Raible Designs

[TSE] The Holy Grails of Web Frameworks with Guillaume LaForge

I only made it to the 2nd half of this talk because I got stuck in traffic on I-95.

Under the hood, Grails uses Spring MVC. It has support for "flash scope" between requests.

I find it funny that flash scope is so popular these days, we've had this in AppFuse for four years. However, web frameworks didn't add native support for it until it had a name (provided by Rails). To be fair to Struts Classic, they had support for it before Rails was even invented.

Rather than JSPs, Grails uses Grails Server Pages, which look much like JSPs. Grails uses SiteMesh by default and allows you to easily change the layout used with a meta tag.

<meta name="layout" content="main"/>

Most of the dynamic attributes in a GSP are rendered using the various "g" tags. There's dynamic taglibs for logic (if, else, elseif), iterating, linking, ajax (remoteFunction, remoteLink, formRemote, submitToRemote), form (select, currencySelect, localeSelect, datePicker, checkBox), rendering (render*, layout*, paginate), validation (eachError, hasError, message) and UI (i.e. richtexteditor).

Grails also allows you to write your own taglibs with a much simpler syntax. For example:

Then you can use it in your GSP:

<g:isAdmin user="${myUser}"> 
    some restricted content 
</g:isAdmin> 

Is Grails Enterprise Ready?
Yes, because it uses existing Java libraries. Since you can create a WAR from your Grails project (using "grails war"), you can "protect your investment" and deploy it to your expensive app server. Although Grails is based on Groovy, it's a very easy language to learn for Java developers. In fact, there's hardly anything to learn. Most of the learning involves learning simpler ways of doing things. You can also use GORM (and its dynamic finder methods) outside of Grails. You can re-use the EJB3 annotated mapped beans and even the taglibs in your JSPs - it's all Java bytecode in the end.

More to come! On the roadmap: DSL for scripting Spring, plugins, flow/conversation concept with Spring Web Flow, JPA support, Web Services convention, customized URL mapping, JSP custom taglib support and finer-grained DB schema control. "It's up to you to vote for and prioritize new features!"

Books: Groovy in Action will be printing next week and The Definitive Guide to Grails will be out early next year. The existing documentation for Grails is 224 pages - so there's lots of information freely available as well.

My Thoughts
I didn't know that Grails allows you to generate Canoo WebTest tests for your UI. I agree that WebTest is an excellent way to test UIs, but I think Selenium is better. The major reason they're using WebTest seems to be because one of the WebTest guys happens to be a Groovy committer. I plan on learning (and hopefully using) Groovy and Grails in 2007.

The reasons for the Groovy and Grails projects seem kinda strange. I created AppFuse to solve my needs when starting new Java projects. Rails was extracted from Basecamp because it solved problems for DHH. Grails seems to be invented as a Rails clone. It doesn't actually solve a problem - except that Groovy needs a "killer app" like Ruby has with Rails.

Regardless of Grails' reason for living, I still plan on adding it to my toolbox as it seems like a very nice way to develop web applications. Maybe that's its reason for living? My question is this: do its developers use it to write real-world applications, or is this another project (like Craig McClanahan and Struts) where the lead guys don't actually write real-world applications?