9,154 research outputs found
A Method for Mapping XML DTD to Relational Schemas In The Presence Of Functional Dependencies
The eXtensible Markup Language (XML) has recently emerged as a standard for
data representation and interchange on the web. As a lot of XML data in the web,
now the pressure is to manage the data efficiently. Given the fact that relational
databases are the most widely used technology for managing and storing XML,
therefore XML needs to map to relations and this process is one that occurs
frequently. There are many different ways to map and many approaches exist in the
literature especially considering the flexible nesting structures that XML allows. This
gives rise to the following important problem: Are some mappings ‘better’ than the
others? To approach this problem, the classical relational database design through
normalization technique that based on known functional dependency concept is
referred. This concept is used to specify the constraints that may exist in the relations
and guide the design while removing semantic data redundancies. This approach
leads to a good normalized relational schema without data redundancy. To achieve a
good normalized relational schema for XML, there is a need to extend the concept of
functional dependency in relations to XML and use this concept as guidance for the
design. Even though there exist functional dependency definitions for XML, but these definitions are not standard yet and still having several limitation. Due to the
limitations of the existing definitions, constraints in the presence of shared and local
elements that exist in XML document cannot be specified. In this study a new
definition of functional dependency constraints for XML is proposed that are general
enough to specify constraints and to discover semantic redundancies in XML
documents.
The focus of this study is on how to produce an optimal mapping approach in the
presence of XML functional dependencies (XFD), keys and Data Type Definition
(DTD) constraints, as a guidance to generate a good relational schema. To approach
the mapping problem, three different components are explored: the mapping
algorithm, functional dependency for XML, and implication process. The study of
XML implication is important to imply what other dependencies that are guaranteed
to hold in a relational representation of XML, given that a set of functional
dependencies holds in the XML document. This leads to the needs of deriving a set
of inference rules for the implication process. In the presence of DTD and userdefined
XFD, other set of XFDs that are guaranteed to hold in XML can be
generated using the set of inference rules. This mapping algorithm has been
developed within the tool called XtoR. The quality of the mapping approach has
been analyzed, and the result shows that the mapping approach (XtoR) significantly
improve in terms of generating a good relational schema for XML with respect to
reduce data and relation redundancy, remove dangling relations and remove
association problems. The findings suggest that if one wants to use RDBMS to
manage XML data, the mapping from XML document to relations must based be on
functional dependency constraints
UML to XML-Schema Transformation: a Case Study in Managing Alternative Model Transformations in MDA
In a Model Driven Architecture (MDA) software development process, models are\ud
repeatedly transformed to other models in order to finally achieve a set of models with enough details to implement a system. Generally, there are multiple ways to transform one model into another model. Alternative target models differ in their quality properties and the selection of a particular model is determined on the basis of specific requirements. Software engineers must be able to identify, compare and select the appropriate transformations within the given set of requirements. The current transformation languages used for describing and executing model transformations only provide means to specify the transformations but do not help to identify and select from the alternative transformations. In this paper we propose a process and a set of techniques for constructing a transformation space for a given transformation problem. The process uses a source model, its meta-model and the meta-model of the target as input and generates a transformation space. Every element in that space represents a transformation that produces a result that is an instance of the target meta-model. The requirements that must be fulfilled by the result are captured and represented in a quality model. We explain our approach using an illustrative example for transforming a platform independent model expressed in UML into platform specific models that represent XML schemas. A particular quality model of extensibility is presented in the paper
An automated model-based test oracle for access control systems
In the context of XACML-based access control systems, an intensive testing
activity is among the most adopted means to assure that sensible information or
resources are correctly accessed. Unfortunately, it requires a huge effort for
manual inspection of results: thus automated verdict derivation is a key aspect
for improving the cost-effectiveness of testing. To this purpose, we introduce
XACMET, a novel approach for automated model-based oracle definition. XACMET
defines a typed graph, called the XAC-Graph, that models the XACML policy
evaluation. The expected verdict of a specific request execution can thus be
automatically derived by executing the corresponding path in such graph. Our
validation of the XACMET prototype implementation confirms the effectiveness of
the proposed approach.Comment: 7 page
Hijacker: Efficient static software instrumentation with applications in high performance computing: Poster paper
Static Binary Instrumentation is a technique that allows compile-time program manipulation. In particular, by relying on ad-hoc tools, the end user is able to alter the program's execution flow without affecting its overall semantic. This technique has been effectively used, e.g., to support code profiling, performance analysis, error detection, attack detection, or behavior monitoring. Nevertheless, efficiently relying on static instrumentation for producing executables which can be deployed without affecting the overall performance of the application still presents technical and methodological issues. In this paper, we present Hijacker, an open-source customizable static binary instrumentation tool which is able to alter a program's execution flow according to some user-specified rules, limiting the execution overhead due to the code snippets inserted in the original program, thus enabling for the exploitation in high performance computing. The tool is highly modular and works on an internal representation of the program which allows to perform complex instrumentation tasks efficiently, and can be additionally extended to support different instruction sets and executable formats without any need to modify the instrumentation engine. We additionally present an experimental assessment of the overhead induced by the injected code in real HPC applications. © 2013 IEEE
Information Exchange Between Humanitarian Organizations: Using the XML Schema IDML
This article explains challenges that arise when humanitarian organizations want to coordinate their development activities by means of distributed information systems. It focuses on information exchange based on the eXtensible Markup Language (XML) and relational databases. This piece discusses how to save hierarchical XML documents in relational databases. It introduces conversion rules to derive a relational database model from XML schemas. The rules are applied for the design of a database for the management of humanitarian development projects. The underlying schema for the database is the International Development Markup Language (IDML). This exchange standard for development-related activities is described. The article gives details on how a traditional relational database can import or export XML documents, i.e. how it can be XML-enabled
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