pythagoras karampiperis, demetrios sampson e-mail:{pythk, sampson}@iti.gr

University of PiraeusDepartment of Technology Education and Digital Systems

Centre for Research and Technology - Hellas(C.E.R.T.H.) Informatics and Telematics Institute (I.T.I.)

Pythagoras Karampiperis ICALT 20031

Enhancing Educational Metadata Enhancing Educational Metadata Management Systems to Management Systems to

support Interoperable Learning support Interoperable Learning Object RepositoriesObject Repositories

Pythagoras Karampiperis, Demetrios Sampsone-mail:{pythk, sampson}@iti.gr




What the problem is ?What the problem is ? A large number of digital learning resources exist, being

already described using different metadata models or even different application profiles of the same metadata model

“harmonising” this, by expecting that these resources will be eventually re-described in a standard and universally accepted model or profile might be too much to anticipate …

in order to avoid disregarding the possibility of searching and re-using LOs in these repositories, certain functional requirements should be considered when designing LRM Management Systems.




Design RequirementsDesign Requirements

Educational MetadataCreation / Modif ication

MappingEducational Metadata

Schemas

Support ofEducational Metadata

Standards

Structural & SemanticValidation

Educational MetadataManagement




Architecture of a LRM Management SystemArchitecture of a LRM Management System

Users

Editor / Wizard

Learning ResourceMetadata

XML SchemasXML Transformation

Maps

ManagementSystem

PublishingSystem

Map Generator

ValidationMapping




Architectural LayersArchitectural Layers

Interface Layer: A layer visible by the users of the LRMMS. It contains all the components of the user-interface. These are the XML editor/wizard, the management interface, the publishing interface and the map generator.

Non-visible Layer: contains all the repositories involved and the operations, which are performed. The repositories involved are the Learning Resource Metadata repository, the XML Schema repository and the XML Translation Maps repository and the operations are validation and mapping




Information StorageInformation Storage

XML Schemas Repository: contains the XML Schema files for the educational metadata models

Learning Resource Metadata Repository: stores the metadata description of the learning objects

XML Transformation Maps Repository: Transformation maps should be automatically generated by a corresponding mechanism, by associating a number of elements of one metadata schema to a number of elements of another schema




Editor / Wizard

XMLFiles XML Schemas

DOM


Validation Process

StructuralValidation

SemanticValidation

Fail

Fail

Pass

Pass

Validation Process Flow ChartValidation Process Flow Chart




XML Schemas


Map Generator

XMLFiles

Mapping

XML TransformationMaps

Mapping ProcessMapping Process




Multi-tiered Database Model (1)Multi-tiered Database Model (1)

Ensures processing and storage effectiveness increased opportunity for security portability and extensibility




Multi-tiered Database Model (2)Multi-tiered Database Model (2)LRM Management system is partitioned into: Client application: provides a user interface on the

user's machine. Ideally, it knows nothing about how the data is stored or maintained.

Application server (middle tier): resides in a central networking location accessible to all clients and provides common data services. Coordinates and processes requests and updates from multiple clients and handles all the details of defining datasets and interacting with the database server.

Remote database server: provides the relational database management system (RDBMS).




Advantages (1)Advantages (1)

Encapsulation of business logic in a shared middle tier. Different client applications all access the same middle tier.

Thin client applications. Client applications can be written to make a small footprint by delegating more of the processing to middle tiers. Not only are client applications smaller, but they are easier to deploy. Thin client applications can be distributed over the Internet for additional flexibility.




Advantages (2)Advantages (2) Distributed data processing. Distributing the work of

an application over several machines can improve performance because of load balancing, and allow redundant systems to take over when a server goes down.

Increased opportunity for security. This model provides the capability of isolating sensitive functionality into tiers that have different access restrictions. This provides flexible and configurable levels of security. Middle tiers can limit the entry points to sensitive material, allowing controlling access more easily.




EMMA – A prototype implementation (1)EMMA – A prototype implementation (1)

The architectural design of the EMMA toolkit is based onmulti-tier database modeluse of Memory Based XML Native Repositories

conforming with the IMS Digital Repositories Interoperability – Core Functions Information Model specification

Use of the Simple Object Access Protocol (SOAP). The metadata produced by the EMMA are

conformed with the IEEE Learning Object Metadata 1484.12.1-2002 Standard.




EMMA – A prototype implementation (2)EMMA – A prototype implementation (2)

EMMA supports: authoring of educational metadata for the description of

educational resources and full management of the produced metadata descriptions

integration of different metadata specifications (Dublin Core, IMS Metadata) through the use of an advanced fully automatic mapping mechanism

metadata structural and semantic validation metadata publishing over the Internet through Web

Services and the use of SOAP protocol




EMMA – Authoring WizardEMMA – Authoring Wizard




EMMA – XML Viewer/EditorEMMA – XML Viewer/Editor




EMMA Mapping approach …EMMA Mapping approach … Data-Driven mapping mechanism, that is, it creates the

corresponding map between the attributes of various different schemas by examining the similarity of the data values that the attributes hold …

it does it in 3 nested parts by measuring the percentage of similarity between the data values of the attributes against some predefined similarity threshold value that “defines” the “minumum accepted similarity” between the data values of 2 attributes as a criterion to accept the mapping as valid




Test setting …Test setting … map different representations of the same real-

world entities using Dublin Core Ariadne Gem IEEE LOM

For the designing of the testing datasets, we used the ISO 639 and ISO3166-1 standards as the language

format scheme the ISO 8601 standard as the date format scheme




Classification of DatasetsClassification of Datasetsto examine the effect of data values heterogeneity, 3 different

datasets were identified with varying similarity, that is, low (less than 40%) Medium and high (more than 70%)

similarity

the similarity between the data values of the attributes is measured by the following formula:

DataSetinentitiesofnumberTotal

Similarity

SimilarityDataSetDataSettheofentity




Evaluation CriteriaEvaluation Criteria

Total evaluation criterion : the mean value of confidence, success and

mistakes

producedmappingsofnumberTotal

ContentofSimilarity

Confidencemapping


mappingscorrectofNumberSuccess


mappingswrongofNumberMistakes




Experiment 1: Experiment 1: Robustness Test Robustness Test

Mapping is assumed by the algorithm to be valid if the similarity between the entities is above a

specific thresholdEfficiency of the proposed mapping algorithm

depends on the selection of the similarity threshold parameter

Robustness test for three categories of the datasets according to

the similarity between entities




Robustness TestRobustness Test

0

20

40

60

80

100

Low 47.58 67.34 32.44 60.83

Medium 77.64 83.98 11.49 83.38

High 100.00 99.63 0.24 99.80

Confidence Success Mistakes Total




Experiment 2 : verification of effectivenessExperiment 2 : verification of effectiveness

to verify the effectiveness, we used a full datasets of IEEE LOM and Dublin Core metadata schemes representing the same learning objects (around 250 LOs)

to find that the result of the mapping algorithm were identical to the Annex B (Mapping to Unqualified Dublin Core) of IEEE 1484.12.1-2002 (Draft Standard for Learning Object Metadata) standard




IEEE LOM & DC Mapping (1)IEEE LOM & DC Mapping (1)Dublin Core IEEE LOM

Data Element Identifier Data Element

DC.Identifier 1.1.2 General.Identifier.Entry

DC.Title 1.2 General.Title

DC.Language 1.3 General.Language

DC.Description 1.4 General.Description

DC.Subject 1.5 General.Keyword

DC.Coverage 1.6 General.Coverage

DC.Type 5.2 Educational.LearningResourceType

DC.Date 2.3.3 LifeCycle.Contribute.Date

DC.Creator 2.3.2 LifeCycle.Contribute.Entity

DC.OtherContributor 2.3.2 LifeCycle.Contribute.Entity

DC.Publisher 2.3.2 LifeCycle.Contribute.Entity

DC.Format 4.1 Technical.Format

DC.Rights 6.3 Rights.Description

DC.Relation 7.2.2 Relation.Resource.Description

DC.Source 7.2 Relation.Resource




IEEE LOM & DC Mapping (2)IEEE LOM & DC Mapping (2)




IEEE LOM & DC Mapping (3)IEEE LOM & DC Mapping (3)




ConclusionsConclusions New functional & design considerations should be

satisfied to provide an effective LRM management system Integrating data from different data sources is

time-consuming and labor-intensive only few tools available to ease the task

The proposed architecture can be useful since it Supports the automatic data integration from different

metadata sources through the mapping mechanism Ensures the structural and semantic metadata validity

through the validation mechanismOpen Issues Real-time metadata integration over the Internet through

Web Services




Contact DetailsContact Details

Pythagoras Karampiperis and Prof. Demetrios Sampsonpythk,[email protected]

Informatics and Telematics Institute, Centre for Research and Technology Hellas,42, Arkadias Street,Athens,GR-15234,GreeceandDepartment of Technology Education and Digital Systems,University of Piraeus150, Androutsou Street, Piraeus, GR-18534 Greece

pythagoras karampiperis, demetrios sampson e-mail:{pythk, sampson}@iti.gr

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