Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Computer Aided Design Data Handler with Logical Timer

IP.com Disclosure Number: IPCOM000115220D
Original Publication Date: 1995-Apr-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 6 page(s) / 140K

Publishing Venue

IBM

Related People

Hasegawa, K: AUTHOR

Abstract

This article describes a Computer Aided Design (CAD) data structure handler system, which manages CAD-related graphic/geometry/other attributes data entities representing certain structures by relational pointers. It has new functional capability which makes it possible to get/retrieve data entity or complete structure of any arbitrary time section-cut state without reformatting or restructuring by introducing logical timer concept. o Basically, the logical timer clock value is incremented when change operation is executed.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Computer Aided Design Data Handler with Logical Timer

      This article describes a Computer Aided Design (CAD) data
structure handler system, which manages CAD-related
graphic/geometry/other attributes data entities representing certain
structures by relational pointers.  It has new functional capability
which makes it possible to get/retrieve data entity or complete
structure of any arbitrary time section-cut state without
reformatting or restructuring by introducing logical timer concept.
  o  Basically, the logical timer clock value is incremented when
      change operation is executed.
  o  When data structure is changed by data entity creation/
      modification/deletion or relational pointer update, affected
data
      entities are pushed and new data entities are placed (stored)
      with the logical timer timestamp if the timestamp value is
differ
      from the current logical timer value.
  o  During one data handler call, many data entities may be updated,
      but they are marked with the same timestamp.
  o  On data retrieval, past state of the data structure or
      entities can be viewed or retrieved without any data
      restructuring/movement by using timestamp value as the
secondary
      key.
  o  To avoid excessive storage consumption, user can halt the
logical
      timer, and can restart it again.  it is very important in the
      case when one logical operation for a user requires multiple
data
      handler calls (ex., SET operation in Solid Modeler).
  o  It is possible to extract the secondary data structure set from
      the primary one, which represents the complete state of
specified
      logical timestamp time.
  o  It is possible to extract the secondary data structure set from
      the primary one, which can represent a certain range of
timestamp
      state, giving desired range of timestamp values.
  o  It is possible to back-out the data structure to a certain
      timestamp state.
  o  It is possible to back-out the data structure to the state
      holding a certain range of timestamp.

About Current (Existing) Technologies - In current CAD data
management programs, the following techniques are used to retain past
state.
  o  Technique 1 Store whole data in the storage medium with a unique
      identifier (checkpoints).
  o  Technique 2 Store only changed part (logging).

Following are problems on current technologies:
  Problems on Technique 1
  o  Response/performance problem due to high volume to
store/retrieve.
  o  Strage resource is wasted due to duplicated data.
  o  Because of the above-mentioned reasons, frequency is limited and
      this technique is used for checkpoint data.
  Problems on Technique 2
  o  Response/performance problem in rebuilding the data structure.
  Objectives
  o  To implement high-speed store/reference of data entity set....