Re: Proposal for managing gem dependencies in a Java + JRuby application

>
> Hey all,
>
> I’ve seen a few posts on this mailing list and in the JRuby JIRA loo
> king for
> gem management strategies that don’t rely on a local installation of
>  JRuby
> and locally installed gems in a deployed Java + JRuby application.
>
> The application model I am looking at is a Java application built by  
> Maven
> that embeds JRuby scripts that have gem dependencies. I'd like to  
> support a
> deployment model that doesn't require a local install of JRuby and the
> required gems.
>
> The primary issue appears to be that Ruby and RubyGems are heavily  
> file
> system dependent so are not friendly to having resources loaded from  
> the
> classpath.
>
> jruby-complete takes care of providing the JRuby and the core Ruby
> dependencies with a strategy where core Ruby libraries are extracted  
> at
> runtime to the file system from the jar.
>
> I have been experimenting with a similar strategy for managing gem
> dependencies and have a working implementation that I’d like to floa
> t out
> here for comment.
>
> It goes something like this:
>
> Package [name]-[version].gem files in the Java application classpath.
> Either at application startup or on demand (by modifying  
> Kernel::gem) find
> the desired gem if it is not already installed by scanning the root  
> of the
> classpath, ala Spring’s PathMatchingResourcePatternResolver
> (http://static.springframework.org/spring/docs/2.0.x/api/org/springframework/core/io/support/PathMatchingResourcePatternResolver.html 
> ).
> Extract and install the gem into an application-specific GEM_HOME  
> using
> Gem::Installer.
> Done.
>
> This enables packaging and deploying gems as jars (the .gem file in  
> the root
> of a jar) and managing these dependencies with Maven, including  
> transitive
> dependencies among gems.
>
> Goldspike (Rails on Tomcat) uses a similar strategy by bundling  
> expanded
> gems in WEB-INF and setting GEM_HOME to that location.
>
> I have a version of this working that first extracts the .gem file  
> to file
> system from the classpath by reading from a classpath resource  
> InputStream.
> I noticed that Gem::Format has a method for reading from an IO stream
> (Gem::Format.from_io). It would be great to skip the intermediate  
> extraction
> step by using this method. I ran into trouble figuring out how to  
> use the
> InputStream from the classloader as an IO object in Ruby. I tried  
> creating
> an org.jruby.RubyIO object from the InputStream but get an error when
> calling Gem::Format.from_io with the created object:
>
>  /lib/ruby/site_ruby/1.8/rubygems/package.rb:411:in `new': Illegal  
> seek
> (Errno::ESPIPE)
>
>
> Comments on the overall strategy? If desired by others I’ll definite
> ly share
> the end result.
>
> Suggestions on the IO issue?
>
> Thanks,
>
> Alon
>
>
> --
> View this message in context: http://www.nabble.com/Proposal-for-managing-gem-dependencies-in-a-Java-%2B-JRuby-application-tf4946209.html#a14161350
> Sent from the JRuby - Dev mailing list archive at Nabble.com.
>
>
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