Index Configurations in Object-Oriented Databases

title: Data security
abstract: Maintaining data quality is an important requirement in any organization. It requires measures for access control, semantic integrity, fault tolerance and recovery. Access control regulates the access to the system by users to ensure that all accesses are authorized according to some specified policies. We briefly survey the state of the art in access control for database systems, discuss the main research issues, and outline possible directions for future research.

title: A Knowledge Based Information System

title: Extending the ODMG object model with composite objects
abstract: In this paper we extend the ODMG object data model with composite objects. A composite object is an object built by aggregating other component objects. Exclusiveness and dependency constraints, as well as referential integrity, can be associated with composition relationships among objects. Our composite object model is developed in the framework of the ODMG object database standard data model, but can be used in both object-oriented and object-relational database systems. In the paper, we propose a language for defining composite objects and we define the semantics of update operations on composite objects.

title: The specification and enforcement of authorization constraints in workflow management systems
abstract: In recent years, workflow management systems (WFMSs) have gained popularity in both research and commercial sectors. WFMSs are used to coordinate and streamline business processes. Very large WFMSs are often used in organizations with users in the range of several thousands and process instances in the range of tens and thousands. To simplify the complexity of security administration, it is common practice in many businesses to allocate a role for each activity in the process and then assign one or more users to each role—granting an authorization to roles rather than to users. Typically, security policies are expressed as constraints (or rules) on users and roles; separation of duties is a well-known constraint. Unfortunately, current role-based access control models are not adequate to model such constraints. To address this issue we (1) present a language to express both static and dynamic authorization constraints as clauses in a logic program; (2) provide formal notions of constraint consistency; and (3) propose algorithms to check the consistency of constraints and assign users and roles to tasks that constitute the workflow in such a way that no constraints are violated.

title: Degrees of Isolation, Concurrency Control Protocols, and Commit Protocols

title: Access control enforcement for conversation-based web services
abstract: Service Oriented Computing is emerging as the main approach to build distributed enterprise applications on the Web. The widespread use of Web services is hindered by the lack of adequate security and privacy support. In this paper, we present a novel framework for enforcing access control in conversation-based Web services. Our approach takes into account the conversational nature of Web services. This is in contrast with existing approaches to access control enforcement that assume a Web service as a set of independent operations. Furthermore, our approach achieves a tradeoff between the need to protect Web service's access control policies and the need to disclose to clients the portion of access control policies related to the conversations they are interested in. This is important to avoid situations where the client cannot progress in the conversation due to the lack of required security requirements. We introduce the concept of k-trustworthiness that defines the conversations for which a client can provide credentials maximizing the likelihood that it will eventually hit a final state.

title: An integrated approach to federated identity and privilege management in open systems
abstract: Online partnerships depend on federations of not only user identities but also of user entitlements across organizational boundaries.

title: Systematic control and management of data integrity
abstract: Integrity has long been considered a fundamental requirement for secure computerized systems, and especially today's demand for data integrity is stronger than ever as many organizations are in-creasing their reliance on data and information systems. A number of recently enacted data privacy regulations also require high in-tegrity for personal data. In this paper, we discuss various issues concerning systematic control and management of data integrity with a primary focus on access control. We first examine some previously proposed integrity models and define a set of integrity requirements. We then present an architecture for comprehensive integrity control systems, which has its basis on data validation and metadata management. We also provide an integrity control policy language that we believe is flexible and intuitive.