Semantics and analysis of business process models in bpmn pdf
File Name: semantics and analysis of business process models in bpmn .zip
- How do humans inspect BPMN models: an exploratory study
- BPMN 2.0 Execution Semantics Formalized as Graph Rewrite Rules
- A Process Semantics for BPMN
He is the author of over publications, from the domains of formal methods, software engineering and knowledge engineering. His fields of interest also include theory of concurrency, systems security and functional programming. He is the leader of the Alvis Project.
How do humans inspect BPMN models: an exploratory study
BPMN models have no formal semantics to conduct qualitative analysis validation and verification. The use of our approach allow to business analysts and designers to perform evaluation i. The application of the approach is aimed to evaluate the behavior of the BP—task model with respect to business performance indicators for instance, service time, waiting time or queue size derived from business needs, as is shown in an instance of an enterprise—project related to Customer Relationship Management.
Received , Revised , Accepted 1 Introduction. Model Checking MC is a formal verification technique that enables exhaustive and automatic checking of whether or not a model meets a given specification [ 1 ]. To apply the MC technique, the BPs need to be described in a formal language. The temporal perspective is a contributing factor to both the design—time and the run—time of a BP. At BP design—time, the temporal perspective allows the modeler to explicitly specify temporal constraints and dependencies to ensure that all temporal requirements of the process are met.
At run—time, the temporal perspective of the BP specification leads to the ability to precisely schedule a BP. The idea of obtaining directly an executable model i. In particular, the formal verification approach explained in [ 6 ] focus on the perspective of temporal and concurrency constraints on BPs, allowing the correctness of BP—task models through the MC technique to support the analysis of the satisfaction of business temporal constraints and dependencies.
In this paper, is proposed an approach based on the MC techniques for the formal verification of BPs based on the construction of a BP—task model as a TA—network i. In this way, the behavioral aspects and temporal constraints in a BP—task model are simulated and verified i. Next, the instantiation of the formal verification approach introduced in [ 7 ] is applied to verify the corresponding BP—task model. As a result, BP designers can verify BPs efficiently through the following steps: 1 description of BPs and their constraints with a formal temporal logic, 2 systematic transformation into TA systematically with the transformation guidelines, and 3 running of the U ppaal model checker with the BP—task model and properties to be verified.
With the verification results, the business analysts and designers can perform improvements to BPs and adjustment of their constraints i. This helps to eliminate serious problems related to temporal and concurrency constraints in the early phases of development and to assure the quality of BPs models.
Since our approach is aimed at representing BP—task model concurrent aspects, the contribution is more focused on verification of consistency and synchronization of concurrent tasks which exist in BP—task model than in other BPs oriented validations. According to our approach, the verification of structured BP—task model can be carried out with correctness by only starting from the verification of the simplest TAs. As final remark, our proposal can be adapted to other BP languages and standards which allow the transformation of the properties to verify and the modelling elements of BP—task model into formal language constructs supported by MC tools.
Section 2 presents the related work. Section 4 explains the BP—task model verification approach. Section 6 shown an application example related to the CRM business, while the concluding remarks are made in Section 7. Reviewing the literature, we found few works to allow us to establish the state of the art in specifying and verifying the temporal perspective in BPs using BPMN. In [ 3 ] is presented a extend survey of existing proposal verification techniques of BPMN diagrams and compare them among each other with respect to motivations, methods, and logics.
Nevertheless, none of cited works take into account the temporal perspective of the behavior of a BP. For the purposes of this paper, it is worth mentioning the work in [ 5 ] , due to that it is an extension of BPMN, called Time—BPMN , with a large set of required temporalities.
This work presents a classification of flexible and inflexible temporal constraints and temporal dependencies. This extensions does not permit to model temporal constraints relating to the duration of the BP activities.
Notwithstanding, Time—BPMN [ 5 ] is limited to the specification phase since no verification mechanism of temporal constraints is provided. The authors extend BPMN to handle temporal, concurrency, and resource constraints. This approach aims at verifying some features, such as deadlocks and bottlenecks; but the scope of this paper is limited to a small subset of BPMN elements.
The extension provided in this work permits to specify temporal constraints related to only one activity within the BP model and does not consider timed properties related to a set of activities, such as inter—activities temporal constraints. Finally, it is worth mentioning the work in [ 11 ] , due to that it incorporates the concept of controllability —capability of executing a workflow for any possible duration of tasks— and its evaluation at design—time; i.
With the work presented here, is incorporated in a practical way the concept of controllability, which allows us to analyze the decisions made at design—time of a BP—task model associated to a specific BP from the behavior of the elements BP—workers specifically that make it up at run—time, as part of a verification approach. The work presented here is aimed at giving a systemic, integrated vision of analysis, design and verification tasks of BPs, by incorporating the use of TA and MC tools in the BP—task model development cycle, to allow us to obtain the expected result: the verification of the complete BP—task model associated to a specific BP.
Following the steps mentioned in the introduction, BP analyst and designers can verify BPs efficiently. In this way, we take full advantage of the strengths that a formalization of the behavioral and temporal aspects of BPMN can offer to the BP analysis both at design—time and run—time, integrating verification software tools.
The Business Process Modeling Notation BPMN provides organisations with the capability of specifying and depicting their BPs using a graphical notation with an emphasis on control—flow. The BPMN Business Process Diagram BPD incorporates constructs adequate to BP modelling, such as events, tasks, gateways and flows , and defines more advanced constructs, such as task looping , parallel multinstances , inclusive OR decission , subprocesses and exception handling.
And hence, a language of this type will include the modelling concepts necessary to describe certain aspects of a BP at a certain abstraction level. An event is something that happens during the course of a process and affects the flow of the process.
The start event indicates where a process will start, and end event indicates where a process will end. An activity is a generic term for work performed in the process; it can be atomic called task or compound. In this work, the term activity refers to an atomic activity or task. A sequence flow is used to show the order in which activities will be performed.
A gateway is used to control the divergence and convergence of sequence flows. Gateways can have several behavior controls and each type of control affects both the incoming and outgoing flow: exclusive , parallel , and inclusive gateways. A Pool typically represents an organization or business entity and a Lane represents a department or BP—worker within that organization, or other modelling entities like functions, applications, and systems.
Both, pools and lanes, represent BP participants. A message flow represents the communication between two asynchronous organizations or business entities; i. An association is used to link information with graphical elements. Text annotations provide additional information for readers of the BPMN diagrams. Consider, for instance, the simple example of a typical choreography model designed in BPMN shown in Figure 2.
The BPD depicts the message flows between two partners, a seller and an auctioning service. The choreography describes the interactions needed for creating an auction. You see message send tasks and intermediate message events that are properly connected through message flow.
Two pools are used. Control flow constructs are available to show the causal dependencies between the different communication actions; thus, the synchronization between both participants is a necessary behavioral property for successful collaboration. Moreover, in order to perform verification of critical properties of BPs, we first need to construct a formal model of the processes that are critical to the conduct of the business.
The BP of interest must be modeled with the adequate formal notation, which is usually determined by the complexity of the communications carried out by the tasks in which the BP is structured. To obtain semantic precision and verifiability of syntactic constructs, in this work is suggests the use of TA theory as a formal description language for BP modelling languages.
According to the TA theory, a timed automaton is a finite directed graph annotated with conditions over and resets of non—negative real valued clocks, and a system is modeled as a collection of finite state machines and a finite set of clocks. In the standard scheme the clocks are synchronized and can be reset by the transition from one state to another.
Clocks are also used to guard transitions. Time is never negative as the clocks can only be resets to 0. Bounded liveness is represented by the requirement that some specific clock can never obtain a value greater than some specified deadline, or cannot do so while a state or collection of states is occupied.
Transitions are defined to be instantaneous and hence it is possible to model behaviors that are not easily implementable. Where there are two or more possible transitions from a state then each is a valid transition. For example, according to the in Figure 3 the transition out of state cannot be taken before time 3. In this example, is a clock; it is resetting when the state is achieve. In a simple model i. A state can also have a temporal invariant to force an exit transition. Figure 3 illustrate this because the state cannot leave before but must leave before.
If for some reason the transition cannot be taken then the automata contains an error condition deadlock. Next are presented the basic definitions for timed automaton and TA—network, which are important for our purposes. Definition 1 Timed Automaton. A timed automaton is a tuple that consists of the following components: is a finite set. The elements of are called the states of. An edge is a transition from state to with action , guard and clock resets. As was introduced previously, the semantics of a timed automaton is defined as a transition system where a state or configuration consists of the current location and the current values of clocks.
There are two types of transitions between states. The automaton may either delay for some time a delay transition , or follow an enabled edge an action transition.
A timed action is a pair , where is an action taken by a timed automaton after time units since has been started. The absolute time is called a time—stamp of the action. A timed trace is a possibly infinite sequence of timed actions where.
To model concurrent systems as the BPs , TA can be extended with parallel composition. In process algebras, various parallel composition operators have been proposed to model different aspects of concurrency —see e. These algebraic operators can be adopted in TA, which allows interleaving of actions as well as hand-shake synchronization. Essentially the parallel composition of a set of timed automaton is the product of the automata, just called TA—network.
Definition 2 TA—network. A TA-network is the parallel composition of a set of timed automata , called processes, combined into a single system by a parallel composition operator with all external actions hidden. Synchronous communication between the processes is by hand—shake synchronization using input and output actions.
The action alphabet is assumed to consist of symbols for input actions denoted , output actions denoted , and internal actions represented by the distinct symbol. TA are designed so that they can be verified by MC. In MC a formal model is checked for correctness against requirements expressed in temporal logic [ 1 ].
Intuitively, MC works by exploring all possible state transition from the initial state of the system. All possible traces from the beginning set of states are explored to see if an unsafe state can be reached or a liveliness condition broken. MC is a technique that requires tool support.
BPMN 2.0 Execution Semantics Formalized as Graph Rewrite Rules
BPMN models have no formal semantics to conduct qualitative analysis validation and verification. The use of our approach allow to business analysts and designers to perform evaluation i. The application of the approach is aimed to evaluate the behavior of the BP—task model with respect to business performance indicators for instance, service time, waiting time or queue size derived from business needs, as is shown in an instance of an enterprise—project related to Customer Relationship Management. Received , Revised , Accepted 1 Introduction. Model Checking MC is a formal verification technique that enables exhaustive and automatic checking of whether or not a model meets a given specification [ 1 ]. To apply the MC technique, the BPs need to be described in a formal language.
Version 2. The latest version is BPMN 2. BPMN has been designed to provide a standard notation readily understandable by all business stakeholders, typically including business analysts, technical developers and business managers. BPMN can therefore be used to support the generally desirable aim of all stakeholders on a project adopting a common language to describe processes, helping to avoid communication gaps that can arise between business process design and implementation. BPMN is one of a number of business process modeling language standards used by modeling tools and processes.
A Process Semantics for BPMN
This paper presents a formalization of a subset of the BPMN 2. The formalization is supported by graph rewrite tools and implemented in one of these tools, called GrGen. The benefit of formalizing the execution semantics by means of graph rewrite rules is that there is a strong relation between the execution semantics rules that are informally specified in the BPMN 2. This makes it easy to validate the formalization.