WebWorkFlow

WebWorkFlow

Zef Hemel, Ruben Verhaaf, Eelco VisserDelft University of Technology, The Netherlands

An Object-Oriented Workflow Modeling Language

coordination

WebWorkFlow

BPEL

Petri nets

BPEL

Petri nets

YAWL

BPEL

Petri nets

YAWL

✘ do not describe full applications✘ separate language, not nicely integrated✘ ignore user interface✘ all or nothing

WebWorkFlow

3 design principles

Linguistic integration

layersabstraction

WebDSL

Procedural Workflow

Process Expressions

WebDSL

Procedural Workflow

Process Expressionsconcise(less flexible)

more verbose(more flexible)

Full application generation

JBoss Seam

GoogleAppEngine

JavaServlet

Scenario

his employees

preparation

meeting

write report

manager

write report

approve comment

employee

write report

approve comment

finalize

manager

WebWorkFlow

Workflow Procedures

WebDSL



Core WebDSL

Core Data Model Core User Interface

WebDSL

Data Model User Interface Access Control

Web Application

...

User Interface LogicData models Access control

entity User { username :: String password :: Secret name :: String manager -> User employees -> Set<User> }

define page editUser(u : User) { form { table { row { "Name: " input(u.name) } row { "Manager: " input(u.manager) } row { "Employees: " input(u.employees) } } action("Save", save())

action save() { u.save(); return home(); } }}

define page editUser(u : User) { derive editPage from u for (name, manager, employees) }

access control rules page editUser(u : User) { principal == u.manager }

User Interface LogicData models Access control

User Interface LogicData models Access control Workflow

Workflows revolve around objects

entity Meeting { employee -> User employeeView :: Text managerView :: Text report :: Text approved :: Bool comment :: Text }

Workflows revolve around objects

and operations (procedures)performed on them

entity Meeting { employee -> User employeeView :: Text managerView :: Text report :: Text approved :: Bool comment :: Text }

employeePreparemanagerPreparewriteReportapproveReportcommentReportfinalizeReport

module workflow

procedure writeReport(m : Meeting) { who { principal == m.employee.manager } view { derive procedurePage from m for (report) } }

module workflow


part of a WebDSL module

module workflow


access control expression language


module workflow


access control expression languageview page language


WebDSL

Procedural Workflow



procedure procedureName(o : Entity) { who { who can perform } when { additional condition } view { view page } enabled { action code } disabled { action code } do { action code } done { action code }}

actorwho { principal == m.employee }

conditionwhen { now() > m.startDate }

user interfaceview { derive procedurePage from m for (employeePreparation) }

actiondo { email(organizeMeetingMail(m));}

enableddisableddone

eventsdone { m.writeReport.enable();}

WebDSL

Process Expressions

Workflow Procedures

concise(less flexible)


procedure meetingWorkflow(m : Meeting) { process { (employeePrepare(m) and managerPrepare(m)); repeat { writeReport(m); (approveReport(m) xor commentReport(m)) } until finalizeReport(m) }}

sequence ;

parallel and

sequence ;

parallel and

sequence ;

deferred choice +

parallel and parallel xor

sequence ;

deferred choice +


sequence ;

deferred choice + repeat ... until loops


sequence ;

deferred choice + repeat ... until loops

conditional if ... else

Transforming Procedures

Core WebDSL


WebDSL


Procedural WebWorkFlow

Data Model User InterfaceAccess

Control

Procedure

Events

Web Application

WebWorkFlow

Data ModelUser

Interface

Access

Control

Procedure

EventsProcess

Expressions

compilationbynormalization

Core WebDSL


WebDSL




Control

Procedure

Events

Web Application

WebWorkFlow

Data ModelUser

Interface

Access

Control

Procedure

EventsProcess

Expressions

concise(high-level)

verbose(low-level)

stateuser interfaceaccess control

procedure writeReport(m : Meeting) { who { principal == m.employee.manager } view { derive procedurePage from m for (report) } done { m.approveReport.enable(); m.commentReport.enable(); }}

Example

extend entity Meeting { writeReport -> WriteReportProcedureStatus}

Procedure (=workflow) state is kept

in the object it operates on


entity ProcedureStatus { isEnabled :: Bool function enable() { isEnabled := true; } function disable() { isEnabled := false; }}

entity WriteReportProcedureStatus : ProcedureStatus { ...}

define page writeReport(m : Meeting) { derive procedurePage from m for (employeeView)}

user interface


access control rules rule page writeReport(m : Meeting) { principal == m.employee.manager && m.writeReport.isEnabled }

access control


extend entity WriteReportProcedureStatus { m -> Meeting

function done() { m.approveReport.enable(); m.commentReport.enable(); }}

control logic


Core WebDSL


WebDSL




Control

Procedure

Events

Web Application

WebWorkFlow

Data ModelUser

Interface

Access

Control

Procedure

EventsProcess

Expressions

encode control flow

enableddisableddone

encode control flowin procedure events

procedure p(o : O) { process { a(o); b(o) }}


extend procedure a(o : O) { done { o.b.enable(); }}


extend procedure a(o : O) { done { o.b.enable(); }}

...right?

procedure p(o : O) { process { a(o); b(o); a(o) }}

procedure p(o : O) { process { a(o); b(o); a(o) }}

extend procedure a(o : O) { done { ?? }}

procedure p(o : O) { process { a(o)[1]; b(o)[2]; a(o)[3] }}

+ transition function


a(o) b(o)

state next0 a.enable(this, 1)

1 b.enable(this, 2)

2 a.enable(this, 3)

3 done

p(o)


a(o) b(o)

[1]


1 b.enable(this, 2)

2 a.enable(this, 3)

3 done

p(o)


a(o) b(o)[1]


1 b.enable(this, 2)

2 a.enable(this, 3)

3 done

p(o)


a(o) b(o)

[1]


1 b.enable(this, 2)

2 a.enable(this, 3)

3 done

p(o)


a(o) b(o)

[2]


1 b.enable(this, 2)

2 a.enable(this, 3)

3 done

p(o)


a(o) b(o)[2]


1 b.enable(this, 2)

2 a.enable(this, 3)

3 done

p(o)


a(o) b(o)

[2]


1 b.enable(this, 2)

2 a.enable(this, 3)

3 done

p(o)


a(o) b(o)

[3]


1 b.enable(this, 2)

2 a.enable(this, 3)

3 done

p(o)


a(o) b(o)[3]


1 b.enable(this, 2)

2 a.enable(this, 3)

3 done

p(o)


a(o) b(o)

[3]


1 b.enable(this, 2)

2 a.enable(this, 3)

3 done

p(o)


a(o) b(o)


1 b.enable(this, 2)

2 a.enable(this, 3)

3 done

p(o)

entity SeqProcedureStatus : ... { o -> O function next(state : Int) { if(state == 0) { o.a.enable(this, 1); } if(state == 1) { o.b.enable(this, 2); } if(state == 2) { o.a.enable(this, 3); } if(state == 3) { processed(); } }}


next function for sequencing

entity ParProcedureStatus : ... { o -> O counter :: Int function next(state : Int) { if(state == 0) { o.a.enable(this, 1); o.b.enable(this, 2); } if(state == 1) { counter := counter + 1; if(counter == 2) { processed(); } } if(state == 2) { counter := counter + 1; if(counter == 2) { processed(); } } }}

procedure par(o : O) { process { a(o)[1] and b(o)[2] }}

next function for parallel and

Encoding Patterns

WebDSL

Procedural Workflow



WebWorkFlow

linguistic integration

WebWorkFlow


abstraction layers

WebWorkFlow


full application generation

abstraction layers

WebWorkFlow


full application generation

abstraction layers

compilation by normalization

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http://www.webdsl.org




state tracking

state tracking task pages

state tracking task pages navigation


task lists

navigation


task lists

navigation

workflow status


task lists

navigation

workflow status access controlrules


task lists

navigation

workflow status access controlrules

the rest

WebWorkFlow

Technology

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