Difference between revisions of "Persistence unified"

Revision as of 09:03, 17 August 2007

Unified persistence for Eiffel

This project is about developing a single, integrated and simple persistence framework for Eiffel.

• Single because nothing else should be needed to access any kind of persistence services.

• Integrated because aims at integrating both the already existing technologies and frameworks, as far as they deliver the intended benefits, and possibly new ones.

• Simple because it should be very easy to use, removing all the unnecessary complexity.

A tentative manifesto

The first proposed task is to agree upon a sort of ‘manifesto’ of desirable features of the framework.

Here is a first proposal:

Three abstractions

The framework should provide just three abstractions to the developer: PERSISTENCE_MEDIUM, PERSISTENCE_FORMAT and PERSISTENCE_MANAGER.

Possible specializations of these abstractions could be:

• FILE_MEDIUM, NETWORK_MEDIUM, RELATIONAL_DB_MEDIUM, CUSTOM_MEDIUM, ...

• BINARY_FORMAT, STRING_FORMAT, XML_FORMAT, DADL_FORMAT, CUSTOM_FORMAT, ...

• SERIALIZATION_MANAGER, RDBMS_MANAGER, CUSTOM_MANAGER, ...

Persistence independence

Classes which objects have to be persisted should not be polluted with persistence code, for example adding specific persistence-related attributes or by inhering from some other class that provides persistence services.

• The access to the persistence services should be as uniform as possible. This can be achieved using the XXX_MANAGER class hierarchy that handles access to specific kinds of persistence stores
• The different media should be properly incapsulated. This can be achieved using the XXX_MEDIUM class hierarchy
• The different formats should be properly incapsulated. This can be achieved using the XXX_FORMAT class hierarchy