Programming Wireless Devices with the Java2 Platform

2.4 Evolution of the J2ME Platform

After the successful completion of the CLDC and MIDP standardization efforts, a number of additional J2ME standardization efforts have been launched to complement the functionality provided by the core standards. Most of these additional efforts define optional packages that can be deployed on top of MIDP. These efforts are summarized in Section 2.4.2, "Optional Packages for the Wireless Market" below. In addition, there are a number of more fundamental, core standardization efforts that are summarized in Section 2.4.1, "Core J2ME Standardization Efforts."

2.4.1 Core J2ME Standardization Efforts

There are a number of standardization activities that have an important role in defining the overall J2ME architecture. These efforts can be viewed as "umbrella" activities that specify the ground rules for a number of standardization activities or provide additional instructions, recommendations, and clarifications for binding together the existing J2ME standards:

• JSR 68: J2ME™ Platform Specification

• JSR 185: Java™ Technology for Wireless Industry

JSR 68: J2ME™ Platform Specification

This specification defines the "ground rules" for the J2ME platform architecture and J2ME standardization activities. It formalizes the fundamental concepts behind J2ME, such as the notions of a configuration and profile, and defines how new J2ME APIs can be formed by subsetting existing APIs from the Java 2 Platform, Standard Edition (J2SE).

JSR 185: Java™ Technology for the Wireless Industry (JTWI)

This specification defines how various technologies associated with MIDP work together to form a complete handset solution for the wireless services industry. The specification provides an exposition of the overall architecture of the wireless client software stack, including a description of the following aspects:

• Which optional packages fit with which profiles?

• How does an end-to-end solution for interoperable Java applications work?

• How does the migration of applications occur, and to which profiles, as the devices become more capable?

A key goal of the JTWI Specification is to minimize the fragmentation of the Java APIs in the mobile handset market by creating a community that coordinates the API evolution and deployment as the industry continues to expand the capabilities of mobile devices. To accomplish this, the JSR 185 expert group coordinates the creation of new J2ME-related JSRs and provides recommendations for new optional packages that could take place within the context of the wireless development community as a whole.

2.4.2 Optional Packages for the Wireless Market

The following standardization efforts define optional packages that can reside on top of MIDP:

• JSR 120: Wireless Messaging API

• JSR 135: Mobile Media API

• JSR 172: J2ME™ Web Services Specification

• JSR 177: Security and Trust Services for J2ME™

• JSR 179: Location API for J2ME™

• JSR 180: Session Initiation Protocol (SIP) for J2ME™

• JSR 184: Mobile 3D Graphics for J2ME™

• JSR 190: Event Tracking API for J2ME™

Each of these efforts is summarized briefly below.

JSR 120: Wireless Messaging API

This JSR defines a set of optional APIs that provide standardized access to wireless communication resources, allowing third-party developers to build intelligent connected Java applications. The specification addresses the following wireless technologies:

• Short Message Service (SMS), and

• Cell Broadcast Service (CBS).

JSR 135: Mobile Media API (MMAPI)

This JSR specifies a multimedia API for J2ME, providing straightforward access and control of basic audio and multimedia resources and files. The MIDP 2.0 Sound API (introduced in Chapter 13 of this book) is a subset of the Mobile Media API defined by JSR 135.

JSR 172: J2ME™ Web Services Specification

This specification defines an optional package that provides standard access from J2ME devices to Web services. The JSR is designed to provide an infrastructure to

• provide basic XML processing capabilities,

• enable reuse of Web service concepts when designing J2ME clients to enterprise services,

• provide APIs and conventions for programming J2ME clients of enterprise services,

• adhere to Web service standards and conventions around which the Web services and Java developer community is consolidating,

• enable interoperability of J2ME clients with Web services, and

• provide a programming model for J2ME client communication with Web services, consistent with that for other Java clients such as J2SE.

JSR 177: Security and Trust Services API for J2ME™

The purpose of this JSR is to define a collection of APIs that provide security services to J2ME devices. These APIs are a necessary step for a device to become trusted, that is, to provide security mechanisms to support a wide variety of application-based services, such as access to corporate network, mobile commerce, and digital rights management.

Many of these services rely on the interaction with a "security element" (such as a smart card) in the device for secure storage and execution, as described below:

• Secure storage to protect sensitive data, such as the user's private keys, public key (root) certificates, service credentials, personal information, and so on.

• Secure execution, such as cryptographic operations to support payment protocols, data integrity, and data confidentiality.

• Custom and enabling security features that J2ME applications can rely on to handle many valued-added services, such as user identification and authentication, banking, payment, ticketing, loyalty applications, and digital media playing.

The JSR 177 specification defines an access model and a set of APIs that enable applications running on a J2ME device to communicate with a smart card inserted in the device, providing a flexible mechanism to allow service and equipment providers to define secure operations.

JSR 179: Location API for J2ME™

This specification defines an optional package that enables developers to write mobile, location-based applications for J2ME devices. The purpose of the specification is to provide a compact and generic API that produces information about the device's present physical location to Java applications. This specification defines a generic interface that works with most positioning methods, such as GPS and E-OTD.

JSR 180: Session Initiation Protocol (SIP) for J2ME™

The Session Initiation Protocol (SIP) is used to establish and manage multimedia IP sessions. This same mechanism can also be used to provide instant messaging, presence, and gaming services. This specification defines a general SIP API for J2ME devices based on the SIP protocol defined by IETF and 3GPP, and targeting resource constrained platforms.

JSR 184: Mobile 3D Graphics API for J2ME™

This specification defines a lightweight, interactive 3D graphics API, which sits alongside J2ME and MIDP as an optional package. The API is targeted at devices that typically have very little processing power and memory, and no hardware support for 3D graphics or floating point math. However, the API also scales up to higher-end devices that have a color display, a DSP, a floating point unit, or even specialized 3D graphics hardware. The API is designed to make rapid development of compelling 3D applications feasible and is intended to be flexible enough for a wide range of applications, including games, animated messages, screen savers, custom user interfaces, product visualization, and so on.

JSR 190: Event Tracking API for J2ME™

This specification defines an optional package that standardizes the tracking of application events in a mobile device and the submission of these event records to an event-tracking server via a standard protocol. The events can be used for purposes such as billing, usage tracking, application revocation, update notification, reviews and ratings, and so on.

The Event Tracking API is intended to work with devices supporting CLDC 1.0 and later. The API is designed as an optional package that can be used with many J2ME profiles, in particular MIDP 1.0 and MIDP 2.0.

For More Information

For additional information on each effort mentioned above, refer to corresponding pages on the Java Community Process web site (http://jcp.org).