Advanced Architectures for Transactional Workflows or Advanced Transactions in Workflow Architectures

In this short paper, we outline the workflow management systems research in the Information Systems division at the University of Twente. We discuss the two main themes in this research: architecture design and advanced transaction management. Attention is paid to the coverage of these themes in the context of the completed Mercurius and WIDE projects and in the new CrossFlow project. In the latter project, contracts are introduced as a new theme to support electronic commerce aspects in workflow management

Extending a multi-set relational algebra to a parallel environment

Parallel database systems will very probably be the future for high-performance data-intensive applications. In the past decade, many parallel database systems have been developed, together with many languages and approaches to specify operations in these systems. A common background is still missing, however. This paper proposes an extended relational algebra for this purpose, based on the well-known standard relational algebra. The extended algebra provides both complete database manipulation language features, and data distribution and process allocation primitives to describe parallelism. It is defined in terms of multi-sets of tuples to allow handling of duplicates and to obtain a close connection to the world of high-performance data processing. Due to its algebraic nature, the language is well suited for optimization and parallelization through expression rewriting. The proposed language can be used as a database manipulation language on its own, as has been done in the PRISMA parallel database project, or as a formal basis for other languages, like SQL

Integrity Constraint Checking in Federated Databases

A federated database is comprised of multiple interconnected databases that cooperate in an autonomous fashion. Global integrity constraints are very useful in federated databases, but the lack of global queries, global transaction mechanisms, and global concurrency control renders traditional constraint management techniques inapplicable. The paper presents a threefold contribution to integrity constraint checking in federated databases: (1) the problem of constraint checking in a federated database environment is clearly formulated; (2) a family of cooperative protocols for constraint checking is presented; (3) the differences across protocols in the family are analyzed with respect to system requirements, properties guaranteed, and costs involved. Thus, we provide a suite of options with protocols for various environments with specific system capabilities and integrity requirement

Protocols for Integrity Constraint Checking in Federated Databases

A federated database is comprised of multiple interconnected database systems that primarily operate independently but cooperate to a certain extent. Global integrity constraints can be very useful in federated databases, but the lack of global queries, global transaction mechanisms, and global concurrency control renders traditional constraint management techniques inapplicable. This paper presents a threefold contribution to integrity constraint checking in federated databases: (1) The problem of constraint checking in a federated database environment is clearly formulated. (2) A family of protocols for constraint checking is presented. (3) The differences across protocols in the family are analyzed with respect to system requirements, properties guaranteed by the protocols, and processing and communication costs. Thus, our work yields a suite of options from which a protocol can be chosen to suit the system capabilities and integrity requirements of a particular federated database environment

Supporting telecom business processes by means of workflow management and federated databases

This report addresses the issues related to the use of workflow management\ud systems and federated databases to support business processes that operate on\ud large and heterogeneous collections of autonomous information systems. We\ud discuss how they can enhance the overall IT-architecture. Starting from the\ud OSCA architecture, we develop an architecture that includes workflow\ud management systems and federated databases. In this architecture, the notion of\ud information systems as a monolithic entity disappears. Instead, business\ud processes are supported directly by workflows that combine presentation\ud blocks, function blocks, and data blocks. We address the specific issues of\ud transaction management and change management in such an architecture

Two Case Studies of Subsystem Design for General-Purpose CSCW Software Architectures

This paper discusses subsystem design guidelines for the software architecture of general-purpose computer supported cooperative work systems, i.e., systems that are designed to be applicable in various application areas requiring explicit collaboration support. In our opinion, guidelines for subsystem level design are rarely given most guidelines currently given apply to the programming language level. We extract guidelines from a case study of the redesign and extension of an advanced commercial workflow management system and place them into the context of existing software engineering research. The guidelines are then validated against the design decisions made in the construction of a widely used web-based groupware system. Our approach is based on the well-known distinction between essential (logical) and physical architectures. We show how essential architecture design can be based on a direct mapping of abstract functional concepts as found in general-purpose systems to modules in the essential architecture. The essential architecture is next mapped to a physical architecture by applying software clustering and replication to achieve the required distribution and performance characteristics

On deep e-contracting

The use of electronic contracts is emerging as a way to improve the effi-ciency of contracting processes. Electronic contracts are, however, often used as a direct replacement for traditional paper contracts - which we call shallow e-contracting. Consequently, business processes in general and contracting processes in particular do not change much through the use of electronic contracts. New business scenarios caused by e-business developments, however, do require new contracting paradigms in which the use of electronic contracts becomes an essential element to obtain a radical paradigm shift in contractual business relations - which we call deep e-contracting. In this position paper, we explore these new para-digms. We link the paradigms to exchanged values described in e-contracts to obtain a mapping from business requirements. We next map the paradigms to contracting activities. Finally, we map the activities to information technology required for their automated support. Based on the paradigms and mappings, this paper provides a concise framework for the exploration of deep e-contracting.\ud

CrossFlow: Integrating Workflow Management and Electronic Commerce

The CrossFlow1 architecture provides support for cross-organisational workflow management in dynamically established virtual enterprises. The creation of a business relationship between a service provider organisation performing a service on behalf of a consumer organisation can be made dynamic when augmented by virtual market technology, the dynamic configuration of the contract enactment infrastructures, and the provision of fine grained service monitoring and control. Standard ways of describing services and contracts can be combined with matchmaking technology to create a virtual market for such service provision and consumption. A provider can then advertise its services in the market and consumers can search for a compatible business partner. This provides choice in selecting a partner and allows the deferment of the decision to a point in time where it can be made on the most up-to-date requirements of the consumer and service offers in the market. The penalty for deferred decision making is the time to set up the infrastructure in each organisation for the dynamically established contract. Thus, a further aspect of CrossFlow was to exploit the contract in the dynamic and automatic configuration of the contract enactment and supervision infrastructures of the respective organisations and in linking them in a dynamic fashion. The electronic contract, which results from the agreement between the newly established business partners, completely specifies the intended collaboration between them. Given the importance of the business process enacted by the provider, this includes fine-grained monitoring and control to allow tight co-operation between the organisations

Implementing PRISMA/DB in an OOPL

PRISMA/DB is implemented in a parallel object-oriented language to gain insight in the usage of parallelism. This environment allows us to experiment with parallelism by simply changing the allocation of objects to the processors of the PRISMA machine. These objects are obtained by a strictly modular design of PRISMA/DB. Communication between the objects is required to cooperatively handle the various tasks, but it limits the potential for parallelism. From this approach, we hope to gain a better understanding of parallelism, which can be used to enhance the performance of PRISMA/DB.\ud The work reported in this document was conducted as part of the PRISMA project, a joint effort with Philips Research Eindhoven, partially supported by the Dutch "Stimuleringsprojectteam Informaticaonderzoek (SPIN)