30303692
A Meta-model of Temporal Workflow and Its Formalization
Current researches on time constraints in workflow mainly focus on time-relevant process modeling and efficiency analysis based on the temporal attributes of processes and activities. This paper presents the concept of Temporal Workflow. Through extending and modifying the WfMC’s Basic Process Definition Meta-model, a modified workflow meta-model is presented, and the temporal attributes of elements and their relations in it are analyzed in detail. Based on this, the primary elements in workflow are formalized, and time is introduced into workflow as a dimension.
33694964
Workflow scheduling in grids: an ant colony optimization approach
Grid applications in virtue of open service grid architecture (OGSA) are promising next-generation computation techniques. One of the most important and challenging problems about grid application is the workflow scheduling problem to achieve the users' QoS (quality of service) requirements as well as to minimize the cost. This paper proposes an ant colony optimization (ACO) algorithm to tackle this problem. Several new features are introduced to the algorithm. First, we define two kinds of pheromone and three kinds of heuristic information to guide the search direction of ants for this bi-criteria problem. Each ant uses either one from these heuristic types and pheromone types in each iteration based on the probabilities controlled by two parameters. These two parameters are adaptively adjusted in the process of the algorithm. Second, we use the information of partial solutions to modify the bias of ants so that inferior choices will be ignored. Moreover, the experimental results in 3 workflow applications under different deadline constraints show that the performance of our algorithm is very promising, for it outperforms the Deadline-MDP algorithm in most cases.
9006284
A workflow model based on fuzzy-timing Petri nets
Time information management in workflow has been recognized as one of the most significant tasks in workflow management. The uncertainties in time and time-related constraints in workflow models should be taken into consideration. Based on introducing time constraints on elements in fuzzy-timing Petri nets, this paper propose a new workflow model named fuzzy temporal workflow nets (FTWF-nets). The calculation of temporal elements in FTWF-nets is given. Then time modeling and time possibility analysis of temporal phenomena in FTWF-nets are investigated. Finally an example is given to illustrate how to use these methods. Research results show that FTWF-nets can be used to model time information in those workflows, which have time uncertainty and have time constraints on resources and activities, and analyze the time possibility on some constraints.
14448098
Research on Dynamic Task Assignment in Grid Workflow System
Task assignment in grid workflow system should be designed to adapt well with the grid which allow people from different organizations to work together in the same workflow process. To ensure grid workflow systems could assign the task to the most suitable person, a novel solution is proposed firstly. Then two description languages GHRSL and HRRL are defined. GHRSL (grid human resource specification language) describes people as grid resources. HRRL (human resources requirement language) describes human resources requirement of workflow tasks. Finally, the evaluation method and the algorithm of dynamic task assignment are also proposed. Based on these, the grid workflow system could assign tasks dynamically to the correct person(s)
15993806
A Workflow Model with Temporal Logic Constraints and Its Automated Verification
Traditional workflow models are weak in describing the temporal properties and constraints between activities, while some high-level extensions based on time or temporal logic have another problem that the soundness verification of the model requires high academic knowledge. In order to solve these problems, a new workflow model LTL-WF based on WF-net and linear temporal logic is proposed in this paper. Besides introducing the new model, we also bring forward a method for automated verification of LTL-WF. The method proposed here provides the verification of workflow model with a convenient environment for model checking.
9457575
Secure Mobile Code Execution Service
Mobile code refers to programs that come into a host computer over the network and start to execute with or without a user's knowledge or consent. Because these programs run in the execution context of the user that downloads them, they can issue any system calls that the user is allowed to make, and thus pose a serious security threat when they are malicious. Although many solutions have been proposed to solve the malicious mobile code problem, none of them are truly effective at striking a good balance between defeating zero-day attacks and minimizing disruption to the execution of legitimate applications. 
 
This paper describes a commercial system called SEES that secures the execution of mobile code that comes into a host computer as an email attachment or as a web document downloaded through an anchor link by running them on a separate guinea pig machine rather than on the user machine. Effectively, it takes an isolation approach to the secure mobile code execution problem. As a result, SEES guarantees that no malicious email attachments or web documents that act on behalf of the user that downloads them, can damage the resources of the user machine, or can leak any confidential information. In particular, even zero-day virus cannot cause any harms. We present the design, implementation and evaluation of SEES on the Windows platform, and contrast it with other existing approaches to the same problem.
15985894
Communication models for algorithm design in networked sensor systems
Towards building a systematic methodology of algorithm design for applications of networked sensor systems, we formally define two link-wise communication models, the collision free model (CFM) and the collision aware model (CAM). While CFM provides ease of programming and analysis for high level application functionality, CAM enables more accurate performance analysis and hence more efficient algorithms through cross-layer optimization, at the cost of increased programming and analysis complexity. We use the example of optimizing a probability based broadcasting scheme under CAM to illustrate algorithm optimization. Our analytical results indicate that the optimal broadcast probability for either maximizing the reachability within a given latency constraint or minimizing the latency for a given reachability constraint decreases rapidly with node density.
6854477
Confining windows inter-process communications for OS-level virtual machine
As OS-level virtualization technology usually imposes little overhead on virtual machine start-up and running, it provides an excellent choice for building intrusion/fault tolerant applications that require redundancy and frequent invocation. When developing Windows OS-level virtual machine, however, people will inevitably face the challenge of confining Windows Inter-Process Communications (IPC). As IPC on Windows platform is more complex than UNIX style OS and most of the programs on Windows are not open-source, it is difficult to discover all of the performed IPCs and confine them. In this paper, we propose three general principles to confine IPC on Windows OS and a novel IPC confinement mechanism based on the principles. With the mechanism, for the first time from the literature, we successfully virtualized RPC System Service (RPCSS) and Internet Information Server (IIS) on Feather-weight Virtual Machine (FVM). Experimental results demonstrate that multiple IIS web server instances can simultaneously run on single Windows OS with much less performance overhead than other popular VM technology, offering a good basis for constructing dependable system.
723568
A Bayesian Network Approach to Ontology Mapping
This paper presents our ongoing effort on developing a principled methodology for automatic ontology mapping based on BayesOWL, a probabilistic framework we developed for modeling uncertainty in semantic web. In this approach, the source and target ontologies are first translated into Bayesian networks (BN); the concept mapping between the two ontologies are treated as evidential reasoning between the two translated BNs. Probabilities needed for constructing conditional probability tables (CPT) during translation and for measuring semantic similarity during mapping are learned using text classification techniques where each concept in an ontology is associated with a set of semantically relevant text documents, which are obtained by ontology guided web mining. The basic ideas of this approach are validated by positive results from computer experiments on two small real-world ontologies.
8755762
FEM Based Numerical Analysis on the Temperature Field in Grind-hardening
The grind-hardening is a new type of surface modification technology, which utilizes the dissipated grinding heat for hardening the surface layer of the workpiece. Currently, most of the researchers studying the grind-hardening have used Design of Experiments approach, by varying grind-hardening processes parameters with a great deal of experiments which has significant degree of uncertainty of the results. In this paper, temporal and spatial temperature distributions of the workpiece are simulated based on the FEM (finite element method). The simulated hardness penetration depth is deduced from the local temperature distribution and the time history of workpiece and its martensitic phase transformation conditions. The numerical simulation results were validated with experimental data. The results of this research indicate that the finite element method can be used in temperature field simulation in the grind-hardening technology. Thus the experiment cost and time in grind-hardening can be reduced by FEM simulation of the grind-hardening temperature field.