“Connected Device Configuration”的意思、由来-开放百科全书

The Connected Device Configuration (CDC) is a specification of a framework for Java ME applications describing the basic set of libraries and virtual-machine features that must be present in an implementation. The CDC is combined with one or more profiles to give developers a platform for building applications on embedded devices ranging from pagers up to set-top boxes.^[1] The CDC was developed under the Java Community Process as JSR 36^[2] (CDC 1.0.2) and JSR 218^[3] (CDC 1.1.2).

Typical requirements

Devices that support CDC typically include a 32-bit CPU with about 2 MB of RAM, and 2.5 MB of ROM available for the Java application environment. The reference implementations for CDC profiles are based on Linux running on an Intel-compatible PC, and optimized implementations are available for a variety of other CPUs and operating systems.^[1]

Profiles

A profile is a set of APIs that support devices with different capabilities and resources within the CDC framework to provide a complete Java application environment. Three profiles are available, which build on each other incrementally and allow application developers to choose the appropriate programming model for a particular device.

Foundation Profile

This is the most basic of the CDC family of profiles hackedis a set of Java APIs tuned for low-footprint devices that have limited resources that do not need a graphical user interface system.^[4] It provides a complete Java ME application environment for consumer products and embedded devices but without a standards-based GUI system. Version 1.1.2 is specified in JSR 219^[5] and implements a subset of Java SE 1.4.2, including a set of security-related optional packages, such as Java Authentication and Authorization Service (JAAS), Java Secure Socket Extension (JSSE), and Java Cryptography Extension (JCE).

Personal Basis Profile

The Personal Basis Profile provides a superset of the Foundation Profile APIs and supports a similar set of devices, with lightweight graphical user interface requirements.^[6] A framework for building lightweight graphical user interface components is provided with support for some AWT classes. There are no heavyweight GUI components provided because these components assume the availability of a pointing device such as a mouse. The specification is described in JSR 217^[7] and is used for products that require a standards-based graphical user interface but without full AWT compatibility. The Xlet application programming model is used for application development within this profile, including advanced content on Blu-ray discs conforming to the BD-J specification.

Personal Profile

The Personal Profile extends the Personal Basis Profile with a GUI toolkit based on AWT.^[8] It provides a complete Java ME application environment with full AWT support and is intended for higher end devices, such as PDAs, smart communicators, set-top boxes, game consoles, automobile dashboard electronics, and so on.^[9] This is the recommended profile for porting of legacy PersonalJava-based applications. The specification is described in JSR 62^[10] and uses the Applet programming model for application development.

Optional Packages

CDC supports a number of optional packages that allow developers to access specific pieces of extra functionality within the restricted resource constraints of a Java ME device.

See also

References

1. ^¹CDC Overview http://java.sun.com/javame/technology/cdc/overview.jsp
2. ^JSR 36, CDC 1.0.2 http://www.jcp.org/en/jsr/detail?id=36
3. ^JSR 218, CDC 1.1.2 http://www.jcp.org/en/jsr/detail?id=218
4. ^Foundation Profile Overview http://java.sun.com/products/foundation/overview.html
5. ^JSR 219, Foundation Profile Specification http://www.jcp.org/en/jsr/detail?id=219
6. ^Personal Basis Profile Overview http://java.sun.com/products/personalbasis/overview.html
7. ^JSR 217, Personal Basis Profile Specification http://www.jcp.org/en/jsr/detail?id=217
8. ^Personal Profile Overview http://java.sun.com/products/personalprofile/overview.html
9. ^J2ME FAQ, Writing an application for the J2ME Personal Profile http://developers.sun.com/mobility/personal/questions/gui/
10. ^JSR 62, Personal Profile Specification http://www.jcp.org/en/jsr/detail?id=62