Beautiful Code

Chapter 21. ERP5: Designing for Maximum Adaptability

Rogerio Atem de Carvalho and Rafael Monnerat

Enterprise resource planning systems are generally known as large, proprietary, and highly expensive products. In 2001, work on an open source ERP system known as ERP5 (http://www.erp5.com) began in two French companies, Nexedi (its main developer) and Coramy (its first user). ERP5 is named after the five main concepts that compose its core. It is based on the Zope project and the Python scripting language, both of which are also open source.

We have found that ERP5 is exceptionally easy to enhance, and easy for both developers and users to build on. One reason is that we adopted an innovative document-centric approach, instead of a process- or data-centric paradigm. The core idea of a document-centric paradigm is that every business process relies on a series of documents to make it happen. The document’s fields correspond to the structure of the process—that is, the fields reflect the data and the relationships among this data. Thus, if you watch how the business experts who use the ERP5 system navigate through the documents, you will discover the process workflow.

Zope’s Content Management Framework (CMF) tools and concepts supply the technology behind this approach. Each instance of the CMF, called a portal, contains objects to which it offers services such as viewing, printing, workflow, and storage. A document structure is implemented as a Python portal class, and its behavior ...