On Wed, Aug 7, 2013 at 11:24 AM, janI <j...@apache.org> wrote:
> On 7 August 2013 18:55, Andrea Pescetti <pesce...@apache.org> wrote:
>
> > Oliver-Rainer Wittmann wrote:
> >
> >> Important note for discussion: it is all about platform Windows.
> >> On my work to update the AOO build environment for Windows I recognized
> >> that it is hard to get an official JDK 1.5 (Java 5) or JDK 1.6 (Java 6)
> >> for Windows. Thus, I decided to go with JDK 1.7. The resulting AOO
> >> installation on Windows no longer works together with an JRE 6. It does
> >> not recognize an installed JRE 6 as an valid Java runtime environment.
> >>
> >
> > May we frame the problem in more technical terms, just to know what is
> > broken? For example, why is this affecting only Windows and why is Java 6
> > not recognized in your build? Could the problem be in detection rather
> than
> > in the actual compatibility?
> >
> > Java issues were extensively discussed in earlier times, so here's a
> quick
> > summary that also answers most of the questions in this thread:
> > - As of 4.0, OpenOffice can be built with Java 5, 6 or 7
> > - Whatever you use for building, the resulting binary has a "Java
> > baseline" of 1.5 as per http://wiki.openoffice.org/**
> > wiki/Policies/Java_Usage<
> http://wiki.openoffice.org/wiki/Policies/Java_Usage>(means: runs with
> Java 5, 6 or 7)
> > - We built 4.0 with Java 6 (on Linux at least; not 100% sure about other
> > platforms)
> >
> > In general, I agree that we should build on the most secure platform
> > available. But, based on the above, what is the relationship between
> > "building on Java 7" and "running on Java 6"? To reuse Rob's Windows XP
> > argument, sure we should build on a supported (by Microsoft) Windows
> > version, but, if at all possible/reasonable, we shouldn't break
> > compatibility with Windows XP.
> >
>
> I am sorry if this posting is obvious to everyone, but reading the remarks,
> make me think there are some confusion about what we mean with using java
> for development and runtime.
>
> One of the strength of java is "program once, run everywhere" . This is
> accomplished by by 2 magic trix (compared to eg. C++).
> 1) Java does not compile to machine code but to pcode (a virtual machine),
> therefore you can build the program on linux, and run the build on window
> (or even one of the big mainframes).
> 2) Java also does late binding (think of a very smart dll), so libraries
> are not part of your build.
>
> This means you can use a java development 1.7 on any platform, to make a
> build that runs on any platform and (nearly) any java runtime version. As
> an example I use areca backup, its a java program, the exact same jar files
> run on vista,xp,win7,ubuntu and even android, areca is programm towards
> java 1.4, and I have 1.6 and 1.7 installed depending on platform.
>
> The problem is the classes and the API. If our code use just a single java
> 1.7 specific call, the runtime must be at least 1.7. This is however no
> problem today, our code is build for the classes and api available in java
> runtime 1.5, so it will run there.
>
> Oracle have promised to keep the API and classes for 1.4 and forwards
> stable, and available in new versions. They are pretty good at living up to
> the promise
>
> So in theory we can change build environment to java 1.7 and not tell user,
> as long as we only use 1.5 API and classes. As part of a release cycle, we
> should of course test once with runtime 1.5.
>
> I wrote "in theory" because in the real world, we might want to (in future
> releases) use the 1.7 api for e.g. performance reasons, when that time
> comes we would have to make a wrapper class, just like we have in C++ to
> cover differences Linux/windows.
>
> Sorry again, if I misread the postings, but this is very much different
> from the XP scenario.
>
> rgds
> jan I.
>
>
>
Thank you for this great explanation! So basically, review the AOO java API.
> >
> > Regards,
> > Andrea.
> >
> >
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