Research Papers

Model Consistency and Conflict Resolution With Data Preservation in Multi-User Computer Aided Design

[+] Author and Article Information
Ammon Hepworth

Research Staff
Brigham Young University,
152 Clyde Building,
Provo, UT 84602
e-mail: ammon.hepworth@byu.edu

Kevin Tew

Assistant Professor
Brigham Young University,
152 Clyde Building,
Provo, UT 84602
e-mail: kevin_tew@byu.edu

Mark Trent

Research Assistant
Brigham Young University,
152 Clyde Building,
Provo, UT 84602
e-mail: marktrent11@gmail.com

Daniel Ricks

Research Assistant
Brigham Young University,
152 Clyde Building,
Provo, UT 84602
e-mail: daniel.ricks2@gmail.com

C. Greg Jensen

Brigham Young University,
152 Clyde Building,
Provo, UT 84602
e-mail: cjensen@byu.edu

W. Edward Red

Brigham Young University,
152 Clyde Building,
Provo, UT 84602
e-mail: ered@byu.edu

Contributed by the Design Engineering Division of ASME for publication in the JOURNAL OF COMPUTING AND INFORMATION SCIENCE IN ENGINEERING. Manuscript received October 08, 2013; final manuscript received January 17, 2014; published online March 12, 2014. Assoc. Editor: Joshua D. Summers.

J. Comput. Inf. Sci. Eng 14(2), 021008 (Mar 12, 2014) (9 pages) Paper No: JCISE-13-1206; doi: 10.1115/1.4026553 History: Received October 08, 2013; Revised January 17, 2014

Simultaneous multi-user computer aided design (CAD) allows multiple designers to contribute to the same model at the same time. The resulting parallel design workflow shortens product development cycles. In a replicated, simultaneous multi-user CAD system, modeling data must be kept consistent between clients. This paper presents a method that keeps independent copies of the models in sync between distributed CAD clients. This is accomplished by enforcing modeling operations to occur in the same order on all the clients. In case of conflict, a resolution method preserves conflicting operations locally for later reuse or resolution by the user. These methods are implemented in a commercial CAD system which has been enhanced to enable simultaneous multi-user. Validation tests are run to demonstrate that the methods implemented ensure model consistency and resolve conflicts while preserving conflicting operation data.

Copyright © 2014 by ASME
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Grahic Jump Location
Fig. 1

Two clients become inconsistent when order of operations is ignored

Grahic Jump Location
Fig. 2

Operation B is received by the server first, the OSN is incremented, and operation C is ignored when it arrives

Grahic Jump Location
Fig. 3

Operation B is sent to clients 1 and 3, verification is sent to client 2, the ROSN is updated on all clients and operation B is applied before operation C on client 1

Grahic Jump Location
Fig. 4

After operation C is re-sent to the server, verification and operation messages are sent to clients and the ROSN is reassigned

Grahic Jump Location
Fig. 5

Left the new operation is applied after it is complete; Right: the operations in the queue are applied before the new operation

Grahic Jump Location
Fig. 6

Client 1 edits operation C to validate it and it is forwarded to client 2

Grahic Jump Location
Fig. 7

The result of conflicting operations leaving an invalid operation on Client 2

Grahic Jump Location
Fig. 8

Client 1 performs a trim while client 2 performs a shell on the same body (before)

Grahic Jump Location
Fig. 9

The trim body on client 1 is inserted before the shell so the clients become consistent (after)

Grahic Jump Location
Fig. 10

Client 1 performs a chamfer while client 2 performs an edge blend on the same edge

Grahic Jump Location
Fig. 11

Client 1 and client 2 have a consistent model of a cylinder intersecting a cube (not united)

Grahic Jump Location
Fig. 12

Client 1 unites the cylinder and cube while client 2 edits the extrusion, finishing first

Grahic Jump Location
Fig. 13

Client 2 edits the extrusion while client 1 unites the cylinder and cube, finishing first



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