Interoperability-based Optimisation of Architectural Design

INTEROPERABILITY-BASED OPTIMISATION OF ARCHITECTURAL DESIGN The layering or separation was a fundamental idea in the STEP approach. It separates an application level from the logical level, suggesting a way to define subsets of a complete model. Information modelling methods are used to specify required conceptual structure of the information to be represented. IDEF1x (Bruce 1992), Natural Language Information Analysis Method (NIAM) (Nijssen and Halpin 1989) and EXPRESS-G (ISO 1994b) are the information modelling techniques initially accepted by the standardisation committee for this purpose. Later IDEF1x and NIAM have been discarded as modelling techniques because of the reasons stated in section 0. In addition, an intermediate-level specification language for defining the logical structure of a model, separate from its physical implementation has been developed. The resultant description method is known as EXPRESS (ISO 1994b) language.

The specification for STEP is structured in different sections with the following numbering methodology, details of which are shown in Figure 3.14 (Neil 2001): Part 1 - Overview and fundamental principles Parts 11-13 - EXPRESS Parts 21-30 - Implementation methods (SPF, SDAI, C++, XML, Java) Parts 31-35 - Conformance testing methodology and framework Parts 41-58 - Integrated-Generic Resources Parts 101-110 - Integrated-Application Resources Parts 201-240 - Application Protocols (APs) Parts 501-523 - Application-Interpreted Constructs Parts 1001-1514 - Application Modules Conventionally, information models were developed as a closed loop where a complete information model was first developed then subsets were taken. STEP development is based around various part models, also known as APs (Application Protocols), with the expectation that the APs would later be re-established as larger domain specific models. The incremental development approach of STEP has significant advantages over previous efforts as existing applications with rich semantic content can be clustered into specialised domains before a complete model can be developed. This has been particularly useful to larger industries like the AEC. The STEP system architecture identifies five classes of tools (Figure 3.11) (Eastman 1999): Description methods Description methods are the information modelling languages employed in specifying the information models used in the architecture, i.e., to define the Integrated Resources, Application Reference Models and Application Interpreted Models. The formal description methods include 54