ThreeTen-Backport实现与JSR-310的反向移植？

Question

Note: this is not a duplicate of Comparing ThreeTen backport to JSR-310 . My question is more specific.

In my company, I'm trying to get DevOps to OK the use of ThreeTen-Backport for refactoring legacy code (which because of deployment constraints with WebLogic 10.3.6.0 we can't upgrade from Java 6 and can't use any version of JodaTime beyond version 1.2.1).

I can see DevOps having an issue with this statement on ThreeTen-Backport's Github page:

The backport is NOT an implementation of JSR-310, as that would require jumping through lots of unnecessary hoops. Instead, this is a simple backport intended to allow users to quickly use the JSR-310 API on Java SE 6 and 7.

When they ask me what "Not an implementation" means, I need to be able to explain it to them. However, the word implementation can have a wide semantic range, and I'm not sure exactly what is meant by that myself.

So my question is, in contexts like this, what is meant by implementation vs. backport ? Since JSR-310 is a backport and not an implementation, is there a counter example of something that I could use, that is an implementation of something else, in the same sense that ThreeTen-Backport is not an implementation of JSR-310? What would an actual implementation of JSR-310 for Java 6 look like if such a thing existed, and how would it be different from ThreeTen-Backport?

Answer 1

JSR 310: Date and Time API is a formal specification controlled by the Java Community Process (JCP) and with a whole heap of legalistic controls. An implementation of any JSR, including JSR-310, requires passing the testing kit and other hurdles.

In the case of JSR-310, the JSR is integrated into Java 8 itself , which means that it simply is not possible to implement the JSR independently. There is no testing kit for JSR-310 outside the JDK. Thus no piece of code can implement JSR-310 outside the JDK itself.

Thus, ThreeTen-Backport is as close to an implementation of the JSR-310 specification without actually being an implementation, where "implementation" is with reference to the JSR-310 specification .