Towards interoperability of Learning Activities Design: Transforming BPEL Workflows to IMS Learning

1
Towards interoperability of Learning Activities
Design Transforming BPEL Workflows to IMS
Learning Design Level A Learning Flows
Pythagoras Karampiperis (pythk_at_iti.gr) Demetrios
Sampson (sampson_at_iti.gr)
This work is licensed under the Creative Commons
Attribution-NoDerivs-NonCommercial License. To
view a copy of this license, visit
http//creativecommons.org/licenses/by-nd-nc/1.0
or send a letter to Creative Commons, 559 Nathan
Abbott Way, Stanford, California 94305, USA.
2
Outline

• Introduction
• Problem Definition
• Overview of IMS LD Authoring Tools
• Interoperability between IMS LD Authoring Tools
• Representing Learning Flows with IMS Learning
  Design
• The proposed Solution
• Improving interoperability between high level IMS
  LD Authoring Tools
• Using BPMN to graphically represent IMS LD Core
  Components
• Algorithm for Transforming BPEL workflows to IMS
  LD Level A Learning flows
• Conclusions

3
Problem 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

4
Overview 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

5
Interoperability between IMS LD Authoring Tools
6
Representing Learning Flows with IMS LD
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
7
Improving Interoperability between IMS LD
Authoring Tools
8
The Business Process Modeling Notation (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?

9
Mapping of BPMN Graphical Elements to IMS LD Core
Components

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

10
From BPMN workflows to IMS LD XML 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
• 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.
• 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.

11
Algorithm for Transforming BPEL workflows to IMS
LD Level A Learning 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 isnt 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 isnt
  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.

12
Algorithm for Transforming BPEL workflows to IMS
LD Level A Learning flows (2/2)

• Step A Calculate Sequences
• Starting from each End Node, go through the
  reverse of the links defined and calculate all
  activity sequences until reaching a Split Node
• For each sequence of activities found
• Define an activity structure with type equal to
  sequence, containing all the activities of the
  sequence found in reverse order
• Delete all the links between the activities of
  this specific sequence
• Delete the activities contained in this sequence
  from the Activity Graph
• 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 Selections
• Find all the End Split Nodes of the Activity
  Graph
• For each one of them
• Define an activity structure with type equal to
  selection, containing all the children of this
  End Split Node
• Delete all the links between this End Split Node
  and its children
• Delete all the children of this End Split Node
  from the Activity Graph
• Set the defined activity structure as a child to
  this End Split Node
• Step C Termination
• If Activity Graph contains only 1 Node
• then Define a Rolepart with reference to the
  remaining node (activity or activity structure)
  and Terminate
• else Repeat from Step A

13
Transformation Example (1/4)
14
Transformation Example (2/4)
15
Transformation Example (3/4)
16
Transformation Example (4/4)
17
Conclusions

• Argued on the need of introducing a new modeling
  layer to better support interoperability of high
  level IMS LD Authoring Tools
• Analyzed the learning flow representation
  mechanisms of the IMS Learning Design
  specification and identified the structural
  components that need to be linked with a
  graphical learning flow representation.
• Examined the ability of using the BPMN standard
  as a common graphical representation for learning
  flows
• Discussed the use of BPEL language as the mean
  for translating BPMN representations to BPEL XML
  documents
• Presented an algorithm for transforming BPEL
  workflows to IMS Learning Design Level A learning
  flows

18
Contact Details

• Demetrios Sampson (sampson_at_iti.gr)
• Advanced e-Services for the Knowledge Society
  Research Unit (ASK)
• Informatics and Telematics Institute (ITI)
• Center for Research and Technology Hellas (CERTH)
  
• (http//www.ask4research.info)