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    荆树旭, 何发智, 蔡贤涛, 程 媛. 协同建模系统中的一种对象引用正确性保证方法[J]. 计算机研究与发展, 2011, 48(11): 2031-2038.
    引用本文: 荆树旭, 何发智, 蔡贤涛, 程 媛. 协同建模系统中的一种对象引用正确性保证方法[J]. 计算机研究与发展, 2011, 48(11): 2031-2038.
    Jing Shuxu, He Fazhi, Cai Xiantao, Cheng Yuan. A Method for Object Reference in Collaborative Modeling System[J]. Journal of Computer Research and Development, 2011, 48(11): 2031-2038.
    Citation: Jing Shuxu, He Fazhi, Cai Xiantao, Cheng Yuan. A Method for Object Reference in Collaborative Modeling System[J]. Journal of Computer Research and Development, 2011, 48(11): 2031-2038.

    协同建模系统中的一种对象引用正确性保证方法

    A Method for Object Reference in Collaborative Modeling System

    • 摘要: 乐观并发控制允许操作并发执行,由此将产生对象引用发生时刻与对象引用使用时刻的几何模型的不一致,结果将导致命名机制的失效而不能保证对象引用的正确性.将引用对象分为可替代与不可替代2种类型,对于可替代对象引用,通过构建对象引用发生时刻的临时几何模型保证该类对象引用的正确性;对于不可替代对象引用,通过恢复对象引用发生时刻的几何模型,然后完成引用该类对象的操作,最后Redo模型恢复过程中被Undo的并发操作来保证该类对象引用的正确性.在原型系统中对提出的方法进行了验证.

       

      Abstract: In order to support natural and free multi-user interaction, a replicated architecture and optimistic concurrency control are adopted in collaborative 3D modeling system. On the one hand, topological elements in the geometric model are referred as operation parameters to define a completed modeling operation which is exchanged and executed among replicated sites. Only when topological objects of the geometric model are correctly referred, can the modeling operations be executed with a correct result. On the other hand, optimistic concurrency control will lead to geometric model inconsistency between the moment of reference generation in local site and moment of reference use in remote sites. The inconsistency will lead to incorrect naming and consequently the failure of object reference. In this paper, the functions of referred topological elements are analyzed and referred objects are categorized into replaceable ones and irreplaceable ones. For replaceable object reference, temporary geometric model is constructed to guarantee the correct object reference by providing the geometric information needed for positioning purposes. For irreplaceable object reference, geometric model is restored and object reference applied, finally redo all the concurrency operations undone during model restoration procedure. The proposed method has been implemented in a prototype system and it works well.

       

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