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Closed 10 years ago.
I'm looking to develop a greenfield web application which will reuse a lot of Java components. To me, the obvious options for this are Grails or jRuby on Rails, but I'm having trouble finding objective comparisons of the two. Are there any clear reasons to pick one over the other with respect to:
ease of integration with existing Java components (outside the persistent domain), e.g. JMS, EIP
support for functional testing frameworks
performance on a single machine
scalability
I am not looking for answers relating to the availability of developers or activity of communities.
(I've checked Grails vs. Rails, and it's not relevant to me)
Try both, and pick the language and environment that suits you best. It's true that the Grails stack out of the box is more suited towards Java integration, but many components are just a few lines of Ruby code away from integration with Rails. Rails 3 is a great release that doesn't require you to use ActiveRecord, in fact it would be trivial to use Hibernate for your models instead. See also DataMapper, MongoMapper and a whole host of database adapters for SQL and NoSQL databases alike.
Also, JUnit != functional testing. Instead, have a look at Cucumber + Cucumber-Rails + Capybara + Selenium for an integrated browser automation testing experience. Take a look at https://github.com/elabs/front_end_testing for an example application that demonstrates this stack.
I'll suggest that Ruby is better suited as a web integration language, and JRuby hits the sweet spot of making integration with Java easy as well as pleasing while making a wealth of non-Java libraries available to you. Don't think that Groovy automatically wins because it's "closer" to Java. Sometimes you need to step into a refreshingly different environment in order to have a new look at how to solve a problem.
Disclosure: as a member of the JRuby team my bias is evident in my answer.
I know Grails very well (right now I'm working on a Grails project), but not JRuby, so take this as a probably biased opinion: looking at the JRuby documentation, it looks that JRubys integration with Java is a bit more cumbersome, since Java is more native in Groovy than it is in Ruby; therefore, in JRuby, you have a lot of java-specific keywords and methods (e.g. java_import, java_send). Put simply, Groovy is a language targeted specifically at the Java world, while JRuby is, well, Ruby put on the JVM.
Grails has JUnit tests built in.
Can't say much about performance and scalability, but given the good integration with Java, one can always write performance-critical parts in Java when Groovy is too slow.
ease of integration with existing Java components:
it's easier with groovy, cause groovy is basically java. you do not have big context-switches
support for functional testing frameworks
ruby has it's own pile of testing frameworks like rspec/shoulda/cucumber/steak and tons more. since i like ruby syntax i would prefer those
performance on a single machine
as far as i know, grails is better in multithreading, because rails did not fokus too much on that in the past. they are currently catching up, so it might be tie.
scalability
both scale with the jvm environement. if you have a running infrastructure for java, grails is easier to integrate.
As phoet said, Grails has first-class Spring support, so it's typically very easy to integrate Spring libraries - that's what many plugins do, including the JMS plugin.
Java code can either be provided in JARs or put in to the project's src/java directory. Groovy classes can reference Java classes which can reference Groovy classes. It's pretty seamless.
Grails has support for HtmlUnit, Selenium-rc & WebDriver through various plugins. Geb has a lot of interest at the moment, especially when combined with Spock.
Test them. I don't know if there are any recent comparisons, but performance typically depends heavily on your application. http://grails.org/ and http://beta.grails.org/ are both running on a single machine - and both are Grails applications.
I gather it's pretty easy to cluster Grails via Terracotta. You can also do it with plain Tomcat if you want. There are options for distributed caching - SpringSource has its own (commercial) offering in the form of GemFire.
Hope that helps, and in the interests of full disclosure I'm a member of the Grails team.
In the end, you are going to make a decision on personal choice, comfort with the two languages and the availability of resources, but in the end, the fact that Grails is based on Spring led me to the conclusion that it was the right choice for me. I knew that if all else failed I could fall back to utilizing the tried and true Spring Framework
For newcomers interested in this question in 2012...
"With the #CompileStatic, the performance of Groovy is about 1-2 times slower than Java, and without Groovy, it's about 3-5 times slower. (...) This means to me that Groovy is ready for applications where performance has to be somewhat comparable to Java."
Performance Test: Groovy 2.0 vs. Java http://java.dzone.com/articles/groovy-20-performance-compared
And besides the autor, I've used Groovy since 2008 with great success, not only for CV, just to make job done in time business need. Performance is ever relative to what you want to do.
About integration, Grails is really "that good". I've never needed to make one step further to integrate it with existing libraries. On the contrary, the Spring-based nature of Grails made the job even easier.
For those who could complain about micro-benchmarks and real use cases, here is a somewhat old (Grails 1.8) but good one with web frameworks (Grails 1.3.7): http://www.jtict.com/blog/rails-wicket-grails-play-lift-jsp/
Hope this helps!
PS.: I would like to see recent benckmarks with JRuby and other really dynamic JVM languages.
Related
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Closed 12 years ago.
I know that there have been plenty of topics describing this topic but I still can't put up my mind what to choose.First of all, I need you to know that I am a student in his last year, who will probably continue studying for a few years. However, I'm trying to find what I would benefit most from.
I've been in contact with RoR last year; seeing Ruby's squirky syntax amazed me, and Rails CoC and DRY principles make me dream. I've written some scripts to generate sql statements in Ruby, but that is about all.
I'm considered to be a java developer, as they call me the java guy on school, (no, i do not consider myself good, on the contrary, every day I realise more how much more i've got to learn). Now, I've taught myself several technologies related to java. To make my work easier, I opted learning hibernate and maven. Now we are developping an application in Spring + Spring MVC.
Grails caught my attention lately since it is built on top of these technologies, and uses a language that is similar to java, and allows access to java classes.
However, i'm not sure what is the best way to go. Should I struggle through Ruby's quirkyness first, and learn Rails? Or would learning Grails first give me an advantage over learning RoR?
Also, as far as from what i've read, RoR would give me a bigger advantage on the market than grails would; but how do I get a "proof" that I can use RoR? Would it be enough to be able to show applications made using RoR?
I've used both frameworks pretty extensively, and both have their warts and advantages, but when you come right down to it, there aren't that many differences for someone coming from your background.
In my area (Minneapolis), the grails market is larger than the rails market, but that isn't the case everywhere.
I'd pick whichever one has the user group in your area that you connect with the most. That will be your best bet for finding work with whichever one you choose.
You've mentioned that you're already into Java, Spring and Hibernate. Well, Grails is based on those - in continuation.
Spring is a very comprehensive, powerful, and modular, framework. Hibernate has been a de-facto standard, and is compliant with Java EE 6's JPA. Both are most relevant in the Java world.
So, there's the aspect of consistency of your technical knowledge. From Spring/Hibernate to Grails/GORM you'll have cohesive knowledge.
Another central aspect is your options. When dealing with Spring, you'll probably soon learn how easy it is to change complete architectural layers, like, changing the view technology, or database layer, or simply exporting a web service by configuration. Spring-based applications can be highly modular, and you can plug-in almost any technology scope you could think of. - So you have many ways to go further if desired.
The Spring framework has been written from the ground to foster best practices. Just dealing with that framework will teach you a lot.
Admittedly, I haven't dealt with Ruby on Rails, at all. I regard it a rather isolated technology, while Grails is a (Java and Spring) integration framework to me, with the backends/grounds and options as mentioned above.
When evaluating practical aspects of technologies, it's always a good idea to do some research on Google Trends and Indeed job trends. Other indicators on popularity/relevance are the numbers (and trends) of mailing list messages for Grails vs. Ruby on Rails, and (not quite an accurate measurement for niche languages) the TIOBE programming languages index.
Finally, Java had experienced several years of starvation and uncertainty in the past (despite of being one of the few all-time languages and frameworks, at all, and a long-burner). Recently, however, several evident signs came up that appear to seriously forecast a much brighter future than before.
As a Grails developer...
Grails runs on mature and proven virtual machine (JVM) and really do the best performance compared to any dynamic language, even static Java/JSP when using Freemarker Plugin! http://www.jtict.com/blog/rails-wicket-grails-play-lift-jsp/
Grails uses Groovy, so it has an almost flat learning curve for Java developers. You can write Java syntax and gradually learning Groovy syntax, closures, meta-programming and more... getting expressiveness and agility of a dynamic language like Ruby.
Grails uses modern principles and practices like Convention over Configuration and Scaffolding, just like Rails taught us all.
Grails uses a mature platform, so it comes w/ all great existing java libs, mature groups and projects like Apache, Eclipse, JBoss and so on for reporting, file exporting, legacy integration... and many new well-supported libs and frameworks from Google and others like Guice, Guava, Collections and so on...
Grails uses a vastly used platform, so you can reuse all your existing java libs. You could reuse your entities, utilities, and so on...
Grails use existing Java infrastructure, so it comes with many ready & mature server w/ great documentation (i.e install, configuration) Tomcat, Jetty, Glassfish, and so on...
Grails use existing Java infrastructure, so it scales very well w/ many ready & mature options: Server Clustering, Open Terracotta, Second Level Cache, and so on...
Grails runs on top of well-know and vastly documented frameworks like Hibernate, Spring MVC, Hibernate, SiteMesh, and so on... and you can step down into abstraction when you need, i.e batch imports, complex reporting queries, complex interfaces, and so on..
Grails has a great plugin ecossystem much like Ruby Gems and can use all existing Maven-based lib repositories to resolve dependencies.
Grails uses a solid platform, so you'll always reuse your libs (JARs) with the next Language of The Year (LOTY). "Write Once, Run Ever"
Hope that helps! :-)
If you liked Ruby's syntax and simplicity, go with Rails, and run it on top of JRuby, which will give you access to Java classes as well.
Check: http://blogs.oracle.com/coolstuff/entry/using_java_classes_in_jruby
SpringSource (now VMWare) has two very similar technologies: Grails and Spring Roo. I have been using Grails, but I see that SpringSource is actively working on something that is a competitor for that technology and that makes me worried about the future of Grails.
Does anyone know how these technologies relate, are they going to be merged, or one of them will be abandoned?
Besides, are there any important technical differences betweent Grails and Roo?
SpringSource's goal is to make it as fast and easy as possible for people to build, run and manage Spring-based solutions. We have both Grails and Spring Roo because we deeply care about developer productivity and unquestionably both of these tools deliver a serious boost to what teams can achieve on top of Spring.
We have both technologies because Roo and Grails are very different at philosophical and implementation levels (as already noted in the other replies). Each technology approaches its primary language (Java or Groovy) and operating model (dev-time or runtime) with the philosophy of "how do we make the value proposition unbelievably good using this language and operating model combination?". As such you'll see each technology adopting a different style that maximises that combination (Roo's Java+Dev-time or Grail's Groovy+Runtime) and the commensurate benefits.
These differences are actually very positive, because they mean the Spring community can chose which "flavour" of productivity solution they prefer. While these initial differences around language choice and runtime/dev-time operation are immediately apparent, the choice of Grails or Roo also extends to more subtle considerations such as the default technologies used, user interaction model, IDE support, dependencies, standards, roadmap, extensions etc. Nearly all of these differences are a natural consequence of pursuing a best-of-breed solution for a particular language style.
Our best advice is to consider both solutions. Each have their sweet spots, but there are differences between the two which will make your overall experience better with one technology or the other in a given context. Both reference guides detail the respective benefits of each solution. Of course, remember the time investment is minimal in trying both out. In 10 minutes you can build a project in Roo or Grails, so give them a try and see what feels more natural for you given your specific background and project needs.
The main difference is that Roo is a pure Java framework whereas Grails leverages Groovy as well as Java. Both are built on the core Spring libraries and make use of popular Java open source libraries.
This question was asked back when Roo was announced and Graeme Rocher (Grails lead) says that both frameworks have a place within Spring and are supported equally.
If anything, I think Grails has a brighter future than Roo. I love developing with it and don't see any downsides to it not being pure Java.
Grails and Roo are very different. The first major difference is the language used. While you can write Groovy code like traditional Java code you still need the Groovy dependencies to run Grails applications. To be as productive as possible in Grails you also need to have a grasp of features in Groovy that are not currently part of Java such as Closures. Another difference is the philosophy the frameworks take to generating code. Grails generates a lot of methods at runtime while Roo generates them on request during the development process. Roo has no behind the scenes magic accept for the usage of aspect oriented programming, and you can view all the code that Roo generates. For example in Roo you must use a command to have it generate dynamic finder methods such as findByBook() and then view the generated code in the .aj files. In Grails the findByBook() method is created at runtime, and you can’t view the generated code. Roo also allows you to stop using the framework if you chose while continuing to have a running application by merging all the generated code into normal .java files. You then have no dependencies on any Roo libraries at either runtime or design time. If you decide you don’t like Grails there’s no way to stop using the framework while continuing to have a functioning application.
IMO the two are not very similar. Even though there are similarities the following are significant differences:
Roo uses "Stock-Standard Java",
Grails is based on Groovy
Grails is a Web framework, Roo is not
Roo is very similar to Grails' command line system (e.g. the create-app, create-domain-class, test-app type commands found in Grails). I would not be surprised to see some "cross-pollination" between this part of the Grails framework and Roo.
Ben Alex from SpringSource talks about Roo in this interview and he is asked about Grails vs Roo. The main difference besides using different languages (Groovy vs Java as others mentioned) is that Roo is mainly a development time tool and Grails is more involved in runtime.
They're actually not that similar. Roo does it's magic at compile time, where Grails is does it runtime. Because of that Roo projects does not take any performance hits at runtime.
I can't see how they could be merged as Grails is built upon Groovy and Roo on Java.
I saw some comments on the Grails mailing lists which indicated that the authors believed that Roo exists only as a stepping-stone to Grails! However I am personally considering a possible switch from Grails to Roo. I think the main difference is between dynamic and statically typed languages - to me this is huge. I love many features of Grails but I prefer the IDE support and compile-time checking of a statically typed language. Some others feel exactly the opposite, hence horses for courses. That said, static groovy is currently under heavy development so who knows what the future holds.
We had a requirement where we had an application in production and was developed in Spring MVC and the velocity of developing new features were slow. We had to explore alternate frameworks like Grails and Roo. I personally spent close to a month exploring which one was better.
If you want to see the details of the analysis visit # http://krishnasblog.com/2012/05/08/roo-vs-grails/
We explored following features in both these and below is our findings. The final verdict we are not sure we will use either one, we are still exploring
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Closed 11 years ago.
I have been using Grails for the past few months and I really like it, specially GORM. However, I am getting interested into Scala's Lift. Therefore, I would like to know your opinion about which kind of web apps are better suited for which of those two frameworks or it is just a matter of taste, which framework to use?
Finally, which of those frameworks do you think will be more used in the future?
I have the feeling that Grails is far from reaching a critical mass and it still remains very obscure (in the past few months I had the opportunity to work with middle size companies and IT startups working mostly with the JVM stack and only one person knew and used Grails) and I am not even sure if it can become the "RoR" of the Java world (Indeed reports a drop of growth in the last few months even if other frameworks have a positive growing rate). And I love Groovy, it is really easy to learn but I have noticed how slow it can be for some tasks.
On the other hand, Scala seems to be more popular (Tiobe Index) and the fact that Twitter is using it now gave it even more presence in the blogosphere with lots of lovers and haters making buzz. It is famous for being fast and scalable. However, the language seems somewhat hard to understand and learn for lots of developers (so maybe it will never gain mainstream status). Lift is little known and I have read some reports that it is better suited for small apps (less than 20 domain classes).
By seeing the number of books published Groovy-Grails dominate right now, but many publishers have Scala books on the works, so I think this advantage will not last long.
Finally, we have the problem that both languages and frameworks still have poor IDE support (it is getting better by the day but far away from what Java shops expect to be productive).
I do not want to start a flame wars, but I would be very interested to hear other users' opinions.
The accepted answer here takes a really ignorant view on Groovy - it is a modern, dynamic language (dynamic vs. static is a huge debate in and of itself, and not particularly relevant here). This is by design, and therefore not a disadvantage, just a difference. It has a lot of modern language features that Java does not have such as closures, native regexp, polymorphic iteration, some optional static typing (matter of debate, but also look at groovy++), native syntax for lists and maps, etc.- you can see a comparison here http://groovy.codehaus.org/Differences+from+Java
To address the actual question of Grails vs. Lift, I'd say Grails hands-down. It has the SpringSource behind it, and just look at the plugins page http://www.grails.org/plugin/category/all - I can't even find what plugins or equivalent are available for Lift. Grails is also on top of the latest cloud-friendly technologies, with features like native RabbitMQ messaging support, and turnkey GORM support for MongoDB and Redis.
Grails is a nice idea(but only "stolen" from rails) but the fact that the groovy guys are not interested in getting proper Eclipse support is hindering it's success a lot. I've even seen Eclipse questions not being answered at all on the grails lists.
I agree with Tim that Netbeans 6.7 finally delivers the first half way usable Open Source IDE support for groovy/grails - and eventually, SpringIDE will also feature better groovy/grails support.
The reason many Java folks love Java is the static typing, which enables tools to help you a lot with many things. This is lost with a language as groovy.
Yes, I could write every really important piece of Code in Java and still use Grails - but then, why should I, just to save a bunch of lines of glue code, do that instead of learning to use a Java framework highly effectively?
To come to an end: I did not yet look at scala, but built some simple apps with grails - and I tend to go back to java, even reimplementing every app that needs further development in a plain Java framework - I think wicket and Seam.
I'll also look at Scala/Lift, I heard many good things about it!
BTW: I'd compare communities and look at mailing lists - how many peope are there, do they get good answers on their important questions?
Grails seems to have a non-answered rate from nearly 50%, which I feel is bad.
Grails support in netbeans 6.7 is really good, as well as the idea intellij support in Maia.
Eclipse is still pretty sucky.
I looked at lift, but was concerned about the resources available now; this will change in the future, but my projects can't wait.
I would like to specifically answer the question "for which kind of applications". The main difference between the philosophies of Grails and Lift seems to be that Grails enforces MVC whereas Lift seems to be more liberal i.e. it doesn't enforce MVC but provides enough avenues to use MVC if you want to.
Also Lift seems to be excellent for 'Single-Page Applications', especially if you need to implement a server-push functionality using technology like Comet (which obviously doesn't imply it's not good for other types of applications). On the other hand, Grails seems to be better for the 'Enterprisy' applications, especially if you are already familiar with Spring and Hibernate but want your app to be much more concise (using Convention over Configuration) than what a non-Grails app would be using these technologies.
References:
Simply Lift, chapter 13
Single-Page Application
Disclaimer:
I have just started exploring Lift and built some simple apps using Grails.
With all the performance improvements and advancements of Grails2.0, with great support provided by IntelliJ 11 for the framework, an ability to plugin pretty much any advanced web technology into your grails app., and yes - VMware weight behind it - I really don't see how Lift could be an advantage or a good choice. Just think of using two different languages in the same application, need for double expertise in the team, etc.
The original question has been posted like 2+ years ago and I think time showed on which side is the choice of the dev community ;)
Given that both Ruby on Rails (RoR) and Grails can run on the JVM (Java Virtual Machine), which language and framework enables equally competent and experienced developers to be more productive and roughly by what percentage? (i.e., deliver more business functionaity for the same amount of effort)
I know that Grails is easier for a Java developer to transition to. And I realize that the entire Java Library is available to a Grails developer. My question is regarding developer productivity in an environment where one runs on an JVM on Linux using the standard application servers (WAS, Weblogic, JBOSS, TOMCAT etc.). Note: JRuby will be used to enable RoR to run on the JVM.
I would requests answers from those that have done significant web applications development using both ROR and Grails.
If all you're looking for is a 75% answer: grails
I've done significant development on both platforms, though my major rails experience ended about a year and a half ago (before rails 2.x was released).
I've been heavily involved in grails development since grails 0.5.
The answer really depends quite a bit more on the developers and infrastructure that will be available to work on the project. If you're looking to deploy to a standard java app container (like Tomcat), I think that Grails is the better choice. If you're looking to do something with mongrel/rack/pound/etc. Pick rails.
If there are particular gems/jars that fit your business problem, that would obviously affect your decision.
The choice of Grails for me isn't so much because I think that it's better at solving all kinds of problems, but more because I like the grails developer community better and I like the groovy language a little more.
I've also found grails to be an easier sell to the places I've worked at over ruby/rails. There are many more java shops around here and it's less of a leap for them to make that transition.
This is a personal preference and I could easily see someone else going the other way.
Rails has quite a few things going for it, and I think the test driven development story there is much better (though I'm working on trying to fix that).
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Closed 10 years ago.
Grails vs Rails. Which has better support? And which one is a better choice to develop medium size apps with? Most importantly which one has more plug-ins?
One other thing worth mentioning: the design philosophy of both framework is somewhat different when it comes to the model. Grails is more "domain-oriented" while Rails is more "database-oriented".
In Rails, you essentially start by defining your tables (with field names and their specifics). Then ActiveRecord will map them to Ruby classes or models.
In Grails, it's the reverse: you start by defining your models (Groovy classes) and when you hit run, GORM (Grails ActiveRecord equivalent) will create the related database and tables (or update them). Which may also be why you don't have the concept of 'migrations' in Grails (although I think it will come in some future release).
I don't know if one is better than the other. I guess it depends on your context.
This being said, I'm still myself wondering which one to choose. As Tom was saying, if you're dependent on Java you can still go for JRuby - so Java reuse shouldn't be your sole criterion.
I guess if you are a Java developer and want to have access to all the existing enterprise Java libraries and functionality... go with Grails.
Rails is more mature, has more plugins, has a bigger userbase, has better documentation and support available. It can also run on JRuby giving access to Java libraries if you require.
Grails has some interesting qualities, but can't claim to be up there with rails just yet. However, if you're predominantly a Java or groovy developer you may prefer it. Otherwise though, I'd suggest using Rails for medium sized projects right now.
I say grails since there are so many java libraries out there. But I am a bit biased due to the fact that I come from a java background.
If the app isn't going to be big, either suffices - and the choice ought to depend on existing infrastructure. Say if you already have a java servlet container server running, you might as well stick with grails instead of provisioning another server for rails.
I used rails before and liked it quite a bit. However, my current company had a lot of legacy java code and therefore the natural choice was grails.
When I started with rails, very few sites were using it and documentation was atrocious. There was railscast that was great and railsforum.com, but anything out of the ordinary, you're on your own. Deploying it was a nightmare, and using mongrel-clusters was not really production ready. This is very different now as everybody can see, much more mature and deployed everywhere.
Over a year back, I had to learn grails due to reason I cited above. Transitioning to grails was very easy, since it is very similar to Rails. Again, it was very similar to the early stages of rails, with one huge difference. Because you can easily import java code, grails users can use almost all the production tested java libraries available out there. I've been able to successfully integrate our legacy java projects into grails projects and very little tweaking are needed. You will also notice that plugin development has been rapid, mainly because developers are just writing grails "hooks" but the underlying code are the old java libraries. Deploying grails is also just deploying a WAR file.
Another thing you have to look at is IDE. If you're comfortable with eclipse, then eclipse-STS for grails gives you all the bells and whistles. I still see a lot of rails developers use textmate, though rubymine has made great strides (the early version of rubymine used to grind my ubuntu to a halt).
The bottom line, both are great MVC frameworks. RoR is much more mature and has a lot more developers. Grails is where RoR was 3-4 years ago, but I see the progress a lot more faster. Hope this helps.
It depends on your skills with Ruby and/or Groovy, whether you have legacy Java systems to deal with, and where you want to deploy your applications.
I was initially thrilled with Rails. At the time, there wasn't an option of deploying on the application servers at work since work is all Java. This has changed. I couldn't abandon the Java infrastructure and applications already in place and switch to Ruby, even though I thought Rails was awesome. Grails works because we can mix and match Groovy with the existing Java solutions.
Outside of work, Ruby is easier to find hosting for at the low end of the price spectrum. Because Grails uses a lot of existing Java projects the .war files, even for a small app, tend to be large. If you have a dedicated server this isn't a problem but trying to run on shared hosting with 128 MB RAM doesn't work.
2008 is the year of Groovy and Grails books but there are still many more Rails resources available.
Based on your specific criteria, Rails may be a better framework to learn. If you have any Java knowledge, or baggage ;-), you should look at Grails.
Seeing as how the guys who make Grails just got bought out by Spring source yesterday, I would say Grails.
Also, since Groovy is a superset of Java, you can dive right in just using the Java you know without having to learn Ruby. Now, you'll learn a lot of dynamic stuff too and eventually write Groovy code instead of Java code, but it lowers the barrier to entry.
Grails all the way!
I would go with Grails since I like its approach (specify your domain classes and have Grails generate everything else) better than the Rails one (build database tables and have Rails generate everything else). If you're a Java developer, you'll also like that Java code is valid Groovy code, and a Groovy class is a Java class so the integration is seamless both ways.
As a Grails developer coming from Java, I loved it from the very first time.
Now, I'm starting to dig into Rails and having problems with gem. While MySQL connection setup with Grails was pretty straightforward, I'm still struggling to make it work with Rails.
The command gem install mysql is not working, apparently because I don't have XCode intalled.
If it weren't for its memory consumption issue, I'd say Grails is perfect.
May I suggest Merb? It is rack-based, modular, ORM-agnostic, built for speed from ground up by Ezra Zygmuntowicz. It is starting to gain some heat now...
Rails is more mainstream, but less flexible. Grails is still changing rapidly, doesn't have the same developer ecosystem, and the documentation isn't nearly as mature, but it will work in some situations Rails won't.
I have used turbogears and rails a little bit. Before using rails, I tried using grails because I was using groovy for my scripting. Grails was a difficult experience.
The groovy call stack is difficult to read for a small program, but when you add in several heavy weight frameworks a simple error can yield 100s of lines. Unlike rails the grails version that I was using didn't have tools to help me determine what was mine and what belonged to the framework.
I eventually switched to using the Google Web toolkit since I really didn't need the database.
I think Grails and Groovy hold promise, but the user experience of working with them is cumbersome at present (present being last spring).
I think it depends on the environment you're working in to some extent.
Grails seems to have more corporate level acceptance.
Rails has the Koolaid-vibe, and is very acceptable for start-ups with no legacy systems.
Personally I'm using both. Though only really just starting out in the Grails world - I like that authentication/authorisation is easier in Grails-one simple plugin; Shiro. I like that Rails isn't dependant on JVM, and doesn't take a minute or so to startup.
I find setting up BDD/Cucumber within Rails was far easier, but that could just be because that's what I'm comfortable with! There's definitely efforts in the Grails world (cuke4duke etc) to make this easier-and an active community developing Grails.
Just my 2p·
Try both :)