Output schemas of XSLT stylesheets and their applications

The capabilities of XSLT processing are widely used to transform XML documents into target XML documents. These target XML documents conform to output schemas of the used XSLT stylesheet. Output schemas of XSLT stylesheets can be used for a static analysis of the used XSLT stylesheet, to automatically detect the XSLT stylesheet of target XML documents or to reason on the output schema without access to the target XML documents. In this paper, we develop an approach to automatically determining the output schema of an XSLT stylesheet. We also describe several application scenarios of output schemas. The experimental evaluation shows that our prototype can determine the output schemas of nearly all typical XSLT stylesheets and the improvements in preciseness in several application scenarios when using output schemas in comparison to when not using output schemas.     

Compiler support for effective XSL transformation

XML is a markup language used to describe data or documents. The main goal of XML is to facilitate the sharing of data across diverse information systems, especially via the Internet. XML Stylesheet Transformations (XSLT) is a standard approach to describing how to transform an XML document into another data format. The ever‐increasing number of Web technologies being used in our everyday lives commonly employs XSLT to support data exchange among heterogeneous environments, and the associated increasing burdens on XSLT processors have increased the demand for high‐performance XSLT processors. In this paper, we present an XSLT compiler, named Zebu, which can transform an XSLT stylesheet into the corresponding C program. The compiled program can be used to transform documents without the processing of XSLT stylesheets. The results of experimental testing using standard benchmarks show that the proposed XSLT compiler performs well in processing XML transformations. Copyright © 2011 John Wiley & Sons, Ltd.     

Optimizing the execution of XSLT stylesheets for querying transformed XML data

We have to deal with different data formats whenever data formats evolve or data must be integrated from heterogeneous systems. These data when implemented in XML for data exchange cannot be shared freely among applications without data transformation. A common approach to solve this problem is to convert the entire XML data from their source format to the applications’ target formats using the transformations rules specified in XSLT stylesheets. However, in many cases, not all XML data are required to be transformed except for a smaller part described by a user’s query (application). In this paper, we present an approach that optimizes the execution time of an XSLT stylesheet for answering a given XPath query by modifying the XSLT stylesheet in such a way that it would (a) capture only the parts in the XML data that are relevant to the query and (b) process only those XSLT instructions that are relevant to the query. We prove the correctness of our optimization approach, analyze its complexity and present experimental results. The experimental results show that our approach performs the best in terms of execution time, especially when many cost-intensive XSLT instructions can be excluded in the XSLT stylesheet.     

Towards practical meta-querying

We describe a meta-querying system for databases containing queries in addition to ordinary data. In the context of such databases, a meta-query is a query about queries. Representing stored queries in XML, and using the standard XML manipulation language XSLT as a sublanguage, we show that just a few features need to be added to SQL to turn it into a fully-fledged meta-query language. The good news is that these features can be directly supported by extensible database technology.     

Typechecking for XML transformers

We study the typechecking problem for XML (eXtensible Markup Language) transformers: given an XML transformation program and a DTD for the input XML documents, check whether every result of the program conforms to a specified output DTD. We model XML transformers using a novel device called a k-pebble transducer, that can express most queries without data-value joins in XML-QL, XSLT, and other XML query languages. Types are modeled by regular tree languages, a robust extension of DTDs. The main result of the paper is that typechecking for k-pebble transducers is decidable. Consequently, typechecking can be performed for a broad range of XML transformation languages, including XML-QL and a fragment of XSLT.     

XML技术在化学深层网数据提取中的应用

Internet上的化学数据库是宝贵的化学信息资源,如何有效地利用这些数据是化学深层网所要解决的问题。本文总结了化学深层网的特点,基于XML技术实现从数据库检索返回的半结构化HTML页面中提取数据的目标,使之成为可供程序直接调用做进一步计算的数据。在数据提取过程中,先采用JTidy规范化HTML,得到格式上完整、内容无误的XHTML文档,利用包含着XPath路径语言的XSLT数据转换模板实现数据转换和提取。其中XPath表达式的优劣决定了XSLT数据转换模板能否长久有效地提取化学数据,文中着重介绍了如何编辑健壮的XPath表达式,强调了XPath表达式应利用内容和属性特征实现对源树中数据的定位,并尽可能地降低表达式之间的耦合度,前瞻性地预测化学站点可能出现的变化并在XSLT数据转换模板中采取相应的措施以提高表达式的长期有效性。为创建化学深层网数据提取的XSLT数据提取模板提供方法指导。     

Active rules for XML: A new paradigm for E-services

XML is rapidly becoming one of the most widely adopted technologies for information exchange and representation. As the use of XML becomes more widespread, we foresee the development of active XML rules, i.e., rules explicitly designed for the management of XML information. In particular, we argue that active rules for XML offer a natural paradigm for the rapid development of innovative e-services. In the paper, we show how active rules can be specified in the context of XSLT, a pattern-based language for publishing XML documents (promoted by the W3C) which is receiving strong commercial support, and Lorel, a query language for XML documents that is quite popular in the research world. We demonstrate, through simple examples of active rules for XSLT and Lorel, that active rules can be effective for the implementation of e-commerce services. We also discuss the various issues that need to be considered in adapting the notion of relational triggers to the XML context. Received: 30 October 2000 / Accepted: 19 December 2000 Published online: 27 April 2001     

XML graphs in program analysis

XML graphs have shown to be a simple and effective formalism for representing sets of XML documents in program analysis. It has evolved through a six year period with variants tailored for a range of applications. We present a unified definition, outline the key properties including validation of XML graphs against different XML schema languages, and provide a software package that enables others to make use of these ideas. We also survey the use of XML graphs for program analysis with four very different languages: Xact (XML in Java), Java Servlets (Web application programming), XSugar (transformations between XML and non-XML data), and XSLT (stylesheets for transforming XML documents).     

基于XSLT的XML文档节点间约束关系验证

提出一种基于W3C XSLT技术标准的验证方法,利用XSLT和XPath相关技术,通过定义规范化的输入输出信息结构以及约束规则,完成了对XML文档节点之间约束关系的验证.     

基于DTD的XML与SQL查询转换算法

针对如何将XML查询转换成SQL查询提出了一个XSLT查询到SQL查询的转换框架和算法，研究了文档类型定义(DTD)和关系模式的相互映射方法及基于XML DTD且不使用任何中间语言将XSLT查询转换为SQL查询的具体过程和算法：从XSLT代码中抽取指令集合，合并、简化并分割其中的XPath，最后抽取出SQL语句的各个组成部分。该算法具有较高的通用性。     

Query optimization in XML structured-document databases

While the information published in the form of XML-compliant documents keeps fast mounting up, efficient and effective query processing and optimization for XML have now become more important than ever. This article reports our recent advances in XML structured-document query optimization. In this article, we elaborate on a novel approach and the techniques developed for XML query optimization. Our approach performs heuristic-based algebraic transformations on XPath queries, represented as PAT algebraic expressions, to achieve query optimization. This article first presents a comprehensive set of general equivalences with regard to XML documents and XML queries. Based on these equivalences, we developed a large set of deterministic algebraic transformation rules for XML query optimization. Our approach is unique, in that it performs exclusively deterministic transformations on queries for fast optimization. The deterministic nature of the proposed approach straightforwardly renders high optimization efficiency and simplicity in implementation. Our approach is a logical-level one, which is independent of any particular storage model. Therefore, the optimizers developed based on our approach can be easily adapted to a broad range of XML data/information servers to achieve fast query optimization. Experimental study confirms the validity and effectiveness of the proposed approach.     

一种基于结构特征的XML数据查询方法

针对XML数据特有的树型结构模式,提出了一种将树型结构的XML数据和查询语句转化为特定格式的字符串,基于串匹配原理对结构复杂的XML数据进行查询的方法,避免了传统的基于路径的查询方式所必需的路径之间的连接（join）操作,从而提高查询效率。利用本文提出的编码方式,可以建立关于XML数据结构和数据内容舍为一体的索引。实验显示,本文使用的针对XML数据查询的方法比传统的基于连接操作的数据查询方式高效,且本方法具有良好的扩展性。     

Meta-Stylesheets for the Conversion of Mathematical Documents into Multiple Forms

It is sometimes necessary to convert mathematical documents into a number of different forms. This may be achieved by applying different XSLT stylesheets, one for each required form, to the document. We describe how meta-stylesheets may be used to automatically generate the stylesheets which will be applied to the mathematical documents to generate the multiple forms required. The resources required by the meta-stylesheets may be encoded in extended OpenMath Content Dictionaries. We discuss how the presentational information may be stored in the Content Dictionaries for various different notational styles.     

Result Merging Technique for Answering XPath Query over XSLT Transformed Data

Caching stores the results of previously answered queries in order to answer succeeding queries faster by reusing these results. We propose two different approaches for using caches of XSLT transformed XML data in order to answer queries. The first approach checks whether or not a current query Q can be directly answered from the result of a previously answered query Qi stored in the cache. The new query is otherwise submitted to the source over the network, the answer of the query is determined, transmitted back to the client, and stored in the cache. The second approach determines only the intersection Q−Qi and integrates the result of Q−-Qi into the previous results in the cache, which requires applying a numbering scheme for the output of the XSLT stylesheet. We show by experimental results that the second approach can significantly speed up the answering time in comparison to the first approach, but is not significantly slower in few worst cases than the second approach.     

Dual syntax for XML languages

XML is successful as a machine processable data interchange format, but it is often too verbose for human use. For this reason, many XML languages permit an alternative more legible non-XML syntax. XSLT stylesheets are often used to convert from the XML syntax to the alternative syntax; however, such transformations are not reversible since no general tool exists to automatically parse the alternative syntax back into XML.

We present XSugar, which makes it possible to manage dual syntax for XML languages. An XSugar specification is built around a context-free grammar that unifies the two syntaxes of a language. Given such a specification, the XSugar tool can translate from alternative syntax to XML and vice versa. Moreover, the tool statically checks that the transformations are reversible and that all XML documents generated from the alternative syntax are valid according to a given XML schema.     

一种基于关键字的XML文档查询算法

对XML文档查询的常用方法有两种：一种是使用查询语言;另一种是使用关键字,而使用关键字查询XML文档比使用查询语言更为简单方便。给出了一种使用关键字查询XML文档的索引查找算法。该算法只需要扫描一次关键字对应的编码列,就可以找到需要的编码,提高了查询效率。实验表明该算法是可行的和有效的。     

基于XSLT的Web包装器环境

Web包装器将网页内容转换为XML格式,用于系统集成。进行XML转换的XSLT技术能较好地支持包装器的信息抽取和组织。本文从包含查询接口、结果模式和映射规则的包装器描述文件（XML）出发,给出了自动生成可执行代码的技术方案。包装器的执行及其生成过程完全基于XSLT技术,系统具有较强的可移植性。提出“元数据对齐”方法进行内
容辅助定位,提高了对页面变化的容忍度。原型系统的实现验证了以上技术的可行性。     

Universal fuzzy system representation with XML

An XML schema and an XML DTD (Document Type Definition) are designed as syntax to represent general fuzzy systems in XML. We demonstrate how fuzzy systems described in XML with our proposed schema can be universally compatible with different software by using appropriate XSLT (eXtensible Style Language Transformation) stylesheets. The proposed schema offers a standard platform for fuzzy system developers and users to collaborate without compatibility issues. We demonstrate how a fuzzy logic design coded in accordance with our XML schema can subsequently be understood and integrated with two different software like MATLAB and FuzzyJess.     

A high concurrency XPath-based locking protocol for XML databases

Providing efficient access to XML documents becomes crucial in XML database systems. More and more concurrency control protocols for XML database systems were proposed in the past few years. Being an important language for addressing data in XML documents, XPath expressions are the basis of several query languages, such as XQurey and XSLT. In this paper, we propose a lock-based concurrency control protocol, called XLP, for transactions accessing XML data by the XPath model. XLP is based on the XPath model and has the features of rich lock modes, low lock conflict and lock conversion. XLP is also proved to ensure conflict serializability. In sum, there are three major contributions in this paper. The proposed XLP supports most XPath axes, rather than simple path expressions only. Conflict conditions and rules in the XPath model are analyzed and derived. Moreover, a lightweighted lock mode, P-lock, is invented and integrated into XLP for better concurrency.     

An efficient algorithm of frequent XML query pattern mining for ebXML applications in e-commerce

Providing efficient query to XML data for ebXML applications in e-commerce is crucial, as XML has become the most important technique to exchange data over the Internet. ebXML is a set of specifications for companies to exchange their data in e-commerce. Following the ebXML specifications, companies have a standard method to exchange business messages, communicate data, and business rules in e-commerce. Due to its tree-structure paradigm, XML is superior for its capability of storing and querying complex data for ebXML applications. Therefore, discovering frequent XML query patterns has become an interesting topic for XML data management in ebXML applications. In this paper, we present an efficient mining algorithm, namely ebXMiner, to discover the frequent XML query patterns for ebXML applications. Unlike the existing algorithms, we propose a new idea by collecting the equivalent XML queries and then enumerating the candidates from infrequent XML queries in our ebXMiner. Furthermore, our simulation results show that ebXMiner outperforms other algorithms in its execution time.