Difference between revisions of "Event"
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Revision as of 13:37, 15 January 2021
| Event | |
|---|---|
| Graphical Notation | |
| |
| IsSubClassOf | IsSubClassOf::Process element |
| Successors | hasSuccessor::Function, hasSuccessor::AND Operator |
| Predecessors | hasPredecessor::Function, hasPredecessor::Operator |
| HasIncomingControlFlow | hasIncomingControlFlow::0, hasIncomingControlFlow::1 |
| HasOutgoingControlFlow | hasOutgoingControlFlow::0, hasOutgoingControlFlow::1 |
| HasResource | hasResource::0 |
| HasAttribute | hasAttribute::0, hasAttribute::n |
| Edit the Properties | |
Brief Information
This is an autogenerated section!
You are not able to edit this information by hand, but by edit the Form (and therefore the properties) of this page. Please refer to the Edit the properties link at the bottom of the info box. {{#show: Event | ?Is a | Intro=The Event is a }}. {{#show: Event | ?contains | Intro=It contains }}. {{#show: Event | ?hasSuccessor | Intro=Possible succeeding element(s) is/are }}. {{#show: Event | ?hasPredecessor | Intro=Previous element(s) can be }}. {{#show: Event | ?hasIncomingControlFlow | Intro=The cardinalities are | Outro= (incoming)}} {{#show: Event | ?hasOutgoingControlFlow | Intro=and | Outro= (outgoing) respectively }}. {{#show: Event | ?refersTo | Intro=The Event refers to }}. {{#show: Event | ?attachedTo | Intro=The Event is attached to a }}.
Syntax
The EPC Syntax requires an event either to be preceded by an operator or a function. In contrast, an event may be followed by a function or an AND Operator. An event is linked to its predecessor and successor via a control flow arc. The control flow arc cannot connect two events directly.[1], [2], [3] An event with no incoming arc is called “start event”, while an event with no outgoing arc is called “end event”.[4] The requirements of a well-formed EPC-model demand it to contain at least one start-event and one end-event.[3]
Semantic
In contrast to the function element, the event is a passive element since it represents a change of state but does not cause it. Furthermore it can characterize the conditions and the results of an activity, which in turn triggers the next function.[5], [6], [7], [8], [9], [10] Due to the semantics of events as passive elements, they lack the ability to determine the function(s) that should follow.[11] Therefore an event may be followed by a function or an AND Operator, but not by an OR or XOR Operator.[3] In the literature there is an ongoing debate on state representation in EPCs. [12] Some authors say that the current process state is represented by events[11], while others identify states with control flow arcs[13].
Semantic Representation
An event E is a part of an EPC = (E, F, P,C, l, A ), for which E is defined: An element of E is called event. E ≠ ∅ E is a pairwise disjoint and finite set: E ∩ F= ∅, E ∩ C =∅ 1
An event also is a node N, being part of N = E ∪ F ∪ P ∪ C. [14]
An EPC begins with an amount of start events and ends with an amount of end events. Every other event is called intermediate event. An event is connected to other nodes (•e and e•) by incoming and outgoing arcs. The following subsets are defined:
- Es= {e ∈ E | |•e| = 0 ∧ |e•| = 1} being the set of start events
- Eint = {e ∈ E | |•e| = 1 ∧ |e•| = 1} being the set of intermediate events
- Ee = {e ∈ E | |•e| = 1| ∧ e•| = 0} being the set of end events
- CEF = {c ∈ C | ∗c c ⊆ E ∧ c c* ⊆ (F ∪ P)} as the set of event-function connectors. [15], [16]
- CFE = {c ∈ C | *c ⊆ (F ∪ P) ∧ c* ⊆ E} as a set of function-event (fe)-operators.
- nin = {(x,n) | x ∈ N ∧ (x,n) ∈ A) as a set of incoming control flow edges.
- nout = {(n,y) | y ∈ N ∧ (n,y) ∈ A) as a set of outcoming control flow edges.
Following requirements are made on events so an EPC can be called relaxed syntactically correct:
- ∀ n ∈ N : ∃e1 ∈ Es, e2 ∈ Ee such that e1 → n → ee the EPC is a direct and coherent graph →
Functions and events (maybe linked by connectors) should alternate along the control flow
- |Es ∪ Ps| ≥ 1 ∧ |Ee ∪ Pe| ≥ 1. There is at least one start node and one end node in an EPC
- ∀ e ∈ E : |•e| ≤ 1 ∧ |e•| ≤ 1 Events have at most one incoming and one outgoing arc
This implies that Es, Eint, and Ee partition E
- ∀ e ∈ E : •e ⊆ (F ∪ P ∪ CFE) (F ∪ P ∪ CEF )
Events must have function, process interface, or fe-connector nodes in the preset and function, process interface, or ef-connector nodes in the postset . ALSO Events must neither have an XOR, nor an OR connector in the postset . If •es ≠ ∅ (source node) and •ee ≠ ∅ (sink node) and every node n ∈ N is on a path from estart to efinal, a EPC is called regular. [17]
Linguistic Correctness
To satisfy the demands of pragmatic correctness every label of the model elements should follow a specified naming convention. In an EPC events are representing the change of a process state, so the linguistic correctness requires the label to be created from a substantive and a verb in the past participle form. The following table shows examples for one EPC modelled in German and one modelled in English.[3]
| Language | Rule | Example |
|---|---|---|
| English | Substantive(s) + Verb in Past Participle | "Order processed" |
| German | Substantive(s) + Verb in Past Participle | "Bestellung bearbeitet" |
To improve the ease of understanding the name of an event should reflect its characteristic as a point in time. Events should be named in a way that each event is produced by the preceding activity and that the same event triggers the execution of the next activity.[5]