Monday, April 6, 2009

Creating Grails Application

[From the series - creating software books reviews grails web application]

In this post just for the sake of completeness I will shortly describe how to create grails application. As in the series of the post I will more or less explain some aspects of programming in the Grails and partially recreate software books reviews site the project to create I will call sbr (short for software books reviews).

Note: I am currently using Grails 1.0.3 version.

Creating Grails application is very easy. Open some command line tool and execute the command:

grails create-app sbr

Now the folder named sbr is create and in this folder is new grails application.

Actually you are already able to start this web application by executing following command from the sbr folder:

grails run-app

To access the application in the browser enter: http://localhost:8080/sbr.

In the case you want to start application on another port you can do that using following command:

grails -Dserver.port=[port_number] run-app

And of course instead of the [port_number] you should enter number of the port on which you want to start web application.

When Grails application is started this way without any changes it is run using embedded Jetty web container and in-memory HSQLDB that is default Grails configuration. Later on I will explain how to change database and how to deploy to Tomcat.

Let me shortly explain folders of the grails application. The top level folders are displayed on the following screen shot:


Short explanation of generated folders is:

  • grails-app actually contains the main part of the grails application and will be explained separately
  • lib - contains all external dependencies to other java libraries and is by default empty
  • scripts - contains scripts and is by default empty
  • src - contains java and groovy source files and is by default empty
  • test - contains unit and integration tests and is by default empty
  • web-app - contains web application

The content of the grails-app folder is much more interesting because it contains the heart of your web application.


Names of the folders should be self descriptive enough but shortly:

  • conf - contains configuration of the application. From this folder you are able to configure different aspects of the grails application like: datasources, hibernate, spring, bootstrap and so on. In the later post I will explain at least some of those files.
  • controllers - contains controllers of the web application. Controllers are accessed from the views and of course represents C of the MVC pattern
  • domain - is folder that will contain all application domain objects. All application domain objects are persisted while the database schema is automatically generated using hibernate. All domain objects are thanks to Groovy by default enriched with number of useful methods.
  • i18n - is folder used to localized application
  • services - are different services that can be used by controllers or domain objects. They are automatically initialized and inserted using spring. They also provide transactional behavior.
  • taglib - folder that will contain custom tag libraries. Tag libraries are excellent feature of the grails that enables you to modularize front-end of the grails application. I am using them heavily.
  • views - is the folder that contains html and gsp files of the application. In the one word it contains "pages" of the web application.

And although not directly visible in the folder list, another important part for modularizing front-end of the grails application are templates. I will explain how templates can be used in the later posts.

In the next post I will shortly explain general aspects of the grails application, or namely all folders of the grails-app folder. So stay tuned :)

P.S. Don't forget to write some review or post summary on the software books reviews.

1 comment:

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