Digital Object Architecture

Transcription

1 Digital Object Architecture Christophe Blanchi Jason Petrone Corporation for National Research Initiative

2 Presentation Overview Introduction Digital Information Object Notions of Digital Object Digital Object Architecture Digital Object Chaining

3 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.

4 Introduction Contemporary Internet DNS specifies who is where, as long as who does not move often. Addresses such as 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.

5 Presentation Overview Introduction Digital Information Object Notions of Digital Object Digital Object Architecture Digital Object Chaining

6 Digital Information Object 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.

7 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.

8 Presentation Overview Introduction Digital Information Object Notions of Digital Object Digital Object Architecture Digital Object Chaining

9 Digital Object Overview Information Unique Identifier Content Type(s) Digital Object Requests Disseminations

10 Digital Object Overview Hamlet Hamlet It s a Book Get Page(2)

11 Digital Object Overview Hamlet Hamlet Data Element Data Element Content Type Operations Content Type Operations 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.

12 Presentation Overview Introduction Digital Information Object Notions of Digital Object Digital Object Architecture Digital Object Chaining

13 Digital Object Repository Provides distributed Digital Object storage. Behaves as a Digital Object. Repository 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). Deposit RAP Client Disseminate

14 Content Type Extensibility Type Signature Type Signature Implementation Content Type Operations Type Signature API 1 to many References Servlet Servlet Implementation Services API Servlet API

15 Content Type Registration hdl:type/typedef hdl:type/book Type Signature Register Handle Service hdl:type/repository hdl:type/typeimpl hdl:type/book1 Servlet hdl: type/book URN hdl: type/typedef URN hdl: type/book1 URN hdl:type/typeimpl URN hdl: type/typedef hdl: type/repository hdl: type/typeimpl hdl:type/repository hdl:type/repository DLS URL IOR:

16 Digital Object Structures Identifier Identifier Identifier Disseminator Identifier Type Signature Disseminator Type Signature Servlet Attachments Servlet Attachments hdl:type/repository Handle Service Data Element Data Element Type Registry

17 Content Type Extensibility Mechanism Client C Identifier Client A Disseminate Identifier Disseminator Type Signature XYZ Servlet XYZ-1 Attachment Deposit XYZ Deposit Client B Deposit Repository Data Element Data Element Repository 2 XYZ-1 Dynamic Acquisition of Mobile code

18 Extensible Dissemination Mechanism Secure Digital Object Environment Extensible Services Disseminations Type Signature Servlet Services API Repository Services Requests Results Signature API Servlet API Identifier Identifier Disseminator Requests Results Attachments Type Signature Servlet Attachments Disseminations Data Element

19 Presentation Overview Introduction Digital Information Object Notions of Digital Object Digital Object Architecture Digital Object Chaining

20 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.

21 Content Chaining Mechanism Extensible Services Data Element Static Service Request Type Signature ID Servlet ID Method Request Parameters or Digital Object ID Disseminator ID Method Request Parameters Type Signature Servlet Digital Object Typed Bytes

22 Operation Chaining Mechanism Method Request Servlet Servlet API Services API Dynamic Service Request Type Signature ID Servlet ID Method Request Parameters or Digital Object ID Disseminator ID Method Request Parameters Extensible Services Type Signature Servlet Digital Object self Digital Object

23 Digital Object Chaining Example Example: ask the Babel Fish Object: generate an audio version of a French translation of Shakespeare's Hamlet. Babel Fish Shakespeare 1 4 Babel Fish Type Audio Tools 2 3 Babel Translator Hamlet

24 Data Exchange By Chaining 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 A Type A Type B Services Query System Type A