Peter, I just wanted to chime in privately to pass on two things. 1) I and Chris are both grateful to see the leadership you are providing to River after a long period after Sun dropped active involvement. We are both heavily committed to Jini within our Corporate environment and appreciate the fact that the "community" is coming alive with your leadership. 2) Chris is a solid "open-source" citizen (he is active in several other open-source projects) and sincerely wants to contribute back to River in whatever way he can (he has discussed it with me personally). The work we've done on the Jini codestream internally is something that Chris wants to contribute back - I am working through the Corporate hoops that we need to jump through here at Avid to get official sign-off to make that happen (and have our asses covered). Bob Craig Avid Technology
________________________________ From: Peter Firmstone [mailto:[email protected]] Sent: Sat 2/6/2010 5:19 PM To: [email protected] Subject: River Core Platform [was: Re: sketches] Christopher Dolan wrote: > Honest question: considering that Sun end-of-lifed Java 1.5 back in > October 2009, what's the value in continuing to support the Java 1.4 > platform in River? > Honest Answer: Just a few billion blue ray players, set top boxes and multifunction network printers and any other device that run Java cdc. Let me make one thing very clear: No code will be rejected because it uses a later JAVA version. What we do need to define is what constitutes the core platform, so that when I want to run River on a cdc device, that provides or consumes a simple service, I can. Which again highlights another problem, modularity, the Jini Specification is supposed to be able to have multiple implementations. I receive an endless stream of resistance about modularity, or versioning, every time I try to get the blessing of the River dev list to start working towards something, so here I sit doing the menial tasks, getting out the new release, posting discussions to river-dev, hesitant to make changes in case it turns out to be a wast of my valuable time. I have children and have paid work to do also. This isn't directed at you Chris, I want to see you participate, I just happened to pick up your thread response, it's directed at the list in general. Modularity allows us to have multiple implementations, if we provide a Service that uses Java 5 language features and if it's proxy is a smart proxy then if that smart proxy also uses Java 5 or later then it isn't available to Java 1.4 J2SE or cdc. However if it is a simple reflective proxy with typical classes it's bytecode is generated dynamically at runtime. We need a way to annotate what Java Version a Service provides, well that's what you call modularity, it should be handled for you automatically by the River platform, it can be annotated in MarshalledObject. Compatibility Checkers Some tools used by Apache projects: * Java o Clirr <http://clirr.sourceforge.net//> works on binaries o JDiff <http://jdiff.sourceforge.net/> uses sources Once a core platform has been decided upon, then that is all we check for Java 1.4 compatibility and those that want the Java 1.4 platform support are obliged to maintain that compatibility, namely me, but it was me that pushed later Java language feature support in the first place and still support it, I want as large an adoption and user pool as possible. So if we put the effort into defining just what the minimum requirements are for producing or consuming a basic service, we have the core platform, this can then be a small download. Eg, the JERI Relay service that Sim is working on is not part of the core platform, why not take advantage of the Concurrency libraries? Reggie Services shouldn't be restricted either, you wouldn't provide a Reggie service with java cdc, however it's proxy stub would need to be compiled with the -jsr1.4 option. (Actually Reggie still uses rmic, we need to convert to JERI) NO CODE WILL BE REJECTED BECAUSE IT USES LATER JAVA LANGUAGE FEATURES If you want to prove to yourself the -jsr14 compiler option works, edit build.xml, add the option, use JDK1.6 to compile the current codebase and specify source=5 instead of 1.4. I'm actually starting to wonder if we need two Releases of Apache River: 1. River for Trusted Intranet Networks 2. River for Untrusted Networks Both could use the same core platform, one would be secure by default and require more configuration, the other simple, with few concerns about security, or codebase evolution (Preffered Class loading mechanisms will suffice). BR Peter. > I've found it to be tricky to avoid using new methods when striving for > backward runtime compatibility. Extensive unit testing or static > analysis are the only ways to ensure you've found all the problems, > since the compiler won't help you. > > Googling for "-target jsr14" revealed this less-than-inspiring quote: > "It is convenient, if unsupported, and the compiler generates mostly > compatible bytecode in a single pass." > http://twit88.com/blog/2008/08/26/java-understanding-jsr14/ > > > Chris > > -----Original Message----- > From: Peter Firmstone [mailto:[email protected]] > Sent: Friday, February 05, 2010 5:16 PM > To: [email protected] > Subject: Re: sketches > > Yes, Java 5 language features next release. > > Although I'd like to find just what our core jini platform should be and > > compile it with -jsr14 to produce Java 1.4 bytecode from Java 5 source. > > In that core platform, we couldn't use any new methods or libraries not > in Java 1.4, however we could use generics. > > So for instance the Java cdc platform can consume and provide simple > services. > > Cheers, > > Peter. > >
