Feature Informaiton Extraciton And XML Document Exchange Technology Based On STEP Neutral File

With the progress in computer technology, all kinds of CAD, CAM，CAPP, CAEsoftware promote the development of manufacturing automation, in the face of avariety of CAX software, it is necessary to ifnd a universal data transition model tosolve the data communications and data sharing problem in heterogeneousenvironment. STEP (Standard for the Exchange of Product Model Data) standard is aset of international standard about product data description and transmission in thewhole life of cycle. It achieves consistency and integrity of product information dataexpression in the whole life cycle by neutral mechanism independent from anyparticular system. XML language is an extensible markup language. The features ofgood extensibility and self-description make it not only can transfer product datainformation, but also product data structure. It is a web-based carrier language fortransmitting information. XML language provides effective technical support fortransmitting complicated structured product data information. This article is based onSTEP neutral ifle，established the EXPRESS described relationship of STEP neutralifle and XML language mapping by analyzing the structure, and designed modelparser for reading neutral ifle carried information, and adopted method of attributeadjacent graph to recognize features, and ifnally abstracting the feature informationand achieving transformation between STEP neutral ifle and XML document. Theresearch results of the article effectively solve the interface problem ofmulti-platforms and multi-system CAX software by connection STEP standard andXML. The research content and results includes the following aspects:1. To understand the STEP standard and AP203application protocol, study STEPformalized description language EXPRESS, analyze the connection of differencefrom C++language, and identiyf feature mapping relationship between EXPRESSand C++language, provide technical support for extracting STEP neutral ifle feature information.2.To analyze STEP neutral ifle feature information model，study geometricinformation, topology information, to set up the corresponding C++class of maingeometrical and topological entity by STEP formalized description languageEXPRESS.3.Designing model parser of STEP neutral ifle，according to EXPRESS model，achieving nested-looping by using model parser, calling for indicator to extractorderly physical layer, surface layer, boundary layer and point layer, adoptingmethod of attribute adjacent graph to recognize features, and ifnally abstractingfeature information of geometric entities in neutral ifle.4.Studying the binding method of STEP neutral ifle EXPRESS and XMLmapping, and the correspondence of EXPRESS model and XML syntactic structure,establishing mapping mechanism, and achieving transformation of STEP neutral ifleand XML document.