Measuring and Evaluating a Design Complexity Metric for XML Schema Documents

The eXtensible Markup Language (XML) has been gaining extraordinary acceptance from many diverse enterprise software companies for their object repositories, data interchange, and development tools. Further, many different domains, organizations and content providers have been publishing and exchanging information via internet by the usage of XML and standard schemas. Efficient implementation of XML in these domains requires well designed XML schemas. In this point of view, design of XML schemas plays an extremely important role in software development process and needs to be quantified for ease of maintainability. In this paper, an attempt has been made to evaluate the quality of XML schema documents (XSD) written in W3C XML Schema language. We propose a metric, which measures the complexity due to the internal architecture of XSD components, and due to recursion. This is the single metric, which cover all major factors responsible for complexity of XSD. The metric has been empirically and theoretically validated, demonstrated with examples and supported by comparison with other well known structure metrics applied on XML schema documents

Functional dependencies for XML : axiomatisation and normal form in the presence of frequencies and identifiers : a thesis presented in partial fulfilment of the requirements for the degree of Master of Sciences in Information Sciences at Massey University, Palmerston North, New Zealand

XML has gained popularity as a markup language for publishing and exchanging data on the web. Nowadays, there are also ongoing interests in using XML for representing and actually storing data. In particular, much effort has been directed towards turning XML into a real data model by improving the semantics that can be expressed about XML documents. Various works have addressed how to define different classes of integrity constraints and the development of a normalisation theory for XML. One area which received little to no attention from the research community up to five years ago is the study of functional dependencies in the context of XML [37]. Since then, there has been increasingly more research investigating functional dependencies in XML. Nevertheless, a comprehensive dependency theory and normalisation theory for XML have yet to emerge. Functional dependencies are an integral part of database theory in the relational data model (RDM). In particular, functional dependencies have been vital in the investigation of how to design "good" relational database schemas which avoid or minimise problems relating to data redundancy and data inconsistency. Since the same problems can be shown to exist in poorly designed XML schemas 1 , there is a need to investigate how these problems can be eliminated in the context of XML. We believe that the study of an analogy to relational functional dependencies in the context of XML is equally significant towards designing "good" XML schemas. [FROM INTRODUCTION

Ensuring Query Compatibility with Evolving XML Schemas

During the life cycle of an XML application, both schemas and queries may change from one version to another. Schema evolutions may affect query results and potentially the validity of produced data. Nowadays, a challenge is to assess and accommodate the impact of theses changes in rapidly evolving XML applications. This article proposes a logical framework and tool for verifying forward/backward compatibility issues involving schemas and queries. First, it allows analyzing relations between schemas. Second, it allows XML designers to identify queries that must be reformulated in order to produce the expected results across successive schema versions. Third, it allows examining more precisely the impact of schema changes over queries, therefore facilitating their reformulation

Consistency check between XML schema and class diagram for document versioning

A consistency check between design and implementation is usually done in order to check the correctness of the system’ requirements. However, if the requirements are changed over time, then the document versioning occurred within the requirements. For XML Schema, document versioning exists when there is a change in the XML Schema from its previous Schema. In order to detect the versioning of both XML Schemas, consistency rules check need to be performed to both class diagrams produced by both Schemas. The consistency between two XML Schemas are checked based on transformation rules and versioning rules. Transformation rules are used for translating the XML Schema into class diagram and versioning rules are used for checking the existing of document changes between two XML Schemas. Once two XML Schemas are different the consistency rules will be used for the consistency check. This paper presents an approach based on transformation rules and versioning rules to check consistency between XML Schema and UML class diagram when document versioning exist. The approach is then used for the case study to show how the consistency is checked in order to detect the versioning of two different XML Schemas. Based on the case study, the approach shows that two XML Schemas can be checked for their consistency when document versioning exist

A Grammatical Inference Approach to Language-Based Anomaly Detection in XML

False-positives are a problem in anomaly-based intrusion detection systems. To counter this issue, we discuss anomaly detection for the eXtensible Markup Language (XML) in a language-theoretic view. We argue that many XML-based attacks target the syntactic level, i.e. the tree structure or element content, and syntax validation of XML documents reduces the attack surface. XML offers so-called schemas for validation, but in real world, schemas are often unavailable, ignored or too general. In this work-in-progress paper we describe a grammatical inference approach to learn an automaton from example XML documents for detecting documents with anomalous syntax. We discuss properties and expressiveness of XML to understand limits of learnability. Our contributions are an XML Schema compatible lexical datatype system to abstract content in XML and an algorithm to learn visibly pushdown automata (VPA) directly from a set of examples. The proposed algorithm does not require the tree representation of XML, so it can process large documents or streams. The resulting deterministic VPA then allows stream validation of documents to recognize deviations in the underlying tree structure or datatypes.Comment: Paper accepted at First Int. Workshop on Emerging Cyberthreats and Countermeasures ECTCM 201

Consistency Check between XML Schema and Class Diagram for Document Versioning

A consistency check between design and implementation is usually done in order to check the correctness of the system’ requirements. However, if the requirements are changed over time, then the document versioning occurred within the requirements. For XML Schema, document versioning exists when there is a change in the XML Schema from its previous Schema. In order to detect the versioning of both XML Schemas, consistency rules check need to be performed to both class diagrams produced by both Schemas. The consistency between two XML Schemas is checked based on transformation rules and versioning rules. Transformation rules are used for translating the XML Schema into the class diagram, and versioning rules are used for checking the existing of document changes between two XML Schemas. Once two XML Schemas are different the consistency rules will be used for the consistency check. This paper presents an approach based on transformation rules and versioning rules to check consistency between XML Schema and UML class diagram when document versioning exist. The approach is then used for the case study to show how the consistency is checked in order to detect the versioning of two different XML Schemas. Based on the case study, the approach shows that two XML Schemas can be checked for their consistency when document versioning exist.

ANALYSIS AND IMPLEMENTATION OF APPLICATION SCHEMAS FOR THE INSPIRE BUILDINGS THEME

Implementing the INSPIRE directive involves transforming various data themes into the structure and content given by Data Specifications published by the Joint Research Center of the European Commission. The data is to be published in the GML format, which is the standard for the Open Geospatial Consortium. The validity of the data structure is ensured by validation against XML schemas. These schemas are usually also provided by JRC, though not necessarily for all application schemas. Six application schemas are defined for the currently implemented Buildings theme, but XML schemas are available for only three of them. All application schemas have been analyzed, and it has been found that the most suitable data model corresponds most closely to the BuildingsExtended2D application schema. No XML schema has been provided by JRC in the current version. The BuildingsExtendedBase abstract XML schema was also needed when using the previous schemas. There is now a need to create these missing XML schemas