Configuration and Profile

The Java Community Process Program has used a twofold approach to addressing the needs of small computing devices.

JCP通过采用2步骤方法来表述小型计算设备的需求。(JCP使用JSR（Java Specification Requests）作为正式规范文档，描述被提议加入到Java体系中的的规范和技术,如JSR 179为Location API for J2ME的规范文档)

First, they defined the Java run-time environment and core classes that operate on each device. This is referred to as the configuration. A configuration defines the Java Virtual Machine for a particular small computing device.There are two configurations, one for handheld devices and the other for plug-in devices.

首先，它定义Java运行时环境和可以在任意设备上操作的核心类，这被称为Configuration(配置）。配置定义了针对一个特定小型计算设备的JVM。有两类配置，一种是针对手持设备，另一种针对即插式设备。

Next, the Java Community Process Program defined a profile for categories of small computing devices. A profile consists of classes that enable developers to implement features found on a related group of small computing devices.

其次，JCP为不同种类的小型计算设备定义了简表（Profile）。一个简表包含一些类，这些类允许开发者扩展基于某一类小型计算设备的特性。

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There are two configurations for J2ME as of this writing. These are Connected Limited Device Configuration (CLDC) and the Connected Device Configuration (CDC). 

两种配置，CLDC和CDC

The CLDC is designed for 16-bit or 32-bit small computing devices with limited amounts of memory. CLDC devices usually have between 160KB and 512KB of available memory and are battery powered. They also use an inconsistent, small-bandwidth network wireless connection and may not have a user interface. CLDC devices use the KJava Virtual Machine (KVM) implementation, which is a stripped-down version of the JVM. CLDC devices include pagers, personal digital assistants, cell phones, dedicated terminals, and

handheld consumer devices with between 128KB and 512KB of memory.

CLDC是为16位或32位的受内存限制小型计算设备而设计的。CLDC设备通常有160K到512K的可用内存并且是电池供电的。它们还使用不稳定、低带宽的无线网络连接，甚至可能没有用户界面。CLDC设备包括寻呼机、PDA、手机、专业终端和内存在128K和512K之间手持消费电子设备等。

CDC devices use a 32-bit architecture, have at least two megabytes of memory available, and implement a complete functional JVM. CDC devices include digital set-top boxes, home appliances, navigation systems, point-of-sale terminals, and smart phones.

CDC设备使用的是32位体系结构，拥有至少2MB内存可用，并且实现了完整的JVM功能。CDC设备包括数字电视机顶盒、家用电器、导航系统、销售终端和智能手机等。

A profile consists of Java classes that enable implementation of features for either a particular small computing device or for a class of small computing devices. Small computing technology continues to evolve, and with that, there is an ongoing process

of defining J2ME profiles. Seven profiles have been defined as of this writing. These are the Foundation Profile, Game Profile, Mobile Information Device Profile, PDA Profile, Personal Profile, Personal Basis Profile, and RMI Profile.

简表包括了那些实现针对某一类或某一特定计算设备的特性的Java类。随着小型设备计算技术的不断发展，定义J2ME简表也有不断发展的过程。本文包含7种简表。分别是基本简表、游戏简表、移动信息设备简表（MIDP）、PDA简表、个人简表

个人基本简表和远程方法调用简表。

■ The Foundation Profile is used with the CDC configuration and is the core for

nearly all other profiles used with the CDC configuration because the Foundation

Profile contains core Java classes.

■ The Game Profile is also used with the CDC configuration and contains the

necessary classes for developing game applications for any small computing

device that uses the CDC configuration.

■ The Mobile Information Device Profile (MIDP) is used with the CLDC

configuration and contains classes that provide local storage, a user interface,

and networking capabilities to an application that runs on a mobile computing

device such as Palm OS devices. MIDP is used with wireless Java applications.

■ The PDAProfile (PDAP) is used with the CLDC configuration and contains classes

that utilize sophisticated resources found on personal digital assistants. These

features include better displays and larger memory than similar resources found

on MIDP mobile devices (such as cell phones).

■ The Personal Profile is used with the CDC configuration and the Foundation Profile

and contains classes to implement a complex user interface. The Foundation

Profile provides core classes, and the Personal Profiles provide classes to implement

a sophisticated user interface, which is a user interface that is capable of displaying

multiple windows at a time.

■ The Personal Basis Profile is similar to the Personal Profile in that it is used with

the CDC configuration and the Foundation Profile. However, the Personal Basis

Profile provides classes to implement a simple user interface, which is a user

interface that is capable of displaying one window at a time.

■ The RMI Profile is used with the CDC configuration and the Foundation Profile

to provide Remote Method Invocation classes to the core classes contained in the

Foundation Profile.

from: James Keogh, J2ME the Complete Reference.2003 page12