Search

A new structure for streaming the XML data is proposed which guarantees confidentiality of the XML data over the wireless stream.An access mechanism is proposed to efficiently process XML queries over the encrypted XML stream. Recently, the use of XML for data broadcasting in mobile wireless networks has gained many attentions. One of the most essential requirements for such networks is data confidentiality. In order to secure XML data broadcast in mobile wireless networks, mobile clients should obey a set of access authorizations specified on the original XML document. In such environments, mobile clients can only access authorized parts of encrypted XML stream based on their access authorizations. Several indexing methods have been proposed in order to have selective access to XML data over the XML stream. However, these indexing methods cannot be used for encrypted XML data. In this paper, we define a new structure for XML stream which supports data confidentiality of XML data over the wireless broadcast channel. We also define an access mechanism for our proposed structure to efficiently process XML queries over the encrypted XML stream. The experimental results demonstrate that the use of our proposed structure and access mechanism for XML data broadcast efficiently disseminates XML data in mobile wireless networks.

The gap between storing data in relational databases and transferring data in form of XML has been closed e.g. by SQL/XML queries that generate XML data out of relational data sources. However, only few relational database systems support the evaluation of SQL/XML queries. And even in those systems supporting SQL/XML, the evaluation of such queries is quite slow compared to the evaluation of SQL queries. In this paper, we present S2CX, an approach that allows to efficiently evaluate SQL/XML queries on any relational database system, no matter whether it supports SQL/XML or not. As a result to an SQL/XML query, S2CX supports different output formats ranging from plain XML to different compressed XML representations including a succinct encoding of XML data, schema-aware compressed XML to grammar compressed XML. In many cases, S2CX produces compressed XML as a result to an SQL/XML query even faster than the evaluation of SQL/XML queries into non-compressed XML as provided by Oracle 11 g and by DB2. Furthermore, our approach to query evaluation scales better, i.e., the larger the dataset, the faster is our approach compared to SQL/XML query evaluation in Oracle 11 g and in DB2.

In temporal and multi-version XML environments, several research works have focused on changes to traditional aspects of XML schemas like element/attribute declarations and simple/complex type definitions. However, advanced aspects of XML schemas have been either considered only to a limited extent, like XML namespaces or not studied at all, like XML schema design styles. In this paper, we deal with this last aspect and propose, in the temporal and multi-version τXSchema (temporal XML schema) framework, an approach for: 1) easily specifying changes to the design styles of an XML schema through the use of a high-level schema change operation based on our previously proposed StyleVolution approach; 2) correctly propagating the possible effects to the underlying XML document instances through the transparent management of the schema and document versions; 3) dealing with the interaction between design styles and conventional schema changes, by means of a semi-automated conflict resolution.

An XML schema definition can be organized according to one of the following design styles: "Russian Doll", "Salami Slice", "Venetian Blind", or "Garden of Eden"; otherwise, it is said to be in "Bologna" style, which actually means free format. Converting a complex XML schema from a style to another without automated support is not a trivial task. The "Garden of Eden" style can be considered as a normalized format since the definitions of all components (i.e., elements, attributes and types) are global and, thus, can be re-used in the definition of other XML schema constructs (e.g., when expanding the schema or importing it into another schema or using it to define an XML namespace). In this work, we present a Normalize procedure, which can be used to convert any given XML schema to the "Garden of Eden" style, by automatically transforming and rearranging all declarations and definitions it contains.

With the extensive application of XML, especially in e-commerce field, XML data security has become the focus of people, which particularly shows in its structural attack specific to the location relation to elements in tree structure. Combined with the characteristics of tree structure of XML data as well as the basic features of traversing binary tree, the paper proposes a method to protect the structural-integrity of XML digital signature, so as to protect XML data element from structural attack through the basic features of traversing binary tree, and ensure the absolute location relationship among elements.

This paper proposes an XML representation of octgrid completely. Octgrid is a data structure based on octal grid graphs for heterogeneous rectangular dissections. This model is represented by a list structure called H3-Code. The file format of H3-Code is a plain text file that consists of a plurality of space separated field. Therefore we introduced the XML representation called H14-Code.

The development of the smart grid calls for enhanced power system application interoperability and knowledge management. The IEC Common Information Model (CIM) supports semantic interoperability but multiple identities attributed to common power system resources present challenges to unambiguous metadata model merging within a repository. This paper describes an original methodology for the building of a novel metadata model repository that concentrates our knowledge of enterprise power system resources. We leverage the value of model namespaces and resource description framework (RDF) technology in providing contexts for multiple identities referring to common power system resources. This novel approach aims to develop a more realistic understanding of network reality than repositories depending on a single CIM XML namespace and contributes to engineering an “enterprise ontology” supporting interoperability and business intelligence. We demonstrate this novel approach with reference to National Grid use cases for network operation and planning model management roles.

Recently, researches are studied in developing efficient techniques for accessing, querying, and managing XML documents which are frequently used in the Internet. In this paper, we propose a new method to cluster XML documents efficiently. An element and an inclusion relationship of a XML document corresponds to a node and a level of the corresponding tree, respectively. Therefore, when two XML documents are similar then their nodes' names and levels of the corresponding trees are also similar. In this paper, we cluster XML documents by using nodes' names and levels of the corresponding tree as a feature of a document. The experiment shows that our proposed method has a good performance.

Along with the increase of XML applications, Native XML database technology is gaining the attention of the field of database, and query optimization is still one of the key research contents. This article，from a new perspective, represents the research on the relationship between XML nodes and proposes a query optimization model based on the associated elements of XML data file . In order to query the information of the related elements in the XML data file, this method takes the strategy of index; and proposed the query algorithms on the query optimization model based on associated elements.

In XML databases, several works have dealt with changes of basic components of XML Schemas: element and attribute declarations, simple types, and complex type definitions. However, there is no work that has dealt with changes to advanced concepts of XML Schemas like XML namespaces, local/global qualified/unqualified declarations, and schema definition styles. In this paper, we deal with XML namespace evolution. To the best of our knowledge, we are the first to study such a topic (and in an environment that supports schema versioning). More precisely, we propose an approach for managing changes to XML namespaces defined in XML Schemas, and their effects on XML documents that are valid to these schemas, while keeping track of all XML schema and XML instance versions.

Keyword search is a user-friendly approach for users to retrieve information from XML data. Since an XML document can have a large size and contain a lot of information, an XML keyword search result should be a fragment of an XML document dynamically constructed at query time, which is achievable due to the structuredness of XML. Processing keyword searches on XML has several challenges, e.g., what are the elements in the XML document that are relevant to the query? How to generate the results efficiently and rank the results meaningfully? How to present the results to the user in a way such that the user can quickly find the desired information? In this survey, we review the papers in the literature that attempted to address these problems. We divide the existing approaches into several classes based on the problem they tackled, and perform a comprehensive analysis of these works.

Querying over XML elements using keyword search is steadily gaining popularity. The traditional similarity measure is widely employed in order to effectively retrieve various XML documents. A number of authors have already proposed different similarity-measure methods that take advantage of the structure and content of XML documents. They do not, however, consider the similarity between latent semantic information of element texts and that of keywords in a query. Although many algorithms on XML element search are available, some of them have the high computational complexity due to searching a huge number of elements. In this paper, we propose a new algorithm that makes use of the semantic similarity between elements instead of between entire XML documents, considering not only the structure and content of an XML document, but also semantic information of namespaces in elements. We compare our algorithm with the three other algorithms by testing on the real datasets. The experiments have demonstrated that our proposed method is able to improve the query accuracy, as well as to reduce the running time., Comment: 9 pages

XML publishing has been an emerging technique for transforming (portions of) a relational database into an XML document, for example, to facilitate interoperability between heterogeneous applications. Such applications may update the XML document and the source relational database must be updated accordingly. In this paper, we consider such XML documents as (possibly) recursively defined XML views of relations. We propose new optimization techniques to efficiently support XML view updates specified via an XPATH expression with recursion and complex filters. The main novelties of our techniques are: (1) we propose a space-efficient relational encoding of recursive XML views; and (2) we push the bulk of update processing inside a relational database. Specifically, a compressed representation of the XML views is stored as extended shared-inlining relations. A space-efficient and updatable 2-hop index is used to optimize XPATH evaluation on XML views. Updates of the XML views are evaluated on these relations and index. View update translation is handled by a heuristic procedure inside a relational database, as opposed to previous middleware approaches. We present an experimental study to demonstrate the effectiveness of our proposed techniques.

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.

XML instances are not necessarily self-contained but may have connections to remote XML data residing on other servers. In this paper, we show that-in spite of its minor support and use in the XML world-the XLink language provides a powerful mechanism for expressing such links both from the modeling point of view and for actually querying interlinked XML data: in our dbxlink approach, the links are not seen as explicit links (where the users must be aware of the links and traverse them explicitly in their queries), but define views that combine into a logical, transparent XML model which serves as an external schema and can be queried by XPath/XQuery. We motivate the underlying modeling and give a concise and declarative specification as an XML-to-XML mapping. We also describe the implementation of the model as an extension of the eXist [eXist: an Open Source Native XML Database, http://exist-db.org/] XML database system. The approach can be applied both for distribution of data and for integration of data from autonomous sources.

In this paper, we study the use of XML tagged keywords (or simply key-tags) to search an XML fragment in a collection of XML documents. We present techniques that are able to employ users' evaluations as feedback and then to generate an adaptive ranked list of XML fragments as the search results. First, we extend the vector space model as a basis to search XML fragments. The model examines the relevance between the imposed key-tags and identified fragments in XML documents, and determines the ranked result as an output. Second, in order to deal with the diversified nature of XML documents, we present four XML Rankers (XRs), which have different strengths in terms of similarity, granularity, and ranking features. The XRs are specially tailored to diversified XML documents. We then evaluate the XML search effectiveness and quality for each tailored XR and propose a meta-XML ranker (MXR) comprising the four XRs. The MXR is trained via a machine learning training scheme, which we term the ranking support vector machine (RSVM) in a co-training framework (RSCF). The RSCF takes as input two sets of labelled fragments and feature vectors and then generates as output adaptive rankers in a learning process. We show empirically that, with only a small set of training XML fragments, the RSCF is able to improve after a few iterations in the learning process. Finally, we demonstrate that the RSCF-based MXR is able to bring out the strengths of the underlying XRs in order to adapt the users' perspectives on the returned search results. By using a set of key-tag queries on a variety of XML documents, we show that the precision of the result of the RSCF-based MXR is effective.

Conventional approaches to XML clustering by content and structure are generally affected by a limitation due to the adoption of the bag-of-word model for the representation of their textual contents. This choice may lead to consider structure-constrained textual items of separate XML documents as related, even though the actual meaning of such items in their respective contexts is different. To overcome such a limitation, we propose XML clustering by structure-constrained phrases. The latter is a previously unexplored method relying on the more accurate bag-of-phrase model of the XML textual content, with which to better preserve the meaning of the structure-constrained content items for improved clustering effectiveness. In order to conduct an in-depth and systematic study of the effectiveness of the proposed method, we develop a parameter-free prototypical approach to XML partitioning, which projects the XML documents into a space of XML features representing fixed-length sequences of adjacent textual items in the context of root-to-leaf paths. Feature selection without any tunable threshold is used to choose a subset of the XML features on the basis of their relevance to clustering, which is assessed through a new scoring scheme. A comparative experimentation on real-world benchmark XML corpora reveals a higher effectiveness than several state-of-the-art competitors.

Classical XML keyword search based on the Lowest Common Ancestor (LCA) framework requires users to be well versed with data and semantic relationships between the query keywords to extract meaningful response, restricting its applicability. GKS (Generic Keyword Search), on the other hand, allows users to browse and navigate XML data without such constraints. GKS enables discovery of deeper insights (DI) in the XML data, found in the context of the search results. Such insights not only expose patterns hidden in the search results but also help users tune their queries, thus enabling the navigation of complex XML repositories with ease. We further show how, for a search query, different insights can be discovered from the data by varying a single parameter.

With the rapid development of information technology, lots of enterprises are being faced with resource share and information exchange under global heterogeneous environment. However, the MOM and XML technology can provide a better solution for the realization of information exchange and resource share of distributed heterogeneous environment. In this paper, we adopt four procedures to realize data synchronization between different databases. 1) get incremental data of source by triggers; 2) convert incremental data into XML file via XML mapping layer; 3) send XML file to destination in a message format; 4) parse data by XML parser. Keywords-MOM; XML; heterogeneous environment; information exchange;data synchronization; trigger

We developed three different rule-based systems, each designed to take XML as input and produce XML as output and manipulate intermediate facts as XML. They use very different methods of representing the XML during rule processing. Our series of benchmarks show when each representation is best. We also developed an XML language for representing the rules. The markup to recognize an input XML is a sample of that input; certain fields are replaced with special tags to match variables against text or subtrees within the input XML. The output or intermediate XML is also represented by a sample of the output XML. We also report on a graphical user interface developed for developing the rules in this special XML language.

Administrators often prefer to keep related sets of files in different locations or media, as it is easier to maintain them separately. Users, however, prefer to see all files in one location for convenience. One solution that accommodates both needs is virtual namespace unification---providing a merged view of several directories without physically merging them. For example, namespace unification can merge the contents of several CD-ROM images without unpacking them, merge binary directories from different packages, merge views from several file servers, and more. Namespace unification can also enable snapshotting by marking some data sources read-only and then utilizing copy-on-write for the read-only sources. For example, an OS image may be contained on a read-only CD-ROM image---and the user's configuration, data, and programs could be stored in a separate read-write directory. With copy-on-write unification, the user need not be concerned about the two disparate file systems.It is difficult to maintain Unix semantics while offering a versatile namespace unification system. Past efforts to provide such unification often compromised on the set of features provided or Unix compatibility---resulting in an incomplete solution that users could not use.We designed and implemented a versatile namespace unification system called Unionfs . Unionfs maintains Unix semantics while offering advanced namespace unification features: dynamic insertion and removal of namespaces at any point in the merged view, mixing read-only and read-write components, efficient in-kernel duplicate elimination, NFS interoperability, and more. Since releasing our Linux implementation, it has been used by thousands of users and over a dozen Linux distributions, which helped us discover and solve many practical problems.

XML query processing is one of the most active areas of database research. Although the main focus of past research has been the processing of structural XML queries, there are growing demands for a full-text search for XML documents. In this paper, we propose XICS (XML Indices for Content and Structural search), which aims at high-speed processing of both full-text and structural queries in XML documents. An important design principle of our indices is the use of a B+-tree. To represent the structural information of XML trees, each node in the XML tree is labeled with an identifier. The identifier contains an integer number representing the path information from the root node. XICS consist of two types of indices, the COB-tree (COntent B+-tree) and the STB-tree (STructure B+-tree). The search keys of the COB-tree are a pair of text fragments in the XML document and the identifiers of the leaf nodes that contain the text, whereas the search keys of the STB-tree are the node identifiers. By using a node identifier in the search keys, we can retrieve only the entries that match the path information in the query. The STB-tree can filter nodes using structural conditions in queries, while the COB-tree can filter nodes using text conditions. We have implemented a COB-tree and an STB-tree using GiST and examined index size and query processing time. Our experimental results show the efficiency of XICS in query processing.

XML is the commonly utilized content specification format for data interchange over the Internet. In Publish/Subscribe model, producer is the source for an XML document and disseminates the XML content to the consumer using a mediator called publisher. Producer labels the XML document and defines access control policies for the consumers. Securely labeled XML document are encrypted and sent to the publisher with consumers access details. Encryption is used to provide confidentiality and integrity for XML content dissemination. Consumer queries the publisher for their accessible content. Here, XML label plays a vital role which locates the XML content uniquely. The objective is to design a secure label that has to identify each XML tag uniquely, should not reveal any additional information about the source XML document. Also, XML label size should be optimal with less label generation time. We proposed a secure and efficient XML labeling scheme called Secure Dewey Coding (SDC) that prevents information leak and assures minimal memory space and time. The implementation results of the proposed XML labeling scheme showed that the XML label size has been reduced to a maximum and an average of 68% and 59% respectively and the generation time also decreased significantly.

XML database systems emerge as a result of the acceptance of the XML data model. Recent works have followed the promising approach of building XML database management systems on underlying RDBMS’s. Achieving query processing performance reduces to two questions: (i) How should the XML data be decomposed into data that are stored in the RDBMS? (ii) How should the XML query be translated into an efficient plan that sends one or more SQL queries to the underlying RDBMS and combines the data into the XML result? We provide a formal framework for XML Schema-driven decompositions, which encompasses the decompositions proposed in prior work and extends them with decompositions that employ denormalized tables and binary-coded XML fragments. We provide corresponding query processing algorithms that translate the XML query conditions into conditions on the relational tables and assemble the decomposed data into the XML query result. Our key performance focus is the response time for delivering the first results of a query. The most effective of the described decompositions have been implemented in XCacheDB, an XML DBMS built on top of a commercial RDBMS, which serves as our experimental basis. We present experiments and analysis that point to a class of decompositions, called inlined decompositions, that improve query performance for full results and first results, without significant increase in the size of the database.

We propose a three-step technique to achieve this purpose. First, we utilize a collection of XML namespaces organized into hierarchical structure as a medium for expressing data semantics. Second, we define the format of resource descriptor for the information source discovery scheme so that we can dynamically register and/or deregister the Web data sources on the fly. Third, we employ an inverted-index mechanism to identify the subset of information sources that are relevant to a particular user query. We describe the design, architecture, and implementation of our approach—IWDS, and illustrate its use through case examples.

In this paper we claim that the current approach to learning objects and metadata standards is counter productive for the integration of e-learning in higher education. We explain why higher education is different with regard to E-learning and we suggest an approach that avoids the use of global standards and favors an approach of an evolving set of metadata tags for an evolving community of practice. We demonstrate how XML technologies and some minimal technical help for the participating teachers can provide the required foundation for a productive process of integrating E-learning in higher education.

Several alternatives to manage large XML document collections exist, ranging from file systems over relational or other database systems to specifically tailored XML base management systems. In this paper we give a tour of Natix, a database management system designed from scratch for storing and processing XML data. Contrary to the common belief that management of XML data is just another application for traditional databases like relational systems, we illustrate how almost every component in a database system is affected in terms of adequacy and performance. We show how to design and optimize areas such as storage, transaction management - comprising recovery and multi-user synchronization - as well as query processing for XML.

The present article specifies revision 2.1 of SXML. SXML is an abstract syntax tree of an XML document. SXML is also a concrete representation of the XML Infoset in the form of S-expressions. The generic tree structure of SXML lends itself to a compact library of combinators for querying and transforming SXML.The master SXML specification file is written in SXML itself. The present paper is the result of translating that SXML code into L A T E X, using an appropriate "stylesheet". A different stylesheet converted the specification to HTML. The master file, the stylesheets and the corresponding HTML and L A T E Xdocuments are available at http://pobox.com/~oleg/ftp/Scheme/xml.html.

The advances in storage and communications enable users to store massive amounts of data, and to share it seamlessly with their peers. With the advent of XML, we expect a significant portion of this data to be in XML format. We describe here the architecture and implementation of an XML repository that promotes a novel navigation paradigm for XML documents based on content and context. Support for these capabilities is achieved by bringing to bear the organizational power of information retrieval to the domain of semistructured documents. File systems remain the preferred storage infrastructure for the home and business desktop environments. We have built a system, XMLFS, based on the ideas stated above. XMLFS presents a storage abstraction that manifests itself to the client as a familiar file system. However, it breaks the tight coupling between the directory hierarchical structure and the file system. XMLFS creates automatically a directory organization of any XML document collection based on content and context. Each user can navigate through the file system according to her/his domain of interest at that point in time. Our result is a first step towards a solution to the discovery and navigation problems presented by the collective repositories of XML documents in peer-to-peer environments.

As an essential basis of relational database theory, integrity constraints such as functional dependency provide a basis for well-designed databases. Integrity constraints are also useful for the normalization of the XML schema design in the expensive applications of XML data. As a semi- structure feature, XML data are usually located by a path expression and multiple data items may be represented by the same path. Thus, functional dependencies for XML should be constraints between sets of XML data items if the path expression is used. These constraints also result in data redundancy. Same as functional dependency, this kind of data redundancy for XML can lead to update anomalies too. This paper proposes a kind of XML integrity constraint to describe the dependent relationship between different sets of XML data items, and defines a general functional depend- ency based on XML node sets. Moreover, this paper propos- es a group of inference rules for the implication problem of the XML functional dependency, and proves that they are sound and complete. Index Terms—Integrity constraints, XML, Functional de- pendencies, Database semantics

XML co-clustering is a promising method to overcome the effectiveness of traditional XML clustering approaches, due to the exploitation of the mutual relationships between XML documents and their respective XML features while clustering both simultaneously. To shed light on this so far unexplored research direction, we conduct a systematic study of the effectiveness of XML co-clustering, by viewing the task as parametric with respect to the XML features. Thus, the definition and exploitation of three distinct types of XML features, which are respectively informative of the content, structure and both aspects of the XML documents, allows an in-depth investigation of all three different instances of the XML co-clustering task, i.e., XML co-clustering by content alone, structure alone as well as both structure and content. XML co-clustering relies on a non-negative matrix trifactorization technique, that efficiently processes large-scale input data, which is especially useful with large corpora of text-centric XML documents. The relevance of the structural and content features of the XML documents is assessed through a new weighting scheme. An intensive experimental evaluation on real-world benchmark XML corpora reveals a higher effectiveness of XML co-clustering in comparison with state-of-the-art approaches to XML clustering. Insights are also provided on the effectiveness of XML feature clustering.

While using an algebra that acts on sets of variable bindings for evaluating XML queries, the problem of constructing XML from these bindings arises. One approach is to define a powerful operator that is able to perform a complex construction of a representation of the XML result document. The drawback is that such an operator in its generality is hard to implement and disables algebraic optimization since it has to be executed last in the plan. Therefore we suggest to construct XML documents by special query execution plans called construction plans built from simple, easy to implement and efficient operators. The paper proposes four simple algebraic operators needed for XML document construction. Further, we introduce an optimizing translation algorithm of construction clauses into algebraic expressions and briefly point out algebraic optimizations enabled by our approach.

Medical Markup Language (MML) has been developed over the last 6 years in order to create a set of standards by which medical data, within Japan and hopefully worldwide, can be stored, accessed and exchanged in any number of physical locates. The MML version 2.21 is characterized by XML as meta-language, module structure for each document and enhancement of linking function among documents. Data exchange specification has been also added for query and reply. MML instances are composed of MML header and MML body. The MML header includes information for data transmission, while MML body includes several module items. One module item contains two elements: document information and module content. Nine MML module contents are defined at the present time: patient information, health insurance information, diagnosis information, lifestyle information, basic clinic information, particular information at the time of first visit, progress course information, surgery record information and clinical summary information.

Version control systems provide a methodology for maintaining changes to a document over its lifetime and provide better management and control of evolving document collections, such as source code for large software systems. However, no version control system supports similar functionalities for office documents. Version Aware XML documents integrate full versioning functionality into an XML document type, using XML namespaces to avoid document type errors. Version aware XML documents contain a preamble with versions stored in reverse delta format, plus unique ID attributes attached to the nodes of the documents. They support the full branching and merging functionalities familiar to software engineers, in contrast to the constrained versioning models typical of Office applications. LibreOffice is an open source office document suite which is widely used for document creation. Each document is represented in the Open Office Document Format, which is a collection of XML files. The current project is an endeavor to show the practicality of the version aware XML documents approach by modifying the LibreOffice document suite to support version awareness. We are modifying LibreOffice to accept and preserve both the preamble and the IDs of the version aware framework. Initially, other functionality will be provided by wrapper applications and independent tools, but full integration into the LibreOffice user interface is envisioned.

The eXtensible Mark-up Language rapidly has become a very powerful standard for the data exchange. Labeling schemes have been introduced to optimize data retrieval and query processing on XML database documents. This is done by providing labels that hold information about XML tree nodes. In this paper we introduce a novel labeling scheme XDAS whose labeling technique is inspired by IP addressing and subnetting technique used in computer networks. This technique is used when dividing a network into several sub-networks. Each sub-network is assigned a subnet mask that helps in identifying the parent network. So, this labeling scheme treats XML documents as a network with sub-networks and assigns labels for XML tree nodes using the masking technique. Experimental results show that XDAS, when compared to Dewey and Range labeling schemes, provides an efficient label size, disk space required to store labels and matching time required to identify relationships between nodes.

A great deal of research into the learning of schemas from XML data has been conducted in recent years to enable the automatic discovery of XML schemas from XML documents when no schema or only a low-quality one is available. Unfortunately, and in strong contrast to, for instance, the relational model, the automatic discovery of even the simplest of XML constraints, namely XML keys, has been left largely unexplored in this context. A major obstacle here is the unavailability of a theory on reasoning about XML keys in the presence of XML schemas, which is needed to validate the quality of candidate keys. The present article embarks on a fundamental study of such a theory and classifies the complexity of several crucial properties concerning XML keys in the presence of an XSD, like, for instance, testing for consistency, boundedness, satisfiability, universality, and equivalence. Of independent interest, novel results are obtained related to cardinality estimation of XPath result sets. A mining algorithm is then developed within the framework of levelwise search. The algorithm leverages known discovery algorithms for functional dependencies in the relational model, but incorporates the properties mentioned before to assess and refine the quality of derived keys. An experimental study on an extensive body of real-world XML data evaluating the effectiveness of the proposed algorithm is provided. The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Research Foundation - Flanders (FWO) and the Flemish Government – department EWI. The authors acknowledge the financial support of the Fondecyt grant no. 1131049, FP7-ICT-233599, FWO G082109, and ERC grant agreement DIADEM, no. 246858.

Keys are very important for data management. Due to the hierarchical and flexible structure of XML, mining keys from XML data is a more complex and difficult task than from relational databases. In this paper, we study mining approximate keys from XML data, and define the support and confidence of a key expression based on the number of null values on key paths. In the mining process, inference rules are used to derive new keys. Through the two-phase reasoning, a target set of approximate keys and its reduced set are obtained. Our research conducted experiments over ten benchmark XML datasets from XMark and four files in the UW XML Repository. The results show that the approach is feasible and efficient, with which effective keys in various XML data can be discovered.

XQuery Update Facility (XQUF), which provides a declarative way of updating XML, has become recommendation by W3C. The SQL/XML standard, on the other hand, defines XMLType as a column data type in RDBMS environment and defines the standard SQL/XML operator, such as XML Query() to embed XQuery to query XMLType column in RDBMS. Based on this SQL/XML standard, XML enabled RDBMS becomes industrial strength platforms to host XML applications in a standard compliance way by providing XML store and query capability. However, updating XML capability support remains to be proprietary in RDBMS until XQUF becomes the recommendation. XQUF is agnostic of how XML is stored so that propagation of actual update to any persistent XML store is beyond the scope of XQUF. In this paper, we show how XQUF can be incorporated into XML Query() to effectively update XML stored in XMLType column in the environment of XML enabled RDBMS, such as Oracle XMLDB. We present various compile time and run time optimisation techniques to show how XQUF can be efficiently implemented to declaratively update XML stored in RDBMS. We present how our approaches of optimising XQUF for common physical XML storage models: native binary XML storage model and relational decomposition of XML storage model. Although our study is done using Oracle XMLDB, all of the presented optimisation techniques are generic to XML stores that need to support update of persistent XML store and not specific to Oracle XMLDB implementation.

For the redundancy of XML documents, it requires large number of resources for storage and transmitting XML data in current applications. Many approaches have been proposed to compress XML data. However, some of them do not support directly executing queries on compressed XML data, while the others are hard to be integrated into existing XML database systems. In this paper, we propose a new compression model called SQcx, which supports directly executing queries on compressed XML data. Moreover, SQcx is also easy to be integrated into existing native XML database system. The SQcx employees different compression algorithms for different parts of XML, and preserves the structure of the original XML data on compressed data. We implement the SQcx in Berkeley DB XML, and execute experiments on this system. Experimental results on data generated by XMark shows that the SQcx has a well performance.

Due to the growing use of XML data format in global information, an effective XML data management system is needed. An Enabled XML DB is one of the recent widely accepted approaches to store XML documents. This ability coupled with the increase use of XML data in different areas have triggered the need for a better method to structure a large data in order to improve query performance. Issues concerning the ways to efficiently partition large XML documents into a more manageable form are yet to be addressed. At the same time, it is essential to ensure that the partitioning method maintains the preservation of XML data hierarchical structure. For this reason, this paper introduces OXDP that structures large XML data logically by partitioning them into object based XML components. An evaluation is shown to demonstrate the effectiveness of OXDP in XML partitioning which subsequently has the potential of improving query performance in Enabled XML DB environments.

Probabilistic XML is a hierarchical data model capturing uncertainty of both value and structure. The ability to compute the similarity between an XML document and a probabilistic XML document is a building block of many applications involving querying, comparison, alignment and classification, for instance. The new challenge in efficiently computing such similarity is the multiplicity of the possible worlds represented by a probabilistic XML document. We devise and discuss an algorithm for the efficient computation of the similarity between an XML document and a probabilistic XML document. We empirically and comparatively evaluate the performance of the algorithm and its variants.

In publish/subscribe systems, XML message filtering performed at application layer is an important operation for XML message multicast. As a specific case of content-based multicast in application layer, XML message multicast depends on the data filtering and matching processes and the forwarding and routing schemes. As the XML data emerges in transition, XML message filtering and matching becomes more and more desirable. BFilter, proposed in this paper, conducts the XML message filtering and matching by leveraging branch points in both the XML document and user query. It evaluates user queries that use backward matching branch points to delay further matching processes until branch points match in the XML document and user query. In this way, XML message filtering can be performed more efficiently as the probability of mismatching is reduced. A number of experiments have been conducted and the results demonstrate that BFilter has better performance than the well-known YFilter for complex queries.

This paper proposes a DHT-based namespace solution for a Grid system-Virtual Organization File System(VOFS).Different from previous version of VOFS,this solution doesn't demand complete namespace metadata be stored in all peers.By using peer-to-peer Chord, specified peers are chosen for storing specified namespace of resource.

In this paper, we study the use of XML path query to search an XML fragment in a collection of XML documents. We present efficient techniques that are able to employ bit-slice bloom-filtered signature file as filter and investigate an approach that are able to measure semantic similarity between the query and the XML document in the collection by considering their structures and contents. A ranked list of XML fragments is generated as the search results. By using a set of path queries on a variety of XML documents, the experiments show that the precision and efficiency of the results perform better than ever.

With the rapid increase of XML documents on the web, how to index, store and retrieve these documents has become a very popular and valuable problem. At present, there are two normal ways of retrieving XML documents. One is structure-based retrieval; the other is keyword-based retrieval. However, XML keyword search is becoming more and more popular because it is easy to master and manipulate. In XML keyword search system, a key problem is how to store the structure information into XML indices efficiently. At present, Dewey numbers are often used to label XML nodes in XML indices. However, Dewey numbers may lead to redundancy in XML indices. In this paper, we propose a new labeling method called LAF numbers for XML indices and we device a new indexing structure called Two-Layer index for XML keyword retrieval systems. At last, we have conducted an extensive experimental study and the experimental results show that our indexing method achieves better space efficiency than prevailing Dewey-number-based indexing method

International audience; We propose to demonstrate LiquidXML, a platform for managing large corpora of XML documents in large-scale P2P networks. All LiquidXML peers may publish XML documents to be shared with all the network peers. The challenge then is to efficiently (re-)distribute the published content in the network, possibly in overlapping, redundant fragments, to support efficient processing of queries at each peer. The novelty of LiquidXML relies in its adaptive method of choosing which data fragments are stored where, to improve performance. The "liquid" aspect of XML management is twofold: XML data flows from many sources towards many consumers, and its distribution in the network continuously adapts to improve query performance.

XML Keyword Search is a user-friendly information discovery technique, which is well-suited to schema-free XML documents We propose a novel scheme for XML keyword search called XKLUSTER, in which a novel semantic-distance model is proposed to specify the set of nodes contained in a result Based on this model, we use clustering approaches to generate all meaningful results in XML keyword search A ranking mechanism is also presented to sort the results.