文章基本信息

标题：Memory Scalability in Constraint-Based Multimedia Style Sheet Systems
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作者：Terry Cumaranatunge ; Ethan V. Munson
期刊名称：Journal of Digital Information
印刷版ISSN：1368-7506
电子版ISSN：1368-7506
出版年度：2000
卷号：1
期号：5
出版社：Texas A&M University Libraries
摘要：Multimedia style sheet systems uniformly use a constraint-based model of layout. Constraints provide a uniform mechanism for all aspects of style managementand layout and are better-suited to non-textual media than flow models.We have developed a prototype style sheet system, Proteus, and have used it with a variety of document types, including program source code. This work has exposed a critical performance problem in constraint-based style sheet runtime systems: memory usage. Existing constraint systems treat cached attribute values and constraints as first-class objects, each with its own storage. Program syntax trees are very large and the constraint data for a medium-sized source file can easily consume tens of megabytes of main memory. This scalability problem would be exposed by any document of any type containing thousands of objects.We present here a new constraint-based runtime system that is substantially faster and dramatically more space-efficient than its predecessor, which had first-class constraint objects. The improved performance is the result of exploiting important common cases and a sophisticated constraint representation that allows considerable sharing of information between individual constraints