08 Mar 2011 14:01:20 UTC
- Distribution: Reaction
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- License: perl_5
- Perl: v5.8.1
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- This version
- Latest versionARCANEZ Justin Hunterand 1 contributors
- Matt S Trout
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- DOMAIN MODELS AND INTERFACE MODELS
- WHAT YOU'LL NEED TO KNOW
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- SEE ALSO
Reaction::Manual::Intro - Introduction to Reaction
Moose + Catalyst + Layered Models = eternal happiness
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....
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.
The default view renderer is Template::Toolkit. To edit your views, you'll need to know something about it.
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 Reaction::Class for authors.
See Reaction::Class for the license.