21.2. ERP5

ERP5 is developed and used by a growing business and academic community in France, Brazil, Germany, Luxembourg, Poland, Senegal, and India, among other countries. It offers an integrated business management solution based on the open source Zope plat-form (http://www.zope.org), written in the Python language (http://www.python.org). Among the key components of Zope used by ERP5 are:

ZODB

An object database

DCWorkflow

A workflow engine

Content Management Framework (CMF)

An infrastructure for adding and moving content

Zope Page Templates (ZPT)

Rapid GUI scripting based on XML

In addition, ERP5 heavily relies on XML technologies. Every object can be exported and imported in XML format, and two or more ERP5 sites can share synchronized objects through the SyncML protocol. ERP5 also implements an object-to-relational mapping scheme that stores the indexing attributes of each object in a relational database and allows much faster object search and retrieval than ZODB. In that way, objects are kept in ZODB, but searches are made using SQL, which is a standard query language.

ERP5 was conceived to be a very flexible framework for developing enterprise applications. Being flexible means being adaptable to various business models without incurring high costs for changes and maintenance. To accomplish this, it is necessary to define a core object-oriented model from which new components can be easily derived for specific purposes. This model must be abstract enough to embrace all basic business concepts.

As the name indicates, ERP5 therefore defines five abstract concepts that lay the basis for representing business processes:

Resource

Describes a resource necessary to realize a business process, such as individual skills, products, machines, and so on.

Node

A business entity that receives and sends resources. It can be related to a physical entity (such as industrial facilities) or an abstract one (such as a bank account). Metanodes are nodes containing other nodes, such as companies.

Path

Describes how a node accesses resources it needs from another node. For instance, a path may be a trade procedure that defines how a client obtains a product from a supplier.

Movement

Describes a movement of resources among nodes at a given moment and for a given period of time. For example, one such movement can be the shipping of raw material from the warehouse to the factory. Movements are realizations of Paths.

Item

A unique instance of a resource. For instance, a CD driver is a resource for assembling a computer, while the CD driver Part Number 23E982 is an item.

These, along with some other supporting concepts like Order and Delivery, form the ERP5 Unified Business Model (UBM). It is possible to implement a new business process by combining and extending the five concepts, as we will see in this chapter. The relationships among the five core concepts are shown in Figure 21-1. A Path is related to a source node that sends a Resource to a destination node. A Movement is similar, representing a movement of an item that is described by a Resource from a source node to a destination node.

Figure 21-1. ERP5 core classes