Java Platform, Micro Edition

Java Platform, Micro EditionorJava MEis acomputing platformfor development and deployment ofportable codeforembeddedandmobile devices(micro-controllers, sensors, gateways, mobile phones, personal digital assistants, TV set-top boxes, printers).Java ME was formerly known asJava 2 Platform, Micro EditionorJ2ME.

The platform uses theobject-orientedJavaprogramming language, and is part of theJava software-platformfamily. It was designed bySun Microsystems(nowOracle Corporation) and replaced a similar technology,PersonalJava.

In 2013, with more than 3 billion Java ME enabled mobile phones in the market,the platform was in continued decline as smartphones have overtaken feature phones.

History

The platform used to be popular in feature phones, such as Nokia'sSeries 40models. It was also supported on theBadaoperating system and onSymbianOS along with native software. Users ofWindows CE,Windows Mobile,Maemo,MeeGoandAndroidcould download Java ME for their respective environments ( "proof-of-concept" for Android).

Originally developed under theJava Community Processas JSR 68, the different flavors of Java ME have evolved in separate JSRs. Java ME devices implement aprofile.The most common of these are theMobile Information Device Profileaimed at mobile devices such as cell phones, and thePersonal Profileaimed at consumer products and embedded devices likeset-top boxesand PDAs. Profiles are subsets ofconfigurations,of which there are currently two: theConnected Limited Device Configuration(CLDC) and theConnected Device Configuration(CDC).

In 2008, Java ME platforms were restricted toJRE1.3 features and use that version of the class file format (internally known as version 47.0).

Implementations

MicroEmulator screenshot

Oracle provides areference implementationof the specification, and some configurations and profiles for MIDP and CDC. Starting with the JavaME 3.0 SDK, aNetBeans-based IDE supported them in a single IDE.

In contrast to the numerous binary implementations of the Java Platform built by Sun for servers and workstations, Sun tended not to provide binaries for the platforms of Java ME targets, and instead relied on third parties to provide their own.

The exception was an MIDP 1.0 JRE (JVM) for Palm OS.Sun provides no J2ME JRE for theMicrosoft Windows Mobile(Pocket PC) based devices, despite an open-letter campaign to Sun to release a rumored internal implementation ofPersonalJavaknown by the code name "Captain America".Third party implementations are widely used by Windows Mobile vendors.

At some point, Sun released a now-abandoned reference implementation under the namephoneME.

Operating systems targeting Java ME have been implemented byDoCoMoin the form ofDoJa,and bySavaJeas SavaJe OS. The latter company was purchased by Sun in April 2007 and now forms the basis of Sun'sJavaFX Mobile.

The open-sourceMika VMaims to implement JavaME CDC/FP, but is not certified as such (certified implementations are required to charge royalties, which is impractical for an open-source project). Consequently, devices which use this implementation are not allowed to claim JavaME CDC compatibility.

The Linux-based Android operating system uses a proprietary version of Java that is similar in intent, but very different in many ways from Java ME.

Emulators

• Sun Java Wireless Toolkit(WTK, for short) — is a proprietary Java ME emulator, originally provided by Sun Microsystems, and later by Oracle.
• MicroEmulator(MicroEMU, for short) — is an open-source Java ME emulator.

There are other emulators, including emulators provided as part of development kits by phone manufacturers, such as Nokia,Sony-Ericsson,Siemens Mobile, etc.

Connected Limited Device Configuration

Main article:Connected Limited Device Configuration

TheConnected Limited Device Configuration(CLDC) contains a strict subset of the Java-class libraries, and is the minimum amount needed for aJava virtual machineto operate. CLDC is basically used for classifying myriad devices into a fixed configuration.

A configuration provides the most basic set of libraries and virtual-machine features that must be present in each implementation of a J2ME environment. When coupled with one or more profiles, the Connected Limited Device Configuration gives developers a solid Java platform for creating applications for consumer and embedded devices. The configuration is designed for devices with 160KB to 512KB total memory, which has a minimum of 160KB of ROM and 32KB of RAM available for the Java platform.

Mobile Information Device Profile

Designed for mobile phones, theMobile Information Device Profileincludes aGUI,and a data storage API, and MIDP 2.0 includes a basic 2D gamingAPI.Applications written for this profile are calledMIDlets.

JSR 271: Mobile Information Device Profile 3(Final release on Dec 9, 2009) specified the 3rd generation Mobile Information Device Profile (MIDP3), expanding upon the functionality in all areas as well as improving interoperability across devices. A key design goal of MIDP3 is backward compatibility with MIDP2 content.

Information Module Profile

TheInformation Module Profile(IMP) is a profile for embedded, "headless" devices such as vending machines, industrial embedded applications, security systems, and similar devices with either simple or no display and with some limited network connectivity.

Originally introduced bySiemens MobileandNokiaasJSR-195, IMP 1.0 is a strict subset ofMIDP1.0 except that it does not includeuser interfaceAPIs — in other words, it does not include support for the Java packagejavax.microedition.lcdui.JSR-228, also known as IMP-NG, is IMP's next generation that is based onMIDP2.0, leveragingMIDP2.0's new security and networking types and APIs, and other APIs such asPushRegistryandplatformRequest(),but again it does not include UI APIs, nor the game API.

Connected Device Configuration

Main article:Connected Device Configuration

TheConnected Device Configurationis a subset ofJava SE,containing almost all the libraries that are not GUI related. It is richer than CLDC.

Foundation Profile

The Foundation Profile is a Java ME Connected Device Configuration (CDC) profile. This profile is intended to be used by devices requiring a complete implementation of the Java virtual machine up to and including the entire Java Platform, Standard Edition API. Typical implementations will use some subset of that API set depending on the additional profiles supported. This specification was developed under the Java Community Process.

Personal Basis Profile

The Personal Basis Profile extends the Foundation Profile to include lightweight GUI support in the form of anAWTsubset. This is the platform thatBD-Jis built upon.

JSRs (Java Specification Requests)

Foundation

JSR #	Name	Description
68	J2ME Platform Specification
30	CLDC 1.x
37	MIDP 1.0
118	MIDP 2.x
139	CLDC 1.1
271	MIDP 3.0	Java ME 3.4 and earlier only, Last Specification for Mobile Phones, Java Language features as Java SE 1.3
360	CLDC 8	New in Java ME 8
361	MEEP 8	New in Java ME 8, Language feature as Java SE 8, forInternet of Everythingdevices

Main extensions

JSR #	Name	Description	MSA
75	File Connection and PIM API	File system, contacts, calendar, to-do
82	Bluetooth	Bluetooth serial port communications and file exchanges (OBEX)
120	Wireless Messaging API (WMA)
135	Mobile Media API(MMAPI)	Audio, video, multimedia
172	Web Services API	XML parsers and RPC
177	Security and Trust Services API (SATSA)	APDU, Java Card RMI (JCRMI), Public Key Infrastructure (PKI) and cryptography
179	Location API	GPS coordinates, street addresses, orientation sensors, landmark stores
180	SIP API
184	Mobile 3D Graphics(M3G)	High level 3D graphics
185	Java Technology for the Wireless Industry (JTWI)	General
205	Wireless Messaging API (WMA) 2.0	Sending and receiving SMS and MMS
211	Content Handler API (CHAPI)
226	Scalable 2D Vector Graphics API for J2ME (M2G)	Handling SVG Tiny
228	Information Module Profile – Next Generation (IMP NG)
229	Payment API
234	Advanced Multimedia Supplements(AMMS)	MMAPI extensions
238	Mobile Internationalization API	Localized resources, locale date and number formatting, locale comparison of strings
239	Java Bindings for the OpenGL ES API
248	Mobile Service Architecture (MSA)
253	Mobile Telephony API
256	Mobile Sensor API	Reading values from accelerometers, gyroscopes, compasses, thermometers, barometers, and some more
257	Contactless Communication API
258	Mobile User Interface Customization API
272	Mobile Broadcast Service API for Handheld Terminals
280	XML API for Java ME
281	IMS Services API
287	Scalable 2D Vector Graphics API 2.0 for Java ME
293	Location API 2.0
298	Telematics API for Java ME
300	DRM API for Java ME
325	IMS Communication Enablers

Future

JSR #	Name	Description
297	Mobile 3D Graphics API (M3G) 2.0	Proposed Final Draft for 14 Apr, 2009

ESR

The ESR consortium is devoted to Standards for embedded Java. Especially cost effective Standards. Typical applications domains are industrial control, machine-to-machine, medical, e-metering,home automation,consumer, human-to-machine-interface,...

ESR #	Name	Description
001	B-ON (Beyond CLDC)	B-ON serves as a very robust foundation for implementing embedded Java software. It specifies a reliable initialization phase of the Java device, and 3 kind of objects: immutable, immortal and regular (mortal) objects.
002	MicroUI	MicroUI defines an enhanced architecture to enable an open, third-party, application development environment for embedded HMI devices. Such devices typically have some form of display, some input sensors and potentially some sound rendering capabilities. This specification spans a potentially wide set of devices.
011	MWT	MWT defines three distinct roles: Widget Designers, Look and Feel Designers, and Application Designers. MWT allows a binary HMI application to run the same on all devices that provide a compliant MWT framework (embedded devices, cellphones, set-top box TV's, PC's, etc...) allowing for true consistency and ubiquity of applications across product lines (ME, SE, EE).
015	ECLASSPATH	ECLASSPATH unifies CLDC, CDC, Foundation, SE, and EE execution environments with a set of around 300 classes API. Compiling against CLDC1.1/ECLASSPATH makes binary code portable across all Java execution environments.

See also

• Android (operating system)
• iOS
• BlackBerry OS
• Danger Hiptop
• Embedded Java
• JavaFX Mobile
• Mobile development
• Mobile games
• Mobile learning
• Qualcomm Brew
• Smartphone

References

Notes

• JSR 232: Mobile Operational Management– an advanced OSGi technology based platform for mobile computing
• JSR 291: Dynamic Component Support for Java SE– symmetric programming model for Java SE to Java ME JSR 232

Bibliography

• Ben Hayun, Roy (March 30, 2009).Java ME on Symbian OS: Inside the Smartphone Model(1st ed.).Wiley.p. 482.ISBN978-0-470-74318-8.
• Knudsen, Jonathan (January 8, 2008).Kicking Butt with MIDP and MSA: Creating Great Mobile Applications(1st ed.).Prentice Hall.p.432.ISBN978-0-321-46342-5.
• Li, Sing; Knudsen, Jonathan (April 25, 2005).Beginning J2ME: From Novice to Professional(3rd ed.).Apress.p.480.ISBN1-59059-479-7.

External links

• Sun Developer Network, Java ME
• Nokia's Developer Hub Java pages
• Nokia S60 Java Runtime blogs
• Sony Ericsson Developer World
• Motorola Developer NetworkArchivedJuly 21, 2009, at theWayback Machine
• J2ME Authoring Tool LMA Users Network
• Samsung Mobile Developer's site
• Sprint Application Developer's Website
• Performance database of Java ME compatible devices
• MicroEJ platforms for embedded systems
• Book - Mobile Phone Programming using Java ME (J2ME)ArchivedMarch 5, 2016, at theWayback Machine
• Tutorial Master ng, J2ME