Monday, November 28, 2011

Grails 2.0 - the power is back

Recently I've been bitching about the stability of Grails 2.0 and specifically the lack of it. Tons of stuff was just wrong: the new GSP parser was buggy like hell, hot-reloading using the new agent just didn't work - you name it. But with the RC1 release most of it is gone and the new version of Grails starts to look like something you could actually use!

Hot reloading.

Since its early days Grails was the number one framework and that in most part due to its hot-reloading capabilities. You could just change a view, controller or service, wait just a few seconds and the result would emerge after refreshing the page. That presented a huge advantage over classic Java EE development where a single change in the code forced the developer to recompile and restart the whole application. That's why I hate regular Java EE development with a passion. Sure there's the Java Rebel thingy but it costs money - a lot of money!

Grails 2.0 uses a different approach than the one in 1.x series but a similar one to Java Rebel. There's a Java agent that does all the heavy lifting of incorporating new code into existing application. So let's summarize what works and what doesn't:

- reloading controller - check
- reloading services - check
- reloading url mappings definition - check (with the exception of mapping to HTTP codes)
- reloading domain classes - not working
- reloading Groovy sources under /src/groovy - check!
- reloading Java sources under /src/java - check!

There might be other areas but the general impression is really awesome!

New scaffolding templates

Well.. they are nice and green and dandy and... well I liked the old ones better (from the general look-and-feel point of view). The new ones still use the word "main" for everything: CSS, template and the application.js. Does anyone knows who made that stupid decision to call "main" or "application" something that should be called "scaffold"??? In the current state of things if you're thinking about doing anything serious with Grails you should install the templates and rename them to something that makes sense, like for example main.gsp -> scaffold.gsp or main.css -> scaffold.css. Other than that it's looking really good! Just the fricken naming...

Resources and other capabilities

Well, finally the resources plugin made it into the core! So from now on the problems like having lots of small JavaScript or CSS files and cramming'em together for the release version are gone. This is probably the only platform out there (besides ASP.NET :D) that does it right from the start. Granted it doesn't come for free - you need to configure it properly and it can be an unpleasant experience all along (unlike in ASP.NET where it's actually a part of the page itself). But at the end of the day it is really useful and you should use it.

Also the Datasources plugin found its sibling in the new release! This will be a blessing for everyone that needs to work with multiple databases in their Grails applications. In the databases plugin configuration was "almost" like the one you'd normally have but different enough to make you curse the creator more than once. I'm delighted to say that this has been unified and finally all datasources can be specified in the same configuration file, DataSource.groovy. Yay!!!

And last but not least - testing. Finally someone took the hard dependency on old 3.x JUnit and flushed it down the toilette! Man that was really what I was looking for. All test cases are now JUnit version independent and use the coolest Groovy feature ever: Mixins!
Finally testing domain classes in isolation is possible and doesn't make you puke at the mockDomain() call every time you see it. Finally the power is back!


I've received some notifications that the plugin architecture has change a bit and that some of my plugins (namely the json-rest-api) don't work properly. It's sad but not unexpected. The general idea is that plugin authors will have to take a good look into regression before they can 'certify' their plugins as 2.0-ready.


The general feeling of Grails 2.0 is really great. Finally playing around with most of the UrlMappings is simple and fast (which it wasn't in 1.x), testing is fun again (even with Spock and the like) and all the rest is just great. So I guess the final message should be "go and use and forget about 1.3.7 that has been around for like ages".

And finally I really need to get this out of my chest: when it comes to regular Java EE development like with JSF (outch), Struts or what have you one should really go kick some corporate butts to get them to start thinking again that web development shall not be a nightmare anymore. We have the technology, you know, to make it right for a change!

Go spread the word!


Leo said...

There are still some critical bugs in RC1 and snapshot versions so take care not to break your code when upgrading. It probably make sense to wait for RC2 to be released in a few days.

Matthias Hryniszak said...

@Leo: care to share what they are?

Leo said...

In RC1 one of the critical issue was incorrectly working totalCount property (see GRAILS-8206) . In the current snapshot the most critical issue seems to be a broken Spring Security plugin when used together with Resources plugin - (see GPRESOURCES-111). There were other major issues as well which can be checked out in Grails JIRA.

Matthias Hryniszak said...

Non the less the RC1 is stable enough to start testing your code against it. Previous versions were simply not usable at all...

Let's keep our fingers crossed for the guys at SpringSource to do a good job.