Design and Verification of

Design and Verification of

Information Systems (DVIS)

Information Systems (DVIS)

lectures 3-4

lectures 3-4



Two problems with current WFMS

Two problems with current WFMS



Five perspectives on WFMS

Five perspectives on WFMS



Reference nets - nets with reference semantics

Reference nets - nets with reference semantics



Introduction to Renew

Introduction to Renew



Enacting Inter-organizational Workflows Using

Enacting Inter-organizational Workflows Using

Nets in Nets

Nets in Nets

Five Perspectives on WFMS

Five Perspectives on WFMS



1. The

1. The

control flow

control flow

(routing)

(routing)

perspective

perspective



2. The

2. The

resource

resource

(organization)

(organization)

perspective

perspective



3. The

3. The

data

data

(information) perspective

(information) perspective



4. The

4. The

task

task

(function) perspective

(function) perspective



5. The

5. The

operation

operation

(application)

(application)

perspective

perspective

Five Perspectives on WFMS,

Five Perspectives on WFMS,

ctnd.

ctnd.



WFMS should support the five perspectives

WFMS should support the five perspectives



the build-time part

the build-time part

of the WFMS allows for the

of the WFMS allows for the

specification of five perspectives

specification of five perspectives



the run-time part

the run-time part

of WFMS takes care of the

of WFMS takes care of the

actual enactment

actual enactment



the fact that the control flow perspective

the fact that the control flow perspective

dominates all other perspectives restricts the

dominates all other perspectives restricts the

reuse of parts of the workflow definition and

reuse of parts of the workflow definition and

limits the extensibility of the WFMS with

limits the extensibility of the WFMS with

additional perspectives

additional perspectives

Five Perspectives on WFMS,

Five Perspectives on WFMS,

ctnd.

ctnd.



Since all perspectives are intertwined, it is

Since all perspectives are intertwined, it is

impossible to exchange cases, resources, data,

impossible to exchange cases, resources, data,

tasks, or operations between workflow enactment

tasks, or operations between workflow enactment

services in different organizations

services in different organizations



E-commerce

E-commerce

- exchange information between

- exchange information between

business partners and suppliers and inside of

business partners and suppliers and inside of

companies

companies



Inter-OWS

Inter-OWS

- workflows crossing boundaries

- workflows crossing boundaries

between corporations in an E-commerce setting

between corporations in an E-commerce setting



Intra-OWS

Intra-OWS

- workflows involving multiple business

- workflows involving multiple business

units within one corporation

units within one corporation

Five Perspectives on WFMS,

Five Perspectives on WFMS,

ctnd.

ctnd.



Commercial WFMS use a centralized

Commercial WFMS use a centralized

enactment service both the build-time

enactment service both the build-time

and run-time - problems with IOWS

and run-time - problems with IOWS

Reference Nets - “nets in nets

Reference Nets - “nets in nets

paradigm”

paradigm”



Definition of Reference Nets

Definition of Reference Nets

- Petri Nets where

- Petri Nets where

the tokens can be references to other Petri nets

the tokens can be references to other Petri nets



Reference Nets

Reference Nets

are used for specifying and

are used for specifying and

enacting IOWF; they model mobility of a

enacting IOWF; they model mobility of a

business object like a workflow instance, a

business object like a workflow instance, a

resource, a data element, a task, or an operation

resource, a data element, a task, or an operation



object-nets

object-nets

- token of system net correspond to

- token of system net correspond to

marked PNs on a lower level, called object-nets

marked PNs on a lower level, called object-nets



since object-nets actually reside in the system-

since object-nets actually reside in the system-

net, we call this

net, we call this

the value semantics approach

the value semantics approach

Reference Nets - “nets in nets

Reference Nets - “nets in nets

paradigm”

paradigm”



Reference nets use a different approach

Reference nets use a different approach

- the object-nets do not actually reside

- the object-nets do not actually reside

in the system net, but tokens are

in the system net, but tokens are

references to object-nets; this means

references to object-nets; this means

that multiple tokens can reference the

that multiple tokens can reference the

same object-net - this is called

same object-net - this is called

reference semantics

reference semantics

Two Problems with Current

Two Problems with Current

WFMS

WFMS



1. Unclear

1. Unclear

mixture of perspectives

mixture of perspectives

in

in

the current generation of WFMS making

the current generation of WFMS making

workflow specifications incomplete and

workflow specifications incomplete and

difficult to interpret.

difficult to interpret.



2. Absence of tools to describe and

2. Absence of tools to describe and

enact the

enact the

mobility of business

mobility of business

objects

objects

required for IOWF.

required for IOWF.

Introduction to Reference Nets

Introduction to Reference Nets

and Renew

and Renew



Renew

Renew

- The

- The

Re

Re

ference

ference

Ne

Ne

t

t

W

W

orkshop

orkshop



Renew

Renew

- the only tool supporting execution of

- the only tool supporting execution of

any kind of nets in nets, and it uses reference

any kind of nets in nets, and it uses reference

semantics

semantics



all five perspectives on WFMS are modeled

all five perspectives on WFMS are modeled

in terms of reference nets

in terms of reference nets



an instance of each perspective corresponds

an instance of each perspective corresponds

to one marked object-net

to one marked object-net



the system-net joins all perspectives and can

the system-net joins all perspectives and can

be seen as the enactment service of WFMS

be seen as the enactment service of WFMS

Introduction to Reference Nets

Introduction to Reference Nets

and Renew, ctnd.

and Renew, ctnd.



Since every aspect is modeled in a separate

Since every aspect is modeled in a separate

object-net, it is not necessary to intertwine

object-net, it is not necessary to intertwine

all aspects

all aspects



the

the

system-net is generic

system-net is generic

, i.e.,

, i.e.,

independent of actual workflows and

independent of actual workflows and

organization

organization



one can think of the

one can think of the

system-net as an

system-net as an

architectural model

architectural model

and the object-nets as

and the object-nets as

the actual content - the workflow designer

the actual content - the workflow designer

only creates object-nets

only creates object-nets