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A Normal Form for XML Documents
"... This paper takes a rst step towards the design and normalization theory for XML documents. We show that, like relational databases, XML documents may contain redundant information, and may be prone to update anomalies. Furthermore, such problems are caused by certain functional dependencies among p ..."
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Cited by 167 (8 self)
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This paper takes a rst step towards the design and normalization theory for XML documents. We show that, like relational databases, XML documents may contain redundant information, and may be prone to update anomalies. Furthermore, such problems are caused by certain functional dependencies among paths in the document. Our goal is to nd a way of converting an arbitrary DTD into a well-designed one, that avoids these problems. We rst introduce the concept of a functional dependency for XML, and de ne its semantics via a relational representation of XML. We then de ne an XML normal form, XNF, that avoids update anomalies and redundancies. We study its properties and show that it generalizes BCNF and a normal form for nested relations when those are appropriately coded as XML documents. Finally, we present a lossless algorithm for converting any DTD into one in XNF.
Integrity Constraints for XML
, 1999
"... this paper, we extend XML DTDs with several classes of integrity constraints and investigate the complexity of reasoning about these constraints. The constraints range over keys, foreign keys, inverse constraints as well as ID constraints for capturing the semantics of object identities. They imp ..."
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Cited by 97 (11 self)
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this paper, we extend XML DTDs with several classes of integrity constraints and investigate the complexity of reasoning about these constraints. The constraints range over keys, foreign keys, inverse constraints as well as ID constraints for capturing the semantics of object identities. They improve semantic specifications and provide a better reference mechanism for native XML applications. They are also useful in information exchange and data integration for preserving the semantics of data originating in relational and object-oriented databases. We establish complexity and axiomatization results for the (finite) implication problems associated with these constraints. In addition, we study implication of more general constraints, such as functional, inclusion and inverse constraints defined in terms of navigation paths
Consistency Management with Repair Actions
- IN PROCEEDINGS OF THE 25TH INTERNATIONAL CONFERENCE ON SOFTWARE ENGINEERING
, 2003
"... Comprehensive consistency management requires a strong mechanism for repair once inconsistencies have been detected. In this paper we present a repair framework for inconsistent distributed documents. The core piece of the framework is a new method for generating interactive repairs from full first ..."
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Cited by 97 (5 self)
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Comprehensive consistency management requires a strong mechanism for repair once inconsistencies have been detected. In this paper we present a repair framework for inconsistent distributed documents. The core piece of the framework is a new method for generating interactive repairs from full first order logic formulae that constrain these documents. We present a full implementation of the components in our repair framework, as well as their application to the UML and related heterogeneous documents such as EJB deployment descriptors. We describe how our approach can be used as an infrastructure for building higherlevel, domain specific frameworks and provide an overview of related work in the database and software development environment community.
Keys for XML
, 2001
"... this paper. The proposal extends the key speci cation of XML Data by allowing one to specify keys in terms of XPath [24] expressions. There are a number of technical problems in connection with XPath. XPath is a relatively complex language in which one can not only move down the document tree, but ..."
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Cited by 88 (18 self)
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this paper. The proposal extends the key speci cation of XML Data by allowing one to specify keys in terms of XPath [24] expressions. There are a number of technical problems in connection with XPath. XPath is a relatively complex language in which one can not only move down the document tree, but also sideways or upwards, not to mention that predicates and functions can be embedded as well. The problem with XPath is that questions about equivalence or inclusion of XPath expressions are, as far as the authors are aware, unresolved; and these issues are importantifwewant to reason about keys as wedo in relational databases. Yet until we know how to determine the equivalence of XPath expressions, there is no general method of saying whether two such speci cations are equivalent. Another technical issue is value equality. XML Schema restricts equality to text, but the authors have encountered cases in whichkeys are not so restricted. See Section 7.1 for a more detailed discussion. However, the main reason for writing this paper is that none of the existing key proposals address the issue of hierarchical keys, which appear to be ubiquitous in hierarchically structured databases, especially in scienti c data formats. A top-level key may be used to identify components of a document, and within each component a secondary key is used to identify sub-components, and so on. Moreover, the authors believe that the use of keys for citing parts of a document is suciently important that it is appropriate to consider key speci cation independently of other proposals for constraining the structure of XML documents
Two-variable logic on data trees and XML reasoning
"... Motivated by reasoning tasks for XML languages, the satisfiability problem of logics on data trees is investigated. The nodes of a data tree have a label from a finite set and a data value from a possibly infinite set. It is shown that satisfiability for two-variable first-order logic is decidable i ..."
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Cited by 84 (17 self)
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Motivated by reasoning tasks for XML languages, the satisfiability problem of logics on data trees is investigated. The nodes of a data tree have a label from a finite set and a data value from a possibly infinite set. It is shown that satisfiability for two-variable first-order logic is decidable if the tree structure can be accessed only through the child and the next sibling predicates and the access to data values is restricted to equality tests. From this main result, decidability of satisfiability and containment for a data-aware fragment of XPath and of the implication problem for unary key and inclusion constraints is concluded.
XML access-control using static analysis
- In Proceedings of the 10th ACM Conference on Computer and Communication Security
, 2003
"... Access control policies for XML typically use regular path expressions such as XPath for specifying the objects for access-control policies. However such access-control policies are burdens to the query engines for XML documents. To relieve this burden, we introduce static analysis for XML access-co ..."
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Cited by 70 (1 self)
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Access control policies for XML typically use regular path expressions such as XPath for specifying the objects for access-control policies. However such access-control policies are burdens to the query engines for XML documents. To relieve this burden, we introduce static analysis for XML access-control. Given an access-control policy, query expression, and an optional schema, static analysis determines if this query expression is guaranteed not to access elements or attributes that are hidden by the access-control policy but permitted by the schema. Static analysis can be performed without evaluating any query expression against actual XML documents. Run-time checking is required only when static analysis is unable to determine whether to grant or deny access requests. A side effect of static analysis is query optimization: access-denied expressions in queries can be evaluated to empty lists at compile time. We further extend static analysis for handling value-based access-control policies and introduce view schemas.
Dependencies revisited for improving data quality,
, 2008
"... Abstract Dependency theory is almost as old as relational databases themselves, and has traditionally been used to improve the quality of schema, among other things. Recently there has been renewed interest in dependencies for improving the quality of data. The increasing demand for data quality te ..."
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Cited by 69 (4 self)
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Abstract Dependency theory is almost as old as relational databases themselves, and has traditionally been used to improve the quality of schema, among other things. Recently there has been renewed interest in dependencies for improving the quality of data. The increasing demand for data quality technology has also motivated revisions of classical dependencies, to capture more inconsistencies in real-life data, and to match, repair and query the inconsistent data. This paper aims to provide an overview of recent advances in revising classical dependencies for improving data quality.
Strong Functional Dependencies and Their Application to Normal Forms in XML
- ACM TRANSACTIONS ON DATABASE SYSTEMS
, 2004
"... In this article, we address the problem of how to extend the definition of functional dependencies (FDs) in incomplete relations to XML documents (called XFDs) using the well-known strong satisfaction approach.We propose a syntactic definition of strong XFD satisfaction in an XML document and then j ..."
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Cited by 56 (9 self)
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In this article, we address the problem of how to extend the definition of functional dependencies (FDs) in incomplete relations to XML documents (called XFDs) using the well-known strong satisfaction approach.We propose a syntactic definition of strong XFD satisfaction in an XML document and then justify it by showing that, similar to the case in relational databases, for the case of simple paths, keys in XML are a special case of XFDs. We also propose a normal form for XML documents based on our definition of XFDs and provide a formal justification for it by proving that it is a necessary and sufficient condition for the elimination of redundancy in an XML document.
