二进制数据的XML集成方法研究与实现*

XML正逐渐成为WWW数据表示和交换的标准,如何有效实现将二进制数据与XML文档有效集成是充分利用XML所提供的优势的重要方面。给出了二进制数据与XML文档集成的框架,提出了一种有效的二进制数据编码算法和与XML文档的集成算法,用C++成功地实现了上述所有算法。     

基于XML和JSON的格式化网络参数文件研究

在机动通信系统中通信设备的通信参数主要以二进制方式显示和组织,给用户的使用和参数的传递带来了许多不便。提出采用XML技术表示通信设备的系统组成和配置参数,并在比较和分析XML和JSON 2种当前最广泛应用的文本数据交换格式的基础上,结合当前机动通信系统保障需求,提出了基于XML和JSON格式化网络参数的组织和表示方式。     

XML加密及其在电子公文中的应用

可扩展标记语言XML正逐渐成为分布式计算的通用语言.随着XML的广泛应用,XML数据的安全问题已成为关注的焦点.分析了XML加密规范.基于NET平台,通过把C#语言和XML加密规范有机地结合起来,实现了XML加密系统.该系统能够对XML文档、XML元素以及任意二进制数据加密.利用公钥基础设施PKI技术,把XML加密应用于电子公文,保证了电子公文的安全.     

基于XML Web 服务的产品数据共享模型研究

提出了基于XML Web服务的产品数据共享模型。首先,分析将产品数据作为服务发布的意义,并制定以XML Web服务方式共享产品数据的原则;其次,探讨了产品数据XML Web服务中二进制数据的发布的问题;最后,提出基于XML Web服务的产品数据共享体系结构。     

数据字典在转换工具中的应用设计

因各系统记录的二进制数据的数据格式不同,为开发系统耦合度低,可重用性好的转换工具,结合树型结构数据字典和模块化设计思想,利用XML文档存储和维护数据字典内容,设计了基于XML存储的数据字典的转换工具系统框架.将转换工具划分为预处理模块、提取载荷模块、读取XML文件模块,数据字典模块和解析结果显示模块共5个功能模块,完成了二进制数据的译码过程.使用XML数据字典设计转换工具系统框架,结构清晰,可维护性好.     

BSC：一种高效的动态XML树编码方案

确定一篇XML文档中任意两个节点之间是否存在某种结构关系,是XML查询处理过程的一个重要组成部分.XML树编码方案为每个节点分配唯一编号,仅通过比较节点编号而不必访问原XML文档,就可以快速有效地确定节点间的结构关系.随着XML应用不断普及,能否高效地支持更新操作,已成为XML树编码方案研究的一个重要课题.本文基于二进制小数的特性,提出了一种新的XML树编码方案-BSC,它可以完全高效地支持XML更新操作而不需要重新编码.实验结果证明,与已有的动态编码方案相比,BSC编码无论在静态编码方面还是在动态更新方面都具有很好的性能.     

Mac应用程序从PowerPC向Intel架构过渡的研究

对在不同的Macintosh架构下编写通用二进制代码进行了研究和实践。分析了PowerPC和Intel架构间的差异,结合具体应用程序的移植,介绍了如何在Macintosh下编写通用二进制代码,并提出了以XML形式进行数据传递的解决方案。     

一种高效的动态XML文档树编码机制

针对现有XML编码机制时空效率不高、对XML文档动态更新支持不够等问题,结合素数和IBSL 2种编码机制,提出一种新的XML文档树编码机制——基于素数的二进制字符串编码机制。理论分析和实验均证明该编码机制具有较好的查询效率,能够高效地支持XML文档更新操作,大幅降低空间成本。     

基于XML多重数字签名方案的设计与应用

XML数字签名是W3C和IETF于2002年共同提出的草案,它为任何数据提供了完整性、消息认证、以及签名者认证服务,可以应用于任何数据对象(包括XML文档和二进制数据).Java XML数字签名编程接口是XML数字签名的一个标准接口,它定义在JSR105规范中,并在最近发布的Java SE6中得到实现.本文基于Eric Jui-Lin Lu的签名方案,利用Java XML编程接口,设计XML多重签名方案:提高了签名的效率和灵活性,具有一定的可扩展性.     

.NET中XML与二进制数据集成技术的研究和应用

XML标记语言提供了对文本数据极好的支持,但在Internet中经常需要传输和处理大量的二进数据文件,xml对这一类型的数据处理能力有限,因此必须有效实现二进制数据和xml文档的集成。.NET提供了对xml完美的内置支持,在研究了二进制数据和xml文档集成的方法和.NET中实现数据集成的关键技术的基础上,在实际应用中实现了两者的有效集成和二进制文件的重构。     

An XML query engine for network-bound data

XML has become the lingua franca for data exchange and integration across administrative and enterprise boundaries. Nearly all data providers are adding XML import or export capabilities, and standard XML Schemas and DTDs are being promoted for all types of data sharing. The ubiquity of XML has removed one of the major obstacles to integrating data from widely disparate sources - namely, the heterogeneity of data formats. However, general-purpose integration of data across the wide are a also requires a query processor that can query data sources on demand, receive streamed XML data from them, and combine and restructure the data into new XML output - while providing good performance for both batch-oriented and ad hoc, interactive queries. This is the goal of the Tukwila data integration system, the first system that focuses on network-bound, dynamic XML data sources. In contrast to previous approaches, which must read, parse, and often store entire XML objects before querying them, Tukwila can return query results even as the data is streaming into the system. Tukwila is built with a new system architecture that extends adaptive query processing and relational-engine techniques into the XML realm, as facilitated by a pair of operators that incrementally evaluate a query's input path expressions as data is read. In this paper, we describe the Tukwila architecture and its novel aspects, and we experimentally demonstrate that Tukwila provides better overall query performance and faster initial answers than existing systems, and has excellent scalability.     

XML压缩文档上的数值更新方法

近年来，XML已成为Web上信息交流和资源共享的主要载体。但XML自身的自冗余特性限制了它的普遍应用。目前，已经有研究成果提出了XML的压缩方法。压缩的XML文档能够有效利用存储空间，节省网络带宽。在实际应用中，经常需要对压缩存储的XML文档进行更新。对于大的压缩文档，如果先解压再更新，会消耗大量时间，因此，高效的更新方法应该避免解压缩文档，在压缩的XML文档上直接进行更新操作。本文针对压缩XML文档中的数值类型（包括整型和浮点型）数据，研究了在保持压缩状态条件下如何进行有效的数值更新，提出了基于XPRESS实现的Naive数值更新方法，以及修改XPRESS编码方法实现的更为高效的Pivot数值更新方法。通过大量的实验证明，Pivot数值更新方法不仅能够提供高效的更新处理，而且保持了XPRESS的高压缩率。     

Efficient recursive XML query processing using relational database systems

Recursive queries are quite important in the context of XML databases. In addition, several recent papers have investigated a relational approach to store XML data and there is growing evidence that schema-conscious approaches are a better option than schema-oblivious techniques as far as query performance is concerned. However, the issue of recursive XML queries for such approaches has not been dealt with satisfactorily. In this paper we argue that it is possible to design a schema-oblivious approach that outperforms schema-conscious approaches for certain types of recursive queries. To that end, we propose a novel schema-oblivious approach, called Sucxent++ (Schema Unconcious XML Enabled System), that outperforms existing schema-oblivious approaches such as XParent by up to 15 times and schema-conscious approaches (Shared-Inlining) by up to eight times for recursive query execution. Our approach has up to two times smaller storage requirements compared to existing schema-oblivious approaches and 10% less than schema-conscious techniques. In addition Sucxent++ performs marginally better than Shared-Inlining and is 5.7–47 times faster than XParent as far as insertion time is concerned.     

An adaptive path index for XML data using the query workload

Due to its flexibility, XML is becoming the de facto standard for exchanging and querying documents over the Web. Many XML query languages such as XQuery and XPath use label paths to traverse the irregularly structured XML data. Without a structural summary and efficient indexes, query processing can be quite inefficient due to an exhaustive traversal on XML data. To overcome the inefficiency, several path indexes have been proposed in the research community. Traditional indexes generally record all label paths from the root element in XML data and are constructed with the use of data only. Such path indexes may result in performance degradation due to large sizes and exhaustive navigations for partial matching path queries which start with the self-or-descendent axis(“//”). To improve the query performance, we propose an adaptive path index for XML data (termed APEX). APEX does not keep all paths starting from the root and utilizes frequently used paths on query workloads. APEX also has a nice property that it can be updated incrementally according to the changes of query workloads. Experimental results with synthetic and real-life data sets clearly confirm that APEX improves the query processing cost typically 2–69 times compared with the traditional indexes, with the performance gap increasing with the irregularity of XML data.     

Secure query processing against encrypted XML data using Query-Aware Decryption

Dissemination of XML data on the internet could breach the privacy of data providers unless access to the disseminated XML data is carefully controlled. Recently, the methods using encryption have been proposed for such access control. However, in these methods, the performance of processing queries has not been addressed. A query processor cannot identify the contents of encrypted XML data unless the data are decrypted. This limitation incurs overhead of decrypting the parts of the XML data that would not contribute to the query result. In this paper, we propose the notion of Query-Aware Decryption for efficient processing of queries against encrypted XML data. Query-Aware Decryption allows us to decrypt only those parts that would contribute to the query result. For this purpose, we disseminate an encrypted XML index along with the encrypted XML data. This index, when decrypted, informs us where the query results are located in the encrypted XML data, thus preventing unnecessary decryption for other parts of the data. Since the size of this index is much smaller than that of the encrypted XML data, the cost of decrypting this index is negligible compared with that for unnecessary decryption of the data itself. The experimental results show that our method improves the performance of query processing by up to six times compared with those of existing methods. Finally, we formally prove that dissemination of the encrypted XML index does not compromise security.     

Dynamically Updating XML Data: Numbering Scheme Revisited

Almost all existing approaches use certain numbering scheme to encode XML elements to facilitate query processing when XML data is stored in databases. For example, under the most popular region-based numbering scheme, the starting and ending positions of an element in a document are used as the code to identify the element so that the ancestor/descendant relationship between two elements can be determined by merely examining their codes. While such numbering scheme can greatly improve query performance, renumbering large amount of elements caused by updates becomes a performance bottleneck if XML documents are frequently updated. Unfortunately, no satisfactory work has been reported for efficient update of XML data. In this paper, we first formalize the XML data update problem by defining the basic operators to support most XML update queries. We then present a new numbering scheme that not only requires minimal code-length in comparison with existing numbering schema but also improves update performance when XML data is frequently updated at arbitrary positions. The fundamental difference between our new scheme and existing ones is that, instead of maintaining the explicit codes for elements, we only store the necessary information and generate the codes when they are needed in query processing. In addition to present the basic scheme, we also discuss some optimization techniques to further reduce the update cost. Results of a comprehensive performance study are provided to show the advantages of the new scheme.     

Efficiently Querying Large XML Data Repositories: A Survey

Extensible markup language (XML) is emerging as a de facto standard for information exchange among various applications on the World Wide Web. There has been a growing need for developing high-performance techniques to query large XML data repositories efficiently. One important problem in XML query processing is twig pattern matching, that is, finding in an XML data tree D all matches that satisfy a specified twig (or path) query pattern Q. In this survey, we review, classify, and compare major techniques for twig pattern matching. Specifically, we consider two classes of major XML query processing techniques: the relational approach and the native approach. The relational approach directly utilizes existing relational database systems to store and query XML data, which enables the use of all important techniques that have been developed for relational databases, whereas in the native approach, specialized storage and query processing systems tailored for XML data are developed from scratch to further improve XML query performance. As implied by existing work, XML data querying and management are developing in the direction of integrating the relational approach with the native approach, which could result in higher query processing performance and also significantly reduce system reengineering costs.     

高效XML验证技术的实现

XML解析器是分析、处理XML文档的基础软件.对XML解析器的高效验证技术进行了研究,实现了支持StAX接口的验证型解析器OnceStAXParser2.0.该解析器采用了多项性能优化措施,包括属性验证的高效实现、元素验证自动机的优化、基于统计的预测算法等.性能测试表明,在进行验证的条件下,OnceStAXParser2.0具有出色的解析性能.     

A Semantic Cache Framework for Secure XML Queries

Secure XML query answering to protect data privacy and semantic cache to speed up XML query answering are two hot spots in current research areas of XML database systems. While both issues are explored respectively in depth,they have not been studied together,that is,the problem of semantic cache for secure XML query answering has not been addressed yet. In this paper,we present an interesting joint of these two aspects and propose an efficient framework of semantic cache for secure XML query answering,which can improve the performance of XML database systems under secure circumstances. Our framework combines access control,user privilege management over XML data and the state-of-the-art semantic XML query cache techniques,to ensure that data are presented only to authorized users in an efficient way. To the best of our knowledge,the approach we propose here is among the first beneficial efforts in a novel perspective of combining caching and security for XML database to improve system performance. The efficiency of our framework is verified by comprehensive experiments.     

一种高效的Web服务性能优化策略

Web服务是构建面向服务架构(SOA)的主流分布式计算技术.基于XML的数据传输格式在给Web服务带来众多优点的同时,严重影响了其性能,制约了Web服务的应用.众多研究表明,XML解析和数据绑定是Web服务的主要性能瓶颈.着眼于避免传统XML解析和运行时Java反射过程的开销,提出了一种新颖的Web服务性能优化策略.它为每个Web服务生成一个特定于该服务的SOAP消息处理器,通过在对SOAP消息的一遍扫描中高效地生成服务业务逻辑调用所需的参数对象.实验结果表明,该优化策略能够有效地提高Web服务的性能.