Outline of IFC Model Server Development Project

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Outline of IFC Model Server Development Project Powered By Docstoc
					VTT-TEC-ADA-01                                                                                                                                   Page 1

                                                                 SECOM Co., Ltd. / VTT Building and Transport
                                                                                             Yoshinobu Adachi
                                                                                E-Mail: yoshinobu.adachi@vtt.fi

                                                          VTT-TEC-ADA-01

                 Outline of IFC Model Server Development
                                  Project
                                                                    2001/07/25


1.     INTRODUCTION..........................................................................................................................1

2.     OBJECTIVE .................................................................................................................................1

3.     GOAL ...........................................................................................................................................2

4.     COMPONENTS IN IFC MODEL SERVER ....................................................................................2
     4.1. EXPRESS TO XML S CHEMA CONVERTER (EXC) ..............................................................2
     4.2. IFC MODEL DATA ACCESS LAYER COMPONENT (DALC)....................................................3
     4.3. WEB SERVICE LAYER (WSL)................................................................................................4
5.     CONCLUSION..............................................................................................................................4

6.     SCHEDULE ..................................................................................................................................5




1. Introduction
   This document describes a proposal for development of IFC Model Server which stores IFC object model
within the database system and runs on the internet. I believe that the necessity of IFC compatible model server
has been increased by the worldwide IFC implementation experiences in recent years.
   Without this kind of model server functionality, sharing of IFC data by IFC compatible applications would be
limited to file base exchanges. If a model server functionality is provided on the internet, IFC compatible
applications can communicate with each other via the internet and utilize function implemented in the model
server such as partial model import / export.
  The model server will import and export IFC model by BLIS-XML and STEP file format. In the future
development, it will also provide a wide variety of Web Service functions, i.e. scheduling doors windows,
external library data merger into IFC model with property set system, VRML converter, and so on. On top of that,
using SOAP for the communication between model server and client software, the model server functionality can
be used by many kinds of client software such as web browsers and java applets.
 To realize this model server, several basic technologies need to be cleared up.
         • Storing IFC model data in a database system. (SQL Server, Oracle, etc)
         • Automatic schema conversion from IFC EXPRESS to database schema
         • XML based SOAP communication between model server and client software
   By storing IFC model data in a database, the model server secures the utilization of a large size building model.
At present, most of database management systems include XML data storing functions, thus the development of
IFC model server will utilize those XML related tools and functions in order to cooperate with BLIS-XML
technology.


2. Objective
  The objective of this project is to develop an IFC Model Server prototype. The prototype will be positioned as
a basis of the future IFC Model Server products for IFC compliant software applications, and therefore the

                                            SECOM Co., Ltd. Intelligent Systems Lab.
VTT-TEC-ADA-01                                                                                                          Page 2

prototype must have extensibility, scalability and be built on standard technologies.
  In this development stage, IFC Release 2.0 is focused on, because the first wave of BLIS project products will
come up in 2001. Tools and components that will be developed by this development project will be compatible
with further IFC releases like IFC 2x.


3. Goal
The goal of this development project is to realize following points:
       • Storing IFC model data in a database system. (SQL Server, Oracle, etc)
       • Automatic schema conversion from IFC EXPRESS schema to database schema by using XML
            technology
       • XML based SOAP communication between model server and client software


4. Components in IFC Model Server
In this project, following components will be realized:
         • EXPRESS to XML schema Converter (EXC)
         • IFC Object Model Data Access Layer Component (DALC)
         • Web Service Layer (WSL)

4.1.      EXPRESS to XML Schema Converter (eXc)
 This component realizes conversion from EXPRESS to XML Schema format. This conversion consists of tow
stages. At the first stage, EXPRESS schema information is converted to an intermediate XML format, i.e. Part28
XML format, OIM1 (Open Information Model) format, or ifcXML format. In the second stage, the intermediate
XML format is converted a specific schema defining language such as SQL DDL by XSLT, scripting and applet
by using DOM parser.
 There is a need to research about the necessity to develop the first stage, because the functionality that converts
EXPRESS to Part28 XML format will be able to use some existing tools or library.

          •    EXPRESS parser Module:
               The CSTB open source project will be utilized in this part. Other possibility is the public software
               from NIST.

          •     EXPRESS schema intermediate XML schema Module:
               After parsing EXPRESS schema, the schema information is stored in XML DOM tree in the
               memory of the converter. This DOM tree will be based on Part28 XML format, OIM format or
               ifcXML format.

          •    Intermediate XML to destination Schema Module:
               The intermediate XML format is very neutral information and contains almost the same information
               as EXPRESS schema. This module converts intermediate XML data into the destination schema
               defining language, i.e. SQL DDL(Data Definition Language) or other XML Schema format.




1
    OIM: Open Information Model is a framework that was developed by MDC(Meta Data Coalition) for defining meta data.


                                     SECOM Co., Ltd. Intelligent Systems Lab.
VTT-TEC-ADA-01                                                                                      Page 3




                                                       EXPRESS




                                                   EXC
                                       EXPRESS To XML Schema Converter




                                                      XML Schema


                                Part28                   OIM             ifcXML




                       XSL Module                     XSL Module                  XSL Module




                         SQL DDL                       SQL DDL
                                                                            other XML Schema
                      for SQL Server                   for Oracle




                        SQL Server                       Oracle                   XML Datastore




                        Fig. 1: Outline of EXPRESS to XML Schema Converter


4.2.   IFC Model Data Access Layer Component (DALC)
 DALC accesses a database for importing and exporting IFC model data. It provides functions that resemble
SDAI model server function, and includes following APIs :

       •   BLIS-XML importing and exporting
       •   IfcXML support will be a challenge
       •   Primitive IFC object access functions
       •   IFC object search (by entity type, GUID)

DALC is based on the database schema which is made by EXC tool. ADO component is used for accessing to

                              SECOM Co., Ltd. Intelligent Systems Lab.
 VTT-TEC-ADA-01                                                                                                              Page 4

 the database in DALC.
   In this project, Microsoft SQL Server 2000 will be a target database system, because it has XML compatible
 functions. ADO can access to other database such as Oracle by changing the database provider component.
  To handle the STEP files, IFCsvr ActiveX Component will be used in DALC. When a client application uses
 STEP files, IFCsvr component accesses the STEP files and invokes DALC primitive IFC object access functions
 to import and export the IFC model data with database.

 4.3.        Web Service Layer (WSL)
  WSL provides the IFC model data upload and download services. There are two ways to upload and download
 the IFC model data in this proposal.

        1. With user interface on the web pages: Users operate upload and download procedures on the web pages
           manually. This is a quite traditional way to use web pages. ASP scripts will run the DALC directly. Http
           protocol is used for downloading/uploading IFC files.
        2. By using SOAP protocol: Client applications can access to the Web Service Component on the IFC
           Model Server site via SOAP protocol. A request is sent out to the Web service by client applications in
           order to download and upload the IFC Model Data. The IFC Model data written by BLIS-XML will be
           encapsulated by SOAP.

  WSL also provides IFC Model handling user interfaces to client applications. This means that a kind of partial
 model select and merge functions, quantity take off function, property set edit function and so on, will be
 attached into the Web Service in the future. In this proposal, preliminary limited model select and merge function,
 defined by the building storey, will be implemented.

  In the first stage of this proposal, ASP (Active Server Page) on IIS (Internet Information Server) will be used.
 To support XML and SOAP protocol, Windows 2000 Server, SOAP SDK and BizTalk Server (if needed) will be
 necessary.


 5. Conclusion
                                                                                                                EXPRESS XML Schema
                                                 Model As BLIS-                                                      Converter
                                                     XML
                                                Request by SOAP                            IFC EXPRESS Schema

  Application              Internet
     via                                                                                                              Database
    SOAP                                                                                                               Schema
                                                                    SOAP                                                (SQL)
                                                                    Listner
     CAD           IFC Model Data
                   (XML or STEP)


   Non CAD                                                                                 IFC Object
                                                                                 IFCsvr
                             Internet                                                        Model
                                                     Web Server                 ActiveX                  ADO          Database
                                                                                             Access
                                                                               Component
 Web Browser                                                       Scriptlet                 Module


   .Net client
                                     Catalog Data
                                    (XML by PSML)


IFC Model Server

                                                         Web Service Layer           Data Access Layer



                       Door Window
                       Manufacturer


                                            Fig. 2: Outline of IFC Model Server Components


  In this development project, following software modules will be implemented:

      •     EXPRESS to XML Schema Converter (eXc)

                                                SECOM Co., Ltd. Intelligent Systems Lab.
VTT-TEC-ADA-01                                                                                                                                        Page 5

    •   Data Access Layer Component (DALC)
    •   Web Service Layer (WSL)

This development project aims to solve following key points:
    • How to define the database schema
    • What should be the intermediate XML schema
    • Design for APIs of Data Access Layer Component
    • How to use the SOAP function for Web Services


6. Schedule

                 1/7          1/8          1/9       1/10      1/11       1/12     1/1       1/2      1/3        1/4        1/5
        6/2001                                                                                                                       6/2002




                        Preparation

         1/6     30/6
                                                                          EXRRESS to XML Database Schema
                                                                                     Converter
                              1/8          1/9       1/10
                 1/7                                          31/10

                                      Research for XML Schema candiates
                 2/7          31/7
                                                 EXPRESS to XML Converter Progrm Design
                              1/8         31/8
                                                                       EXPRESS to XML Converter Implementation
                                          1/9                  31/10

                                                                                           Data Access Layer Component
                                                               1/11        1/12
                                                      1/10                         31/12

                                                                                                                         Web Service Layer
                                                                                              1/2       1/3
                                                                                    1/1                           31/3

                                                                                                                                         Test and evaluation
                                                                                                                              1/5
                                                                                                                   1/4                31/5


                                          Fig. 3: Schedule of IFC Model Server Project


Note: The schedule is tentative and might be changed.




                                            SECOM Co., Ltd. Intelligent Systems Lab.

				
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