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A s mobile technology matures,handheld-device vendors arelooking for ways to maketheir products more func-tional, and Java is one

approach they are turning to. This isparticularly the case with smart cellu-lar phones, which are using Java tohelp add new capabilities.

In smart phones, Java functions as alayer between the operating systemand the hardware, or runs parallel tothe OS within a separate chip.

In the past, the key constraint to run-ning Java on mobile devices has beentheir processing, memory, and power-consumption limitations. However, newmobile hardware and software devel-opments are reducing these limitations.

Thus, industry observers expect Javause in mobile devices, which is alreadysupported by many vendors, toexplode during the coming years. NickJones, a fellow at Gartner Inc., a mar-ket research firm, said Java willbecome a de facto standard on mid-range and high-end cellular phones. Hepredicted that at least 80 percent ofmobile phones will support Java by2006, although some may also run onother technologies, such as Microsoft’sPocket PC operating system.

According to Jones, mobile-devicemanufacturers’ desire for an aftermar-ket is driving interest in Java as a mech-anism for easily adding software todevices.

Java also permits applications towork across platforms. This is impor-tant in the mobile-phone market,

which features many platforms.However, questions about Java’s per-formance and a dearth of Java-basedapplications for cellular phones, par-ticularly in Europe and the US, remainas obstacles to the technology’s wide-spread adoption in mobile devices.

DRIVING JAVA USE IN HANDHELDSWork on Java-enabled handheld

devices began several years ago, butcompletion of the Java 2 PlatformMobile Edition (J2ME) and supportfrom device vendors and cellular-phone-service providers have driven therecent level of interest, explained EricChu, Sun Microsystems’ group prod-uct manager for industry marketing.

Adoption levelsKorea’s LG Telecom in became the

first service provider to deploy Java inSeptember 2000. Since then, users havedeployed between 18 million and 20million Java-enabled telephones, saidSun spokesperson Marie Domingo.

Companies such as Nextel in the US,NTT DoCoMo in Japan, and British

Telecom are now selling Java phones.And, said Ben Wang, manager of sys-tems development for Sprint PCS, 80percent of the new phones the com-pany sells will be Java enabled after thebig rollout next month. Nokia aloneplans to ship 50 million Java phonesthis year and 100 million next year. Infact, 15 handset makers either are orsoon will be selling 50 models of Javaphones.

AdvantagesAccording to Sun’s Chu, one of

Java’s major benefits for cellular phonesis support for packet-based networksrunning TCP/IP. Using TCP/IP makesit easier to write applications that com-municate directly with the phone,rather than relying on an intermediatetechnology such as the wireless appli-cation protocol (WAP). Also, Chu said,Java, unlike WAP, supports picturesand colors. In addition, he explained,the Java environment provides goodsecurity because it includes a sandboxthat limits downloaded code’s access tothe rest of a host system.

Moreover, Java’s ability to work withdifferent platforms is important in thefragmented cellular-phone market. Thiscapability lets a Java-enabled phone runapplications and services written forother mobile platforms and also letssoftware vendors save time and moneyby writing a single, Java-based versionof an application to run on multipleplatforms. And Java-enabled phonesand servers could communicate directlywith each other, thereby enhancinginteractive applications.

Java enables smart-phone users todownload applications directly fromthe Internet. Similarly, Java lets usersdownload Java applets that customizetheir devices in various ways, such aswith special ring tones or improvedcaller ID. This lets users get new fea-tures more easily. In the past, users hadto buy new phones, run new applica-tions remotely using WAP, or downloadprograms first downloaded to a PC.

Meanwhile, there are many Javadevelopers, which makes it easier for

Moving Java intoMobile PhonesGeorge Lawton

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vendors of Java-enabled mobile de-vices to find people to write their soft-ware.

MAKING JAVA WORK IN HANDHELDS

Sun, which designed and managesdevelopment of Java, is in the forefrontof making the technology work in hand-held devices. However, other vendorshave also become active in this area.

Sun MicrosystemsSun and a group of partners created

J2ME to make Java work on smallerdevices. J2ME includes some core Javainstructions and APIs but runs moreeasily on small devices because it has asmaller footprint than the Java 2Platform Standard Edition (J2SE) orEnterprise Edition (J2EE), shown inFigure 1, and has only those featuresrelevant for the targeted devices. Forexample, J2ME’s graphics and data-base-access capabilities are less sophis-ticated.

J2ME generally incorporates theconnected limited device configuration(CLDC), which is implemented on topof operating systems and serves as aninterface between the OS and Java-based applications. The CLDC gener-ally uses the K virtual machine (KVM),a slimmed-down, less-functional ver-sion of the Java virtual machine (JVM)for small devices. The J2ME mobileinformation device profile (MIDP) sitson top of the CLDC and provides a setof APIs that define how mobile phoneswill interface with applications.

Other vendorsSeveral vendors besides Sun are cre-

ating Java-based technologies for hand-held devices. Hewlett-Packard makesthe MicroChaiVM (http://www.hp.com/products1/embedded/products/devtools/microchai_vm.html), a clonedJVM that doesn’t have Sun’s licensingfees and usage restrictions. Several ven-dors, including Ericsson and HP, planto use MicroChaiVM-based phones.

Other approaches help Java tech-nologies designed for larger computerswork on mobile devices.

For example, SavaJe developed theSavaJe OS, which supports Java appli-cations in a mobile environment byoptimizing J2SE libraries for commonmobile CPUs. Mathew Catino,SavaJe’s cofounder and vice presidentof marketing, said Java applicationstypically spend 80 to 90 percent oftheir time executing the libraries.Therefore, he explained, optimizingthe libraries enables applications to run10 to 20 times faster.

Zeosoft has developed ZeoSphereDeveloper, which permits the creationof mobile applications that supportEnterprise Java Beans, Sun’s Java-basedsoftware-component architecture. Thiscould simplify the development of com-plex enterprise applications that com-municate and run across servers (viaJ2EE), PCs (via J2SE), and mobiledevices (via J2ME).

Software development toolsApplication developers can use exist-

ing tools to create Java programs forhandheld devices by limiting their codeto libraries and APIs supported byJ2ME.

However, J2ME includes only a lim-ited number of development libraries,noted Jacob Christfort, chief technol-ogy officer of Oracle’s Mobile Division.

Also, said Gartner’s Jones, enter-prises might shy away from J2MEbecause of the poor user interface de-signed for small device screens, theprimitive threading model, and mini-mal native data-handling facilities. Inessence, he explained, the designapproach that lets J2ME work on smalldevices sometimes makes it inappro-priate for large-scale enterprise uses.

To address these concerns, severalvendors have released or will soonrelease development toolkits or toolkitextensions to help developers moreeasily meet enterprise applications’needs. The new approaches includeSun’s Forte for Java ProgrammingTools, the Oracle 9i Application Server

KVMJVM

CLDCCDC

MIDPFoundation profile

Java 2PlatformStandardEdition(J2SE)

Personalprofile

Personalbasis profile

Optionalpackages

Java 2Platform

EnterpriseEdition(J2EE)

Optionalpackages

Source: Sun Microsystems

Java 2 PlatformMicro Edition (J2ME)

Java 2PlatformStandardEdition(J2SE)

Figure 1. Sun’s three primary Java platforms are each designed primarily to run on a differ-ent type of machine. The Java 2 Platform Enterprise Edition is designed for servers; theJava 2 Platform Standard Edition for workstations, PCs, and laptops; and the Java 2 Plat-form Micro Edition for PDAs, smart cellular phones, and other smaller systems. J2EE andJ2SE use the full Java virtual machine (JVM). J2ME also works with the slimmed-down Kvirtual machine (KVM), the connected limited device configuration (CLDC), and the mobileinformation device profile (MIDP).

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Components Group, said his companyhas developed techniques for speedingup the software process, which used tobog down when the CPU switchedfrom instructions it could accelerate toinstructions it couldn’t.

In addition, Intel and other soft-ware-based Java proponents say thelatest mobile processors can run Javafast enough to compete with hard-ware-based approaches.

Analyst Markus Levy with Micro-Design Resources, a semiconductor-industry research firm, disagreed. Hesaid, “People are spending a lot ofenergy fine-tuning the software-basedapproaches. For some people that maybe good enough, but if you really wantthe most efficient implementation youneed a hardware-based approach.”

Java hardwareCompanies such as ARC Cores,

ARM Ltd., Aurora VLSI, DigitalCommunications Technologies, inSili-

Wireless architecture toolkit, and theSprint PCS Wireless Toolkit.

Because of J2ME’s shortcomings,Jones said, corporate applications willprobably be based on the larger-foot-print J2SE as mobile devices get moreprocessing power.

Regardless, said John Montgomery,product manager with Microsoft’s.NET Development Group, currentJava tools are too primitive and diffi-cult to use for most developers.

Server-side handheld JavaAnother Java-enabling approach

would link handheld devices to Javaapplications and services on servers.AT&T Wireless, BEA Systems, IBM,Nokia, NTT DoCoMo, Sun, and othercompanies have created the Java-basedOpen Mobile Architecture for linkingcellular phones and servers. The projectwould augment J2EE, designed pri-marily for servers, so that it would sup-port standards that mobile devices canuse with Internet-based information.The standards include XHTML (fordisplaying Web pages on mobiledevices), SyncML (for synchronizingdata between mobile devices and othermachines), WAP 2.0 (to access Internetcontent and services), and the multime-dia messaging service (for handheldmessaging).

IMPLEMENTATION IN HARDWARE AND SOFTWARE

Java technology can be implementedin software or in hardware on either aspecialized Java acceleration chip or acore within the main processor.

Software implementations tend torun less efficiently because systems musttranslate each Java instruction intonative instructions that the CPU canrun. Separate hardware chips are moreefficient but represent additional devicecomponents and cost. Java cores inte-grate some of both approaches.

Software approachIn the software approach, a device’s

CPU runs the Java code. David Rogers,marketing manager for Intel’s PCA

con, and Zucotto Wireless are devel-oping hardware that runs Java, eitheras Java coprocessing cores for integra-tion into CPUs or as stand-alone Javachips.

Both hardware-based approachespromise to increase Java-based appli-cation performance and, by runningmore efficiently, reduce power de-mands on battery-dependent cellularphones.

Different companies’ chips executedifferent subsets of the Java instruc-tions. For example, ARM’s Jazellechip, shown in Figure 2, executesabout 68.2 percent of all possible Javainstructions, while Aurora’s DeCafruns about 95 percent. Running a big-ger set of Java instructions providesmore functionality but makes a chipcost more and consume more power.

Joan Pendleton, Aurora’s cofounderand chief architect, said there are twoclasses of acceleration. The first, usedby most vendors, translates Java byte-

InstructionTCM

interface

ARM9EJ-Score

Instructioncache

Memorymanagement

unit

DataTCM

interface

Datacache

Memorymanagement

unit

ETM9 interface

Write buffer

AHB interface

Instruction Data

Control logic and bus interface unit

Coprocessorinterface

AR

M96

EJ-S

Source: ARM Ltd.

Figure 2. ARM Ltd.’s ARM926EJ-S chip includes the company’s Jazelle technology in itsARM9EJ-S Java-enabled processor core. In addition, the chip includes separate ETM(embedded trace macrocell), data TCM (tightly coupled memory), and AHB (advancedhigh-performance bus) interfaces.

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code into native processor instructions.The second directly executes Java byte-code, which offers better performancebut requires a larger footprint becauseof the additional circuitry necessary torun the software in hardware.

Levy predicted that Java cores will bemore popular than stand-alone Javaprocessors. This approach’s primaryconstraint is that developers must usea system-on-chip approach to createtheir products. Putting multiple func-tions on a chip is more expensive todevelop, but the elimination of addi-tional chips reduces device costs. Stand-alone Java chips are less expensive todesign but lead to higher device costs.

CONCERNS AND CHALLENGESMobile Java is still a relatively new

technology. Many industry watcherssay the technology has kinks that stillneed to be worked out.

For example, Gartner’s Jones ex-pressed concern about vendors’ differ-ing Java implementations. He saidsome developers are complaining abouthaving to manually optimize their Javagames for different cellular phones.

And although there are many Javadevelopers, there are fewer who haveexperience working with J2ME andwriting code for small, resource-con-strained devices.

Overall, said Microsoft’s Mont-gomery, “J2ME is an interesting set ofengineering compromises, but I wouldargue exactly the wrong set of compro-mises. It is too big for the smallestdevices but too small to have the featuresyou want on the smartest devices.”

PerformanceJones said that mobile Java can be

somewhat slow because the KVM isnot particularly fast. However, headded, the KVM should become fasterin the future, particularly as phoneswith more memory can run just-in-timecompiler technology, which enhancesperformance. “In five years,” he said,“[performance] will be a nonissue.”

Another problem, said Levy, is a lackof standards to objectively measure

performance across platforms. Levyhas thus launched a Java-processorgroup within the Embedded Micro-processor Benchmark Consortium(http://www.eembc.org/). The groupexpects to release its first benchmarkby next month.

Not enough applicationsThere are currently some mobile-

Java applications, including games andweather and traffic maps. However,Jones said, there are not enough desir-able mobile-Java applications yet. Thereason is not the technology, he said,but instead the lack of an effective busi-ness model and a commercial infra-structure that would enable developersto profit from their work.

The growth of publishing interme-diaries that would certify and sellmobile-Java software may eliminatethis problem.

HANDHELDS AND THE FUTURE OF JAVA

Jones said Java is doing well onback-end servers because Java-basedapplications can easily be redeployedas companies buy new servers. How-ever, he noted, client-side Java use has faded considerably because manyenterprise-application developers turnedto Visual Basic to work within the cor-porate environment, which is typicallyMicrosoft-based. Thus, the battle forthe mobile platform is important toSun.

However, Sun’s Java initiatives forcellular phones are facing stiff compe-tition from various sources, includingMicrosoft’s wireless efforts, the Sym-bian operating system, Linux, and Qual-comm’s binary runtime environment forwireless (http://www.qualcomm.com/brew/).

“We are still in a phase of marketconfusion and have not yet gotten to astate of market consolidation,” Jonesexplained.

A ccording to Jones, J2ME willattract more application devel-opers as it becomes a richer and

less constrained environment. A sur-vey by Evans Data, a market researchfirm, found that wireless developerswho have used Java expect to use thetechnology a bit more in 2003 thanthey will this year.

Java will also become even moreattractive as smart phones get moreprocessing power and vendors designbetter APIs for color screens, higherquality sound, intellectual-propertyprotection, and user-location capabil-ities, he added. However, he cautioned,these extra features would give vendorsmore opportunity to create their ownJava implementations, which couldfragment the application-developmentenvironment.

Sprint PCS’s Wang said the initialfocus of mobile Java will be on games,multimedia, and ring tones. Over time,Levy added, Java will become a defacto standard built into smart phones.

SavaJe’s Catino predicted thatMicrosoft and Java-based technologiesare likely to coexist in phones duringthe coming years. Third-party vendorscould help this process by developingsoftware-integration techniques thatwould combine the two environmentsin devices. �

George Lawton is a freelance technol-ogy writer based in Brisbane, Califor-nia. Contact him at glawton@glawton.com.

Editor: Lee Garber, Computer, 10662 LosVaqueros Circle, PO Box 3014, Los Alamitos,CA 90720-1314; l.garber@computer.org

Industry observers say mobile Java

still has kinks that must be worked out.