What I mean by this is if I install jRuby on Rails, can I use only the ruby language to build my application? I wanted to install my rails application with jRuby in case I wanted to use Java in the future, though I don't need it now. Or do I not understand? Is jRuby ruby that has access to java libraries?
yes, jruby is ruby (your ruby scripts need no modification to run under jruby). in addition, it has full access to java libraries - check out the wiki for how easy it is to integrate a java class or library into your ruby code.
The others have answered your direct question. I just want to say that I've been using jruby full time at work for the past 6 months and it's great. Deploying a rails app with the glassfish gem is very easy and jruby performs better than MRI ruby 1.8.x.
I've seen no real downside after 6 months other than the fact that we can't use gems that have pieces written in C. However, we've taken a C library and created a gem using FFI and it wasn't too much trouble.
It's also really easy to speed up your app by writing a few key pieces in java (which is easier t work with than C).
Related
I'm trying to make a simple multiple choice question app. Is this possible on ruby?
I've tried using shoes but I don't know how to create multiple classes and a GUI that uses them.
I'm also trying to connect all of this to a database.
I'm having trouble in understanding how to connect all of this together.
According to the comments the main problem seems to be with using the mysql gem part.
Gem usage depends on the version of shoes you are using. For green_shoes you should be good with the standard gems, but it is unmaintained. Shoes 3.1 has problems with gems that have C extensions (such as mysql). Shoes 3.2 should work. With Shoes4 you can't install the normal Ruby gems with C extensions as it uses JRuby and C extension support in JRuby is disabled. You have to use different gems to connect to the database, functionality is the same. A starting point might be activerecord-jdbc.
I'm working on building a GUI for my checkers implementation. I'm utilizing a GUI framework that only works with Ruby 1.8, yet my game engine, which I have packaged as a gem, only works with Ruby 1.9.
I can't change the code for the GUI framework and reworking my game engine to make it compatible with 1.8 is undesirable, to say the least.
I'm using RVM though, and it looks like you can write RVM scripts to change Ruby versions on the fly.
Does anyone have any experience with that or what the script might look like?
You could run it in two processes. Give the GUI a 1.8 process and talk to it via a shared db or an API on the other side. That's how I'd do it. The good part about that is you can have on online version of your game as well because other clients will be able to talk to it as well.
You can't run one app with two versions of Ruby. How do you imagine this?
RVM has an ability to automatically change current ruby when you cd into a directory. Just create in that directory a file called .rvmrc with content like
rvm use 1.8.7
I'm interested in promoting JRuby in our office as the platform hosting Rails applications.
But how reliable is it?
Is its performance better than MRI 1.8.7?
JRuby 1.5 states that it is 100% compatible with Ruby 1.8.7, does this mean that JRuby can run any Ruby/Rails code?
Yes, JRuby is reliable! Oracle uses JRuby for Oracle mix (http://mix.oracle.com/), Sun had used it for Kenai (http://kenai.com), and it's gonna be the next base for java.net (from kenai site: "Work is on-going for migrating the Java.net domain over to the Kenai infrastructure")!!
You can run almost every code, some gems uses native C extension and in JRuby there's a primitive support to it, but yes...rails just works.
You can deploy Rails apps in Application Servers like Tomcat or JBoss with Warbler that wraps Rails apps inside a .war file, it's pretty awesome!
update: you can see a lot of benchmarks here: http://programmingzen.com/2010/07/19/the-great-ruby-shootout-july-2010/
I am doing a lot of jruby work right now and can tell you that rails is certainly a viable option under the jruby interpreter. I've been pretty pleased and in my case have to use many native Java libraries, so jRuby is just such an awesome wrapper around that java code. I will say that I have had some technical challenges some that are worked out, some that are not yet.
unit testing: spooling up the jvm and then spooling up rails takes much longer, so your tests take longer to run - solution, potentially something like nailgun that keeps the jvm running
deployment: i have not gotten warbler to work for me, with my flavor of tomcat. this is a major issue for us.
pick your libraries, while some c extensions work, they are not all equally compatible.
if you are interested I would highly reccomend the jruby book, in beta, from Pragmantic Programmers at http://pragprog.com
JRuby rocks!! The simple reason being its portability features and integration with Java libraries. I personally use it with Netbeans and the fast debugger that comes with that seems very handly. Plus you do not want to see that native build errors and handling them. All these gems that you download for JRuby work 100% across any platform. With JRuby, you are simply bringing in the advantages of the Java's Platform independence.
Moreover, JRuby uses native threading which uses OS threads instead of Green threads as in CRuby (i think its not the case with the latest versions though)
In Gist, go JRuby!!
for windows I have found it to be much more stable than MRI when working with larger amounts of data. There are some bugs on windows still but they are actually work-around-able. Recommend.
Disclaimer: I don't use jruby in my day job - I merely experimented with running existing code using jruby.
It doesn't mean that it'll run all code successfully. For example, bioruby currently calls fork on jruby even though jruby doesn't really support it. (That's more of a bug in bioruby than a bug in jruby though)
I wouldn't call such behaviour "unreliable" though. It's fail-safe, like a plane that would not get off the ground, much less crash.
Background: I'm writing a 'standard' (nothing special) web application in Ruby (not Rails) and I need to start thinking about deployment.
So I've been hearing a lot of recommendations to use JRuby to deploy Ruby web applications, regardless of whether you actually need Java libraries or not. How true is this? Is it worth using the Java implementation just for speed? Would I gain anything else by doing so? Would I run into any issues?
PS: I don't know Java that well, so "you can write parts of it in Java" isn't very helpful.
JRuby is one of the most complete ruby implementations (there are a lot other ones out there such as IronRuby, Maglev, Rubinius, XRuby, YARV, MacRuby). It is very comprehensive, therefore, unless you use gems that use native C code, you will very very likely be just fine compatibility-wise.
JRuby is a bit faster than the actual C implementation, but it supports actual threads, whereas the official implementation is struggling a bit into getting it (it still uses Green Threads). Using Java threads from JRuby is quite trivial, even though it will require you to couple your code with Java (with a little DI, this coupling will only happen once, though).
Another benefit: runtime tools. Java, as a platform, instead of a language, has a lot of runtime tools to help you diagnose problems and check the state of the application (profilers, JConsole, and so on).
Twitter engineers also mentioned that the Ruby VM kinda has trouble being an environment for long lived processes, while the JVM is very good at that, because it’s been optimized for that over the last ten years.
Ruby also had a little security issue recently, which did not affect JRuby's implementation.
On the other hand, your project requires more artifacts (JVM, JRuby jars, etc). If you are using an application that will stay alive for long, and you want better runtime support, JRuby can be a great way to go. Otherwise, you can safely wait until you need these things to actually make the move (it is likely to go smoothly).
I use and love JRuby on daily basis, but I suggest you use MRI (a.k.a. C-Ruby) unless you have a actual need for JRuby.
Reasons for using JRuby:
Java integration
Restricted environment (your machine has Java installed by not ruby and you don't have root)
Restricted environment (you have ruby installed but don't have root so can't install gems you need)
You reached the limits of Ruby 1.8 performance and cannot use 1.9
From what you've described, you don't have any of the above reasons.
C-Ruby 1.9 has significant performance improvements over C-Ruby 1.8. I've yet to read (or find out for myself) how C-Ruby 1.9 compares with JRuby 1.8 or JRuby 1.9. In anycase, you don't have a performance problem (yet) so don't worry about it.
The good news is, you can start with either and convert later if needs be. It's all Ruby, and the Webrick and Mongrel gems work with both.
As mentioned above, ruby gems that have C extensions cannot be installed under JRuby. Hopefully this will change in the future if ruby C extensions utilize FFI.
http://kenai.com/projects/ruby-ffi/pages/Home
http://isitjruby.com/
What are the advantages/disadvantages of the major Ruby VMs (things like features, compatibility, performance, and quirks?) I know there are also some bonus features like being able to use Java interfaces through JRuby, too. Those would also be helpful to note. Does any VM have a clear advantage at this point, and in what contexts?
I've used both Matz's Ruby and JRuby, and they solve different tasks. If you are developing a straight Ruby or Rails app, then that will probably suffice, but if there are some powerful Java libraries that would help a lot, then JRuby might be worthwhile.
I haven't done anything overly complicated, but JRuby seemed to match up pretty well, at least as far as implementing the core language features (I haven't run into any differences yet, but they may exist).
One little anecdote I wish to share... I was writing a script to interact with a DB2 database. The DB2 support in Ruby is abysmal... you have to install the whole DB2 express version just to be able to compile the Ruby drivers, which didn't even work for me. I got fed up and switched to JRuby, using JDBC and a few small DB2 JDBC jars. It resolved my problem perfectly. The point? Well, if gaining access to some Java libraries will simplify the problem at hand, by all means go for it!
I hope this was helpful! Sorry I don't have any experience with other VMs....
One more caveat I have read about, but I don't know the details too well... JRuby I think supports threading via Java threads, instead of the "green" threads supported in Matz's implementation... so if you want multithreading on multicore systems, JRuby will probably serve you better... unless you want to do the threading in C.
Here's a bit of info I scrounged up on the main VMs: Ruby MRI, Ruby 1.9 (YARV), JRuby, XRuby, Rubinius, and IronRuby
There was a performance benchmark last year that compared the major VMs, but with how quickly VM development has been it probably is not as relevant today. Ruby 1.9 was generally the fastest, and still has the edge over JRuby for now, I believe.
Four VMs are currently capable of running Ruby on Rails: Ruby MRI, Ruby 1.9, JRuby, and Rubinius.
XRuby runs on the JVM, as does JRuby, and compiles the Ruby source files to a Java .class.
IronRuby runs on .NET, making use of their DLR, and allows you to integrate Ruby with the .NET libraries and infrastructure. It cannot yet run Ruby on Rails.
There is also a VM called HotRuby that lets you run Ruby source code in the browser or in Flash.