A Java object or a relational table are frozen when writing code or creating database. To make them evolve, you have to go back into the code, write a migration process,...
It is also really hard to maintain a coherent code when you want to develop the same application for similar needs with only little differences. Between the common code and the specific code, it can easily be a real burden.
Wikitty tries to bring some answers to those problems bringing a technical solution easy to put into place and to use.
An object never has predefined fields, but only a unique id. You can add extensions to this object. An extension is the definition of a group of fields. To knw all the fields of an object, you just have to know which extensions have been added. For example, we can define the extension Person and the extension Employee and use them on the same object. The said object will have all the fields of the Person extension and all the fields of the Employee extension and will carry the two notions. If the project is used by a company that needs to add fields to the Employee extension, there is no need to modify the existing extensions or the database scheme. You just need to create a new extension, depending on Employee extension, and that you will use to display your Employee data. If the main project evolve, there is absolutely no impact on the specific extension used by the company. The core application developers do not have to worry (or know) about specific stuff that might have been developed by others. The same way, there is no maintenance costs for people that have made specific extensions, those extensions are re-usable from version to version without any modification or maintenance.
Wikitty core brings the base services :
Bean generating for easy use by developers.
A WikittyProxy class that masks the Wikitty objects and only uses generated Beans.
Creation, restoration, update, delete of entities.
Search for entities (full text, facets, ...)
Some other extra-services exists :
security : authentification and authorisation
notification (synchronisation between two servers, client/server notification, listener on modifications)
Complementary add-ons : - Labels (to labelize objects) - Import/Export - Internationalization (i18n)
The concept is two have a core as simple as possible, with a few methods (around 20). - read - write - search - login/logout - rights checking (read, write, delete)
The new services (cache, security, notification, ...) are on top of the core to provide the services.
The core delegate all the work to 3 services that can be implemented using different technologies : - extensions storage (in-memory, jdbc, hbase, jpa, ...) - data storage (in-memory, jdbc, hbase, jpa, ...) - indexation and search (in-memory, SolR, ...)
So it is possible to add new high-level services, or to add new ways to store the info.
For some needs, there is no need to implement a new level (WikittyService), so we speak of AddOn. Those AddOns work directly using the WikittyService API, this is for example the case for import/export.
The lient part of the applications only work through WikittyProxy who masks the Wikitty object notion to return Beans that can be easily used by the developer.