对该JSR for CLDC Public Review版的投票结果如下：
投票已经通过，重要的是他们都说了些什么，为什么有些公司投弃权票，下面是投票的记录。我们来重点来关注他们的Comments，为了明确起见，笔者用了下面的标识方式：
- 黑色加粗字体标识某个EC；
- 红色加粗字体标识该EC所投的票。
On 2005-10-20Vodafone Group PLC voted Yes withno comment.
------------------------------------------------------------------------------
On 2005-10-20Sony Ericsson Mobile CommunicationsAB voted Yeswith no comment.
------------------------------------------------------------------------------
On 2005-10-23Sun Microsystems, Inc. voted Yes withthe following comment:
Sunis encouraged with the progress made by the JSR-248 expert group and thecontribution this specification will make to the wireless industry. However,Sun believes that the smaller version of the JSR-248 specification (fewercomponent JSRs) contemplated by the EG is also necessary to facilitate asmoother transition from JSR-185 (JTWI) and meet the requirements of massmarket devices.
Additionally,Sun believes the policy that the current draft recommends for referencing theversion number of the component JSRs should be modified to provide a morepredictable platform for application developers and help minimizefragmentation.
------------------------------------------------------------------------------
On 2005-10-23Orange France SA voted Yes withthe following comment:
TheMobile Security Architecture expert group has done an outstanding job. MSA EGhas collected, organized, addressed and dispatched an incredible amount ofclarifications for many important packages. This work is likely to have adramatical impact over the Java ME ecosystem. Nevertheless, Orange believes too few vendors will be ableto bring the full JSR 248 technology to the market within an acceptabletimeframe. This issue should be addressed in final release in order to bringMSA's benefit to the largest number as fast as possible.
------------------------------------------------------------------------------
On 2005-10-23Research In Motion, LTD (RIM) voted Yes withthe following comment:
ResearchIn Motion welcomes the community-wide effort to define a common Javaapplication platform in mobile environment that meets different segments of themobile industry. The platform needs tobalance the needs of different regions, type of in-market handsets as well asapplication types (e.g. Games/Entertainment, Enterprise) and believe that a singlecollection of JSRs is hard pressed to meet all the needs. The current platformis most appropriate for highly capable multimedia handsets / applications buttoo large for a majority of handsets thereby not addressing a large industrysegment. We therefore request SLs to consider creating at least one subset ofthe overall set of JSRs so that it can serve as a minimum subset that meetsmost of the industry needs. This is in addition to the current specificationand we believe this is feasible in the same timeframe as set for JSR 248.
------------------------------------------------------------------------------
On 2005-10-24IBM voted Yes with no comment.
------------------------------------------------------------------------------
On 2005-10-24Nokia Mobile Phones voted Yes withno comment.
------------------------------------------------------------------------------
On 2005-10-24Siemens AG voted Yes withno comment.
------------------------------------------------------------------------------
On 2005-10-24NTT DoCoMo, Inc. voted Abstainwith the following comment:
NTTDoCoMo fully supports the targeted goal and objectives of this JSR. In thiscontext, we also value many of the feedbacks from the community. Regarding therecent situation, it seems that the current "full" specification isnot completely satisfying the majority of market, especially in terms of itsbalance of functionality and size/cost; as we had pointed out at the verybeginning of the activity. We strongly encourage the EG to reconsider theseissues, but also fully appreciate the SLs' great effort to move this forward tobe on time. Our abstain vote is based on this background, and hoping everyrelated party to take chance to carefully review the specification regardingthis perspective.
------------------------------------------------------------------------------
On 2005-10-24Philips Electronics UK Ltd voted Abstainwith the following comment:
Withthe advertised price of TCKs being $50K per JSR, we wonder if the TCKs neededfor MSA will actually be affordable for smaller manufacturers.
------------------------------------------------------------------------------
On 2005-10-24Intel Corp. voted Yes withno comment.
------------------------------------------------------------------------------
On 2005-10-24Samsung Electronics Corporationvoted Abstainwith no comment.
------------------------------------------------------------------------------
On 2005-10-24Matsushita Electric Industrial Co.,Ltd. voted Abstainwith no comment.
------------------------------------------------------------------------------
On 2005-10-24Motorola voted Yes with no comment.
------------------------------------------------------------------------------
2 分析
ME EC都对JSR 248的目的和动机以及JSR 248 EG的工作表示了肯定。做出JSR 248的完全实现是个什么概念，也就是除了具有基本的MIDP 2.0和CLDC 1.1 Java功能之外，还具有无线消息、蓝牙、多媒体、2D/3D、PDA、SIP、Web Service、支付、安全、位置服务以及国际化支持等功能。
这样的移动终端开发出来固然功能十分强大，但它的市场定位，市场表现呢？据说定位是中低端市场，MSA for CDC（JSR 249）才是高端市场。那么JSR 248的前景到底如何？从ME EC投票的Comment中也可以找到他们对此的担心，总结起来有：
－JTWI（JSR185）到MSA for CLDC（JSR 248）的平滑过渡问题。目前市场主体还是MIDP和CLDC，连JWTI都还没有普及，SUN的观点是做一个JSR 248的小版本，包含一些Component JSR来满足目前这个巨大的市场。[SUN: Yes]
－ 要更具有可预见性，满足未来的发展并减小他们之间的隔阂。[SUN:Yes][注：JSR 248中指定的是Component JSR一个版本，但由于他们本身也是独立发展演进的，未来某个Component JSR和JSR 248中指定的版本就会有差距，因而会出现这种问题]
－一定时间内，很少有厂家能够开发出具有完全JSR 248 技术的产品。[Orange:Yes]
－考虑不同市场和领域，应该制定最小的子集来满足这些主体需求。[RIM: Yes]
－ JSR 248不能完全满足市场的主体，突出表现在功能与尺寸大小和价格的平衡问题上不能很好的满足。[NTT DoCoMo: Abstain]
－ TCK测试费用巨大。每一个JSR的TCK测试费用是$50K，那么只是为了通过MSAfor CLDC的测试所需的费用就不是一般厂商能够负担得起的。[Philips: Abstain]
总结
其实，EC也是各方利益的代表，从他们的观点也看出MSA for CLDC的前途。总的来说，MSA for CLDC前途是很美好，但有个前提——他能被市场接受和认可，并有不俗的表现。鉴于JSR 248的EG和ME EC都有运营商和终端厂商中的国际巨头在参与，并且考虑3G终端市场以运营商为主体的运营模式，JSR 248也许会是未来J2ME领域统一的标准。
我们拭目以待！
参考资料
1. JCP网站：http://www.jcp.org/
2. JSR 248, Expert Group. Mobile ServiceArchitecture for CLDC. Public Review Version 0.80 – 06-September-2005
关于作者
田海立，国家认证系统分析师，中国系统分析员协会专业顾问。您可以通过 haili.tian@csai.cn或 tianhaili@nju.org.cn 与他联系，到 http://blog.csdn.net/thl789/看他最新的文章。
术语缩写表
[1]MSA - Mobile Service Architecture
[2]CLDC - Connected Limited Device Configuration
[3]J2ME – Java 2 Platform, Micro Edition
[4]JTWI – Java Technology for Wireless Industry
[5]JSR - Java Specification Request
[6]EC - Executive Committee
[7]EG - Expert Group
[8]RI - Reference Implementation
[9]TCK - Technology Compatibility Kit
[10]CDC - Connected Device Configuration
（本文可自由转载，但必须给出原文链接：http://blog.csdn.net/thl789/archive/2006/01/08/573521.aspx）。