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Digital Object: A Virtual Online Storage Solution

Digital Object: A Virtual Online Storage Solution. 598C Course Project Huajing Li. Digital Contents: not just documents…. Some conventional objects. Complex, compound, dynamic objects. Traditional Online Access Method.

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Digital Object: A Virtual Online Storage Solution

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  1. Digital Object: A Virtual Online Storage Solution 598C Course Project Huajing Li

  2. Digital Contents: not just documents… • Some conventional objects • Complex, compound, dynamic objects

  3. 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.

  4. 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 affiliation=“Penn State”; • For on-disk file access, a file path needs to be specified.

  5. 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

  6. 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?

  7. 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

  8. 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.

  9. System Metadata Digital Object ModelArchitectural 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

  10. A Well-Known Digital Object Management System: Fedora

  11. Fedora Service Framework

  12. 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.

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