Pythagoras Karampiperis (pythk@iti.gr) Demetrios Sampson (sampson@iti.gr)

1. Towards interoperability of Learning Activities Design: Transforming BPEL Workflows to IMS Learning Design Level A Learning Flows Pythagoras Karampiperis (pythk@iti.gr) Demetrios Sampson (sampson@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 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.

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@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)