Siobhán North

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Despite being widely known and accepted in industry, the Z formal specification language has not so far been well supported by automated verification tools, mostly because of the challenges in handling the abstraction of the language. In this paper we discuss a novel approach to building a model-checker for Z, which involves implementing a translation from(More)
Trust-based access is an established technique in many fields, such as networks and distributed systems, but has not previously been used for XML (Extensible Markup Language) databases. In trust-based access control, user privileges are calculated dynamically depending on the user's trust value. Applying the technique to XML databases should have many(More)
This paper presents a performance analysis of strategies for storing XML data sets in relational databases, focusing on XML datasets that are a combination of structured and semi-structured data. The analysis demonstrates advantages of a hybrid approach combining structure mapping and XML data type instances. However problems remain with current technology(More)
Logging is an important process in databases and is used for recovery and security purposes. Logging in XML databases has rarely been discussed in the literature. In this paper the Xlog file is presented as a dynamic and temporary log file for XML databases. It is used, not for recovery, but to calculate user trust values by recording users' bad(More)
Logging is an important process in databases and is used for recovery and security purposes. Logging in XML databases has rarely been discussed in the literature. In this paper the Xlog file is presented as a dynamic and temporary log file for XML databases. It is used, not for recovery, but to calculate user trust values by recording users' bad(More)
In order to improve security and provide dynamic access control for XML databases, we developed trust based access control for XML databases. Trust based access control for XML databases manages the access policy depending on users' trustworthiness and prevents unauthorized processes, malicious transactions and misuse from both outsiders and insiders. Trust(More)