Design and Verification of Design and Verification of Information Systems (DVIS) Information Systems (DVIS) lectures 3-4 lectures 3-4

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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

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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

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Five Perspectives on WFMS, Five Perspectives on WFMS,

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

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Five Perspectives on WFMS, Five Perspectives on WFMS,

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

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Five Perspectives on WFMS, Five Perspectives on WFMS,

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

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Reference Nets - “nets in nets Reference Nets - “nets in nets

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

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Reference Nets - “nets in nets Reference Nets - “nets in nets

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

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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.

 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.

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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 in all five perspectives on WFMS are modeled in terms of reference nets

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

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Introduction to Reference Nets Introduction to Reference Nets

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