Eclipse Modeling Framework

Introduction

Building Information Models (BIM) are typically Object Oriented and tend to be large. For example the Industry Foundations Classes (IFC) have more than one thousand different classes. Because the BIMserver has been written in Java (an Object Oriented Language), it is very useful to have typed Java classes in the used BIM model. This is where the Eclipse Modelling Framework (EMF) comes into play. For now, the BIMserver uses IFC2x3tc1 internally.

IFC Schema

Most BIM meta models are described in a data format. As IFC is based on STEP/EXPRESS technology, the schema is available as an .EXP file. This file has been converted to an EMF Core file with the BuildingSMARTLibrary (part of BIMserver project).

Generating Code

The EMF framework generates Java classes with the given ECore file, these classes are used to store BIM models and passed to the database layer .

Caveats

If you load a model from an IFC-Step file, the String values of floating point numbers are being stored as a String as well. If you change the float values programatically, you should update (or clear) the string value.

Three models

BIMserver consists of 5 different EMF models:

• The IFC2x3tc1 Schema model (as described above) that holds IFC data.
• The IFC4 Schema model (as described above) that holds IFC data.
• The Log schema for logging
• The Store model that holds typical BIMserver data like projects, users, revisions etc.
• The Geometry model that stores geometry like vertices/indices/normals/colors