Digital Object: A Virtual Online Storage Solution

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Digital Object A Virtual Online Storage Solution

• 598C Course Project
• Huajing Li

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Digital Contents not just documents

• Some conventional objects

• Complex, compound, dynamic objects

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Traditional Online Access Method

• The web server application must be aware of the
  types and components of the managed digital
  contents.
• HTML documents
• JPG/GIF photos
• Video clips
• Stream media
• System developer and interface designer must
  provide appropriate handler for these file types.

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Traditional Data Storage Access

• For tuples stored in a relational database, the
  system developer must have knowledge of the table
  schema and encode it explicitly in a query
• Select name from authors where affiliationPenn
  State
• For on-disk file access, a file path needs to be
  specified.

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Problems

• Lack of flexibility
• Lack of extensibility
• Lack of support for complex data structures
• Lack of security control at the data level
• Unnecessary duplicate work needs to be performed
  by different applications / parties

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Key Research Questions

• How can clients interact with heterogeneous
  collections of complex objects in a simple and
  interoperable manner?
• How can complex objects be designed to be both
  generic and genre-specific at the same time?
• How can we associate services and tools with
  objects to provide different presentations or
  transformations of the object content?
• How can we associate specialized, fine-grained
  access control policies with specific objects, or
  with groups of objects?
• How can we facilitate the long-term management
  and preservation of objects?

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Look into the Nature, We Have the Hints

• Data is no longer an isolate existence in most
  current applications.
• Metadata
• Structural information
• Legal methods that can be applied to the data
• Access control policies
• Links to other digital contents
• These features can be grouped into an integral
  unit, which in return simplify the applications.
• Sort of similar with a Java class

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Solution

• We propose a middleware which virtually
  represents each digital content in a generic
  model. This middleware separates front-end
  applications from the back-end storages, gives
  abstraction to both sides.

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Digital Object Model Architectural View
Digital object identifier
Persistent ID (
PID
)
Default Disseminator
Service Perspective methods for disseminating
views of content
Your Extension
Your Extension
Datastream (item)
Item Perspective Set of content or metadata
items
Datastream (item)
Datastream (item)
Internal key metadata necessary to manage the
object
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A Well-Known Digital Object Management System
Fedora
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Fedora Service Framework
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My Project Work

• Bring new features into the previous framework.
• Fedora does not provide powerful indexing and
  query capabilities.
• Full text indexing based on Lucene.
• Dynamic field indexing.
• Dynamically build in-memory indexing to improve
  query performance.