Leymann, F., Roller, D.: Production Workflow - Concepts and Techniques. Prentice Hall (2000)  Home/Search   Document Not in Database   Summary   Related Articles   Check

....Access control security mechanisms need to ensure that task dependencies are coordinated and that tasks are performed by authorized subjects only. The maintenance of object integrity is important, in particular, semantic integrity, which concerns the consistency of information with business rules [LR00]. When considering access control in workflows, three important issues need to be addressed, namely, separation of duty, strict least privilege, and order of events. Addressing these issues is referred to as 4 context sensitive access control because each emerges upon the initiation of a specific ....

....access control in workflows, three important issues need to be addressed, namely, separation of duty, strict least privilege, and order of events. Addressing these issues is referred to as 4 context sensitive access control because each emerges upon the initiation of a specific process [LR00]. An effective workflow authorization model should address the following issues. Separation of duties constraints that reflect the business rules of the organization, should be enforced. This concept ensures that the semantic integrity of information is sustained through the prevention of fraud, ....

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F. Leyman and D. Roller. (2000). Production Workflow: Concepts and Techniques. Prentice-Hall.

....that this requirement does not imply that there is one to one correspondence between splits and joins (like for eProcess) Nevertheless this requirement is sufficient for implementing the synchronizing merge using a local rule. MQSeries workflow uses a technique called dead path elimination [LR99, IBM99] Initially, each input arc is in state unevaluated . As long as one of the input arcs is in this state, the activity is not enabled. The state of an input arc is changed to true the moment the preceding activity is executed. However, to avoid deadlocks, the input arc is set to false the ....

F. Leymann and D. Roller. Production Workflow: Concepts and Techniques. PrenticeHall PTR, 1999.

....loop in a process definition should have a single entry and a single exit, as the iteration statements in programming languages. Allowing multiple entries exits makes the complex control flow hard to understand, and induces ambiguities in the evaluation of exit conditions. Leymann F. et al. [14] also claims that race conditions may occur in arbitrary loops. Thus, this work prescribes that a loop must be single entry and single exit. A graphical representation of a process resembles a directed graph [5] in which each node is an activity and each directed edge is a dependency. This work ....

F. Leymann and D. Roller, Production Workflow: Concepts and Techniques. Prentice-Hill, 2000.

....either totally executed or skipped. One could argue that the payment atomicity sphere can actually not be considered to be a traditional sphere as it violates the structural condition that all control connectors that are entering the membrane of the sphere should originate from the same task [leymann2000] However, as we did not want to violate the inherent symmetry of a business transaction, and the contract sphere could enforce deadlines, we decided to carefully allow multiple originators within this specific context. Inspired by Leymann s definition [leymann2000] of atomic spheres, we now ....

....originate from the same task [leymann2000] However, as we did not want to violate the inherent symmetry of a business transaction, and the contract sphere could enforce deadlines, we decided to carefully allow multiple originators within this specific context. Inspired by Leymann s definition [leymann2000] of atomic spheres, we now formally specify the relaxed notion of atomicity spheres in the context of web services: Definition 1 (Atomic Spheres) Let G be an (a)cyclic web service orchestration graph, and T the set of tasks that are connected with a set of connectors Conn. Generally speaking, ....

Leymann, F. and Roller, D., "Production Workflow: Concepts and Techniques", Prentice-Hall, N.J., 2000

....a standard language for workflow modelling [2, 55, 58, 132] Petri nets are graphical. With Petri nets, business activities and the ordering between business activities can be specified. This aspect of workflows is called the control flow dimension or process dimension of workflows in literature [2, 118]. Petri nets o#er some support for modelling resources as well (the resource dimension of workflows) but they are not widely used for this purpose. Recently, another modelling language has been proposed for describing and defining workflows, namely UML activity diagrams [150, 59, 71] The Unified ....

....2.4 focuses on the class of software systems that workflow management systems belong to, the class of reactive systems. Finally, Section 2.5 discusses various possible interpretations of a workflow specification. The first three sections of this chapter are based on literature (among others [2, 31, 76, 81, 82, 103, 118, 135, 159, 161]) and several case studies that we did. 2.1 Workflows The following concepts are important for workflow modelling (see Figure 2.1) A business process is an ordered set of business activities. The goal of a business process is to deliver a certain requested service or product. For example, if ....

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F. Leymann and D. Roller. Production Workflow -- Concepts and Techniques. Prentice Hall, 2000.

....items are claim forms and damage reports. The definition, creation, and management of workflow instances is done by a workflow management system (WFMS) on the basis of workflow models. In general, two important dimensions of workflows are the process logic dimension and the resource dimension [2, 20]. The process logic dimension concerns the ordering of tasks (or activities) in time (what has to be done) The resource dimension concerns the organisational structure (who has to do it) In this report, we focus on modelling the process logic dimension of workflows. When we use the term ....

....modelling. We end with a discussion and conclusions. Formulas are written in the Z notation [26] 2 2 Workflow Concepts Workflow modelling. In the previous section, we already explained some concepts of workflows. We elaborate on this. The following exposition is based on literature (a.o. [2, 20]) and several case studies that we did. Activities are done by actors. An activity is an uninterruptible amount of work that is performed in a non zero span of time by an actor. In an activity, case attributes are updated. Case attributes are work items and other data relevant for the case. ....

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F. Leymann and D. Roller. Production Workflow --- Concepts and Techniques. Prentice Hall, 2000.

....and the design choices that underlie these semantics. In Section 4 we look at workflow modelling with Petri nets. In Section 5 we discuss issues in defining an execution semantics for workflow systems. We end with conclusions. 2 Workflow The following exposition is based on literature (a.o. [1, 15]) and several case studies that we did. A workflow is a set of business activities that are ordered according to a set of procedural rules to deliver a service. A workflow model (a.k.a. workflow specification) is the definition of a workflow. An instance of a workflow is called a case. In a case, ....

....a work item is the claim form of John Smith. The definition, creation, and management of workflow instances is done by a workflow management system (WFMS) on the basis of workflow models. In general, two important dimensions of workflows are the process logic dimension and the resource dimension [1, 15]. The process logic dimension concerns the ordering of activities (or tasks) in time (what has to be done) The resource dimension concerns the organisational structure (who has to do it) Since both Petri nets and UML activity diagrams only model the process logic dimension, we here focus on ....

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F. Leymann and D. Roller. Production Workflow --- Concepts and Techniques. Prentice Hall, 2000.

....two formal semantics. In Sect. 5 we briefly discuss other formalisations of activity diagrams. We end with a summary and a discussion of further work. Formulas are written in the Z notation [17] 2 Workflow Domain Workflow concepts. The following exposition is based on literature (amongst others [1, 14]) and several case studies that we did. Activities are done by actors. Actors are people or machines. An activity is an uninterruptible amount of work that is performed in a non zero span of time by an actor. In an activity, case attributes are updated. Case attributes are data relevant for the ....

....to other state nodes by object flows (dashed edges) There are several ambiguities concerning object flow states, the most important one being that the meaning of parallel object flow states is not defined. Besides, only one vendor of workflow management systems supports object flow states [14]. For the moment, we decide to omit object flow states (and thus object flows) from our syntax. Instead, we represent the case attributes by the local variables of the activity diagram and assume these attributes are stored in a database. Dynamic concurrency (i.e. dynamic instantiation of ....

F. Leymann and D. Roller. Production Workflow --- Concepts and Techniques. Prentice Hall, 2000.

....distributed part has a local state. Multiple instances of the same local state can be active at the same time. The (global) state of a case is therefore a bag, rather than a set, of local states. Architecture. Our semantics is motivated by the following architecture of workflow systems (Fig. 2) [8, 11, 15]. It also resembles the architecture of UML state machines [14, p.2 149] A WFS consists of two components, an event manager and a router, that act in parallel. These two components communicate with each other by means of a queue. The event manager receives events and puts them in the queue. The ....

F. Leymann and D. Roller. Production Workflow: Concepts and Techniques. Prentice Hall, 2000.

....that constitute a single business process, the individual activities are not necessarily independent of each other, but may form a unit of work. The terms transactional workflow and business transaction are commonly used to refer to such business processes that have an all or nothing semantics (Leymann Roller, 2000). Business transactions are, however, different from system level transactions as known from database systems, and as supported by middleware services like the CORBA Object Transaction Service (OTS) Business transactions must reflect the potentially long duration of business processes and must ....

....automatically be undone but instead require some compensation mechanism. While many concepts to support business transactions have been explored (such as the constructs of atomic spheres and compensation spheres to specify collections of activities as a unit of work and for backward recovery (Leymann Roller, 2000)) only very few of the commercially available workflow management systems today support business transactions. This is partly due to the general difficulty of combining workflows and transactions, and to the limited availability of appropriate (system level or higher level) transaction services ....

F. Leymann, D. Roller. Production Workflow: Concepts and Techniques. Prentice-Hall, 2000.

....enterprise wide or even crossorganizational, business applications. Typical examples are insurance claim processing, cargo shipping, or healt care tracking and planning, and workflow technology is also embedded in many e commerce services. Following the terminology of WfMC [32] see also [5, 6, 8, 15, 18]) a workflow is a set of activities that belong together in order to achieve a certain business goal. Activities can be completely automated or based on interaction with a human user and intellectual decision making. In particular, an activity can spawn requests to an arbitrary invoked ....

F. Leymann, D. Roller, Production Workflow: Concepts and Techniques, Prentice Hall, 1999

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F. Leymann, D. Roller. "Production Workflow - Concepts and Techniques". PTR Prentice Hall, 2000.

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Leymann, F., Roller, D.: Production Workflow - Concepts and Techniques. Prentice Hall (2000)

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Frank Leymann and Dieter Roller. Production Workflow -- Concepts and Techniques. Prentice Hall, 1999.

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F. Leymann and D. Roller. Production Workflow -- Concepts and Techniques. Prentice Hall, 1999.

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Leymann, F. & Roller, D. (2000), Production Workflow --- Concepts and Techniques, Prentice Hall.

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F. Leymann and D. Roller: "Production Workflow : Concepts and Techniques". Prentice Hall, 2000.

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F. Leymann and D. Roller. Production Workflow --- Concepts and Techniques. Prentice Hall, 2000.

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F. Leymann, D. Roller, Production Workflow: Concepts and Techniques , Prentice Hall, 1999. 6

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F. Leymann, D. Roller, and A. Reuter. Production Workflow: Concepts and Techniques. Prentice Hall, 1999.

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F. Leymann, D. Roller. Production Workflow: Concepts and Techniques. Prentice-Hall, 2000.

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Leymann, F., & Roller, D. (2000). Production workflow concepts and techniques. Upper Saddle River, N.J USA: Prentice Hall PTR.

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Leymann, F., Roller, D.: Production Workflow: Concepts and Techniques. Prentice Hall 1999

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F. Leymann, D. Roller, Production Workflow: Concepts and Techniques, Prentice Hall, 1999

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F. Leymann, D. Roller, Production Workflow: Concepts and Techniques, Prentice Hall, 1999

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