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Geoinformatics_06-2009
article exchange format, the industry foundation classes (or ifcs). buildingsmart international (formerly international alliance for interoperability, or iai) is the organization chartered to develop and promote the use of ifcs and related standards. ifc s have gained iso recognition, and now most bim software vendors provide programs that convert their proprietary file formats to ifc-compliant data files that can be imported, with varying degrees of difficulty, into other vendors bim software products. bim software + ifcs + open web-based standards = bim 2.0 the limitation of the current file-based ifc approach is that it is oriented towards multi-function, monolithic, and typically expensive bim software products. this runs counter to the computing mainstream, which is headed inexorably in the direction of small, cheap, special-purpose software components that process limited subsets of larger databases, working via loosely coupled web services , or as david weinberger calls it, small pieces loosely joined. . computing is undergoing a paradigm shift. the old paradigm is file-based computing and the new paradigm is web service-based computing. long-time readers of geoinformatics are familiar with this paradigm shift, because it has already occurred in geospatial technology, as shown in figure 2. in the old paradigm, we obtain (usually large) data files and load them in their entirety into our standalone software systems, perhaps after batch conversion from one format to another. in the new paradigm, our client software components send instructions to (usually) remote web servers (data servers or processing servers) that return to us the results of the invoked services. in the old paradigm, we use the internet (or lan or physically transported storage media) to obtain a large and complete data file from which we then painstakingly extract the data we need. in the new paradigm, we reach across the web to get just the information we request. for example, earth browsers enable anyone with a web browser to reach into huge spatial databases to get one particular result typically a local map view without downloading the whole multi-nation database. the user gets an answer, not a file; information, not data. it happens quickly and it does not require special expertise. service chaining , one of the key reasons the new paradigm can deliver such benefits, involves web services that invoke other web services. in the old paradigm, software programs invoke subroutines to provide particular kinds of processing on the local host. interfaces are important: the subroutines must be called in a specific way, provide certain kinds of data in a list of parameters, and return certain kinds of data in a list of parameters. for half a century, subroutines have been invoking other subroutines. in the new paradigm (only in the last decade), a software program that is a web client (such as a javascript app running in a web browser) calls a web service that s available at a particular url, somewhere on the web. interfaces are important here, too: the web-based query must be done in a specific way, and the web service must be provided with certain data in an ordered list of parameters. the invoked web service might call another web service, just as one subroutine can call another, except that, if the interfaces are open, the web services do not all have to be provided by the same software vendor as was the case in the old paradigm. open interfaces make full use of the web s potential, which derives from loosely coupled inter-process communication. that is, any client that implements an open interface can interact with any server that implements the same interface, just like the millions of http clients and servers that communicate over ip networks. this openness unleashes the power of network effects . consider, for example, the implications for bim of metcalf s law (en.wikipedia.org/wiki/metcalfe's_law), the basis for many network effects, which states, the value of a node on a communications network is proportional (by some exponent) to the number of potential users of that node in the network or the total number of nodes. by this law, one telephone in the world has no value. two telephones have value. and one telephone added to a network of 100 telephones has far more value for the user than one telephone added to a network of 2 telephones. similarly, a floor plan has far more value if it can be immediately discovered and used by all the designers, engineers, estimators, modelers, subcontractors, owners and building operators who touch the building information model throughout the lifetime of the building. bim s progress toward web services the buildingsmart alliance (www.buildingsmartalliance.org), in which canada is a participant, is one of the regional councils of buildingsmart international. it is also a council of the us national institute of building sciences, and it is responsible for the us national cad standard and the national building information modeling standard (nbims). early in 2009, the ogc and the buildingsmart alliance announced the completion of their aecoo-1 (architecture, engineering, construction, owner and operator) phase 1 testbed. the aecoo-1 testbed was 9-month international effort in which participants cooperated in solving a discrete set of aecoo community problems defined by the sponsors. the testbed also facilitated cooperation among aecoo standards bodies to achieve results no group could achieve alone. aecoo-1 focused on two important aspects of building design and construction: 1) building performance and energy analysis and 2) quantity take-offs. in all world regions, both national and international standards need to be taken into account by industry. the aecoo-1 testbed activity documented -- in information delivery manuals (idms) - requirements for quantity takeoffs and energy analysis needs, and used these to define model view definitions (mvds) - specific subsets of ifcs -- which are needed to integrate requirements into software used during business workflows. idms, mvds and ifcs are information constructs in the us national bim standard or nbims process, and they are also buildingsmart international standards. these topics were figure 2: bim standards are at approximately the level of maturation of geospatial standards explored within the framework of the american institute of in 1998 when the ogc s first web mapping testbed began. for both geospatial technology architects (aia) integrated delivery process and addressed interand bim, standards development is difficult because of the domains market realities and operability involving intelligent building models with 3d geotechnical complexity. (figure ogc) latest news? visit www.geoinformatics.com 25 september 2009
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