Justin Hunter > Reaction-0.002002 > Reaction::Manual::Intro

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NAME ^

Reaction::Manual::Intro - Introduction to Reaction

SYNOPSIS ^

  Moose + Catalyst + Layered Models = eternal happiness

MOTIVATION ^

While Catalyst is a very powerful and flexible web app framework, many pieces end up being recoded for each new application: user interfaces, in particular.

Meanwhile, advances in Perl metaprogramming (especially Moose) have opened up new possibilities in terms of introspection. Why not build user interfaces based on class metadata? This would allow the user interface templates to be very general where possible.

Thus, Reaction is basically an extended MVC framework, which leverages class metadata to reduce or eliminate UI coding.

But it's much more....

DOMAIN MODELS AND INTERFACE MODELS ^

Many programmers are now comfortable using ORMs of one sort or another - DBIx::Class, Class::DBI, Hibernate, etc. These systems are wonderful for bridging from the world of OO into the world of relational databases (or other datastores). This model is sometimes called a "domain model", because it models the "nouns" of a problem domain in the real world. Domain models are easily shared accross applications, and can enforce validation and other integrity constraints.

However, over time, many application developers find themselves adding business logic to the domain model. This business logic is often application-specific, and reduces the reusability of the domain model. Worse, business logic becomes spread between the model and the contoller.

Reaction adds another layer, the Interface Model. Interface models provide an adaptor to the domain model, customized for a particular application (or group of use cases). This decouples the domain model from the application, allowing it to be reused more freely. Additionally, the Interface Model becomes the natural location for business logic.

Happily, Reaction again uses reflection to make the degenerate case easy - when your IM has no customized functionality, it can simply delegate all work to the DM. When you need to add custom business logic, you can add or replace functionality as needed.

The DM/IM split is sometimes referred to as a FacadeModel - see http://www.twinforces.com/tf/docs/MFCV.html, for example.

WHAT YOU'LL NEED TO KNOW ^

Reaction is based on the Catalyst web application framework. You'll certainly need to be familiar with Catalyst::Manual::Intro.

Currently, only DBIx::Class is supported as a domain model. At least basic familiarity will be needed. DBIx::Class::Manual::Intro is a good starting point.

The default view renderer is Template::Toolkit. To edit your views, you'll need to know something about it.

While you don't need to know Moose directly, a lot of the concepts of metaprogramming will keep coming up as you work with Reaction. Thus, getting to know Moose will serve you well.

NEXT STEPS ^

The Reaction::Manual::Overview document tries to tie the parts of reaction together to form a big picture.

If you'd like an example, see Reaction::Manual::Example.

If you're ready to dive in and start learning step by step, see Reaction::Manual::Tutorial.

As you encounter unfamiliar terms, or want to see how a particular term is used in the context of the Reaction project, refer to the Reaction::Manual::Glossary.

SEE ALSO ^

AUTHORS ^

See Reaction::Class for authors.

LICENSE ^

See Reaction::Class for the license.

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