The Java 2 Platform, Micro Edition (J2ME) is a collection of java classes and interfaces dedicated to small and mobile devices. Like its counterparts for the enterprise (J2EE) and desktop (J2SE) environments, J2ME includes Java virtual machines and a set of standard Java
APIs defined through Java.

J2ME platform is targeted at two product groups.

Personal, mobile and connected information devices such as cellular phones , pagers etc

Shard, fixed, and connected information devices such as set top boxes, Internet TV etc.

J2ME framework is divided into Configurations and Profiles

 

Configurations

Configurations are designed for specific kind of device based on memory constraints and processor power

Connected Device Configuration(CDC)

CDC is designed for “more powerful” wireless devices like TV set top boxes, high end pda’s(personal digital assistant)etc . It specifies a full Java virtual Machine(JVM) as defined in J2EE.

Connected Limited Device Configuration(CLDC)

CLDC is designed for smaller devices than CDC with limited capacity and network connection such as cellular phones , pagers etc. CLDC is build on “scale down” version of JVM called KVM(Kilobytes virtual machine -named to reflect its size is measured in tens of Kilobytes)

 

Profiles

Profiles are more specific than configurations. It is based on a configuration and adds API’s for user interface, persistent storage and factors necessary for developing wireless applications

Foundation profile
Fundamental specification for devices that can support a rich networked J2ME environment. It provides services for other device-specific profiles (such as Personal profile and RMI profile) to be layered on top of it for providing user interface

Personal profile
Personal profile specification repacks the personal Java Application Environment to provide J2ME specification for devices that need a high degree of Internet connectivity. This profile builds on top of foundation profile.

RMI(Remote Method Invocation) profile
RMI profile also builds on top of Foundation profile and supports inter-application RMI over TCP/IP connections for applications written to the Foundation Profile

MIDP profile
The J2ME Mobile Information device profile(MIDP) provides a standard platform for small, resource-limited, wireless-connected mobile information devices. MIDP requires CLDC for implementation.

PDA profile
This Profile is designed for Palmtop devices with limited power ,typical battery operated, user interface displays,a pointing device ,character input, and a minimum of 512kb(and maximum 16MB) combined ROM(read only memory) and RAM(random access memory).