Abstract: Streaming XML data has been used broadly in the Internet field. How to process diversity queries on massive XML streams with high-performance is the problem that puts forward higher requirements to the XML query technology. This paper proposes a novel method for querying streaming XML data. The method is based on pushdown transducer. It supports the core part of XPath, including PC and AD axes and multiple predicates with nesting step（i.e., predicates which are either value based predicates or node tests）. It can handle complex queries with high performance.

Key words: XML streaming data, XPath, pushdown transducer

摘要： XML流数据在互联网领域有着广阔的应用，海量流数据的高性能处理与查询需求的多样性给对XML流数据的查询处理技术提出了更高的要求，针对XML流数据上的XPath查询，以下推转换机（Pushdown Transducer）为基础，提出一种新的查询处理方法。该方法支持包含PC轴、AD轴同时包含多重存在谓词、值谓词和嵌套谓词的XPath查询，覆盖XPath查询的核心部分。该方法能够满足用户复杂的查询需求，同时具有较高的性能。

关键词: XML流数据, XPath, 下推转换机