J2ME&#8482 Standardization Efforts

J2ME™ Standardization Efforts

Once Motorola, Nokia, NTT DoCoMo, Palm Computing, RIM, Siemens, and other device manufacturers became interested in the KVM development effort, standardization was necessary in order to guarantee interoperability between the different kinds of Java Powered™ devices from different manufacturers. Two Java Community Process (JCP) standardization efforts were launched in the fall of 1999.

The first of these standardization efforts, Connected, Limited Device Configuration (CLDC), was launched on October 1, 1999. The goal of this effort was to define the "lowest common denominator" Java platform for a wide variety of small, connected, resource-constrained devices. This specification defines the minimum required complement of Java technology components and libraries for small devices. Java programming language and virtual machine features, core libraries, input/output, networking, and security are the primary topics addressed by the CLDC Specification. The CLDC standard does not target any specific device category. Rather, it defines a general-purpose building block on top of which more device category specific profiles are defined. Eighteen companies participated in the CLDC 1.0 (JSR 30) expert group work.

The second standardization effort, Mobile Information Device Profile (MIDP), was started in November 1999. That effort was based on the platform defined by the CLDC effort, adding features and APIs that focus specifically on two-way wireless communication devices such as cell phones and two-way pagers. Application model, user interface, networking, and storage APIs are the primary focus areas of the MIDP Specification. Twenty-two companies participated in the MIDP 1.0 (JSR 37) expert group work.

After becoming widely accepted in the marketplace, second-generation CLDC and MIDP standardization efforts were launched in the fall of 2001.

The CLDC 1.1 (JSR 139) effort was started in September 2001. CLDC 1.1 adds a number of features that improve the compatibility of the J2ME platform with the full Java 2 Platform, Standard Edition (J2SE™). The most significant new feature added in CLDC 1.1 is floating point support, but there are a number of other important features as well. The CLDC standardization effort is described in more detail in Chapter 4, "Connected Limited Device Configuration," and Chapter 5, "CLDC Libraries."

The MIDP 2.0 (JSR 118) effort was started in August 2001. MIDP 2.0 adds a number of important new libraries such as a Sound API and a Game API, as well as provides important refinements and extensions to the existing MIDP APIs. The MIDP standardization effort is discussed in Chapter 6, "Mobile Information Device Profile" and subsequent chapters.

The general framework for CLDC and MIDP, as well as other Java technology standardization efforts in the small device space, is known as Java™ 2 Platform, Micro Edition (J2ME) or simply Java 2 Micro Edition. An introduction to Java 2 Micro Edition is provided in the next chapter.

In addition to the CLDC and MIDP standardization efforts, there are a large number of additional J2ME standardization efforts that build upon these core standards. A summary of the J2ME optional packages created by the additional standardization efforts will be provided in Section 2.4, "Evolution of the J2ME Platform."

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