Chapter   1

Introduction

These release notes provide information about the release of Sun’s reference implementation of the Connected, Limited Device Configuration (CLDC) Specification, version 1.1, for the Java™ 2 Platform, Micro Edition (J2ME™).

CLDC 1.1 is the result of two Java Community Process efforts (JSR-30, JSR-139) that have standardized a small-footprint Java™ platform for resource-constrained consumer devices. The CLDC specification effort was done in collaboration with a large number of companies representing different industries. Target devices for CLDC are characterized generally as follows:

Cell phones, two-way pagers, personal digital assistants (PDAs), pocket organizers, home appliances, and point of sale terminals are some, but not all, of the devices that might be supported by CLDC.

The CLDC reference implementation runs on Sun’s K Virtual Machine (KVM)™ implementation, which is provided as part of this release.

The CLDC Specification document is available for public downloading at
http://jcp.org/jsr/detail/139.jsp.

Note that CLDC is intended to serve as the “lowest common denominator” building block for various kinds of resource-constrained, Java Powered™ devices. As such, CLDC is not a complete, self-sufficient solution; it needs to be complemented by profiles. For instance, all user interface aspects are outside the scope of CLDC Specification. Another Java Community Process effort called Mobile Information Device Profile (MIDP) has defined the necessary remaining Java platform features and libraries for two-way communication devices such as cell phones, while the JSR-75 effort is focusing on PDA-type devices. Other profiles for other vertical markets or device categories might be defined later.

1.1 Supported Platforms

The J2ME CLDC Reference Implementation runs on the Windows 2000 platform. CLDC-compliant ports for the the Solaris™ and Linux operating systems are also provided as part of this package. (Refer to Section 3.1 “Testing” for the exact compliant configurations that have been tested.)

1.2 Items Included in This Release

This release includes the source code and binaries for:

K Virtual Machine (KVM)
Preverifier tool (for preverifying Java class files)
JavaCodeCompact tool (for prelinking/preloading system classes into KVM)
Debug agent (for plugging the KVM into a third party debugging environment)
Java Application Manager (JAM) reference implementation

Please refer to the KVM Porting Guide (CLDC 1.1), (Sun Microsystems, Inc., 2003) (provided in this package) for more information on the preverifier tool, JavaCodeCompact tool, debug agent and the JAM.

The release includes the following documentation:

J2ME CLDC Reference Implementation Release Notes (this document)
CLDC API document version 1.1 (In Javadoc format), (regenerated from the latest libraries)
KVM Porting Guide (CLDC 1.1), (Sun Microsystems, Inc., 2003)
KDWP (KVM Debug Wire Protocol) Specification, (Sun Microsystems, Inc., 2002)
K Native Interface (KNI) Specification, (Sun Microsystems, Inc., 2002)

1.3 New Features

CLDC 1.1 is the first public release of the CLDC Specification, version 1.1. This release implements all the new features that have been added in CLDC 1.1, including:

Floating point support has been added.
All floating point byte codes are supported by CLDC 1.1.
Classes Float and Double have been added.
Various methods have been added to the other library classes to handle floating point values.
Weak reference support (small subset of the J2SE weak reference classes) has been added.
Classes Calendar, Date and TimeZone have been redesigned to be more J2SE-compliant.
Error handling requirements have been clarified, and one new error class, NoClassDefFoundError, has been added.
In CLDC 1.1, Thread objects have names, like threads in J2SE do. The method Thread.getName() has been introduced, and the Thread class has a few new constructors that have been inherited from J2SE.
Various minor library changes and bug fixes, such as the addition of the following fields and methods:
Boolean.TRUE and Boolean.FALSE
Date.toString()
Random.nextInt(int n)
String.intern()
String.equalsIgnoreCase()
Thread.interrupt()
Minimum total memory budget for CLDC has been raised from 160 to 192 kilobytes, mainly because of the added floating point functionality.
Specification text tightened and obsolete subsections removed.
Much more detailed verifier specification (“CLDC Byte Code Typechecker Specification”) is provided as an appendix.

For a more detailed summary of the differences between CLDC 1.0 and 1.1, refer to the CLDC Specification version 1.1.

In addition to providing support for features that are specific to CLDC Specification version 1.1, this release includes a number of other new features:

Revised class loader implementation.
Revised native finalizer support.

For most up-to-date information, refer to the CLDC product website
( http://java.sun.com/products/cldc).

1.4 Prerequisites and Dependencies

For more details on the Connected, Limited Device Configuration standardization effort, please refer to the Connected, Limited Device Configuration Specification, Java Community Process, Sun Microsystems, Inc., version 1.1, Sun Microsystems, Inc.:
http://jcp.org/jsr/detail/139.jsp

Please refer to the KVM Porting Guide (CLDC 1.1), (Sun Microsystems, Inc., 2003) for information about porting the K Virtual Machine to new platforms.

1.5 Frequently Asked Questions

A Frequently Asked Questions (FAQ) document for the CLDC reference implementation is available at the following website:

http://java.sun.com/products/cldc/faqs.html

The following FAQ documents might also be useful:

http://java.sun.com/products/midp/faq.html

http://java.sun.com/products/j2mewtoolkit/FAQ.html

Release Notes CLDC, 1.1

Copyright © 2003 Sun Microsystems, Inc. All rights reserved.