An Event-driven Process Execution Model for Process Virtual
Machine Dongyao Wu, Jun Wei, Chushu Gao, Wensheng Dou Slide 2
Outline Background Motivation Introduction to Process Virtual
Machine Why Event-driven Event-driven Process Execution Model
Implementation of PVM Evaluation Slide 3 Background Various BPM
Language Slide 4 Background During these years, a number of process
modeling/description languages (such as XPDL[1], BPMN[2], XLANG[3],
WSFL[4], WS-BPEL[5], WS-CDL[6],SEAM[7]) have appeared in order to
describe processes in different domains. Requirement for process
enactment(simulation and execution) Process Engine Slide 5
Background workflow and orchestration engines: Oracle BPEL Process
Manager (Enterprise BPEL Enigine) Bonita (which are XPDL engines
hosted by Red Hat and OW2 respectively), Orchestra(The BPEL engine
from Bull hosted at OW2) ActiveVoS, Apache ODE, JBPM-BPEL (which
are open source orchestration engines supporting WS-BPEL).etc. Most
of these engines only serve with dedicated process language. Slide
6 Motivation Requirement for adaptive BPM engine. Process Virtual
Machine PVM Slide 7 Introduction to PVM Concept diagram of a PVM
Process Virtual Machine BPEL process BPEL Builder Join Action Task
Action line Action Other Process Builder Runtime Execution Elements
Fork Action XPDL/ SEAM/ any other process Scheduling Fork Action
line Action Task Action Join Action Slide 8 Contribution we try to
address the problem above by developing a process virtual machine
PVM using an Event-driven Process Execution Model Why Event-Driven?
Slide 9 Comparison between Events-driven and Thread-based Paradigms
MetricsEvent-drivenThread-based Process Proceedingreactiveactive
Cost of Synchronizationlowhigh Cost of State managementlowhigh
Locality and debuggingeasyhard Stability under pressurestableless
stable Flexibilityflexibleless flexible Portabilitylight
weightheavy weight True concurrency (OS)falsetrue Long running
handlingnon-responsivesupport Local state maintainhardeasy System
architecturecomplexsimple Why Event-Driven Slide 10 Event-driven
Process Execution Model Process Description Model Slide 11
Event-driven Process Execution Model Slide 12 Syntax for Describing
a Process in EPEM process ::= action* process*event* action ::=
context? task_logic port+ task_logic::= connector | behavior
connector::= checkCondition behavior::= doTask port:= input_port |
output_port input_port ::= listenTo event output_port ::= produce
event event:= start_event | complete_event | external_event |
exception_event Slide 13 Formalization of EPEM Definition of EPEM
EPEM (p)= Where = {e(x), e(y), e(z)} A= {a} T= {, } a A, e(u) E =
E(P). Slide 14 Formalization of EPEM Definition of Behavior For
behavior a, EPEM (a) = where = {e(i[a]), e(o[a]) } A= {a} T={, } E=
E(a) ::= e?(i[a]).a.e!(o[a]) Slide 15 Formalization of EPEM
Definition of Connector EPEM (c) = Where = in out in = {e(i 1 ),e(i
2 ),..e(i n ) } out = {e(o 1 ),e(o 2 ),..e(o n ) } A= { c }
T={,...,,... } E= E(c)
