SpecSatisfiabilityTool: A tool for testing the satisfiability of specifications on XML documents

We present a prototype that implements a set of logical rules to prove the satisfiability for a class of specifications on XML documents. Specifications are given by means of constrains built on Boolean XPath patterns. The main goal of this tool is to test whether a given specification is satisfiable or not, and justify the decision showing the execution history. It can also be used to test whether a given document is a model of a given specification and, as a by-product, it permits to look for all the relations (monomorphisms) between two patterns and to combine patterns in different ways. The results of these operations are visually shown and therefore the tool makes these operations more understandable. The implementation of the algorithm has been written in Prolog but the prototype has a Java interface for an easy and friendly use. In this paper we show how to use this interface in order to test all the desired properties.Comment: In Proceedings PROLE 2014, arXiv:1501.0169

Compression vs Queryability - A Case Study

International audienceSome compromise on compression is known to be necessary, if the relative positions of the information stored by semi-structured documents are to remain accessible under queries. With this in view, we compare, on an example, the `query-friendliness' of XML documents, when compressed into straightline tree grammars which are either regular or context-free. The queries considered are in a limited fragment of XPath, corresponding to a type of patterns; each such query defines naturally a non-deterministic, bottom-up `query automaton' that runs just as well on a tree as on its compressed dag

Parameterized XPath Views

We present a new approach for accelerating the execution of XPath expressions using parameterized materialized XPath views (PXV). While the approach is generic we show how it can be utilized in an XML extension for relational database systems. Furthermore we discuss an algorithm for automatically determining the best PXV candidates to materialize based on a given workload. We evaluate our approach and show the superiority of our cost based algorithm for determining PXV candidates over frequent pattern based algorithms

A Decision Procedure for XPath Satisfiability in the Presence of DTD Containing Choice

Abstract. XPath satisfiability is one of the most basic problems of XML query optimization. A satisfiability decision framework, named SAT-DTD, is proposed to determine, given a set of XPath queries P and a DTD τ, which subset of P are satisfiable by an XML tree conforming to DTD τ. In the framework, an indexed NFA is constructed from the set of XPath queries P, and then the NFA is driven by simple API for DTD (SAD, something like SAX) events, derived from DTD τ, to evaluate the predicates in P and to decide the satisfiability of P. Especially, DTD choice (i.e. '|' operator) is taken into consideration, and an algorithm, named SAT-DTD_C, which bases on SAT-DTD, is put forward to determine the unsatisfiability caused by DTD choice. At last, the complexity of the algorithms is analyzed, and the correctness of the algorithms is tested by experiments

Reasoning About Integrity Constraints for Tree-Structured Data

We study a class of integrity constraints for tree-structured data modelled as data trees, whose nodes have a label from a finite alphabet and store a data value from an infinite data domain. The constraints require each tuple of nodes selected by a conjunctive query (using navigational axes and labels) to satisfy a positive combination of equalities and a positive combination of inequalities over the stored data values. Such constraints are instances of the general framework of XML-to-relational constraints proposed recently by Niewerth and Schwentick. They cover some common classes of constraints, including W3C XML Schema key and unique constraints, as well as domain restrictions and denial constraints, but cannot express inclusion constraints, such as reference keys. Our main result is that consistency of such integrity constraints with respect to a given schema (modelled as a tree automaton) is decidable. An easy extension gives decidability for the entailment problem. Equivalently, we show that validity and containment of unions of conjunctive queries using navigational axes, labels, data equalities and inequalities is decidable, as long as none of the conjunctive queries uses both equalities and inequalities; without this restriction, both problems are known to be undecidable. In the context of XML data exchange, our result can be used to establish decidability for a consistency problem for XML schema mappings. All the decision procedures are doubly exponential, with matching lower bounds. The complexity may be lowered to singly exponential, when conjunctive queries are replaced by tree patterns, and the number of data comparisons is bounded

A Rewrite Approach for Pattern Containment

Abstract. In this paper we introduce an approach that allows to handle the containment problem for the fragment XP(/,//,[ ], * ) of XPath. Using rewriting techniques we define a necessary and sufficient condition for pattern containment. This rewrite view is then adapted to query evaluation on XML documents, and remains valid even if the documents are given in a compressed form, as dags

Satisfiability of constraint specifications on XML documents

Jose Meseguer is one of the earliest contributors in the area of Algebraic Specification. In this paper, which we are happy to dedicate to him on the occasion of his 65th birthday, we use ideas and methods coming from that area with the aim of presenting an approach for the specification of the structure of classes of XML documents and for reasoning about them. More precisely, we specify the structure of documents using sets of constraints that are based on XPath and we present inference rules that are shown to define a sound and complete refutation procedure for checking satisfiability of a given specification using tableaux.Peer ReviewedPostprint (author's final draft

Data flow testing of service choreography

This work is supported in part by the General Research Fund of the Research Grants Council of Hong Kong (project nos. 717506 and 717308).ESEC/FSE (Conference)Service computing has increasingly been adopted by the industry, developing business applications by means of orchestration and choreography. Choreography specifies how services collaborate with one another by defining, say, the message exchange, rather than via the process flow as in the case of orchestration. Messages sent from one service to another may require the use of different XPaths to manipulate or extract message contents. Mismatches in XML manipulations through XPaths (such as to relate incoming and outgoing messages in choreography specifications) may result in failures. In this paper, we propose to associate XPath Rewriting Graphs (XRGs), a structure that relates XPath and XML schema, with actions of choreography applications that are skeletally modeled as labeled transition systems. We develop the notion of XRG patterns to capture how different XRGs are related even though they may refer to different XML schemas or their tags. By applying XRG patterns, we successfully identify new data flow associations in choreography applications and develop new data flow testing criteria. Finally, we report an empirical case study that evaluates our techniques. The result shows our techniques are promising in detecting failures in choreography applications. Copyright 2009 ACM.postprin