All releases of Java produced by Sun Microsystems obey the same rules about version numbers. All version numbers are in the form x.y.z, or x.y when z=0. These values change as follows:
- Major release. x is incremented and y and z reset to 0 when an evolution is not backward compatible with the previous version (e.g., Java Card 2.0, MIDP 2.0).
- Minor release. x is unchanged, y is incremented, and z is reset to 0 when new features are incorporated into the product (e.g., CLDC 1.1, J2SE 1.4).
- Maintenance release. x and y are unchanged, and z is incremented when a new version of the product is released without changing its specification (e.g., J2SE 1.4.2).
These rules are simple, clear, and easy to follow for everybody, except for Java Card folks:
- Java Card 2.0 was OK. A successor to Java Card 1.0, it was definitely not backward compatible.
- Java Card 2.1 started the problems. A successor to Java Card 2.0, it was not very backward compatible. For instance, the ISO file system API disappeared. The issue has been solved by “disappearing” the Java Card 2.0 spec, which is definitely a collector item today.
- Java Card 2.1.x versions were almost OK. The only additions are constants that represent new crypto algorithms that can be optionally supported.
- Java Card 2.2 was actually OK. It adds a lot of new things, including a new CAP file format, but it is backward compatible.
- Java Card 2.2.1 does not obey the rule, because the API has been modified – 1 interface (
AppletEvent) and 1 method (isTransient) added, but the change is minor, and related to compatibility with GlobalPlatform. Quite classical. - Java Card 2.2.2 is a different kind of object. It does not modify any existing API, but it adds a bunch of new optional packages. Since all additions are optional, every 2.2.1 card is a valid 2.2.2 card, but does that really make it a maintenance release …
All these are trivial little facts, and the Sun people are not even at fault here, since the naming problems were usually motivated by the industry itself. Of course, the next issue is to figure out how Bandol will be named …
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