Contribute to the DSpace Development Fund

The newly established DSpace Development Fund supports the development of new features prioritized by DSpace Governance. For a list of planned features see the fund wiki page.

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Introduction

The DSpace API was originally created in 2002, very little has changed in the way we work with our API. After working with the API day in day out for over 7 years I felt it was time for a change. In this proposal I will highlight the issues that the current API has and suggest solutions for these issues.

How things are now

Bad distribution of responsibilities

Currently every database object (more or less) corresponds to a single java class. This single java class contains the following logical code blocks:

  • CRUD methods (Create & Retrieve methods are static)
  • All business logic methods
  • Database logic (queries, updating, …)
  • All getters & setters of the object
  • ….

Working with these types of GOD classes, we get the following disadvantages:

  • By grouping all of these different functionality's into a single class it is sometimes hard (impossible ?) to see which methods are setters/getters/business logic since everything is thrown onto a big pile.
  • Makes it very hard to make/track local changes since you need to overwrite the entire class to make a small change.
  • Refactoring/altering GOD classes becomes hard since it is unclear where the database logic begins & where the business logic is located.

Database layer access

All database access is made through a DatabaseManager, this object can be accessed from any object (even the user interface can make database calls).
Any object can query any table, some examples:
  • EPerson table is queried from the Groomer and EPerson class.
  • Item is queried from the LogAnalyser, Item, EPerson classes
This makes it hard to make changes to a database table since it is unclear from which classes the queries are coming from.


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