Re: Installing JRuby on Windows Question Set

> John Miller wrote:
>> Greetings All,
>>
>> I have concluded that I ought to try out JRuby.  Running on windows I
>> get the short end of the stick when it comes to non-ruby-native
>> functionality, and there is an AI package in Java that I want to play
>> with in a language that doesn't require a novel worth of code to use.  I
>> have a few questions about how to make this happen:
>
> I'm late to the party on this one, but here's some answers.
>
>> 1) What is the best way to get MRI and JRuby to live on the same
>> (Windows) system?  The only answer I've found to this question involves
>> bash scripts.
>
> Generally, JRuby lives entirely within its unpacked directory. Run
> <jruby dir>/bin/jruby and it will handle the rest. If you add JRuby's
> bin dir to your path, you can just run "jruby". If you add it after your
> Ruby path, and want to make sure you're running 'gem', or 'rails' or
> other scripts with JRuby, use "jruby -S <scriptname>".
>
>> 2) What do I need to get in terms of a Java Environment.  below is the
>> output of Java -version:
>>   java version "1.4.1_03"
>>   Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1_03-b02)
>>   Java HotSpot(TM) Client VM (build 1.4.1_03-b02, mixed mode)
>> This was likely installed at least 3 years ago, and is probably out of
>> date.  I went to java.sun.com to look for "the latest version" and hit
>> buzzword central.  The last time I did anything more then run a Java App
>> was 6+ years ago and I'm now lost in all the new Lingo.  So, what to I
>> need to run JRuby, and what else outh I get to make Rails work with it?
>
> JRuby 1.1+ requires at least Java 5, but Java 6 (Java SE 6, someone else
> posted info on how to download) will provide the best performance.
> Install it and that should be all you need.
>
> Unless you're going to compile Java code, you don't need the compiler.
> JRuby's compiler is self-contained.
>
>> 3) Is is possible to "move" my installed gems from MRI Ruby1.8.6 to
>> JRuby without having to touch the network.  All I have is a 56.6k modem,
>> and Downloading rails again is a 4 hour job. (BTW: Is there a way in
>> general to download a gem and not install it? For example could I get
>> the latest Rails release on my Laptop at work and bring the files home
>> to install on the desktop?)
>
> Well for Rails, you shouldn't have any problems. Rails installs the same
> gems under any Ruby implementation, so your already-downloaded gems
> (under lib/ruby/gems/1.8/cache) can be installed in JRuby. I don't know
> of a way to just fetch a gem and not install.
>
>> 4) What does it take to get SQLite or some equivalent no configuration
>> database running in JRuby?
>
> Your best bet would be a database like Derby/JavaDB, which is a
> pure-Java embedded database. Using JavaDB, you could produce a DB-driven
> app very quickly, and since it's Java the whole app could be packaged up
> and moved to another machine and run just as well. If you're using
> ActiveRecord, there are gems for derby and other databases. If you're
> not using ActiveRecord, it would probably be easiest to just call JDBC
> APIs directly. There are blog posts and wiki articles out there that
> show how to directly use JDBC from Ruby with JRuby.
>
> Do check out the JRuby Wiki at http://wiki.jruby.org and feel free to
> join the mailing lists or find us on #jruby on Freenode IRC.
>
> - Charlie