59757838
Operating System Support for Data Management.
7923805
A reference model for team-enabled workflow management systems
Abstract Today's workflow systems assume that each work item is executed by a single worker. From the viewpoint of the system, a worker with the proper qualifications selects a work item, executes the associated work, and reports the result. There is usually no support for teams, i.e., groups of people collaborating by jointly executing work items (e.g., the program committee of a conference, the management team of a company, a working group, and the board of directors). In this paper, we propose the addition of a team concept to today's workflow management systems. Clearly, this involves a marriage of workflow and groupware technology. To shed light on the introduction of teams, we extend the traditional organizational meta model with teams and propose a team-enabled workflow reference model. For this reference model and to express constraints with respect to the distribution of work to teams, we use object constraint language (OCL).
14897390
Meta workflows as a control and coordination mechanism for exception handling in workflow systems
A higher level control and coordination mechanism is required for exception handling in workflow systems. This paper describes such a framework based on events, states, and a new kind of process called a meta workflow. Meta workflows have five kinds of meta activities and facilitate control over base workflows. We describe the framework and illustrate it with examples to show its features. The paper gives an architecture for incorporating it into existing workflows and also provides a formal semantics of execution. This framework can be used in Web services, supply chains, and inter-organizational applications where coordination requirements are complex, and flexible and adaptable workflows are needed. It is also useful for handling not just failure recovery but also various kinds of special situations, which arise frequently in web-based applications.
16012186
A fine-grained, controllable, user-to-user delegation method in RBAC
This paper addresses the issues surrounding user-to-user delegation in RBAC. We show how delegations can be incorporated into the RBAC model in a simple and straightforward manner. A special feature of the model is that it allows fine-grained control over what rights a user wishes to delegate as opposed to delegation at the role level where all the rights of a role must be delegated. In addition, the model provides a rich set of controls regarding further delegations of a right, generic constraints that further control delegations, and an innovative model for revocations. Properties of both delegation and revocation are discussed, and our work is compared with other related research.
206778468
A performance study of general grid structures for replicated data
Recently, there has been considerable interest in the study of replica-control protocols which are based on organizing several copies of an object into logical structures, such as rectangular grids. In addition to high availability, another objective in exploiting such structures is to improve the degree of load sharing in a system. The authors extend the scope of grid structures to general grids, which allow holes in various positions of a rectangular structure and are useful to consider because they often produce availabilities that are higher than solid grids, where every position must be occupied by a node. In addition to proposing an improvement to the existing grid protocol, new insights are offered into the performance of the grids, from both availability and load sharing points of view. Algorithms for designing grids to maximize availability independently and also in conjunction with a load sharing constraint are given.<<ETX>>
45847616
EROICA: A Rule-Based Approach to Organizational Policy Management in Workflow Systems
Conventional workflow management systems have been criticized for being too rigid in dealing with changes in organizational policies, in particular for the lack of flexible mechanisms for handling complex role resolution. In this paper we describe a rule-based approach (EROICA) for managing organizational policies in workflow systems. Our approach extends the well-known ECA (event-condition-action) approach used in database systems by elevating roles, objects and time intervals to first class citizens, hence the term EROICA (event-role-object-interval-condition-action). In this paper, we focus on the development of a flexible role resolution mechanism that operates under various business constraints specified with EROICA rules. We further discuss the issues of architecture and implementation and demonstrate that the EROICA framework is promising in making next generation of workflow systems more powerful and flexible.
5368108
A stochastic approximation approach for max-min fair adaptive rate control of ABR sessions with MCRs
The available bit rate (ABR) sessions in an ATM network share the bandwidth left over after guaranteeing service to constant bit rate (CBR) and variable bit rate (VBR) traffic. Hence the bandwidth available to ABR sessions is randomly varying. This bandwidth must be shared by the sessions in a max-min fair fashion. Our point of departure in this paper is to formulate the problem of determining the max-min fair session rates as the problem of finding the root of a certain nonlinear vector equation; the same formulation also arises with our notion of max-min fairness with positive minimum cell rates (MCRs). This formulation allows us to use a stochastic approximation algorithm for online distributed computation of the max-min fair rates. We use the well known ordinary differential equation technique to prove convergence of the algorithm in the synchronous update case. We provide simulation results using the NIST simulator to show that the algorithm is able to track the max-min fair rates for slowly varying random available link bandwidths.
31048080
Advertising data analysis using rough sets model
This study explores the use of rough-set methods for marketing decision support systems in the retail business. A tutorial presentation of Rough Set Data Analysis (RSDA) in the context of knowledge discovery from time series databases is given. We show how an RSDA model can be used to develop a marketing decision support system which can capture the complex relationships between marketing factors, such as advertising and promotion, and the total impact on sales levels in order to find influential advertising strategies. This information is used by the business manager to make faster and better strategy decisions for the business to survive in the rapidly changing and competitive environments. The data set used for RSDA application example contains weekly investments in different media categories: TV, radio, cinema, morning press, evening press, popular press, special interest press, and outdoor posters; for seven makes of cars in the Swedish market.
43715944
Performance Analysis and Scheduling of Stochastic Fork-Join Jobs in a Multicomputer System
The authors model a parallel processing system comprising several homogeneous computers interconnected by a communication network. Jobs arriving to this system have a linear fork-join structure. Each fork of the job gives rise to a random number of tasks that can be processed independently on any of the computers. Since exact analysis of fork-join models is known to be intractable, the authors resort to obtaining analytical bounds to the mean job response time of the fork-join job. For jobs with a single fork-join and, probabilistic allocation of tasks of the job to the N processors, they obtain upper and lower bounds to the mean job response time. Upper bounds are obtained using the concept of associated random variables and are found to be a good approximation to the mean job response time. A simple lower bound is obtained by neglecting queueing delays. They also find two lower bounds that include queueing delays. For multiple fork-join jobs, they study an approximation based on associated random variables. Finally, two versions of the join-the-shortest-queue (JSQ) allocation policy (i.e., JSQ by batch and JSQ by task) are studied and compared, via simulations and diffusion limits. >
36436312
Simplifying CORBA Security Service to Support Service Level Access Control
The CORBA Security Service provides a domain based access control model in which interfaces are grouped in domains and a single security policy applies to all the interfaces in the domain. CORBA Security Service does not directly support object and method level access control rules. Grouping interfaces in domains helps in reducing access control rules in a large system with a large number of objects. In an environment where services are provided using methods and similar services are grouped as the methods of an interface, providing service and interface level access control is desirable.
46145059
Primal-Dual Algorithms for Connected Facility Location Problems
We consider the Connected Facility Location problem. We are given a graph G = (V, E) with cost ce on edge e, a set of facilities F ? V, and a set of demands D ? V. We are also given a parameter M ? 1. A solution opens some facilities, say F, assigns each demand j to an open facility i(j), and connects the open facilities by a Steiner tree T. The cost incurred is ?i?F fi + ?j?D djci(j)j + M ?e?T ce. We want a solution of minimum cost. A special case is when all opening costs are 0 and facilities may be opened anywhere, i.e., F = V. If we know a facility v that is open, then this problem reduces to the rent-or-buy problem. We give the first primal-dual algorithms for these problems and achieve the best known approximation guarantees. We give a 9-approximation algorithm for connected facility location and a 5-approximation for the rent-or-buy problem. Our algorithm integrates the primal-dual approaches for facility location [7] and Steiner trees [1,2]. We also consider the connected k-median problem and give a constant-factor approximation by using our primal-dual algorithm for connected facility location. We generalize our results to an edge capacitated version of these problems.