Task Oriented Programmingin

using

Rinus Plasmeijer – Bas Lijnse - Peter Achten Pieter Koopman - Steffen Michels - Jurriën Stutterheim

Jan Martin Jansen (NLDA) - Laszlo Domoszlai (ELTE)Part 1/2

Radboud University Nijmegen

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Overview

Introduction to Task Oriented Programming

iTask Library

Task Values

Editors

Shared Data

Sequential Tasks

Parallel Tasks

Semantics

Conclusions and Future Work

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Overview

Introduction to Task Oriented Programming

iTask Library

Task Values

Editors

Shared Data

Sequential Tasks

Parallel Tasks

Semantics

Conclusions and Future Work

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Why Task Oriented Programming ?

Tasks are a common notion in daily life / in any organization

a task to do, assigned to one person group of people working together: collection of subtasks

statically known <-> dynamically determined managing tasks is also a task

Computers often play an important role when performing a Task

Filling in a web form Answering an email Writing a piece of text, filling in a spreadsheet, …

Many programming concepts can be seen as Tasks to be executed by a computer

Function call, procedure call, method invocation, calling a web-service, a query process, thread, "App"

Task Oriented Programming

TOPTasks as central concept

New style of programming / New programming paradigm

Declarative (focus on what instead of how)High level of abstractionNo worry about technical realization (unless they matter)

Yields a distributed running (on client and server) application coordinating the tasks to do

Can also be used for Rapid Prototypingto Formalize how work should be organizedfor Simulation (agents): what is the best way of workingfor Training: mix of real people and agentsto Show properties by testing, analysis or by formal proof (semantics formally defined)As common language for communication between domain experts and programmers

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Task Oriented Programming with

Domain Specific Programming Language, embedded inCombinator LibrarySpecify Basic TasksDefine new tasks as a composition of other tasks, using combinators

Abstracts from: (thanks to advanced Functional Programming techniques)graphical user interfaces & handling of user-interaction(client-server) communication informing tasks about the progress made by othersinforming tasks when shared information is being changed

Resulting application: Web-Service coordinating the tasks to be done…Clients can run on computers, laptops, tablets, smart phones

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My iTask Specification

iTasks Architecture

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iTask Web Server

iTask Combinator

Library

My iTask Specification

iTasks Architecture

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WEB

iTask Web Server

iTask Combinator

Library

My iTask Specification

iTask Web Server

iTask Combinator

Library

iTask Specification

Web ServiceWeb Service Web Service RPC

Computer

iTask User

iTask Client

iTask User

iTask AppLaptop

iTask Client Phone

iTask User

iTask Client

Cloud / Database

Tablet

iTask User

iTask Client

Sensor

iTask User

iTask Client

iTasks Architecture

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Papers on iTasks

First paper on iTasks:iTasks: Executable Specifications of Interactive Work Flow Systems for the Web (ICFP 2007)

Extensions: iTasks for a change - Type-safe run-time change in dynamically evolving workflows (PEPM 2011)GiN: a graphical language and tool for defining iTask workflows (TFP 2011)iTask as a new paradigm for building GUI applications (IFL 2010)Getting a grip on tasks that coordinate tasks (LDTA 2011)

Semantics: An Executable and Testable Semantics for iTasks (IFL 2008)Task Oriented Programming in a Pure Functional Language (PPDP 2012)

Client site evaluation of tasks:Transparant Ajax and Client-Site Evaluation of iTasks (IFL 2007)iEditors: Extending iTask with Interactive Plug-ins (IFL 2008)

Applicability: A Conference Management System based on the iData Toolkit (IFL 2007)Web Based Dynamic Workflow Systems for C2 of Military Operations (ICCRTS 2010)Managing COPD exacerberations with telemedicine (AIME 2010)Towards Dynamic Workflows for Crisis Management (ISCRAM 2010) Capturing the Netherlands Coast Guard's SAR Workflow with iTasks (ISCRAM 2011)A Task-Oriented Incident Coordination Tool (ISCRAM 2012)

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"Real" Prototype Applications using iTasks

Simple workflow:

Aerial project: Home Healthcare project (Peter Lucas, Bas Lijnse, e.a.)

Testing chronically lung diseases caused by smoking

Testing pregnancy disease

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Home Healthcare project

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"Real" Prototype Applications using iTasks

Real real-life workflow:

Crisis Management:

Capturing the Netherlands Coast Guard’s Search And Rescue Workflow

(ISCRAM 2011, Bas Lijnse, Jan Martin Jansen, Ruud Nanne, Rinus Plasmeijer)

Prototype : Coast Guard Search And Rescue

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What did we learn ?

Tasks which pass information to each other (one-to-many) is not powerful enough

One has to be able to define tasks which can monitor and coordinate other tasks

Internal: monitor the status of (sub-)tasks (like a process table in an OS)External: monitor the status of the environment (e.g. status of Search And Rescue)

Tasks must be able to share & update information while the task is being performed

Many to many communication, broadcast

User definable dashboard view (windows, menus, buttons) on shared information

System should remain semantically simple, easy to use, implement, and maintain…

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Back to the drawing board

The whole iTask system has been redesigned

More features than ever

Yet the Core of the system consists of only a few primitives

Redesigned API on top enabling easy specification of complex systems

Re-implemented kernel to gain efficiency

Under Construction ….

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Overview

Introduction to Task Oriented Programming

iTask Library

Task Values

Editors

Shared Data

Sequential Tasks

Parallel Tasks

Semantics

Conclusions and Future Work

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How does an i –Tasks look like ?

Embedded Domain Specific Language

iTask Core

Basic tasks Interactive Tasks : Editors Non-interactive Tasks: Lifting & Conversion Integrated Tasks: web-service-call, OS-call, exec application, access a database

Combinators for combining tasks Define control flow (sequential / parallel) and data flow between tasks

+ iTask Library to support frequently occurring work patterns

+ Clean: general purpose pure functional programming language

Recursive -, higher order -, polymorphic -, overloaded -, generic - functions Hybrid typing: strongly statically typed + dynamic typing

Core Concepts

DataLocal data: Task ValuesShared data: Shared Data Sources

TasksBasic Tasks

Non-interactivereturn, throw, …

Interactive Editors

CombinatorsSequentialParallel

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Overview

Introduction to Task Oriented Programming

iTask Library

Task Values

Editors

Shared Data

Sequential Tasks

Parallel Tasks

Semantics

Conclusions and Future Work

Core - Task Values

:: Task a typed unit of work which should deliver a value of type a

While the task is going on, its value may change over time

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Core - Task Values

:: Task a typed unit of work which should deliver a value of type a

While the task is going on, its value may change over time

NoVal

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Core - Task Values

:: Task a typed unit of work which should deliver a value of type a

While the task is going on, its value may change over time

NoValVal a

Unstable

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Core - Task Values

:: Task a typed unit of work which should deliver a value of type a

While the task is going on, its value may change over time

NoValVal a False

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Core - Task Values

:: Task a typed unit of work which should deliver a value of type a

While the task is going on, its value may change over time

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Core - Task Values

:: Task a typed unit of work which should deliver a value of type a

While the task is going on, its value may change over time

:: TaskResult a = ValRes TimeStamp (Value a)| e: ExcRes e & iTask e

:: Value a = NoVal | Val a Stability

:: Stability :== Bool

Task Values (ValRes)have a time stamp can be observed by other tasksinfluence the set of tasks to work oncan be of any type: user defined, higher order (e.g a task or a function)must satisfy the iTask context restriction: at least have to be serializable

A Task can raise an exception (ExcRes)

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Core - Simple Basic Tasks

Lift an ordinary expression to the task domain, delivers a Stable value :

return :: a → Task a | iTask a

Raise an exceptional result (ExcRes)

throw :: e → Task e | iTask e

Conversion of Task Values

(@?) infixl 1 :: (Task a) ((Value a) → (Value b)) → Task b | iTask a & iTask b

(@) infixl 1 :: (Task a) (a → b) → Task b | iTask a & iTask b

"Core" Definitions

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Overview

Introduction to Task Oriented Programming

iTask Library

Task Values

Editors

Shared Data

Sequential Tasks

Parallel Tasks

Semantics

Conclusions and Future Work

ModelModel

ViewView

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Editors - 1

module example

import iTasks

Start :: *World *WorldStart world = startEngine myTask world

myTask :: Task IntmyTask = enterInformation "Enter an integer" []

One can change the value as often as one

likes

Editors never deliver a Stable

value

ModelModel

ViewView

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Editors - 2

:: Person = { name :: String, gender :: Gender, dateOfBirth :: Maybe Date}:: Gender = Male | Female

derive class iTask Person, Gender

myTask :: Task PersonmyTask = enterInformation "Enter your personal information" []

ModelModel

ViewView

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Editors - 3

myTask :: Task [Person]myTask = enterInformation "Please personal information of multiple people" []

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Types treated special…

simpleEditor :: Task NotesimpleEditor = enterInformation "Enter a piece of text" []

chooseDate :: Task DatechooseDate = enterInformation "Choose a date" []

:: Maybe a = Just a | Nothing

chooseDate2 :: Task (Maybe Date)chooseDate2 = enterInformation "Choose a date" []

import GoogleMaps

pointOnMap :: Task GoogleMappointOnMap = enterInformation "Show me the location(s)" []

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Examples of Editors…

taskInt :: Task InttaskInt = enterInformation "Please enter a value" []

taskInt2 :: Task InttaskInt2 = updateInformation "Please enter a value" [] 42

chooseNumber :: Task IntchooseNumber = enterChoice "Choose a number" [] [0..9]

pizzaWith :: Task [String]pizzaWith = enterMultipleChoice "What do you like on your pizza ?" []

["Cheese","Tomato","Ansjofish","Salami"]

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Interactive Editors (see InteractionTasks.dcl)

Basic tasks: Interactive editor for filling in forms of a certain type:

viewInformation :: d [ViewOption a] a Task a | descr d & iTask a

enterInformation :: d [EnterOption a] Task a | descr d & iTask a updateInformation :: d [UpdateOption a a] a Task a | descr d & iTask a

enterChoice :: d [ChoiceOption o] [o] Task o | descr d & iTask oupdateChoice :: d [ChoiceOption o] [o] o Task o | descr d & iTask o

enterMultipleChoice :: d [MultiChoiceOption o] [o] Task [o] | descr d & iTask oupdateMultipleChoice :: d [MultiChoiceOption o] [o] [o] Task [o] | descr d & iTask o

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Interactive Editors (see InteractionTasks.dcl)

Basic tasks: Interactive editor for filling in forms of a certain type:

viewInformation :: d [ViewOption a] a Task a | descr d & iTask a

Task Description

View on a

Resulting Type Value a

Context Restriction

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Types used for interaction tasks…

viewInformation :: d [ViewOption a] a Task a | descr d & iTask a

:: ViewOption a = E.v: ViewWith (a v) & iTask v

Any view can be chosen

Define how to map value a to

view vContext

Restrictionincluded in the

Algebraic Datatype

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Interactive Editors (see InteractionTasks.dcl)

viewInformation :: d [ViewOption a] a Task a | descr d & iTask a

myList1 = viewInformation "View the numbers from 1 to 10" [] [1..10]

myList2 = viewInformation "View the numbers from 1 to 10" [ViewWith (map (\n "Number: " <+++ n))]

[1..10]

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Types used for interaction tasks…

enterInformation :: d [EnterOption a] Task a | descr d & iTask a

:: EnterOption a = E.v: EnterWith (v a) & iTask v

Any view can be chosen

Define how to map view v to

value a

Context Restriction

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Types used for interaction tasks…

updateInformation :: d [UpdateOption a a] a Task a | descr d & iTask a

:: UpdateOption a b = E.v: UpdateWith (a v) (a v b) & iTask v

Any view can be chosen

Define how to map view v to

value aContext

Restriction

Any view can be chosen

Define how to map the view v

back to a value b given the current

value a

Context Restriction

Define how to map value a to

view v

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Types used for interaction tasks…

:: ViewOption a = E.v: ViewWith (a v) & iTask v:: EnterOption a = E.v: EnterWith (v a) & iTask v:: UpdateOption a b = E.v: UpdateWith (a v) (a v b) & iTask v:: ChoiceOption a = E.v: ChooseWith ChoiceType (a

v) & iTask v:: MultiChoiceOption a = E.v: ChooseMultipleWith MultiChoiceType (a v) & iTask v:: ChoiceType = AutoChoice

| ChooseFromComboBox| ChooseFromRadioButtons| ChooseFromGrid| ChooseFromTree

:: MultiChoiceType = AutoMultiChoice| ChooseFromCheckBoxes

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Types used for interaction tasks…

viewInformation :: d [ViewOption a] a Task a | descr d & iTask a

class descr d where initAttributes :: d [TaskAttribute]

instance descr Void, String, (String, String) , (Icon, String, String) , …

class iTask a | gVisualizeEditor {|*|} // creates a form editor, gVisualizeText {|*|} // converts text to html code, gHeaders {|*|} // grid header for record field name, gGridRows {|*|} // grid row for record value, gUpdate {|*|} // handles a form update, gVerify {|*|} // verifies values filled in, JSONDecode {|*|} // convert to JSON to communicate / store, JSONEncode {|*|} // convert from JSON, gEq {|*|} // to compare values / web screens, TC a // conversion to and from Dynamics

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Types used for interaction tasks…

generic gVisualizeEditor a | gVisualizeText a, gHeaders a, gGridRows a :: (Maybe a) *VSt (VisualizationResult,*VSt)

generic gVisualizeText a :: StaticVisualizationMode a [String] generic gUpdate a :: (UpdateMode a) *USt (a, *USt)generic gHeaders a :: a [String]generic gGridRows a | gVisualizeText a

:: a [String] Maybe [String]generic gVerify a :: (Maybe a) *VerSt *VerStgeneric JSONEncode t :: t [JSONNode]generic JSONDecode t :: [JSONNode] (Maybe t, [JSONNode])generic gEq a :: a a Bool

TC is a special class automatically instantiated by the compiler for every “known” type…toDynamic :: a Dynamic | TC afromDynamic :: Dynamic a | TC a

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Overview

Introduction to Task Oriented Programming

iTask Library

Task Values

Editors

Shared Data

Sequential Tasks

Parallel Tasks

Semantics

Conclusions and Future Work