Compiere from the Source

Model Driven Architecture (Part 2)

Active Dictionary or Model Driven Architecture (MDA) systems may generate executable code behind the curtains, but there is no need or no option to modify the low level code. Compiere takes it a step further and executes the model rules directly.

Without any generation or coding you can

• add a new column to a table
• add optional validation rules (list of values, range, table (incl. external), etc.)
• add the new column to a window
• entering values
• create a report to list the new column or use the new column as a query parameter for reports

and all of that within 5 minutes!

More complex scenarios will not take more than an hour - and you can do this in a production system without causing any downtime. As Compiere is designed to be easy customized, the new column is marked as user defined and treated appropriately in upgrades - so changes in the core system does not affect customizations.

If an application claims that it is model driven or based on an active dictionary, ask them to demonstrate the example above. If it takes them longer, requite to take the system down or does not allow the new column to be immediately used in reports or report parameters, it is not a "real" active dictionary based system with the consequence of higher maintenance cost and lower productivity.

Model Driven Architecture (Part 1)

Compiere employs a Model Driven Architecture (MDA) to enable broader application adaptability, faster deployments and lower cost of ownership than is possible with products utilizing earlier generations of enterprise software architectures.

This is the first of two entries on MDA and Compiere. This first article covers the historical foundations of MDA as well as the resulting advantages. The second entry will explore the specifics of how Compiere's employs an MDA. Let me start out with a bit of history.

To manage the increasing complexity of applications, Data Dictionary systems arose in the early 1970's. The early systems abstracted an application's data structure. To facilitate working with large numbers of entities and increasingly complex relationships, these tools evolved into Entity Relationship Diagramming tools.

Next, the need evolved to manage and model also business processes, so the Data Dictionary applications evolved into Application Dictionary systems. Computer Aided Software Engineering (CASE) tools emerged to enable developer productivity with the Application Dictionary. CASE introduced code generation capabilities.

Some CASE tools claimed support for "round trip" engineering. CASE systems with round trip engineering added the important innovation of ensuring that system code modifications drove updates to design documentation, ensuring that the design and system are in sync. Unfortunately, due to the inherent complexity and round-trip restrictions, bigger systems were not able to take advantage of this capability. The business consequence here is that these systems become more and more harder and costly to maintain over time.

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