CIS 581 CIS 581 Design and Verification of Design and Verification of Information Systems (DVIS) Information Systems (DVIS) lectures 3-4lectures 3-4

Two problems with current WFMSTwo problems with current WFMS Five perspectives on WFMSFive perspectives on WFMS Reference nets - nets with reference semanticsReference nets - nets with reference semantics Introduction to RenewIntroduction to Renew Enacting Inter-organizational Workflows Using Enacting Inter-organizational Workflows Using Nets in NetsNets in Nets

Five Perspectives on WFMSFive Perspectives on WFMS

1. The 1. The control flowcontrol flow (routing) (routing) perspectiveperspective

2. The 2. The resourceresource (organization) (organization) perspectiveperspective

3. The 3. The datadata (information) (information) perspectiveperspective

4. The 4. The tasktask (function) perspective (function) perspective 5. The 5. The operation operation (application) (application)

perspectiveperspective

Five Perspectives on WFMS, Five Perspectives on WFMS, ctnd.ctnd.

WFMS should support the five perspectivesWFMS should support the five perspectives the build-time partthe build-time part of the WFMS allows for of the WFMS allows for

the specification of five perspectivesthe specification of five perspectives the run-time partthe run-time part of WFMS takes care of the of WFMS takes care of the

actual enactmentactual 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 perspectivesadditional 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 organizationsservices in different organizations

E-commerceE-commerce - exchange information between - exchange information between business partners and suppliers and inside of business partners and suppliers and inside of companiescompanies

Inter-OWSInter-OWS - workflows crossing boundaries - workflows crossing boundaries between corporations in an E-commerce settingbetween corporations in an E-commerce setting

Intra-OWSIntra-OWS - workflows involving multiple business - workflows involving multiple business units within one corporationunits 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 IOWSand run-time - problems with IOWS

Reference Nets - “nets in nets Reference Nets - “nets in nets paradigm”paradigm”

Definition of Reference NetsDefinition of Reference Nets - Petri Nets where the - Petri Nets where the tokens can be references to other Petri netstokens can be references to other Petri nets

Reference NetsReference Nets are used for specifying and are used for specifying and enacting IOWF; they model mobility of a business enacting IOWF; they model mobility of a business object like a workflow instance, a resource, a data object like a workflow instance, a resource, a data element, a task, or an operationelement, a task, or an operation

object-netsobject-nets - token of system net correspond to - token of system net correspond to marked PNs on a lower level, called object-netsmarked PNs on a lower level, called object-nets

since object-nets actually reside in the system-net, since object-nets actually reside in the system-net, we call this we call this the value semantics approachthe 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 semanticsreference semantics

Two Problems with Current Two Problems with Current WFMSWFMS

1. Unclear 1. Unclear mixture of perspectivesmixture 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 objectsobjects required for IOWF. required for IOWF.

Introduction to Reference Nets Introduction to Reference Nets and Renewand Renew

RenewRenew - The - The ReReference ference NeNet t WWorkshoporkshop RenewRenew - 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 semanticssemantics

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

an instance of each perspective corresponds an instance of each perspective corresponds to one marked object-netto 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 WFMSbe 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 aspectsall aspects

the the system-net is genericsystem-net is generic, i.e., , i.e., independent of actual workflows and independent of actual workflows and organizationorganization

one can think of the one can think of the system-net as an system-net as an architectural modelarchitectural model and the object-nets and the object-nets as the actual content - the workflow as the actual content - the workflow designer only creates object-netsdesigner only creates object-nets