digital object architecture - object management group · 2013-01-30 · corporation for national...
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Corporation for National Research Initiatives
Digital Object Architecture
Christophe [email protected]
Jason [email protected]
Corporation for National Research Initiativehttp://www.cnri.reston.va.us
Corporation for National Research Initiatives
Presentation Overview
•Introduction
•Digital Information Object
•Notions of Digital Object
•Digital Object Architecture
•Digital Object Chaining
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Introduction
Primordial Internet•TCP/IP was created to allow transmission of packets of data between disparate systems on ARPANET.
• Addresses are location dependent.
• Deals with where data goes, but not what it is, or who it is sent to.
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Introduction
Contemporary Internet• DNS specifies who is where, as long as who does not move often.
• Addresses such as email and URLs are still location dependent.
• Application layer protocols such as HTTP use MIME typing to define what data is, but only address one-way communication.
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Presentation Overview
•Introduction
•Digital Information Object
•Notions of Digital Object
•Digital Object Architecture
•Digital Object Chaining
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• Exists within the Digital Object Architecture with the goal of making information a first class citizen on the Internet.
• Allows high level information to be moved around on the Internet much as packets of data are today.
•Aggregates relevant heterogeneous data and metadata.
• Solves the who is where problem of network addressing by using the CNRI Handle System®, a location independent global naming service.
• Describes the what of information in an concise and extensible manner.
Digital Information Object
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Digital Information Object Intents of Use
• The Intents of use extensible typing mechanism specifies what a Digital Information Object contains.
• A specific Digital Information Object’s intent of use is described as a content type.
• Content types are registered and uniquely identifiable.
• A content type defines a unique set of operations that can be performed on specific information type.
• The set of operations is known as a content type signature.
• A content type signature can be implemented in different ways in the form of mobile code called servlets.
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Presentation Overview
•Introduction
•Digital Information Object
•Notions of Digital Object
•Digital Object Architecture
•Digital Object Chaining
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Digital ObjectContent Type(s) Requests
Information
Digital Object Overview
Disseminations
Unique Identifier
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Hamlet
It’s a Book Get Page(2)
Digital Object Overview
Hamlet
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Hamlet
•Digital objects are uniquely identified in a given name space.
•Data elements reference sequences of typed bytes.
•A Digital Object can have zero of more Content Types to reflect the intents of use of its creator.
DataElement
DataElement
HamletContent Type
Operations
Content TypeOperations
Digital Object Overview
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Presentation Overview
•Introduction
•Digital Information Object
•Notions of Digital Object
•Digital Object Architecture
•Digital Object Chaining
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Repository
Digital Object Repository
RA
P
Client
•Provides distributed Digital Object storage.
•Behaves as a Digital Object.
•Provides a dynamic acquisition and execution mechanism for the mobile code that implements the content type operations.
•Exclusively accessed using the Repository Access Protocol (RAP).
DisseminateDeposit
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1 to many
Type Signature
Servlet
TypeSignature
Implementation
Type Signature API
ServletImplementation
Servlet API
Serv
ices
API
Ref
eren
ces
Content TypeOperations
Content Type Extensibility
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hdl:type/repository
hdl: type/repositoryhdl: type/typedef URN
Handle Service
hdl:type/repository IOR:DLShttp://www.type.orgURL
hdl: type/book hdl: type/typedefURN
hdl: type/book1 hdl: type/typeimplURNhdl:type/typeimpl hdl:type/repositoryURN
Registerhdl:type/typedef
hdl:type/book
Type Signature
hdl:type/typeimpl
hdl:type/book1
Servlet
Content Type Registration
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Identifier
Identifier
Type Signature
Servlet Attachments
Disseminator
hdl:type/repository
Digital Object Structures
DisseminatorIdentifier
Type Signature
Servlet Attachments
Identifier
DataElement
DataElement
Type Registry
Handle Service
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Repository
Deposit
IdentifierClient C
Disseminator
Servlet
XYZ-1
Content Type Extensibility Mechanism
Disseminate
Identifier
Type Signature XYZ
Attachment
Repository 2
Deposit
DepositData
ElementData
Element
Client A
XYZ
Client B
XYZ-1
Dynamic Acquisition of Mobile code
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Secure Digital Object EnvironmentExtensible Services
Extensible Dissemination Mechanism
Identifier
DisseminatorIdentifier
Type Signature
TypeSignature
Signature API Servlet API
Serv
ices
API
Servlet
Attachments
Disseminations
Req
uest
s Results
RepositoryServices
Servlet Attachments
DataElement
Disseminations
Req
uest
s Results
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Presentation Overview
•Introduction
•Digital Information Object
•Notions of Digital Object
•Digital Object Architecture
•Digital Object Chaining
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Digital Object Chaining
• Provides a building block approach to information management.
•Enables the creation of information and operation links.
•Content Chaining: a digital object’s data element can reference its respective content.
•Operations Chaining: servlets can dynamically establish links to external resources or digital object when executed.
•Content Type Chaining: chaining servlets can be designed to dynamically build digital object chains from input parameters.
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Content Chaining Mechanism
StaticServiceRequest
Digital Object
•Digital Object ID•Disseminator ID
•Method Request•Parameters
orData Element
Typed Bytes
Type Signature Servlet
Extensible Services
•Type Signature ID•Servlet ID
•Method Request•Parameters
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Operation Chaining Mechanism
or•Digital Object ID
•Disseminator ID•Method Request
•Parameters Digital Object
DynamicServiceRequest
Method RequestSe
rvic
es A
PI
Servlet API
Servlet
•Type Signature ID•Servlet ID
•Method Request•Parameters
Type Signature Servlet
Extensible Services
Digital Object
self
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Digital Object Chaining Example
Example: ask the Babel Fish Object: generate an audio version of a French translation of Shakespeare's Hamlet.
Babel Fish
Babel FishType
4 5
Babel Translator
6
1
Shakespeare
3
8
Audio Tools
7
2
Hamlet
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Data Exchange By Chaining
Query System
•Digital Object chaining allows for homogeneous data exchanges in a heterogeneous data environment.
•Digital Object Chaining provide a layer of abstraction over data formats, encoding and transport protocols.
Type A
Type B
Services
Type A
Type A
Type A