siping@cathedral.cerc.wvu.wvnet.edu (Siping Liu) (03/02/90)
(1). Is IGES represented in EXPRESS?
(2). From my limited references, I assume EXPRESS can represent
entity data type and instances of a generic entity. Can
some one verify this for me? How to make an instance of an
entity?
(3). Does PDES represent instances of the generic entities?
(4). Has anyone tried to make a translation from EXPRESS to a
schema language, such as KEE or Knowledge Craft?
Any information/suggestion will be highly appreciated. Thanks.
siping@cerc.wvu.wvnet.edu
P.S.: I am not sure I am posting on the most relevent groups.
Your suggestion is welcome.wahl@shodha.dec.com (David Wahl) (03/03/90)
For those who may not be familiar with the names, PDES, IGES and Express are various languages and meta-languages for representing data models for data exchange between CAD and CAM tools. They are defined as part of ANSI and ISO (the name in ISO for PDES is STEP) activities to move toward standards for electronic data exchange for CAD/CAM. I don't have an opinion as to whether the comp.object audience cares about these things. Express is based on a lot of ER and OO ideas; the other stuff is mostly graphics for mechanical CAD/CAM. The closest thing to an appropriate newsgroup might be comp.graphics, although the time might be right to consider a comp.cim (computer-integrated manufacturing) newsgroup. If comp.objectians object to a discussion of something which is only casually objective I'll not object to moving this discussion to email. In 1007 siping@cerc.wvu.wvnet.edu asks: >(1). Is IGES represented in EXPRESS? Express is the meta-language for describing entities which are used in a PDES application program. PDES subsumes IGES, but some things are different. >(2). From my limited references, I assume EXPRESS can represent > entity data type and instances of a generic entity. Can > some one verify this for me? How to make an instance of an > entity? >(3). Does PDES represent instances of the generic entities? There is no provision for direct instantiation of Express entities. The intent is for Express to be a specification language for [logical, conceptual, fuzzy, still-kinda-muddled] CAD/CAM entities which is the basis for detail design into concrete PDES schemata. >(4). Has anyone tried to make a translation from EXPRESS to a > schema language, such as KEE or Knowledge Craft? Translation of Express or any ER based language into another really rich schema language is easy. The hard part is using the specification to transform one existing un-objective, less semantically rich CAD format to another where no common exchange protocol currently exists. Regards, Dave Wahl =================================================================== Digital Equipment Corporation Database Systems Research (CXN/2) 1175 Chapel Hills Drive Colorado Springs, CO 80920-2080 Tel 719-260-2758 Email: wahl%cookie.dec.com@decwrl.dec.com %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % The opinions expressed are my own, not Digital's. % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
g2k@mentor.cc.purdue.edu (Frederic Giacometti) (03/05/90)
In article <794@shodha.dec.com> wahl@shodha.dec.com (David Wahl) writes: .... >models for data exchange between CAD and CAM tools. They are defined >as part of ANSI and ISO (the name in ISO for PDES is STEP) activities In order to stop any further confusion at that point: * STEP is the future ISO standard for product data exchange format. * PDES is the american proposal to STEP, it is by NO means STEP. CAD/I and the following project (Esprit program in the EC) are also proposal to STEP. PDES is the continuation of IGES, a project managed by the NIST. It is made by and for the american industry. So far, PDES has much to improve to be accepted as STEP. In the same series of common confusions in america: IGES is an ANSI standard, not ISO. The French developped SET, which is technically much more performant, and has made its place in the aerospace industry. Frederic Giacometti School of Industrial Engineering Purdue University
alanrw@els.uucp (Alan Williams) (03/05/90)
In article <794@shodha.dec.com> wahl@shodha.dec.com (David Wahl) writes: >The closest >thing to an appropriate newsgroup might be comp.graphics, although the >time might be right to consider a comp.cim (computer-integrated >manufacturing) newsgroup. I think that the best newsgroup for a discussion of Express and the ISO STEP initiative is comp.specification as much of the work involves the specification of "information models" in Express. These are then used to determine the format of the STEP physical file which is actually used to pass data between different CAD systems. Alan Williams (alanrw@cs.man.ac.uk)