In the Architectural Engineering and Construction / Facilities Management (AEC/FM) industry, the use of three-dimensional (3D) modeling data is increasing throughout the entire building life cycle process. This data is for architectural design, heating, ventilation, and air conditioning (HVAC) design, mechanical, electrical, and plumbing (MEP) design, and for construction. Moreover, the use of this 3D model data is expected to be continually used for building maintenance and building renewal plans.

Secom is developing a 3D building model application that enables the simulation and optimization of the security system (sensors, monitoring cameras and access control systems) during the early phases of building design. Secom expects that this application service based on the 3D building model technology will provide greater added value, and increasingly secure services in the future.

In this research project, we are working on the development of the Industry Foundation Classes (IFC) model data sharing platform and IFC Model Server framework. The IFC, developed under the umbrella of the International Alliance for Interoperability (IAI), is the industry standard for building object model data. The IFC Model Server enables the storage of IFC model data in a database and the sharing of this data over the Internet. In cooperation with IAI, we are currently working on the development of the IFC Model Server based on the Simple Access to the Building Lifecycle Exchange (SABLE) project, launched in Finland to solve the technical problems of the model server.

The need for IFC compatible model server functionality has been demonstrated by the worldwide experience of IFC pilot projects in recent years, because the large files sizes limit file sharing.

The first version of IFC Model Server was developed by VTT Building and Transport and SECOM Co., Ltd, in 2002. The IFC Model Server provides model server functionality over the Internet, such as import/export of IFC models in XML and STEP Part21 format. By using Simple Object Access Protocol (SOAP) for communication between the model server and client software, the model server functionality can be utilized by heterogeneous systems such as web browsers and Java implementations. SOAP also guarantees the technological independence for the client application developers.

After the IFC Model Server development project, SABLE project was launched in 2003 and completed in 2005. The SABLE project focused on improving the IFC model server technology for practical use. The project defined the common XML Web service interface to allow AEC domain specific applications to communicate with IFC model servers. 15 international partners collaborated to define a common interface for the model server Web service API and to implement the client applications and model server during the project.

We are currently working on the second version of IFC Model Server project based on the results from the previous two projects. The architecture of the new model server is based on the latest XML Web service technologies and the API defined by SABLE project.

The IFC Model Server project aims for practical use of the model server technology. The IFC model server technology enables the sharing of IFC building model data over the Internet between heterogeneous software applications used during the entire lifecycle of buildings.

The IFC standard is defined by the International Alliance for Interoperability (IAI). The vision of IAI is to enable software interoperability during the entire lifecycle of the building. IAI has the international chapters in Australasia, China, the French speaking countries, the German speaking countries, Iberian countries, Italy, Japan, North America, the Nordic countries, Singapore and the United Kingdom. IAI is also working with ISO to standardize IFC as an international standard. In 2005, the IFC specification became ISO/PAS-16739. SECOM ISL has been working very closely with the core IAI technical team to standardize the IFC specification, and in collaborating to develop IFC related technologies with enterprises and research organizations.

The IFC is the object data model containing the 3D geometry information, object attributes, material information, and building elements such as doors, windows, walls, sensors, controllers, etc.. The IFC model can be shared between heterogeneous software applications in the building lifecycle such as 3D CAD systems, quantity take off software, various simulation tools, and facility management systems.

The necessity of an IFC compatible model server has been demonstrated by the worldwide experiences of IFC pilot projects in recent years. The large file sizes and the exchange of the files itself limit the flexible data sharing that the IFC model provides. The IFC Model Server is necessary to provide server functionality over the Internet, and provide an IFC model database for IFC model data storage, creation, updates, and import and export functionality.

In the SABLE project, Secom contributed in defining the XML Web Service API for the common IFC model server. On top of the common IFC model server interface, SABLE project defined the domain specific APIs on the SABLE server. This architecture enables communication between the IFC model servers and software applications in heterogeneous domains. Web based technologies such as XML and SOAP are used as the communication protocol between server and client application.

Figure 1: Overview of model servers and client applications

IFC Model Server consists of following three components:

• EXPRESS Schema Converter
• Database management system (DBMS)
• Data Access Layer Component (DALC)
• Web Service Layer Component (WSLC)

The IFC Model Server architecture is shown in Figure 2.

The EXPRESS Schema Converter converts EXPRESS to an intermediate XML format and other meta-data formats such as SQL. The IFC model data itself is stored in the database through SQL commands. The Data Access Layer Component provides the necessary data access functions for access to the IFC model data database. The Web Service Layer Component provides the model server functionality to client software on the Internet as XML Web Services. The client application can then access to the model server methods through the XML Web Services interface.

Figure 2. IFC Model Server architecture

Currently, the common model server API is completed and we are currently implementing the API for a new version of the IFC model server. For better performance, the database schema, data I/O functionality, and partial model management algorithm will be improved. Secom continues to work on developing the IFC model application technologies while cooperating with worldwide partners in the future.

1. Y. Adachi, Overview of partial model query language, 10th ISPE INTERNATIONAL CONFERENCE ON CONCURRENT ENGINEERING CE 2003
2. Y. Adachi, Overview of IFC Model Server Framework, European Conference of Product and Process Modeling ECPPM 2002
3. Y. Adachi, IFC Model Server development project. Finland: VTT building and Transport, Japan: SECOM Co., Ltd. Intelligent Systems Laboratory, 2002.
4. SABLE Project
5. IAI, International Alliance for Interoperability
6. W3C, World Wide Web Consortium. 2003. Extensible Markup Language (XML).
7. W3C, World Wide Web Consortium. 2003. Simple Object Access Protocol (SOAP) 1.2.