Can Türker

Semantic integrity support in SQL:1999 and commercial (object-)relational database management systems

Abstract. The correctness of the data managed by database systems is vital to any application that utilizes data for business, research, and decision-making purposes. To guard databases against erroneous data not reflecting real-world data or business rules, semantic integrity constraints can be specified during database design. Current commercial database management systems provide various means to implement mechanisms to enforce semantic integrity constraints at database run-time.In this paper, we give an overview of the semantic integrity support in the most recent SQL-standard SQL:1999, and we show to what extent the different concepts and language constructs proposed in this standard can be found in major commercial (object-)relational database management systems. In addition, we discuss general design guidelines that point out how the semantic integrity features provided by these systems should be utilized in order to implement an effective integrity enforcing subsystem for a database.

Decentralized coordination of transactional processes in peer-to-peer environments

Business processes executing in peer-to-peer environments usually invoke Web services on different, independent peers. Although peer-to-peer environments inherently lack global control, some business processes nevertheless require global transactional guarantees, i.e., atomicity and isolation applied at the level of processes. This paper introduces a new decentralized serialization graph testing protocol to ensure concurrency control and recovery in peer-to-peer environments. The uniqueness of the proposed protocol is that it ensures global correctness without relying on a global serialization graph. Essentially, each transactional process is equipped with partial knowledge that allows the transactional processes to coordinate. Globally correct execution is achieved by communication among dependent transactional processes and the peers they have accessed. In case of failures, a combination of partial backward and forward recovery is applied. Experimental results exhibit a significant performance gain over traditional distributed locking-based protocols with respect to the execution of transactions encompassing Web service requests.

PEER-TO-PEER EXECUTION OF (TRANSACTIONAL) PROCESSES

Standards like SOAP, WSDL, and UDDI facilitate the proliferation of services. Based on these technologies, processes are a means to combine services to applications and to provide new value-added s...

Chapter 7: Architectures and Implementations of Spatio-temporal Database Management Systems

This chapter is devoted to architectural and implementation aspects of spatiotemporal database management systems. It starts with a general introduction into architectures and commercial approaches to extending databases by spatiotemporal features. Thereafter, the prototype systems Concert, Secondo, Dedale, Tiger, and GeoToolKit are presented.

Scalable peer-to-peer process management

The functionality of applications is increasingly being made available by services. General concepts and standards such as SOAP, WSDL and UDDI support the discovery and invocation of single web services. The state-of-the-art process management is conceptually based on a centralised process manager. The resources of this coordinator limit the number of concurrent process executions, especially as the coordinator has to persistently store each state change for recovery purposes. In this paper, we overcome this limitation by executing processes in a peer- to-peer way exploiting all peers of the system. By distributing the execution and navigation costs, we can achieve a higher degree of scalability allowing for a much larger throughput of processes compared to centralised solutions. This paper describes our prototype system OSIRIS, which implements such a true peer-to-peer process execution. We further present very promising results verifying the advantages over centralised process management in terms of scalability.

Towards maintaining integrity of federated databases

Supporting integrity constraints is essential for database systems. In consequence, global integrity constraints must be dealt with by federated database systems. Although a lot of work has been done on transaction management in multidatabase systems, the treatment of semantic integrity constraints (e.g. uniqueness conditions), especially detecting (potential) violations and specifying necessary reactions, is often omitted. In this paper, we propose a very flexible way to realize global integrity maintenance in federated database systems. We aim at integrating the active rule paradigm into a federated database framework. Thereby, integrity constraints involving multiple component database systems can easily be supported. Active rules provide a powerful mechanism for communication and cooperation between heterogeneous database systems. In addition, they are to be used for specifying enforcement of constraints in case of violation. For enforcing constraints the existing local mechanisms (e.g. triggers) of the component database systems can be employed. In case this is not possible, an additional layer has to be introduced which realizes the active rule mechanism for the component database system.

Considering Integrity Constraints During Federated Database Design

Correct transformations and integrations of schemata within the process of federated database design have to encompass existing local integrity constraints. Most of the proposed methods for schema transformation and integration do not sufficiently consider explicit integrity constraints. In this paper we present an approach to deal with integrity constraints. Our approach bases on the idea to relate integrity constraints to extensions. A set of elementary operations for schema restructuring and integration is identified. For these operations we define major rules for dealing with integrity constraints. By means of a small example we then demonstrate the application of these rules.

Schema Integration with Integrity Constraints

In this paper we discuss the use and treatment of integrity constraints in the federated database design process. We consider different situations occurring frequently in the schema transformation and schema integration process. Based on that, general rules are given which describe the correct treatment of integrity constraints. Other proposed integration approaches do not consider integrity constraints at all or are restricted to special kinds of constraints. Therefore, our approach can be used to extend or complete existing integration methodologies.

Towards an Agent-Oriented Framework for Specification of Information Systems.

Objects in information systems usually have a very long lifespan. Therefore, it often happens that during the life of an object external requirements are changing, e.g. changes of laws. Such changes often require the object to adopt another behavior. In consequence, it is necessary to get a grasp of dynamically changing object behavior. Unfortunately, not all possible changes can in general be taken into account in advance at specification time. Hence, current object specification approaches cannot deal with this problem. Flexible extensions of object specification are needed to capture such situations.

B-Fabric: a data and application integration framework for life sciences research

Life sciences research in general and systems biology in particular have evolved from the simple combination of theoretical frameworks and experimental hypothesis validation to combined sciences of biology/medicine, analytical technology/chemistry, and informatics/statistics/modeling. Integrating these multiple threads of a research project at the technical and data level requires tight control and systematic workflows for data generation, data management, and data evaluation. Systems biology research emphasizes the use of multiple approaches at various molecular and functional levels, making the use of complementing technologies and the collaboration of many researchers a prerequisite. This paper presents B-Fabric, a system developed and running at the Functional Genomics Center Zurich (FGCZ), which provides a core framework for integrating different analytical technologies and data analysis tools. In addition to data capturing and management, B-Fabric emphasizes the need for quality-controlled scientific annotation of analytical data, providing the ground for integrative querying and exploitation of systems biology data. Users interact with B-Fabric through a simple Web portal making the framework flexible in terms of local infrastructure.