pythagoras karampiperis ([email protected]) demetrios sampson ([email protected])

Towards interoperability of Learning Towards interoperability of Learning Activities Design: Transforming Activities Design: Transforming BPEL Workflows to IMS Learning BPEL Workflows to IMS Learning Design Level A Learning FlowsDesign Level A Learning Flows

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Pythagoras Karampiperis ([email protected])Pythagoras Karampiperis ([email protected])

Demetrios Sampson ([email protected])Demetrios Sampson ([email protected])

TenC Workshop, Manchester, January, 2007TenC Workshop, Manchester, January, 2007 22//1818

OutlineOutline

IntroductionIntroduction– Problem DefinitionProblem Definition

Overview of IMS LD Authoring ToolsOverview of IMS LD Authoring Tools Interoperability between IMS LD Authoring ToolsInteroperability between IMS LD Authoring Tools Representing Learning Flows with IMS Learning DesignRepresenting Learning Flows with IMS Learning Design The proposed SolutionThe proposed Solution

– Improving interoperability between high level IMS LD Authoring Improving interoperability between high level IMS LD Authoring ToolsTools

– Using BPMN to graphically represent IMS LD Core ComponentsUsing BPMN to graphically represent IMS LD Core Components– Algorithm for Transforming BPEL workflows to IMS LD Level A Algorithm for Transforming BPEL workflows to IMS LD Level A

Learning flowsLearning flows ConclusionsConclusions


Problem DefinitionProblem Definition Although there exist several high level authoring tools conformant to

the IMS Learning Design specification, that facilitate the design process of Units of Learning, these tools are not fully interoperable.

This is due to the fact that they are using different human representations of the designed learning process. As a result, despite the fact that any generated UoL can be executed through an IMS LD conformant Run-time system, those UoLs cannot be used within a different high level authoring tool.

Thus, in this paper– we examine the ability of using the BPMN standard as a common

representation notation for learning flows modeled using the BPEL language– present an algorithm for transforming BPEL workflows to IMS Learning

Design Level A learning flows


Overview of IMS LD Authoring ToolsOverview of IMS LD Authoring Tools

1st Generation of IMS LD Authoring Tools:Tools which provide form-based interfaces for the definition of Educational Scenarios and/or Units of Learning, using the XML structure of the IMS Learning Design specification as the main driver of the authoring process. Advantages

– Provide direct control of the IMS Learning Design information model elements. Disadvantages

– Difficult to be used by less experienced designers– Require pre-processing (outside the tool) of the structure of the desired scenario in order for a designer to be able to

express it directly in XML notation.

Examples of these tools include: Reload Editor, CooperAuthor, Alphanet Editor

2nd Generation of IMS LD Authoring Tools:Tools which provide graphical-based, drag-and-drop interfaces for the definition of Educational Scenarios and/or Units of Learning. Advantages

– Support the design process without requiring pre-existing knowledge of the details of the IMS Learning Design information model.

Disadvantages– They generate the IMS LD manifest from a graphical representation of the learning flow but not the other way around;

these tools are not capable of carrying out the transformation of the IMS manifest to the corresponding graphical representation.

Examples of these tools include: MOT+, LAMS, ASK-LDT


Interoperability between IMS LD Interoperability between IMS LD Authoring ToolsAuthoring Tools

ASK-LDT MOT+ LAMS

Reload LD Editor

CooperAuthor

High Level Graphical Tools

Low Level Tools

IMS Learning Design Specification

import/ export import/ export

export exportexport/ partially import

notallowed

notallowed

notallowed


Representing Learning Flows with Representing Learning Flows with IMS LDIMS LD

Learner Support

Role

ActivityActivity Structure

Environment

ResourceLearning Activity

Support Activity

Is-a Is-a

Contain Take Place

Contain Contain

Is-a Is-a

Perform

Act

RolePart Role

Consists of

Refers to

Activity Structure

contains

sequence

selection

is

Activity

Activity Structure

ofor and/or

To represent the learning flow (that is, the sequence of activities performed by each role), the IMS LD notation language uses the Act element. An Act represents a logical categorization of a set of activities. In each act, several roles can participate by performing a Rolepart. Each rolepart represents the activities performed by the corresponding role in a specific act and contains an Activity Structure, which represents the sequence of the performed activities. An activity structure can use a nested structure of activities and/or other activity structures defining the branching of the learning flow.

Learning Flow

Representation


Improving Interoperability between IMS Improving Interoperability between IMS LD Authoring ToolsLD Authoring Tools

High LevelAuthoring Tool

#1

High LevelAuthoring Tool

#2

Reload LD Editor

CooperAuthor

High Level Graphical Tools

Low Level Tools

Low Level Modelling (IMS LD)

import/ export import/ export

High Level Modelling (BPMN)

import/ exportimport/ export

Workflow to Learning Flow Translation

transform to and from

transform to and from


The Business Process Modeling The Business Process Modeling Notation (BPMN) standardNotation (BPMN) standard

The Business Process Modeling Notation (BPMN) standard provides the means for creating human understandable graphical representations of processes (work flows)

Thus, it can be used for defining graphical representations of educational processes (learning flows) modeled with the IMS LD specification.

Questions to be Answered:– Is there an one-to-one mapping of BPMN Core Graphical Elements

to the IMS Learning Design Core Components?– Is the transformation of an IMS LD learning flow to a BPMN

representation (and vice versa) a straightforward process?


Mapping of BPMN Graphical Mapping of BPMN Graphical Elements to IMS LD Core Elements to IMS LD Core

ComponentsComponentsBPMN Graphical ElementBPMN Graphical Element DescriptionDescription BPMN Graphical NotationBPMN Graphical Notation IMS LD ComponentIMS LD Component

PoolPool A Pool represents an actor (role) in a learning process.A Pool represents an actor (role) in a learning process. RoleRole

LaneLaneA Lane is a horizontal sub-partition within a Pool, for logically A Lane is a horizontal sub-partition within a Pool, for logically organizing and categorizing activities.organizing and categorizing activities.

ActActRopePartRopePart

ActivityActivityAn activity represents a working item (task) that one or more actors An activity represents a working item (task) that one or more actors (roles) of the learning process perform.(roles) of the learning process perform.

ActivityActivity

Sequence FlowSequence FlowA Sequence Flow is used to show the order that activities will be A Sequence Flow is used to show the order that activities will be performed in a learning process.performed in a learning process.

Flow of activities represented as nested Flow of activities represented as nested Activity StructuresActivity Structures

GatewayGateway

A Gateway is used to control the divergence and convergence of A Gateway is used to control the divergence and convergence of Sequence Flow. Thus, it will determine branching, forking, merging, Sequence Flow. Thus, it will determine branching, forking, merging, and joining of paths. Internal Markers will indicate the type of and joining of paths. Internal Markers will indicate the type of behavior control.behavior control.

Flow of activities represented as nested Flow of activities represented as nested Activity Structures depending on the type of Activity Structures depending on the type of the Activity Structure (sequence of selection)the Activity Structure (sequence of selection)

The Flow of Activities does not map with an one-to-one relationship with BPMN Graphical Elements !


From BPMN workflows to IMS LD From BPMN workflows to IMS LD XML LanguageXML Language

• Due to the fact that the sequencing information in an IMS LD document is modelled through the use of nested activity structures, the transformation of an IMS LD learning flow to a representation according to BPMN (and vice versa) is not a straightforward process.

• To overcome this, another intermediate model is required with the following key characteristics:1. This model should be low level (represented in XML), so as to be able to be

converted to and/or retrieved from the XML representation of the IMS LD specification.

2. The elements of this model should directly map to BPMN graphical design elements, so that the transfer from the XML representation to the graphical representation (and vice versa) would be straightforward.

• Business Process Execution Language (BPEL) covers the above mentioned requirements! BPEL is an XML based language that represents work flows, and is directly mapped to BPMN graphical design elements.


Algorithm for Transforming BPEL Algorithm for Transforming BPEL workflows to IMS LD Level A Learning workflows to IMS LD Level A Learning

flows (1/2)flows (1/2)• Let us call Activity Graph, a directed graph that represents the BPEL workflow,

consisting of nodes (corresponding to workflow activities) and directed links (corresponding to the flow between two activities), with the following additional definitions:

– As Source of a link we define the starting activity, whereas, as Target of a link we define the activity that follows the source one.

– We define as a Root Node in the Activity Graph, any node that isn’t a target in any of the links contained in the Activity Graph.

– We define as a Split Node in the Activity Graph, any node which is the source of more than one links contained in the Activity Graph.

– We define as an End Node in the Activity Graph, any node which is the target of one or more links contained in the Activity Graph and there isn’t any link with this node as a source.

– We define as an End Split Node in the Activity Graph, any Split Node with all children End Nodes.


Algorithm for Transforming BPEL Algorithm for Transforming BPEL workflows to IMS LD Level A Learning workflows to IMS LD Level A Learning

flows (2/2)flows (2/2)Step A: Calculate Sequences

1. Starting from each End Node, go through the reverse of the links defined and calculate all activity sequences until reaching a Split Node

2. For each sequence of activities found:a. Define an activity structure with type equal to sequence, containing all the activities of the sequence found in reverse

orderb. Delete all the links between the activities of this specific sequencec. Delete the activities contained in this sequence from the Activity Graphd. Replace the target of the link between the relevant Split Node and the Root Node of this sequence, with the defined

activity structure

Step B: Calculate Selections1. Find all the End Split Nodes of the Activity Graph2. For each one of them:

a. Define an activity structure with type equal to selection, containing all the children of this End Split Nodeb. Delete all the links between this End Split Node and its childrenc. Delete all the children of this End Split Node from the Activity Graphd. Set the defined activity structure as a child to this End Split Node

Step C: TerminationIf Activity Graph contains only 1 Nodethen Define a Rolepart with reference to the remaining node (activity or activity structure) and

Terminateelse Repeat from Step A


Transformation Example (1/4)Transformation Example (1/4)

a. BPEL Workflowa. BPEL Workflow b. Calculation of Sequences (Step A)b. Calculation of Sequences (Step A)

A01

A02 A06

A03

A04

A05

A09

A07

A08

A10

A11

A01

A02 A06

A03

A04

AS1

A07

AS2

AS3

AS1

AS2

=

=

A05

A08

A09

A09

AS3 = A10 A11

[sequence]

[sequence]

[sequence]



c. Calculation of Selections (Step B)c. Calculation of Selections (Step B) d. Calculation of Sequences (Step A)d. Calculation of Sequences (Step A)

A01

A02 A06

A03

A04

AS4

A07

AS2

AS3

AS1

AS2

=

=

A05

A08

A09

A09

AS3 = A10 A11

[sequence]

[sequence]

[sequence]

AS4 = AS1 AS2[selection]

A01

A02 A06

AS5

AS6

AS3

AS5

AS6

=

=

A03

A07

A04

AS2

[sequence]

[sequence]

AS4

AS1

AS2

=

=

A05

A08

A09

A09

AS3 = A10 A11

[sequence]

[sequence]

[sequence]




e. Calculation of Selections (Step B)e. Calculation of Selections (Step B) f. Calculation of Sequences (Step A)f. Calculation of Sequences (Step A)

A01

A02 A06

AS5

AS7

AS3

AS5

AS6

=

=

A03

A07

A04

AS2

[sequence]

[sequence]

AS4

AS1

AS2

=

=

A05

A08

A09

A09

AS3 = A10 A11

[sequence]

[sequence]

[sequence]



A01

AS8 AS9 AS3

AS5

AS6

=

=

A03

A07

A04

AS2

[sequence]

[sequence]

AS4

AS1

AS2

=

=

A05

A08

A09

A09

AS3 = A10 A11

[sequence]

[sequence]

[sequence]



AS8

AS9

=

=

A02

A06

AS5

AS7

[sequence]

[sequence]



g. Calculation of Selections (Step B)g. Calculation of Selections (Step B) h. Calculation of Sequences (Step A) h. Calculation of Sequences (Step A) and Terminationand Termination

A01

AS10

AS5

AS6

=

=

A03

A07

A04

AS2

[sequence]

[sequence]

AS4

AS1

AS2

=

=

A05

A08

A09

A09

AS3 = A10 A11

[sequence]

[sequence]

[sequence]



AS8

AS9

=

=

A02

A06

AS5

AS7

[sequence]

[sequence]

AS10 = AS8 AS9[selection] AS3

AS11

AS5

AS6

=

=

A03

A07

A04

AS2

[sequence]

[sequence]

AS4

AS1

AS2

=

=

A05

A08

A09

A09

AS3 = A10 A11

[sequence]

[sequence]

[sequence]



AS8

AS9

=

=

A02

A06

AS5

AS7

[sequence]

[sequence]

AS10 = AS8 AS9[selection] AS3

AS11 = A01 AS10[sequence]

Rolepart è


ConclusionsConclusions

Argued on the need of introducing a new modeling layer to Argued on the need of introducing a new modeling layer to better support interoperability of high level IMS LD Authoring better support interoperability of high level IMS LD Authoring ToolsTools

Analyzed the learning flow representation mechanisms of the Analyzed the learning flow representation mechanisms of the IMS Learning Design specification and identified the structural IMS Learning Design specification and identified the structural components that need to be linked with a graphical learning components that need to be linked with a graphical learning flow representation.flow representation.

Examined the ability of using the BPMN standard as a Examined the ability of using the BPMN standard as a common graphical representation for learning flows common graphical representation for learning flows

Discussed the use of BPEL language as the mean for Discussed the use of BPEL language as the mean for translating BPMN representations to BPEL XML documentstranslating BPMN representations to BPEL XML documents

Presented an algorithm for transforming BPEL workflows to Presented an algorithm for transforming BPEL workflows to IMS Learning Design Level A learning flowsIMS Learning Design Level A learning flows


Contact DetailsContact Details

Demetrios Sampson ([email protected])Demetrios Sampson ([email protected])

Advanced e-Services for the Knowledge Society Advanced e-Services for the Knowledge Society Research Unit (ASK)Research Unit (ASK)

Informatics and Telematics Institute (ITI)Informatics and Telematics Institute (ITI)

Center for Research and Technology Hellas Center for Research and Technology Hellas (CERTH) (CERTH)

(http://www.ask4research.info)(http://www.ask4research.info)

pythagoras karampiperis ([email protected]) demetrios sampson ([email protected])

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