Correlation between Java EE / J2EE to J2SE / JDK versions

Solution 1:

Is there an official correlation between Java EE / J2EE and J2SE / JDK versions?

Sun may try to keep some kind of "correlation" to not confuse users and for marketing purpose but, AFAIK, no, there is no official correlation (and maintaining the pseudo synchronisation might become harder in the future as the JDK evolves faster than the Java EE specification).

UPDATE: I was wrong, there is actually a correlation (see below). But I still think that this might become a problem: Java 7 is scheduled for late 2010, will the expert group succeed to roll out Java EE 7 before Java 8 and Java 7 EOL?

If the answer is yes, where is it written?

Quoting the JSR 151: JavaTM 2 Platform, Enterprise Edition 1.4 (J2EE 1.4) Specification home page:

• J2EE 1.4 is the Enterprise Edition of version 1.4 of the Java platform, and thus will be built on J2SE 1.4.

Quoting the JSR 244: Java(TM) Platform, Enterprise Edition 5 (Java EE 5) Specification home page:

• Java EE 5 is the Enterprise Edition of version 5 of the Java platform, and thus will be built on J2SE 5.0.

Quoting the JSR 316: JavaTM Platform, Enterprise Edition 6 (Java EE 6) Specification home page:

• Java EE 6 is the Enterprise Edition of version 6 of the Java platform, and thus will be built on Java SE 6.

Seriously, why do we have to go to the JCP website to find this (maybe I should have started there though)?

If the answer is no, then why?

Java Enterprise Edition is a specification, not an implementation. It might rely on specific features (like Java EE 5 and Java 5 generics) but the JDK version is actually dependent upon the implementation of the container you are using. See the Websphere example below. (This still applies, even after the big UPDATE above.)

and is there an unofficial version table (e.g. JDK 1.4 goes well with J2EE 1.3, JDK 1.5 goes well with J2EE 1.4, JDK 1.6 with Java EE 5 and so on)

As I said above, "goes well" doesn't really makes sense as this depends on the container you are using and containers might have different compatibility requirements (for example IBM WebSphere's J2EE 1.4 server may not work with JDK 5). So, I'd rather speak in terms of requirements.

The J2EE 1.4 SDK is bundled with JDK 5 but... J2EE 1.4 requires JDK 1.4 or later. Java EE 5 requires JDK 5 or later. Java EE 6 requires JDK 6 or later (JDK 5 is at its EOL for 2+ months now).

Solution 2:

Java EE is a set of specifications and a reference implementation for those specs. A given version may happen to depend on language features present in some version of the JDK, or it may not.

You can think of Java EE the same way you think of any third-party framework or library for Java. There's no reason for the version numbers of Java EE and the JDK to have anything at all to do with each other.

Solution 3:

Generally, Java Enterprise Editions come out after the JDK for the same versions.

Basically, for the past few editions, you've had these download packages:
JDK 5 with J2EE 4.
JDK 5 with Java EE 5.
JDK 6 with Java EE 5.
JDK 6 with Java EE 6 (currently only available from the Java EE page, the Java SE page still has JDK 6 with Java EE 5)

Note that these download packages actually include Sun's version of Java EE (Glassfish these days), which is different than Apache's version of Java EE (Tomcat/Geronimo) or IBM's version of Java EE (Websphere).

If you choose not to use Glassfish, you can download just JDK6 and one of the other Java EE packages. As of right now, Glassfish is the only Java EE 6 product, as Java EE 6 just came out and it's the reference implementation.