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Security is considered to be one of the most critical aspects in a cloud computing environment due to the sensitivity and importance of information stored in the cloud and also because the management of the data might not be fully trustworthy. The risk of malicious insiders in the cloud and the failing of cloud services have received a strong attention by(More)
Data security has become an important requirement for clients when dealing with clouds that may fail due to faults in the software or hardware, or attacks from malicious insiders. Hence, building a highly dependable and reliable cloud system has become a critical research problem. This paper presents BFT-MCDB (Byzantine Fault Tolerance Multi-Clouds(More)
The use of cloud computing has increased rapidly in many organizations. Cloud computing provides many benefits in terms of low cost and accessibility of data. Ensuring the security of cloud computing is a major factor in the cloud computing environment, as users often store sensitive information with cloud storage providers but these providers may be(More)
Security is considered to be one of the most critical aspects in a cloud computing environment due to the sensitive and important information stored in the cloud for users. Users are wondering about attacks on the integrity and the availability of their data in the cloud from malicious insiders and outsiders, and from any collateral damage of cloud(More)
— Despite the increasing demand for an effective XML document repository, many are still reluctant to store XML documents in their natural tree form. One main reason is the inadequacy of XML query languages to update the tree-form XML documents. Even though some of the languages have supported minimum update facilities, they do not concern on preserving the(More)
XML data can be stored in different databases including Object-Relational Database (ORDB). Using ORDB, we get the benefit of the relational maturity and the richness of OO modeling. One modeling concept that can be captured is the collection. Collection structures frequently occur in XML documents especially in two relationship types: aggregation and(More)
In this paper, we propose a typology of the semantic transformations for XPath queries. We focus on two main areas. The first is structural transformation for XPath query, which can be semantically contracted, expanded or complemented using structural constraints. The second is semantic qualifier transformation where the predicates, specified by [ ], in an(More)
Change detection of XML data has emerged as an important research issue in the last decade, however the majority of change detection algorithms focuses on XML documents rather than schemas. This is because documents that contain data are deemed more significant than the schema itself. This paper looks at the problem from a different perspective by(More)