guiwoda/domain-requirements

This package is abandoned and no longer maintained. No replacement package was suggested.

0.1.0 2014-09-22 17:53 UTC

Requires (Dev)

• phpspec/phpspec: ~2.1@dev

MIT

• Guido Contreras Woda

README

This package aims to provide a simple and semantic way of decoupling your presentation needs from your domain objects.

The problem

As we build websites, we often start up with straightforward pages that reflect our data structure. The Controllers we build usually depend on some Repository or adapter Service that works as a data abstraction. As the system grows though, this Controllers start depending on multiple of this objects, and the role of the Controller ends up as a huge coordinator of different parts of our Domain Model.

We recognize this as a problem immediately, and move this logic to our Domain layer. This creates a different architecture, where any new data needed by the presentation layer requires changes in our coordination objects inside our Domain, which is a long way to say we have coupled our Domain to our presentation needs!

The proposed solution

The connection between Controllers and the Domain is usually done through encapsulation. The dependency arrows always point to the Domain. But there are implicit dependencies that are pointing outwards from the Domain, and that is what this package aims to change.

Each controller would create a (set of) Requirement object(s). This Requirements are POPOs that will work as Data Transfer Objects between our presentation layer and the domain. In this objects, the Controller will list all its Domain dependencies, and will include also all associated parameters that will be needed to resolve this dependencies.

Requirement objects will be sent to a Responsible object to be resolved. This Responsibles should be associated beforehand in an identity map fashion, indicating what Domain need they promise to resolve. A CallbackResponsible implementation is provided as an easy way to start using this pattern without changing any of your objects' interface. If a callback is not enough, any object can implement Responsible and respond to a Requirement.

TL;DR

Use Requirements to list what you expect from the Domain. Use Responsibles to respond to those needs. Oh, and always program to an interface!