- front end for end users
- front end for administrators and other special users
- Easy creation of templates and tag libraries
- business logic persisted to database
- (java back end - this can be discussable)
Let see each of these points.
Front End for End Users
Regarding front end for end users different requirements may be important. Maybe you want fancy front end with lot of Ajax. If this is the case you have different plugins available like (GWT, Flex). This means you can easily integrate advance Ajax concepts into front end. If you need only simple Ajax you can achieve this with the core grails functionality. You may want to have a look on one of my previous posts Grails and Simple Ajax. At the final end, as with all frameworks to have really nice user interface you have to work hardly and cannot achieve this in minutes. With Grails it may be faster but need not. But the real velocity comes with further features.
Front End for Administrators
Creation of front end for administrators is mainly out of the box. Just try to think what are administrators responsibilities. They have to create something (usually business objects), they have to approve something - usually on business objects, they need to have overview of the system status - usually on business objects. Mainly they do not need fancy user interface. No fancy user interface means that you can use one of the grails out of the box features - scaffolding. For each domain object grails can for you generate CRUD screens. For administrators to be able to work with these screens minor if any updates are necessary.
Easy Creation of Templates and Tag Libraries
With Grails creation of templates and tags is so easy that very soon you will realize that all gsp files are created from templates and tags. Code that influence readability of gsp files, at least for me, are conditions, loops and similar programmatic constructs. All these constructs are easily replaceable with template or tags. Actually, when I create template, I immediately create tag for that template and after that work only with tag. To see example of template and tag lib you may want to have a look at my post about templates and tag.
Business Logic Persisted to Database
Here comes full power of the Grails. Just create domain object and database tables are generated for you. Even database is automatically updated when you update domain objects. For each domain object or relationship between domain objects you can create basic CRUD screens. Learning how to work with domain objects does not take a long time and if you have experience with Hibernate it can take you less than a day.
Generated front end for administrators and working with domain object on the low level will be useless if there is no security for application. For sure in the most of the cases we cannot allow end users to see domain objects in CRUD screens. It means we have to secure CRUD screens. This is actually not a problem. There are security plugins for grails. I have used acegi security plugin. It will generate all necessary classes and screens for you. All you need to do is to specify what is visible by which role. And this configuration is really very simple. So in matter of minutes you integrate security into application. I am not sure about advance features as I didn't have used them but probably it should not be complex either. How much time it usually takes you to secure web applications developed with other technologies?
These days searching is popular. And of course it is useful. All data on you web site will be useless if users cannot find them. Grails has solution for this too. You can use Searchable plugin. You add line of the code to the domain class(es) and out of the box you have searching integrated into your application.
I must agree that this is really discussable if we need Java or no. But in the case you want to have backend implemented with Java, important thing is that Java is integrated with Grails applications seamlessly.
I have just made short overview of features that was most useful for me so far while working on grails application. Features mentioned are not full set as grails frameworks contains lot of other important capabilities. Just to mention few of them: easy unit, functional and integration testing, excellent plugin system, work with XML, web services...What about your experience with Grails?