Ruby Java Bridge: Are there any?

[Richard Cole]

Hi. Quick question. I've install a database like thingy (kowari) written
in Java that I want to communicate with from a Ruby: send queries get
answers. What's a good way to communicate from a ruby process to Java
process, SOAP? RMI? Corba? A socket? Are there any wrappers that let me
go from ruby straight to the JVM presumably via the java native call
interface? It's all on the same machine, I need only to communicate from
ruby to the Java Client interface that comes with my database thingy
(kowari). The data to be passed back and forth is all strings. The
client interface is a Java Bean. Does that open up any possibilities?

regards,

Richard.

 

[Lyndon Samson]

Hi. Quick question. I've install a database like thingy (kowari) written
in Java that I want to communicate with from a Ruby: send queries get
answers. What's a good way to communicate from a ruby process to Java
process, SOAP? RMI? Corba? A socket? Are there any wrappers that let me
go from ruby straight to the JVM presumably via the java native call
interface? It's all on the same machine, I need only to communicate from
ruby to the Java Client interface that comes with my database thingy
(kowari). The data to be passed back and forth is all strings. The
client interface is a Java Bean. Does that open up any possibilities?

Sockets would probably be easiest with strings. However if the jruby
and cruby marshall formats are compatable you could use that across
shared memory.

 

[Avik Sengupta]

A socket? Are there any wrappers that let me

go from ruby straight to the JVM presumably via the java native call
interface?

It is possible to compile java bytecodes to native objects via gcj, and
wrap that using Ruby's C interface (either manually, or via SWIG)

 

[David Corbin]

Hi. Quick question. I've install a database like thingy (kowari) written
in Java that I want to communicate with from a Ruby: send queries get
answers. What's a good way to communicate from a ruby process to Java
process, SOAP? RMI? Corba? A socket? Are there any wrappers that let me
go from ruby straight to the JVM presumably via the java native call
interface? It's all on the same machine, I need only to communicate from
ruby to the Java Client interface that comes with my database thingy
(kowari). The data to be passed back and forth is all strings. The
client interface is a Java Bean. Does that open up any possibilities?

regards,

Richard.

Depending on the application, you might consider JRuby. (A ruby implementation
in Java that allows direct calls to Java objects). There are, however,
definately applications for which it is NOT the solution at this point in
it's life.

 

[Takaaki Tateishi]

Hi. Quick question. I've install a database like thingy (kowari) written
in Java that I want to communicate with from a Ruby: send queries get
answers. What's a good way to communicate from a ruby process to Java
process, SOAP? RMI? Corba? A socket? Are there any wrappers that let me
go from ruby straight to the JVM presumably via the java native call
interface?

Try rjb,
http://arton.no-ip.info/data/rjb-0.1.9.zip
http://arton.no-ip.info/collabo/backyard/?RubyJavaBridge

 

[Luke Galea]

Wow,
RJB looks really nice!

So: Trying to get a handle on use cases for JRuby versus RJB...
JRuby is for embedding ruby in java applications, RJB is for embedding java in
ruby applications? Or is there overlap between the two?

 

[Richard Cole]

Try rjb,
http://arton.no-ip.info/data/rjb-0.1.9.zip
http://arton.no-ip.info/collabo/backyard/?RubyJavaBridge

Wow, cool library. That was just what I was looking for . Can you
think of any reason why I'm getting a SIGHUP? Here's my short ruby
program, maybe there's something obvious.

----
require 'rjb'
include Rjb

def file_contents_of(filename)
result = nil
File.open(filename) { |file| return file.read() }
return result
end

queryString = file_contents_of('example.itql')
load("itql-1.1.0.jar")
iTQLInterpreterBeanClass = import('org.kowari.itql.ItqlInterpreterBean')
iTQL = iTQLInterpreterBeanClass.new
answer = iTQL.executeQuery(queryString)

vars = answer.getVariables
while answer.next do
for i in 1..vars.length do
puts "i=#{i} val=#{answer.getObject(i-1).toString()}"
end
end
----

Output is:

[snip]
i=1 val=grrg.apache.bcel.classfile.Signature%24MyByteArrayInputStream
i=1 val=gr:java.io.ByteArrayInputStream
itql.rb:19: SIGHUP (SignalException)

Each time I run the program the SIGHUP comes either on answer.next or
answer.getObjects... and with a different amount of output.

regards,

Richard.

 

[vruz]

Hi. Quick question. I've install a database like thingy (kowari) written

in Java that I want to communicate with from a Ruby: send queries get
answers. What's a good way to communicate from a ruby process to Java
process, SOAP? RMI? Corba? A socket? Are there any wrappers that let me
go from ruby straight to the JVM presumably via the java native call
interface? It's all on the same machine, I need only to communicate from
ruby to the Java Client interface that comes with my database thingy
(kowari). The data to be passed back and forth is all strings. The
client interface is a Java Bean. Does that open up any possibilities?

SOAP4R comes standard with Ruby 1.8.x
(for a brief introduction have a look at: http://www.simplesiteuk.com)

I haven't heard of any RMI lib freely available in native Ruby

There's also RJNI: Java binding for Ruby through JNI
http://thekode.net/ruby/rjni/index.html
(though unsupported at the moment, would be interesting for someone to
pick it up)

You may consider JRuby can be a good option for some projects:
http://jruby.sourceforge.net/

There are some other JNI bindings available, can't recall the names
now, someone will probably help adding to the list in this thread.

cheers,
vruz

 

[Richard Cole]

Wow, cool library. That was just what I was looking for . Can you
think of any reason why I'm getting a SIGHUP? Here's my short ruby
program, maybe there's something obvious.

Don't know where SIGHUP is coming from, but putting a signal handler in
at the top of the ruby script allowed me to ignore SIGHUP, i.e:

trap('SIGHUP') {
# puts "SIGHUP Raised!"
}

and now the program is producing the correct output, i.e. correctly
iterating through the result set.

regards,

Richard.

 

[David Corbin]

Wow,
RJB looks really nice!

So: Trying to get a handle on use cases for JRuby versus RJB...
JRuby is for embedding ruby in java applications, RJB is for embedding java
in ruby applications? Or is there overlap between the two?

I"m not familiar with RJB, but JRuby can work "both ways". In fact, I use it
exclusively for times when I need to call Java code from a Ruby application.

David