April 2008 Archives

This is my first review of a book. I am sorry if I am too harsh. But these are my thoughts about the book. Good or bad, I would like to congratulate Packt publishing for accepting the publication of a book about a moving target. Catalyst is all but stable, and things change from week to week.

On to my comments:

The first chapter is a concise introduction to MVC. Instead of describing the details on what this approach means, the author motivates the user for its need. No big definitions are given: just the needed to understand the Catalyst architecture. At the end, a small section discusses the Catalyst framework installation. I would not add that section to the end of the first chapter, but probably as an introduction to the second one. But there are just details.

After this quick presentation on the MVC design pattern, the author introduces the implementation of Views, Controllers and Models. This introduction is very soft, but enough to the reader to start understanding the basics of Catalyst. Sometimes the author tries to explain a little detail that will be expanded later without much success. If you have an idea of Catalyst you will be able to start writing your first application and exploring some new features of Catalyst.

The third chapter main purpose is to present a basic CRUD: Create, Read, Update, Delete application. It starts with the definition of the database model, exactly where the most audacious reader will be making questions. This makes it a good complement of the previous example. Follows some details on how to build a form using Catalyst::Controller::FormBuilder, and how to use this form for creation and updating of database records. While the examples are easy to understand, all this reference to new modules makes it difficult to know the real power of each.

While I was expected some details on how to debug applications, so the reader could make more experiments and grow on his knowledge, the following two chapters are more of the same, presenting more plugins for Catalyst. While their content is relevant I feel like the reader have two choices: or follow just the examples presented on the book, or go digging on Catalyst documentation for help on debugging his application.

The fourth chapter includes two important sections: sessions and authentication/authorization. These sections present the basics for data persistence between requests, and a method for the authentication and authorization of users. Other sections on the same chapter include minor topics that I would defer for later chapters.

Follows a chapter with a new example, with a more complicated database. This new example is used to introduce more details on DBIx::Class module, explaining how to perform chained queries. It is also used to explain the Args attribute for controller methods. It is a shame that there isn't a section about chained actions, and that attributes like Args and Stashed are not present in the final index.

The next chapter is dedicated to the extension of DBIx::Class. It includes some details on how to access databases directly using SQL statements, and how to extend DBIx::Class packages with user-defined functions. Given that the previous sections were written in a tutorial approach, the DBIx::Class details are spread in three or four chapters.

The seventh chapter is another off-topic chapter. I know that it is important to have a WEB API to make other applications cooperate with our. I know that actual web sites are all full of AJAX. I know that I subscribe to a hundred of RSS feeds. But these are not important for somebody who is still learning to use the framework. These three sections are mostly a description of three modules.

Follows two important chapters: testing and deployment. I think these chapters are well placed at the end, and they are useful specially when the application is in the final moments. I still miss a chapter on debugging. How does a Catalyst developer debugs? Should she print debug messages to the standard error? Is there any way to get debugging information well structured?

My final remarks about the book is that it includes a lot of interesting material, and full of good examples. Although there is a good tutorial on CPAN by the same author of the book, I really advise to buy the book. It is a good investment!