Typing OpenDLib Repository Service: Strengths of an Information Object Type Language 1st European Workshop on the use of information object Repository Systems in Digital Libraries (DORSDL), in conjunction with ECDL2006 Leonardo Candela, Donatella Castelli Paolo Manghi, Pasquale Pagano Centro Nazionale delle Ricerche Pisa, Italy
30
Embed
Typing OpenDLib Repository Service: Strengths of an Information Object Type Language 1st European Workshop on the use of information object Repository.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Typing OpenDLib Repository Service: Strengths of an Information Object Type Language
1st European Workshop on the use of information object Repository Systems in Digital Libraries (DORSDL), in conjunction with ECDL2006
Application development and maintenanceFunctionality and content are kept
independent from each otherType correctness: components must be type-
conformantModularityReuse: component-wise and data wise
11
DORSDL Workshop - 21th of September, 2006
Typed Data Models: advantages
Type-driven physical storageData integrity: data can be handled according
to their associated structure onlyType information can be exploited to optimize
space storage and access time
12
DORSDL Workshop - 21th of September, 2006
DL Applications and (Type-less) Repository Services DL Applications are built exploiting Repository Services Repository Services concentrate on physical
management of Information objects Based on a Type-less Information Object Model Offer a set of primitives to
Manage an Information Space of information objects: add, delete, update, search
Extra features: behaviors, communities, users… Historical reasons:
Originally DLs were flat catalogues of pairs file-metadata or metadata only
13
DORSDL Workshop - 21th of September, 2006
Gaps of Type-less Repository Services
DL Applications must “encode” The notion of typed collection of information objects, seen as a
collection of objects with the same structure - Prototypes address this problem (K. Saidis et Al, ECDL2006)
The notion of methods (functionality) of the objects of a given typed collection
Applications are hard to write, maintain, reuse, and extend
No type safety and data integrity The objects into the store are not aware of their type
All the advantages of DB Systems are lost…
14
DORSDL Workshop - 21th of September, 2006
Gaps of Type-less Repository Services
System Interface
Repository Service
InformationObject Model
Application
Objects
Componenton Objects
and Rep primitives
Component:Typed Collections
and methods
data
15
DORSDL Workshop - 21th of September, 2006
Things have changed…
DL Applications are becoming common DL specific issues arise, regarding both
information spaces and functionalities Need for systematic approaches, in order
to maximize reuse and minimize effortSystems for supporting DL-specific,
customizable, and optimized functionalities to DL Applications designers and developers
16
DORSDL Workshop - 21th of September, 2006
Things have changed… Information Space Towards richer Information Object Models
Collections of Complex objects: MF, files, relations, and behaviors
Structured Objects: objects as a compound of other objects, e.g. photo albums, etc.
Dynamic Objects: dynamic created contentObject features: provenance and preservationUsers-Objects relationship: copyrights,
access rights, authentication, etc.Others…
17
DORSDL Workshop - 21th of September, 2006
Things have changed…Functionalities Towards system primitives
User profilingUser recommendationsObject VersioningOAI-PMH HarvestingVirtual Object Collection managementOthers…
18
DORSDL Workshop - 21th of September, 2006
Our goal Design and develop a Typed Repository
Service, along the line of DB Systems
Typed Information Object Model (OO)
Collection Table
Relational Model
<Type, Set of information objects> <Structure, Set of Records>
Type algebra Relational Algebra
19
DORSDL Workshop - 21th of September, 2006
Typed Repository Service
A type defines a set of objects with the same structure and the operations (methods) that can be applied to them
A Collection is a named set of objects defined according to the type assigned to the Collection
A Repository Service Instance is a set of Collections A Repository Service “exposes” to Applications
components all Collections defined in its active Instance Applications can manage, search, and manipulate
objects of Collection according to the methods (functionalities) exposed by the relative type
20
DORSDL Workshop - 21th of September, 2006
Typed Repository Service
System Interface
Typed Repository Service
Typed Information Object Model(Type algebra)
Application
DO1 DO2 DO3
Articles Notes Refs
Componenton Notes and Refs
Componenton Articles
A N R
TypeCollection
21
DORSDL Workshop - 21th of September, 2006
DL Type Algebra
A Type is characterized by: A (possibly empty) set of type properties, i.e.
attributes that depend on the Type features A (possibly empty) set of Metadata Fields (MF)
describing all objects of the Type, to be defined by the DL Designer
A Collection of a given Type offers the primitives (methods) to Search objects according to type properties Search objects according to the MF Add and Delete objects into and from the Collection
22
DORSDL Workshop - 21th of September, 2006
DL Type Algebra
Coll ::= Name = Type, Coll | Name = Virtual(Q, Name) |