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.     

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.     

Equivalences and optimizations in an expressive XSLT subset

XML is the standard data interchange format and XSLT is the W3C proposed standard for transforming and restructuring XML documents. It turns out that XSLT has very powerful query capabilities as well. Hovewer, due to its complex syntax and lack of formal specification, it is not a trivial task to decide whether two XSLT stylesheets yield the same result, even if for an XSLT subset. We isolate such fragment, powerful enough for expressing several interesting queries and for manipulating XML documents and show how to translate them into queries expressed in a properly extended version of TAX, a powerful XML query algebra, for which we provide a collection of equivalence rules. It is then possible to reason about XSLT equivalences, by translating XSLT stylesheets into XTAX expressions and then statically verifying their equivalence, by means of the mentioned equivalence rules.     

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.     

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).     

用Java扩展XSLT

XSLT提供了一种将XML文档转换为HTML的强有力的工具。然而,当这种转换需要涉及更多逻辑的时候,就会显现出它的不足之处。文中讲述了如何使用Java扩展XSLT,从而更好地发挥两种语言的特色。最后给出一实例来具体展示如何将XML节点传送到Java类并返回到样式表以进一步处理。     

On the complexity of typechecking top-down XML transformations

We investigate the typechecking problem for XML transformations: statically verifying that every answer to a transformation conforms to a given output schema, for inputs satisfying a given input schema. As typechecking quickly turns undecidable for query languages capable of testing equality of data values, we return to the limited framework where we abstract XML documents as labeled ordered trees. We focus on simple top-down recursive transformations motivated by XSLT and structural recursion on trees. We parameterize the problem by several restrictions on the transformations (deleting, non-deleting, bounded width) and consider both tree automata and DTDs as input and output schemas. The complexity of the typechecking problems in this scenario ranges from $\text{<mi mathsize="small" is="true">PTIME</mi>}$ to $\text{<mi mathsize="small" is="true">EXPTIME</mi>}$.     

Static analysis of XML transformations in Java

XML documents generated dynamically by programs are typically represented as text strings or DOM trees. This is a low-level approach for several reasons: 1) traversing and modifying such structures can be tedious and error prone, 2) although schema languages, e.g., DTD, allow classes of XML documents to be defined, there are generally no automatic mechanisms for statically checking that a program transforms from one class to another as intended. We introduce XACT, a high-level approach for Java using XML templates as a first-class data type with operations for manipulating XML values based on XPath. In addition to an efficient runtime representation, the data type permits static type checking using DTD schemas as types. By specifying schemes for the input and output of a program, our analysis algorithm will statically verify that valid input data is always transformed into valid output data and that the operations are used consistently.     

Designing XML documents from conceptual schemas and workload information

Due to the increase of XML-based applications, XML schema design has become an important task. One approach is to consider conceptual schemas as a basis for generating XML documents compliant to consensual information of specific domains. However, the conversion of conceptual schemas to XML schemas is not a straightforward process and inconvenient design decisions can lead to a poor query processing on XML documents generated. This paper presents a conversion approach which considers data and query workload estimated for XML applications, in order to generate an XML schema from a conceptual schema. Load information is used to produce XML schemas which can respond well to the main queries of an XML application. We evaluate our approach through a case study carried out on a native XML database. The experimental results demonstrate that the XML schemas generated by our methodology contribute to a better query performance than related approaches.

Rewriting of visibly pushdown languages for XML data integration

In this work, we focus on XML data integration by studying rewritings of XML target schemas in terms of source schemas. Rewriting is very important in data integration systems where the system is asked to find and assemble XML documents from the data sources and produce documents that satisfy a target schema.As schema representation, we consider Visibly Pushdown Automata (VPAs), which accept Visibly Pushdown Languages (VPLs). The latter have been shown to coincide with the family of (word-encoded) regular tree languages, which are the basis of formalisms for specifying XML schemas. Furthermore, practical semi-formal XML schema specifications (defined by simple pattern conditions on XML) compile into VPAs that are exponentially more concise than other representations based on tree automata.Notably, VPLs enjoy a “well-behavedness” that facilitates us in addressing rewriting problems for XML data integration. Based on VPAs, we positively solve these problems, and present detailed complexity analyses.     

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.     

Using XML to improve the productivity and robustness in application development in geosciences

In this paper, we describe an approach to apply Extensible Markup Language (XML) technologies to improve the robustness of geological and geophysical applications as well as to increase the efficacy in the application development process. Geological and geophysical applications are often data centric, I/O intensive and their development is incremental. Therefore, significant amount of development resources is devoted to the design and reengineering of the container data structures that store data. This process is time consuming, mechanical and error prone. Normally, ad hoc parsers are necessary for reading inputs, as well as numerous filters, or adapters to transform the data for integration with other legacy applications. Most of this can be avoided by using XML-related technologies. XML has a type system schema that can be used to define input parameters and constraints. The XML parser can validate the input data using the constraints defined in the schema. Exporting results in XML format allows the use of Extensible Stylesheet Language Transformations (XSLT) to transform XML output to any other format necessary for integration with legacy applications. Additionally, XML-data binding code can be automatically generated in specified languages such C++ and Java. We used this approach to develop applications for seismic ray-tracing and basin modeling with great success, and the major benefits of this approach were the significant gains in productivity during the developement and application robustness.     

基于XML的ER模型的建立

XML已经成为Web上表示结构化和半结构化数据的标准格式,为了描述XML数据的结构和内容,业界已经提出了多个XML模式语言。虽然XML模式对ValidatingXML文档非常有用,但它不适用于要求表示数据有关语义知识的任务,对这样的任务最好使用概念模式。针对XML模式的概念建模,介绍了一种扩展实体关系模型及将用XML模式语言定义的模式转换成扩展实体模式的过程。     

抽取XML文档到关系数据库

XML在关系数据库中的存储问题是XML研究领域中的一个重要问题。在总结多种映射方法的基础上,提出了一种方法将多个相似的XML文档进行解析,根据映射关系,生成各自的关系模式,并分析归纳出一个集成的关系模式,然后创建一个关系数据库,并在映射关系的基础上提取并存储XML文档数据到关系数据库。此方法以较为简洁的结构保存了XML文档的数据信息,其最大的特点就是不用考虑文档的模式信息（DTD,XML Schema）。并通过一个具体的实验结果来说明这种方法的有效性。     

Tractable XML data exchange via relations

We consider data exchange for XML documents: given source and target schemas, a mapping between them, and a document conforming to the source schema, construct a target document and answer target queries in a way that is consistent with the source information. The problem has primarily been studied in the relational context, in which data-exchange systems have also been built. Since many XML documents are stored in relations, it is natural to consider using a relational system for XML data exchange. However, there is a complexity mismatch between query answering in relational and in XML data exchange. This indicates that to make the use of relational systems possible, restrictions have to be imposed on XML schemas and mappings, as well as on XML shredding schemes. We isolate a set of five requirements that must be fulfilled in order to have a faithful representation of the XML data-exchange problem by a relational translation. We then demonstrate that these requirements naturally suggest the in-lining technique for data-exchange tasks. Our key contribution is to provide shredding algorithms for schemas, documents, mappings and queries, and demonstrate that they enable us to correctly perform XML data-exchange tasks using a relational system.     

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。     

XML Schema与DTD的比较及应用

XML是目前广泛应用的数据交换标准，而模式是应用XML进行数据交换的正确性的保证机制之一。模式详细描述了文档的结构，确保文档的元素和属性等的正确性。XML Schema和DTD是其中应用最广泛的模式。文中详细比较了两者的异同，并指出了各自的局限及最佳的应用，DTD非常适合于文本密集型XML文档，而XML Schema更适合于数据密集型XML文档。     

XML文档在关系数据库中的规范化存储

提出了一种存储方法，首先把XML文档映射为泛关系模式，再利用算法DeriveFDs推导出XML键所蕴含的泛关系模式上函数依赖集的规范覆盖，根据此规范覆盖，最后将泛关系模式保持函数依赖地分解为3NF模式集。得到了保持XML键约束的规范化存储模式，实现了XML文档在关系数据库中的规范化存储。实验研究表明文中提出的方法是有效的。