In recent years, due to the complexity of workflow processes and the fluctuation of business environments, the timed security requirements of workflow processes have attracted more and more attentions from the designers and users of workflow processes. The existing methods cannot analyze the security requirements of data-aware workflow processes with dynamic changes. In this paper, we propose a novel analysis approach to verify timed security requirements for data-aware workflow processes with dynamic changes. First, we analyze the feasibility of changes on workflow processes. Second, we propose the analysis procedure to automatically determine the affected segments of changes. Third, the timed security requirements affected by changes are obtained and verified without repeatedly analyzing all of them. Compared with the existing works, our approach can detect incorrect changes in advance so as to avoid meaningless analysis, also can reduce the cost and time of enterprises as well as eliminate repeated verification of all timed security requirements.

In the field of workflow management, a recent hot research point is to analyze secure collaboration plans of multiple workflow processes with dynamic relations and shared users. However, existing research works neither consider the time limits of timed dynamic relations (TDRs), nor analyze the delayed time of activities caused by shared users. In this article, we propose a new approach to analyzing secure collaboration plans of multiple workflow processes withTDRs and user conflicts: 1) we propose the computing patterns for basic structures in workflow processes withTDRs and shared users; 2) we develop the next-generation parametric sprouting graph (NPSG) based on the above patterns; and 3) we obtain the optimal secure collaboration plan based on NPSG. Compared with the existing methods, our approach can effectively deal with the problem of collaboration plans withTDRs and shared users. Furthermore, our approach is more efficient, because NPSG of multiple workflow processes can be constructed in parallel and its recommendation ability is improved by deleting invalid paths in advance.

Currently, recommending collaboration plans of dynamic multiple workflow processes under security requirements or constraints has become a hot topic, as it not only can reduce the risk during execution, but also can avoid enormous financial loss caused by security breaches. However, the existing methods cannot solve the parametric problem caused by dynamic relations of multiple workflow processes or recommend an optimal collaboration plan because of erroneous information. In this article, we propose a new approach to recommend security-aware collaboration plans for multiple workflow processes with dynamic relations. First, we develop three basic computing patterns of dynamic relations and construct a parametric sprouting graph for multiple workflow processes with dynamic relations. Second, we present the procedure of recommending an optimal secure collaboration plan that satisfy security requirements. By comparison with the existing methods via two experiments, our approach not only can solve the parametric problem caused by dynamic relations of multiple workflow processes, but also can recommend an optimal secure collaboration plan under security requirements.

It is very important to obtain assignment plans of roles and users for business processes or workflow processes under security requirements in enterprises. The assignment plans can help the enterprises improve the efficiency of execution as well as reduce their costs. However, the existing methods ignore the dynamics of users and roles, and cannot deal with security requirements. In this article, we propose a new approach to solve the problem of dynamic assignment of roles and users for business processes under security requirements. First, a role and user assignment graph (RUAG) based on Petri nets is constructed to record detailed information about assignment plans. Second, the optimal composition of assignment plans meeting security requirements is extracted from RUAG for multiple concurrent business processes. Third, we analyze the changes of assignment plans during execution of business processes and present the procedure to adjust them. Compared with the existing methods, our approach can improve the accuracy of assignment plans, enhance the efficiency of dynamic assignment, and reduce the costs of enterprises.

Much attention is being paid to security requirements of workflow processes with authorization policies, e.g., safety properties, liveness properties, separation of duties, binding of duties, and constraints of cardinality. However, existing methods neglect the execution condition of activities and the logical structures among activities along with their time attributes, suffer from low efficiency when checking the security requirements of large-scale and structurally complex workflow processes, and provide no solutions as a response to the violations of various security requirements. Thus, existing methods cannot guarantee the absolute security and smooth execution of such workflow processes. In this article, we propose a security team timed automaton (STTA) based approach to analyzing security requirements in timed workflow processes. First, we construct STTAs for timed workflow processes with authorization policies. Second, security requirements are automatically verified based on STTAs. Third, based on two effective strategies, we provide solutions to violated security requirements, if any. Compared with the existing methods, our approach can not only formally describe and analyze five commonly-viewed and frequently-adopted security requirements for timed workflow processes and dramatically decrease their temporal and spatial complexity for verification, but also provide solutions to the violations of security requirements so as to implement the security management of workflow processes.

Self-adaptive execution of workflow processes by dynamically and autonomously updating their decisions is especially important for improving the quality of business management. However, the existing methods neglect the impacts of data relationships and temporal constraints on modeling and execution of workflow processes. In this article, based on sprouting graph we propose a new approach for self-adaptive decision-making for dynamic execution of data-aware workflow processes. First, a data-oriented sprouting graph is developed for retrieving information on data-aware workflow processes, so as to eliminate incorrect paths and handle waiting situations. Second, decision point setting and self-adaptive decision strategies are investigated for solving two fundamental decision problems: waiting for information and selecting one among several paths. Third, the whole procedure of automatic implementation is proposed for self-adaptive execution of data-aware workflow processes. Compared with the existing methods, our approach can improve the efficiency of analysis by reducing the model size and can significantly minimize the overall operational cost of the workflow processes.

Nowadays, workflow process changes frequently in a fast-changing business environment. When updating a workflow process via some structural changes, one of the most important tasks is to maintain its consistency under temporal constraints. Several approaches have been developed to cope with this issue. However, they are either inaccurate in locating changed parts or inefficient in analyzing temporal constraints owing to their excessive or erroneous estimation of affected portions for the updated workflow processes. Based on a sprouting graph (a graph that records the structure and time information of all paths in a workflow process in advance), this paper proposes a novel approach to analyzing temporal constraints for workflow processes with dynamic changes. First, changed parts are located via affected collaboration execution paths in the new model, i.e., the workflow process after changes. Second, instead of updating all the elements, only necessary (changed) nodes corresponding to the changed parts are updated in the sprouting graph of the original model, i.e., the workflow process before changes. Finally, based on the updated sprouting graph, only affected temporal constraints (the temporal constraints whose partial or all paths are contained in the affected collaboration execution paths) are checked. Compared with the existing works, our approach is applicable and efficient to check temporal constraints for large-scale and complex workflow processes thanks to its much lower time and space complexity.

In enterprises, timed compatibility (i. e., temporal constraint satisfiability) have become an important factor to guarantee the timely completion of service composition so that meet the requirements of customers and ensure the success execution of enterprises. However, existing researches do not fully investigate the mixture situations where distributions of service durations are complex and diverse, and consider both the uncertainty of queue time and operation time of services. In this paper, we propose a new approach to modeling and analyzing timed compatibility of service composition where time durations are mixture distributed. First, we calculate the duration of activities in service with considering both the queue time and operation time. Second, we obtain the time information of interactive activities in service. Finally, we get the time information of paths in services and check the temporal constraints. Furthermore, a real-life case is used to illustrate the efficiency and effectiveness of our approach.

Recently, the mediation-aided approach is attracting more attention in Web service composition, in the meanwhile, temporal constraints are regarded as an important aspect to ensure the correctness and QoS in service compositions. This combination leads to a new challenge in analyzing the timed compatibility of mediation-aided service composition. Unfortunately, existing model checking based approaches are lack of the ability of transform mediation-aided service composition to Time Automata (TA) models, and suffer from state space explosion for large-scale and complex compositions. In this paper, we present a new model checking approach to analyzing timed compatibility. Firstly, mediation-aided service composition is automatically decomposed into fragments. Secondly, each fragment is transformed into a TA. Finally, the temporal constraints are checked by the queries of observing TAs. Compared with existing approaches, our approach is able to check timed compatibility of mediation-aided service composition, and is more efficient than them.

Recently, the temporal constraint satisfiability is regarded as an important criterion in Web service composition to guarantee its timely completion. This leads to a new challenge in analyzing the compatibility of Web services under temporal constraints. The existing methods either do not consider message mismatches between services in a composition or suffer from state-space explosion by verifying a service composition model as a whole; or lack the ability to generate execution paths of each participating service. In this paper, we present a Petri net-based method to address these three issues in a holistic manner, and also in a modular way. Compared with the existing work, the proposed approach not only composes Web services by adding a mediation net to deal with message mismatches, but also checks the compatibility w.r.t. temporal constraints by generating modular timed state graphs. Furthermore, the reliable and usable execution paths that satisfy the timed compatibility can be derived to guide service execution and avoid any temporal exception.

In order to guarantee the successful execution of temporal-aware service processes in cloud computing, one important requirement is to effectively and efficiently select the appropriate services for service processes. The existing methods don't consider the dynamic prices of candidate services, or lack the efficient and practical selecting ability when encountering complex and large scale candidate services. In this paper, we propose a new approach to selecting services for temporal-aware service processes with dynamic prices. First of all, the initial execution paths of service processes are obtained by local optimization policy. Then, we judge whether temporal violations occur on these execution paths. If there are some temporal violations, the problem of violation correction is automatically transformed to nonlinear programming model which can be solved efficiently. Finally, the optimal execution paths for service processes are obtained. The advantages of our approach are validated by a practical example.

Recently, mediation-aided composition has been widely adopted when dealing with incompatibilities of services. However, existing approaches suffer from state space explosion in compatibility verification and cannot automatically generate the BPEL code. This paper presents a Petri net approach to mediation-aided composition of Web services. First, services are modeled as open WorkFlow Nets (oWFNs) and are composed using mediation transitions (MTs). Second, the modular reachability graph (MRG) of composition is automatically constructed and the compatibility is analyzed, so that the problem of state space explosion is significantly alleviated. Furthermore, an Event-Condition-Action (ECA) rule-based technique is developed to automatically generate the BPEL code of the composition, which can significantly save the time and labor of designers. Finally, the prototype system has been developed.

Current methods that deal with concurrent workflow temporal violations only focus on checking whether there are any temporal violations. They are not able to point out the path where the temporal violation happens and thus cannot provide specific solutions. This paper presents an approach based on a sprouting graph to find out the temporal violation paths in concurrent workflow processes as well as possible solutions to resolve the temporal violations. First, we model concurrent workflow processes with time workflow net and a sprouting graph. Second, we update the sprouting graph at the checking point. Finally, we find out the temporal violation paths and provide solutions. We apply the approach in a real business scenario to illustrate its advantages: 1) It can dynamically check temporal constraints of multiple concurrent workflow processes with resource constraints; 2) it can give the path information in the workflow processes where the temporal violation happens; and 3) it can provide solution to the temporal violation based on the analysis.