Wireless Java

Chapter 2.  The Connected Limited Device Configuration (CLDC)

The Connected Limited Device Configuration (CLDC) defines a standard, minimum-footprint Java platform for small, resource-constrained devices. As we mentioned in Chapter 1, the CLDC was designed as a lowest common denominator of Java that can be applicable to a wide variety of devices. However, features specific to a certain vertical market, such as cell phones or pagers, are not found in the CLDC but are instead defined in profiles that sit above it. Configurations primarily target devices with similar amounts of memory and processing power.

This leads to a very important point about the CLDC: there are no optional features. Everything that the CLDC provides is usable on the devices that support it. After all, the primary goal of the CLDC is to ensure portability and interoperability between applications running on various kinds of resource-constrained devices, which is the main objective of programming in Java. In this chapter, we discuss the CLDC and its virtual machine, the KVM, in detail.

Examining the CLDC in Detail

Let’s start off with some specifics. According to the specification, the devices targeted by the CLDC have the following characteristics:

160 KB to 512 KB of total memory

At a minimum, a CLDC device should have 128 KB of non-volatile memory for the Java VM and the CLDC libraries, and at least 32 KB of volatile memory for the VM to use at runtime, independent of any applications.

16-bit or 32-bit processor ...