Chapter 2 Discussion Questions
3.6 FILE EXCHANGE VERSUS BUILDING MODEL
REPOSITORIES
Production use of IFC - based data exchange and XML - based e - business exchanges have begun with fi le exchanges. Quickly, however, people are
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learning that management of the versions, updating, and change management of the data associated with an increasingly complex number of heterogeneous applications, leads to major data management challenges. Issues that arise that are best resolved by repositories:
Supporting exchanges between multiple concurrent applications that both read and write project data; that is, the workfl ows are not linear Propagating and managing changes that impact multiple application datasets
When there are multiple authoring applications that must be merged for later use
Supporting very frequent or realtime coordination between multiple application users.
The technology associated with the resolution of these types of issues, and also the smoothing of exchange of data between combinations of appli- cations, is a building model repository . A building model repository is a database system whose schema is based on a published object based format.
It is different from existing project data management (PDM) systems and web - based project management systems in that the PDM systems are fi le based, and carry CAD and analysis package project fi les. Building model repositories are object - based, allowing query, transfer, updating and man- agement of individual project objects from a potentially heterogeneous set of applications. The only broad building level object schema is the IFC, (but also CIS/2 and AP225 could be used for limited applications – see Section 3.3.1). A number of companies have developed building model repositories using the IFCs.
An IFC repository can support integra- tion of the data generated by multiple applications for use in other applications, support iterations on parts of the design, and track changes at the object level. They provide access control, version manage- ment, and various levels of design history, relating the various geometric, material, and performance data that represent a building (Eurostep 2007; Jotne 2007).
While basic capabilities exist today, development is ongoing to provide a range
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Jotne EDM Model Server LKSoft IDA STEP Database EuroSTEP Model Server EuroSTEP SABLE Server
Oracle Collaborative Building Information Management
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Current building model repositories available:
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of effective services for building model repositories. Some early supporting software includes:
viewers for inspecting the geometrical and property data in building model repositories (see Section 3.3.5);
checking product data model repositories, for logical correctness ( ‘ build- ing spell - and grammar - checking ’ ), for building program checking, or building code checking (CORENET 2007; Jotne 2007; Solibri 2007).
Future areas where repositories are expected to provide important services include: dataset preparation for multiple analyses, such as energy analyses of building shells, of interior energy distribution and mechanical equipment sim- ulation; bills of material and procurement tracking; construction management;
building commissioning; facility management and operations. Some of these issues are explored in Section 4.5.5.
In practice, each design participant and application is not involved with the complete representation of the building ’ s design and construction. Each partici- pant is interested in only a subset of the building information model, defi ned as particular views of the building model. Similarly, coordination does not apply universally; only a few users need to know reinforcing layouts inside concrete or weld specifi cations. It is still an open question, then, as to whether there is a need for a single integrated database, or instead, multiple federated databases that can provide limited specifi c consistency checking between dispersed models.
This issue is further complicated by the challenges with storing the required data in the appropriate format to archive and recreate the native project fi les required by the various BIM authoring tools. The neutral format that repositor- ies carry data in is inadequate to recreate the native data formats used by applications, except in a few limited cases. Today, these can only be re - created from the native application datasets themselves. This is due to the basic het- erogeneity of the built - in behavior in the parametric modeling design tools (described in Section 2.2.7). Thus any neutral format exchange information, such as IFC model data, must be augmented by or associated with the native project fi les produced by the BIM authoring tools. While the future for manag- ing project data, especially for large projects, seems to belong to building model repositories, many issues remain to be sorted out for their effective use.
Other industries have recognized the need for product model servers.
Their implementation in the largest industries – electronics, manufacturing, and aerospace — has led to a major industry involving Product Lifecycle Man- agement (PLM). These systems are custom engineered for a single company and
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typically involve system integration of a set of tools including product model management, inventory management, material and resource tracking and scheduling, among others. They rely on supporting model data in one of a few proprietary native formats, possibly augmented by ISO - STEP based exchanges.
These have penetrated only the largest businesses, because the current business model of PLM is based on system integration services. What is not available is a ready - to - use product that can support medium or small scale organizations that dominate the make - up of construction industry fi rms. Thus the medium and small industries – in both construction and manufacturing - are waiting for PLM systems that can be easily tailored for various kinds of use.