Transaction Support for DataWeb Applications - A Requirement\u27s Perspective

W eb-based purely providing read-only access to information in terms of static HTML pages. Rather, more and more web-based information systems store (part of) the information within a database system (DBS) and generate HTML pages on demand. Such information systems are often called DataWeb Applications. Different users interact with the system, and often they perform changes concurrently. As an example in the area of electronic commerce, consider a web-based tourism information system, where an unpredictable number of a priori unknown tourists are allowed to book various tourism facilities at the same time. Whereas financial and security issues of such electronic commerce transactions are extensively discussed in literature, very few work exists on the database transaction aspect in terms of consistency and reliability of electronic commerce transactions and of DataWeb applications in general. The objective of this paper is to discuss the specific requirements that different architectures of DataWeb applications and the web itself pose on transaction management, and to identify promising technologies for enabling web transaction services

Implementing Business Policies Based on a Framework of Rule Patterns

Introduction Application development has to cope with frequently changing requirements which are to a large extent due to changes in the business environment [Loucopoulos et al. 1991]. These facets of business environments are often referred to as business policies. They may be based on ethics, law, culture and organizational commitments by either prescribing a certain action or by constraining the set of possible actions [Odell 1994]. Two main problems arise in the context of implementing business policies. Firstly, business policies are often blurred with code for implementing the basic, unchanging functionality of an application. This makes it difficult to cope with their dynamic nature. This problem can be resolved by factorising out business policies from single applications and representing them in terms of Event/Condition/Action rules (ECA rules). These rules allow the designer to monitor situations represented by event

Coordination in Workflow Management Systems - A Rule-Based Approach

Coordination is a key requirement of software systems where different parts have to be adjusted in order to reach a common goal. A prominent example thereof are workflow management systems (WFMS). They in particular require flexible mechanisms to realize different kinds of coordination, which are called coordination policies. This need for flexibility emerges from the fact that coordination policies in WFMS are subject to frequent changes caused by the business environment. Flexibility is required in different directions, ranging from a dynamic evolution of existing policies to proper reactions to unpredictable situations. Active object-oriented database systems (AOODBS) along with their basic mechanism in terms of Event/Condition/Action (ECA) rules seem to be a promising technology in order to cope with these requirements. ECA rules allow for an event-driven realization of context- and time-dependent behavior which constitutes a major property of coordination policies. By encapsulatin..

A Framework for Workflow Management Systems Based on Objects, Rules and Roles

Introduction Workflow management systems (WFMS) have been introduced to support the design, execution and monitoring of generally long-lasting business processes. A business process or workflow typically consists of various activities which have to be executed in some order involving multiple collaborating persons in a distributed environment to fulfill a certain task in an organization [Jablonski and Bussler 1996]. One of the most challenging issues of WFMS is to provide concepts for flexibly and dynamically reacting to frequently changing requirements in an organization [Ellis et al. 1995]. This has been the driving force behind the development of our framework for WFMS called TriGS flow , which integrates three basic technologies [Kappel et al. 1995]. First, objectoriented database technology is used to build a generic workflow model providing both database functionality and possibilities for model

Rule Patterns for Designing Active Object-Oriented Database Applications

Active object-oriented database systems (AOODBSs) have become widely recognized for smoothly capturing the context-dependent and time-dependent organizational knowledge of large enterprises, also known as business policies. However, not least since the remarkable panel at the RIDE'94 workshop on active database systems [Wido94] the design issue of AOODBS applications is known as one of the most pressing open research problems. This is largely because of the expressive power and flexibility of existing active object-oriented data models together with a lack of design guidelines on how to apply these models. Learning from analogous problems in object-oriented system development and borrowing their solution metaphor we introduce rule patterns as generic rule-based solutions for realizing business policies. The advantages of rule patterns are their predefined, reusable, and dynamically customizable nature allowing the designer to reuse existing experience for building AOODBS applications..

The Benefits of Open Hypermedia Systems Using Advanced Database Concepts

Large engineering enterprises are just one application area of open hypermedia systems (OHS), which are characterized by both, open hyperbase and link server functionality. An open hyperbase allows besides others to store and retrieve an extensible set of hypermedia objects. A link server allows to store and retrieve connectivity information and supports consistency management thereof. To provide these functionalities, open hypermedia systems have to tackle several important issues such as interoperability, extensibility, and computation. Using advanced database concepts as OHS baseline architecture these issues can be elegantly resolved. In particular, this paper proposes an OHS architecture based on an active object-oriented database system as well as SGML/HyTime as standardized interchange formats. By using active object-oriented database systems extensibility and computation including consistency management are ensured. By using international standards interoperability of hypermedi..

TriGSflow - Active Object-Oriented Workflow Management

We present the multi-paradigm architecture TriGS flow for a workflow management system. TriGS flow is based on an active extension of the commercial object-oriented database system GemStone TM . TriGS flow takes full advantage of the capabilities of the underlying database system such as reliability, recovery, transaction management, and authorization. At the current stage of implementation the novel features of TriGS flow are the seamless integration of ECA rules into an object-oriented model, the flexibility of workflow specification due to rule modeling, and the integration of external applications as part of workflow processing. Keywords: workflow model based on ECA rules, active object-oriented database 1. Introduction A workflow management system (WFMS) supports the design, execution and monitoring of in general long-lasting business processes that typically involve multiple activities and multiple collaborating persons in a distributed environement. WFMSs originate from th..