Showing papers on "XML published in 1999"

Relational Databases for Querying XML Documents: Limitations and Opportunities

Abstract: XML is fast emerging as the dominant standard for representing data in the World Wide Web. Sophisticated query engines that allow users to effectively tap the data stored in XML documents will be crucial to exploiting the full power of XML. While there has been a great deal of activity recently proposing new semistructured data models and query languages for this purpose, this paper explores the more conservative approach of using traditional relational database engines for processing XML documents conforming to Document Type Descriptors (DTDs). To this end, we have developed algorithms and implemented a prototype system that converts XML documents to relational tuples, translates semi-structured queries over XML documents to SQL queries over tables, and converts the results to XML. We have qualitatively evaluated this approach using several real DTDs drawn from diverse domains. It turns out that the relational approach can handle most (but not all) of the semantics of semi-structured queries over XML data, but is likely to be effective only in some cases. We identify the causes for these limitations and propose certain extensions to the relational model that would make it more appropriate for processing queries over XML documents.

A query language for XML

Abstract: An important application of XML is the interchange of electronic data (EDI) between multiple data sources on the Web. As XML data proliferates on the Web, applications will need to integrate and aggregate data from multiple source and clean and transform data to facilitate exchange. Data extraction, conversion, transformation, and integration are all well-understood database problems, and their solutions rely on a query language. We present a query language for XML, called XML-QL, which we argue is suitable for performing the above tasks. XML-QL is a declarative, `relational complete' query language and is simple enough that it can be optimized. XML-QL can extract data from existing XML documents and construct new XML documents.

Performance Challenges in Object-Relational DBMSs.

Abstract: XML is rapidly becoming a popular data format. It can be expected that soon large volumes of XML data will exist. XML data is either produced manually (like html documents today), or it is generated by a new generation of software tools for the WWW and/or electronic data interchange (EDI). The purpose of this paper is to present the results of an initial study about storing and querying XML data. As a first step, this study was focussed on the use of relational database systems and on very simplistic schemes to store and query XML data. In other words, we would like to study how the simplest and most obvious approaches perform, before thinking about more sophisticated approaches. In general, numerous different options to store and query XML data exist. In addition to a relational database, XML data can be stored in a file system, an object-oriented database (e.g., Excelon), or a special-purpose (or semi-structured) system such as Lore (Stanford), Lotus Notes, or Tamino (Software AG). It is still unclear which of these options will ultimately find wide-spread acceptance. A file system could be used with very little effort to store XML data, but a file system would not provide any support for querying the XML data. Object-oriented database systems would allow to cluster XML elements and sub-elements; this feature might be useful for certain applications, but the current generation of object-oriented database systems is not mature enough to process complex queries on large databases. It is going to take even longer before special-purpose systems are mature. Even when using an RDBMS, there are many different ways to store XML data. One strategy is to ask the user or a system administrator in order to decide how XML elements are stored in relational tables. Such an approach is supported, e.g., by Oracle 8i. Another option is to infer from the DTDs of the XML documents how the XML elements should be mapped into tables; such an approach has been studied in [4]. Yet another option is to analyze the XML data and the expected query workload; such an approach has been devised, e.g., in [2]. In this work, we will only study very simple ad-hoc schemes; we think that such a study is necessary before adopting a more complex approach. The schemes that we analyze require no input by the user, they work in the absence of DTDs or if DTDs are meaningless, and they do not involve any analysis of the XML data. Due to their simplicity, the approaches we study will not show the best possible performance, but as we will see, some of them will show very good query performance in most situations. Also, there is no guarantee that any of the more sophisticated approaches known so far will perform better than our simple schemes; see [3] for some experimental results in this respect. Furthermore, the results of our study can be used as input for more sophisticated approaches.

Query Optimization for XML

Abstract: XML is an emerging standard for data representation and exchange on the World-Wide Web. Due to the nature of information on the Web and the inherent flexibility of XML, we expect that much of the data encoded in XML will be semistructured: the data may be irregular or incomplete, and its structure may change rapidly or unpredictably. This paper describes the query processor of Lore, a DBMS for XML-based data supporting an expressive query language. We focus primarily on Lore's cost-based query optimizer. While all of the usual problems associated with cost-based query optimization apply to XML-based query languages, a number of additional problems arise, such as new kinds of indexing, more complicated notions of database statistics, and vastly different query execution strategies for different databases. We define appropriate logical and physical query plans, database statistics, and a cost model, and we describe plan enumeration including heuristics for reducing the large search space. Our optimizer is fully implemented in Lore and preliminary performance results are reported. This is a short version of the paper Query Optimization for Semistructured Data which is available at: http://www-db.stanford.edu/~mchughj/publications/qo.ps

XML-based information mediation with MIX

Abstract: The MIX mediator system, MIXm, is developed as part of the MIX Project at the San Diego Supercomputer Center, and the University of California, San Diego.1 MIXm uses XML as the common model for data exchange. Mediator views are expressed in XMAS (XML Matching And Structuring Language), a declarative XML query language. To facilitate user-friendly query formulation and for optimization purposes, MIXm employs XML DTDs as a structural description (in effect, a “schema”) of the exchanged data. The novel features of the system include: Data exchange and integration solely relies on XML, i.e., instance and schema information is represented by XML documents and XML DTDs, respectively. XML queries are denoted in XMAS, which builds upon ideas of languages like XML-QL, MSL, Yat, and UnQL. Additionally, XMAS features powerful grouping and order constructs for generating new integrated XML “objects” from existing ones.The graphical user interface BBQ (Blended Browsing and Querying) is driven by the mediator view DTD and integrates browsing and querying of XML data. Complex queries can be constructed in an intuitive way, resembling QBE. Due to the nested nature of XML data and DTDs, BBQ provides graphical means to specify the nesting and grouping of query results.Query evaluation can be demand-driven, i.e., by the user's navigation into the mediated view.

Document Object Model (DOM) Level 2 Specification

Abstract: This specification defines the Document Object Model Level 2, a platform- and language-neutral interface that allows programs and scripts to dynamically access and update the content, structure and style of documents. The Document Object Model Level 2 builds on the Document Object Model Level 1. The DOM Level 2 is made of a set of core interfaces to create and manipulate the structure and contents of a document and a set of optional modules. These modules contain specialized interfaces dedicated to XML, HTML, an abstract view, generic stylesheets, Cascading Style Sheets, Events, traversing the

Automatic data collection device having a network communications capability

Abstract: The invention provides a system and method for controlling a plurality of automatic data collection (ADC) device platforms. In the invention, a remote computing system having browsing software adapted for receiving and sending Hypertext Mark-Up Language (HTML) documents, Dynamic Hypertext Mark-Up Language (DHTML) documents, and Extensible Mark-Up Language (XML) documents over the World Wide Web communicates with a network of ADC platform devices. A Simple Network Management Protocol (SNMP) master agent at the ADC device platform communicates with the remote computing system and a Hypertext Transfer Protocol (HTTP) server sends HTML documents, DHTML documents, and XML documents to the remote computing system over the World Wide Web. A translator translates SNMP-formatted data sent to the attached ADC devices into a format suitable for reception by each ADC device. Another translator translates data received from the ADC devices into the SNMP format. The SNMP master agent communicates with the remote computing system using the TCP protocol, the UDP/IP protocol, and the UDP+ protocol. The ADC platform device may utilize a wireless communications system for communicating with the remote computing system.

Method for producing composite XML document object model trees using dynamic data retrievals

Abstract: A method, system, and computer-readable code for a technique with which files encoded according to the Extensible Markup Language (XML) notation can be marked up to indicate that the content of the file (or some portion thereof) is dynamic in nature and is to be updated automatically to reflect changing information. The proposed technique provides a novel way to specify that a data repository should be accessed as the source of the updates. Techniques are defined for specifying that this data repository access occurs once, and for specifying that it occurs when a set of conditions are satisfied (which may include periodically repeating the data repository access and content update). In one aspect, the data repository is a database; in another aspect, the data repository is a file system. Preferably, the Lightweight Directory Access Protocol (LDAP) is used as an access method when the data repository being accessed is a database storing an LDAP directory.

XML-GL: a graphical language for querying and restructuring XML documents

Abstract: The growing acceptance of XML as a standard for semi-structured documents on the Web opens up challenging opportunities for Web query languages. In this paper we introduce XML-GL, a graphical query language for XML documents. The use of a visual formalism for representing both the content of XML documents (and of their DTDs) and the syntax and semantics of queries enables an intuitive expression of queries, even when they are rather complex. XML-GL is inspired by G-log, a general purpose, logic-based language for querying structured and semi-structured data. The paper presents the basic capabilities of XML-GL through a sequence of examples of increasing complexity.

System and method for retrieving information from a database using an index of XML tags and metafiles

Abstract: Retrieving information from a database using an index of XML (eXtensible Markup Language) tags and metafiles. The index includes XML tags that correspond to domains and categories. The domains and categories are selected to facilitate searching of the database. An XML tag can have a corresponding metafile that includes XML tags for related domains and categories. The metafile can also establish a hierarchy for the tags within the metafile. Each record of the database includes an index component which lists the domain tags and category tags that are associated with the record. When a search request is received, the request is parsed to identify the terms in the request. The terms are predetermined and generally correspond to the domains and categories of the index. The terms are mapped to tags. Once the appropriate tags are identified, then the metafiles that correspond to those tags are identified. The metafiles can be used to identify additional tags that are relevant to the search. The identified tags are combined to create a unique key. The key is used to search the database to locate records that include the tags in their index component.

Comparative Analysis of Five XML Query Languages

Abstract: XML is becoming the most relevant new standard for data representation and exchange on the WWW. Novel languages for extracting and restructuring the XML content have been proposed, some in the tradition of database query languages (i.e. SQL, OQL), others more closely inspired by XML. No standard for XML query language has yet been decided, but the discussion is ongoing within the World Wide Web Consortium and within many academic institutions and Internet-related major companies. We present a comparison of five, representative query languages for XML, highlighting their common features and differences.

Haskell and XML: generic combinators or type-based translation?

Abstract: We present two complementary approaches to writing XML document-processing applications in a functional language.In the first approach, the generic tree structure of XML documents is used as the basis for the design of a library of combinators for generic processing: selection, generation, and transformation of XML trees.The second approach is to use a type-translation framework for treating XML document type definitions (DTDs) as declarations of algebraic data types, and a derivation of the corresponding functions for reading and writing documents as typed values in Haskell.

Storage of application specific data in HTML

Abstract: A spreadsheet program saves data into a hypertext markup language (HTML) document that can be viewed with a browser program, but persists all of the information associated with that data necessary to maintain formatting and functionality of the data if reintroduced into the spreadsheet program. The HTML document can then be used both for displaying the data over the Internet or other network in a browser program, and also for opening the data in the spreadsheet program. The information necessary for preserving the format and functionality of the data in the spreadsheet program is incorporated into the HTML document using HTML, Cascading Style Sheets (CSS), and Extended Markup Language (XML). HTML is used for expressing cell data information that is displayed in the browser program, CSS are used for expressing cell-level properties of the data, and XML is used for expressing information that is not displayed in the browser program, but which is necessary for some functionality of the data when used in the spreadsheet program. If any formatting of the data are changed to enable display of the data in the browser program as displayed in the spreadsheet program, the original formatting information is retained in a supporting file that is ignored by a browser program.

Selective data encryption using style sheet processing

Abstract: A method, system, and computer program product for selectively encrypting one or more elements of a document using style sheet processing. Disclosed is a policy-driven augmented style sheet processor (e.g. an Extensible Stylesheet Language, or “XSL”, processor) that creates a selectively-encrypted document (e.g. an Extensible Markup Language, or “XML”, document) carrying key-distribution material, such that by using an augmented document processor (e.g. an augmented XML processing engine), an agent can recover only the information elements for which it is authorized. The Document Type Definition (DTD) or schema associated with a document is modified, such that the DTD or schema specifies a reference to stored security policy to be applied to document elements. Each document element may specify a different security policy, such that the different elements of a single document can be encrypted differently (and, some elements may remain unencrypted). The key distribution material enables a document to be encrypted for decryption by an audience that is unknown at the time of document creation, and enables access to the distinct elements of a single encrypted document to be controlled for multiple users and/or groups of users. In this manner, group collaboration is improved by giving more people easier access to information for which they are authorized, while protecting sensitive data from unauthorized agents. A key recovery technique is also defined, whereby the entire document can be decrypted by an authorized agent regardless of how the different elements were originally encrypted and the access protections which were applied to those elements.

DocBook : the definitive guide

Abstract: Preface I. Introduction 1. Getting Started with SGML/XML HTML and SGML vs. XML Basic SGML/XML Concepts Elements and Attributes Entities How Does DocBook Fit In? 2. Creating DocBook Documents Making an SGML Document Making an XML Document Public Identifiers, System Identifiers, and Catalog Files Physical Divisions: Breaking a Document into Physical Chunks Logical Divisions: The Categories of Elements in DocBook Making a DocBook Book Making a Chapter Making an Article Making a Reference Page Making Front- and Backmatter. 3. Parsing DocBook Documents Validating Your Documents Understanding Parse Errors 4. Publishing DocBook Documents A Survey of Stylesheet Languages Using Jade and DSSSL to Publish DocBook Documents A Brief Introduction to DSSSL Customizing the Stylesheets Dealing with Multiple Declarations The DSSSL Architecture. 5. Customizing DocBook Should You Do This? If You Change DocBook, It's Not DocBook Anymore! Customization Layers Understanding DocBook Structure The General Structure of Customization Layers Writing, Testing, and Using a Customization Layer Testing Your Work Removing Elements Removing Attributes Adding Elements: Adding a Sect6 Other Modifications: Classifying a Role II. Reference DocBook Element Reference DocBook Parameter Entity Reference DocBook Character Entity Reference III. Appendixes A. Installation B. DocBook and XML C. DocBook Versions D. Resources E. What's on the CD-ROM? F. Interchanging DocBook Documents G. DocBook V3.1 Quick Reference Glossary

Dynamic business process automation system using XML documents

Abstract: A system for exchanging and merging messages over a network includes a server accessible by a plurality of remote browsers for transmitting a template including fields for information entry and a business system accessible by the server for generating a return document pursuant to information entered in the template on the browsers. The business system includes a first parser for receiving a document from a browser, the document including information about data characteristics of information entered into the template, and a second parser for receiving information about data characteristics to provide a return template. A merging algorithm is implemented to merge the document with the return template for providing a return document to the browser having portions of the return template with data entered therein.

Storage and Retrieval of XML Documents Using Object-Relational Databases

Abstract: This paper describes general storage and retrieval methods for XML documents using object-relational databases The storage method decomposes tree structure of XML documents into nodes, and stores them in relational tables according to the node types By using this method, being independent of DTDs or element types, any XML documents can be stored in databases Also it is possible to utilize index structures (eg B+ trees, R trees, etc) which are provided in database management systems As for retrieval, we show the transformation of XQL queries into SQL queries It is possible to realize the storage method by doing minimal extension to object-relational databases and the retrieval method by adding a preprocessor of a query languageWe also performed experiments using XML documents on the plays of Shakespeare, to show the effectiveness of our methods

On views and XML

Abstract: The notion of views is essential in databases, see for instance [29, 30, 5]. It allows various users to see data from different viewpoints. In the present paper, we informally present works of the author on the topic. Instead of addressing the issue of views in a classical database setting, the paper focuses on XML [32] and looks at these various works in the context of a system of views for XML. The Web has revolutionized the electronic publication of data. It has relied primarily on HTML that emphasizes a hypertext document approach. More recently, XML, although originally a document mark-up language, is promoting an approach more focused on data exchange. In XML, explicit structuring is enforced • and presentation is separated from the data content. For data sources containing information with some structure, it is therefore more appropriate to use XML rather than HTML to export their data to the Web. When data is exported via XML, the problem of views becomes essential. Indeed, views in this setting are even more crucial than in standard database applications because (i) one often has to integrate heterogeneous sources and also (ii) views provide the means to add a structured interface on top of some otherwise (more chaotic) semistructured data. In some sense, a language already allows to define views for XML documents, namely XSL. XSL is the current (still unstable) W3C proposal for expressing stylesheets. Although primarily targeted towards presentation, XSL allows to transform/restructure XML documents using templates rules. We are discussing such restructuring here. However, we will ignore presentation issues and will consider more general views than offered by XSL. A view specification for XML data 1 will primarily

Selective data encryption using style sheet processing for decryption by a client proxy

Abstract: A method, system, and computer program product for selectively encrypting one or more elements of a document using style sheet processing. Disclosed is a policy-driven augmented style sheet processor (e.g. an Extensible Stylesheet Language, or “XSL”, processor) that creates a selectively-encrypted document (e.g. an Extensible Markup Language, or “XML”, document) carrying key-distribution material, such that by using an augmented document processor (e.g. an augmented XML processing engine), an agent can recover only the information elements for which it is authorized. The Document Type Definition (DTD) or schema associated with a document is modified, such that the DTD or schema specifies a reference to stored security policy to be applied to document elements. Each document element may specify a different security policy, such that the different elements of a single document can be encrypted differently (and, some elements may remain unencrypted). The key distribution material enables a document to be encrypted for decryption by an audience that is unknown at the time of document creation, and enables access to the distinct elements of a single encrypted document to be controlled for multiple users and/or groups of users. In this manner, group collaboration is improved by giving more people easier access to information for which they are authorized, while protecting sensitive data from unauthorized agents. A key recovery technique is also defined, whereby the entire document can be decrypted by an authorized agent regardless of how the different elements were originally encrypted and the access protections which were applied to those elements.

Data Management for XML: Research Directions

Abstract: This paper is a July 1999 snapshot of a "whitepaper" that I've been working on. The purpose of the whitepaper, which I initially drafted in April 1999, was to formulate and put into prose my thoughts on the research opportunities XML brings to the general area of data management. It is important to know that this paper is not a survey. It offers my personal opinions and thoughts on Data Management for XML, fully incorporating my biases and ignorances. Related work is not discussed, and references are not provided with the exception of a handful of URLs. Furthermore, I expect the whitepaper to evolve over time; please see http://www-db.stanford.edu/~widom/xml-whitepaper.html for the latest version.

Extensible markup language (XML) server pages having custom document object model (DOM) tags

Abstract: A method for serving a web page uses eXtensible Markup Language (XML) server pages. The first time a page is accessed, a given flat file is parsed into an XML Document Object Model (DOM), and required tag libraries are loaded. The DOM tree is then traversed, preferably in a depth-first, inside-out manner to locate custom tags. Upon locating a custom tag, if the tag is registered as a Java object, the object is loaded. A process method is then called on the object, passing the custom tag's tree node. The Java object then examines the custom tag and replaces it with an object, e.g., script code. Alternatively, if the tag is registered as an XSL stylesheet, the stylesheet is loaded and passed, together with the DOM, to an XSL processor. The processor applies the template to the custom tag and replaces it with given script code. Once all custom tags are reduced to HTML and script code, the DOM is compiled into a Java servlet to service the client request.

Preparation of a software configuration using an xml type programming language

Abstract: Configuring software for a target comprises preparing a command file (509) which specifies a subset of components (545, 546) selected from a group of components, and parameters (546) for tuning at least some of the selected subset of components. The command file is written using a single object-oriented programming language, capable of managing tree structures of objects, preferably an XML type language, having a Document Type Definition enabling it to work as a programming language. An image file (548) is prepared from the command file, to be loaded (550) on the target.

Method for creating network services by transforming an XML runtime model in response to an iterative input process

Abstract: A method and apparatus for creating network services. Instead of programming or hard coding an entire web service, the invention provides the ability to easily create a module/mechanism (referred to as a template) that produces code that may be utilized to create a web service. Thus, a template is formed and utilized to create a model that can generate an application or web service. Each template is comprised of a list of features, and a model (referred to as a run time model or RTM). An RTM is an XML document that declares the structure, functionality, and behavior of a web service application (referred to as a WSA). In one or more embodiments, each feature is responsible for generating XML entities to be output in a new RTM. Each feature may obtain one or more users' input that is utilized to build an XML entity in a new RTM. Further, each feature may be processed sequentially and has the ability to modify any existing XML entities that have already been created (by other features, for example). Consequently, features have the ability to look at an application as a whole to effect a change to the entire existing application instead of merely adjusting and modifying the entity they are responsible for. In one or more embodiments of the invention, when a condition that may affect an application changes, the template may be utilized to regenerate the RTM to produce a new web service or XML document.

Preventing duplication of the data in reference resource for XML page generation

Abstract: A method and computer program product for generating XML documents that include data content and style information from a plurality of data sources. A first file includes control statements that reference at least one resource containing display information. A server pages processor executes a script that includes a control statement referencing the first file, wherein the first file includes references to a plurality of resources containing display information. The resources may reside in at least two different locations in a computer system network.

Enforcing data policy using style sheet processing

Abstract: Enforcing data policy using style sheet processing. A Document Type Definition (DTD) associated with an Extensible Markup Language document is modified to specify a reference to stored data policy to be applied to document elements. Each data element may specify a different data policy. This technique uses minimal network transmission overhead, as the policy itself is not transmitted through the network until the DTD reaches the node where the data policy will be applied. Programming code implementing the data policy is then retrieved, using the references, by an Extensible Stylesheet Language (XSL) processor instrumented according to the present invention. Data policy is preferably enforced by overriding the existing XSL “value-of” method. DTD information describing a document element may be suppressed from a DTD being generated for the output document of the data policy enforcement process, providing privacy protection for the details of the associated policy.

Method for versioning a UML model in a repository in accordance with an updated XML representation of the UML model

Abstract: In a computer system executing a repository program and having a memory, a method is disclosed for versioning a UML model in the repository in accordance with an updated XML representation of the UML model. The method includes the steps of identifying differences between UML objects in the UML model and XML objects in the XML file. Where there is a difference between one of the UML objects and one of the XML objects, it is reserved as a ghost object. The ghost object is updated to match each corresponding one of the XML objects. Objects whose target references have been changed are reserved and updated. Finally, the UML objects are updated in the repository that refer to ghost objects updated in the preceding step. The method includes making changes to the ghost object Attributes, References and owned elements to match Attributes, References and owned elements, respectively, found in the XML object.

XML Bible

Abstract: From the Publisher: "Now revised and expanded to cover the latest XML technologies and applications, this all-in-one tutorial and reference shows you step by step how to put the power of XML to work in your Web pages. From document type definitions and style sheets to XPointers, schemas, the Wireless Markup Language, XHTML and other advanced tools and applications, XML expert Elliotte Rusty Harold gives you all the know-how and examples you need to integrate XML with HTML, solve real-world development challenges, and create data-driven content."--BOOK JACKET.

Representing and reasoning on XML documents: a description logic approach

Abstract: Recent proposals to improve the quality of interaction with the World Wide Web suggest considering the Web as a huge semistructured database, so that retrieving information can be supported by the task of database querying. Under this view, it is important to represent the form of both the network, and the documents placed in the nodes of the network. However, the current proposals do not pay su‐cient attention to represent document structures and reasoning about them. In this paper, we address these problems by providing a framework where Document Type Deflnitions (DTDs) expressed in the eXtensible Markup Language (XML) are formalized in an expressive Description Logic equipped with sound and complete inference algorithms. We provide methods for verifying conformance of a document to a DTD in polynomial time, and structural equivalence of DTDs in worst case deterministic exponential time, improving known algorithms for this problem which were double exponential. We also deal with parametric versions of conformance and structural equivalence, and investigate other forms of reasoning on DTDs. Finally, we show how to take advantage of the reasoning capabilities of our formalism in order to perform several optimization steps in answering queries posed to a document base.