Open Journal Systems  3.0.0
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OJS API Reference

Welcome to the OJS API Reference. This resource contains documentation generated automatically from the OJS source code.

The design of Open Journal Systems 2.x is heavily structured for maintainability, flexibility and robustness. Those familiar with Sun's Enterprise Java Beans technology or the Model-View-Controller (MVC) pattern will note similarities.

As in a MVC structure, data storage and representation, user interface presentation, and control are separated into different layers. The major categories, roughly ordered from "front-end" to "back-end," follow:

  • Smarty templates, which are responsible for assembling HTML pages to display to users;
  • Page classes, which receive requests from users' web browsers, delegate any required processing to various other classes, and call up the appropriate Smarty template to generate a response;
  • Controllers, which implement reusable pieces of content e.g. for AJAX subrequests.
  • Action classes, which are used by the Page classes to perform non-trivial processing of user requests;
  • Model classes, which implement PHP objects representing the system's various entities, such as Users, Articles, and Journals;
  • Data Access Objects (DAOs), which generally provide (amongst others) update, create, and delete functions for their associated Model classes, are responsible for all database interaction;
  • Support classes, which provide core functionalities, miscellaneous common;

Additionally, many of the concerns shared by multiple PKP applications are implemented in the shared "pkp-lib" library, shipped in the lib/pkp subdirectory. The same conventions listed above apply to lib/pkp as well.

As the system makes use of inheritance and has consistent class naming conventions, it is generally easy to tell what category a particular class falls into.

For example, a Data Access Object class always inherits from the DAO class, has a Class name of the form [Something]DAO, and has a filename of the form [Something]DAO.inc.php.

To learn more about developing OJS, there are several additional resources that may be useful: