Thursday, March 26, 2009

Book Review: Learning Ext JS

Learning Ext JS
I recently took the opportunity when approaced by Packt Publishing to review "Learning Ext JS" by Shea Frederick, Colin Ramsay, and Steve Blades.
The book is produced as an "eBook", delivered in a PDF format with the book examples available in a zip file.

For readers not familiar with Ext JS, it is a cross-browser JavaScript library for building rich internet applications. It features highly attractive customizable UI widgets supported by a well designed, documented and extensible Component model.

The book is written with the experienced developer in mind. It's all about getting productive as quickly as possible. We've all been there, thrown into an unfamiliar technology and expected to perform miracles overnight. In these situations you can find yourself floundering, looking for some starting guidence while you try to find your feet.

The book is focused very specifically on Ext JS, so if you've never dealt with HTML or javascript before, I'd suggest a second reference to cover that as well.
Having said that, if your just working with Ext JS for your presentation interface, the book is complete enough to get you up and running.

After an obligitory introduction chapter, and some foundation concepts, your quickly working with Ext widgets. Very soon your creating Ext JS forms, applying textfields, datefields, combos, toolbars and validations. The very popular Grid an Tree components are also well covered, with Layouts appearing surprising late in the book.

I enjoyed the flow of the book, which is written in an easy reading light hearted style. The examples clearly explained the concepts, and raised a few chuckles at the same time. Examples that included server-side code assume a PHP backend, a fairly typical implementation for Ext JS.

I work with Oracle Application Express and PL/SQL, never the less the examples were easy to follow if you focused on the format of the server output rather than the implementation language.

Overall, if your starting out with Ext JS, or struggling understanding the Ext JS examples and scattered forum posts, this book is a good reference.
Chapter 7: Layouts is available as a sample chapter.

Friday, March 20, 2009

APEX Global AJAX variables - gotta love them

I've just added a fully AJAX enabled editable tree on my demo site.
All modifications to the tree are transmitted to the database via an application process using AJAX.

Values are submitted using wwv_flow package variables:
  g_x01 .. g_x10

The application process simply calls a database package, which references the wwv_flow package variables and updates the data.
The key to AJAX functionality in Oracle Apex is based around these "Global input variables for AJAX utilities".

Using these variables, a little javascript to call a simple application process and then we handover to PL/SQL - back in every Oracle developers comfort zone.

This example has a fair bit going on, to see a simpler example check out: