Introduction - JavaTech: An Introduction to Scientific and Technical Computing with Java - page 7

small, low-resolution displays, if any at all. So Sun offers slimmed-down versions
of Java for such applications. Until recently this involved three separate bundles
of Java 1.1-based packages, organized according to the size of the platform. Java
Card is intended for extremely limited Java for systems with only 16 KB non-
volatile memory and 512 bytes volatile. The EmbeddedJava and PersonalJava
bundles are intended for systems with memory resources in the 512 KB and
2MBranges, respectively.
To provide a more unified structure to programming for small platforms,
Sun has replaced EmbeddedJava and PersonalJava (but not JavaCard) with the
Java 2 Micro Edition (J2ME). The developer chooses from different subsets of
the packages to suit the capacity of a given system. (We briefly review J2ME in
Chapter 24.)
At the other extreme are high-end platforms, often involving multiple proces-
sors, that carry out large-scale computing tasks such as online stores, interactions
with massive databases, etc. With the Java 2 Platform came a separate set of
libraries called the Java 2 Enterprise Edition (J2EE) with enhanced resources
targeted at these types of applications. Built around the same core as Standard
Edition packages, it provides an additional array of tools for building these so-
called middleware products.
1.3.3 Naming conventions
We note that the naming and version numbering scheme in Java can be rather
confusing. As we see from the time line above, the original Java release included
the Java Development Kit (JDK) and was referred to as either Java 1.0 or JDK
1.0. Then came JDK 1.1 with a number of significant changes. The name Java 2
first appeared with what would have been JDK 1.2. At that time the JDK moniker
was dropped in favor of SDK (for Software Development Kit). Thus the official
name of the first Java 2 development kit was something like Java 2 Platform
Standard Edition (J2SE) SDK Version 1.2. Versions 1.3 and 1.4 continued the
same naming/numbering scheme.
Meanwhile many people continue to use the JDK terminology - thus JDK
1.4 when referring to J2SE SDK Version 1.4. Another common usage is the
simpler but less specific Java Version 1.x, or even just Java 1.x to mean J2SE
Version 1.x. Both of these usages are imprecise because there is also a Java 2
Enterprise Edition (J2EE) Version 1.4. To make it clear what you mean, you
should probably either use J2SE or J2EE rather than just Java when mentioning
aversion number unless the meaning is clear from context. This topic is not
about J2EE, though we do touch on Java Servlet technology in Chapters 14 and
21 and on web services in general in Chapter 21. Since we never need to refer
to the Enterprise Edition, we use the terms Java 1.x, SDK 1.x, and J2SE 1.x
interchangeably.