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CS 502: Computing Methods for Digital Libraries

Lecture 2

The Nomadic Computing Experiment

Object Models

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Administration

• COM 440 and CS 502

• Knowledge of html

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Nomadic Computing Experiment

Philosophy: We are busy people. Better tools change our work habits.

Questions:

(a) For next decade, the standard computing environment will be a laptop with wireless network. If we all have this equipment how will it change our computing and work habits?

(b) If library access is made more convenient, will students read more of the recommended materials? Will they explore new materials for themselves?

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Nomadic Computing Experiment

Research methodology:

• CS 502 is an information-intensive course.

• Every student taking it for credit is offered a laptop and requested to participate in the experiment.

• Short surveys about how you use computing.

• Connect browsers through a proxy that monitors the URLs that you access.

• Basic research questions: Which of the recommended readings do you read? When do you prepare for class? What else do you read?

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URL Resolution

WWWbrowser

HTTPserver

URL

Resource

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Proxy Resolution

WWWbrowser

Proxyserver

HTTPserver

LogdatabaseURL

Resource

Resource

URL

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Proxy Resolution via Browser

The laptop has two browsers installed: Internet Explorer v.5 with changeable proxy settings Netscape Navigator with changeable proxy settings

See the instructions for changing the proxy settings.

Please use the proxy for all course- related work.

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Nomadic Computing Experiment

Privacy

• Taking part in the research is optional in CS 502.• No information gathered by the study will be used for grading or assessment. • All research results will be reported in a way that conceals the identity of individual students. • The research program has been approved by the University Committee on Human Subjects.

When you pick up your laptop, you will be required to sign:

http://www.cs.cornell.edu/cs502-sp00/consent.html

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The Wireless Network

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The Nomadic Equipment

The Laptop Computers

Information about the equipment, the network, policies and procedures:

http://www.nomad.cornell.edu/techsupport/

Human help:

raj@cs.cornell.edu

Thanks to:

Intel Academic donation programDean Eckstrom and others at CS CIT for network installation

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Points to Note

• The computers are university property. There will be a $50 charge for lost or damage.

• In you withdraw from the course, you must return the computer promptly to Upson 311.

• Remove the Aironet card when carrying the computer in its case. Power off before removing or inserting the card.

• You are responsible for back-up. For security, we recommend that you save your personal files on the D drive.

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Collecting your Laptop

• Read and understand the online instructions

• Pick-up is from 311 Upson HallJanuary 27th, 1:30 to 4:30February 1st, 8:00 to 11:00 AM

February 3rd, 1:30 to 4:30 PM

• Bring your Campus ID

• Sign consent form

• Choose either an Ethernet card or a modem card

• Change password to the Nomad server

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Object Models

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General Architecture

Repositories

Identification services Search services

Userinterface

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Object Models

Digital object: An item as stored in a digital library, consisting of data, metadata, and an identifier.

Object model: The relationship between digital objects and the content that they represent.

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Stored Forms and Presentations

The stored form of a digital object and presentation to user are usually different, e.g.,

• Web page is stored as HTML source, which is rendered by a browser for presentation.

• Flight simulation is stored as collection of programs, data files, etc, but presented to the user as a virtual environment.

A digital object may have many presentations, e.g.,

• An image has a thumbnail presentation and a high-resolution presentation.

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Techniques used Object Models

Identifiers for digital objects and the component parts of digital objects

Data types which specify what the data represents

Structural metadata which represent the relationship between related digital objects and their component parts

Reference links which show relationships between digital objects

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Object Model for a Web Page

Identifier:

http://www.lycos.com/

Data type:

text/html

Structural metadata:

[none - flat file]

Reference links:

[underlined in blue]

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Object ModelSet of Digitized Page Images

Data

Each page:

separate image may have several representations

Metadata

Structure of work:

page sequence page numbers special pages

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Data Structure

Identifier

Data

Metadatapage 3

gif

loc.ndlp/amrlp.13579

page 1gif

page 2gif

doc1page map

object-md

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Object Model for Set of Scanned Page Images

Identifier:

Handle

Data types:

Each page is image/jpeg (MIME type)

The digital object is doc1 (structural type)

Structural metadata:

Page map

Reference links:

[none]

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Data Types

Data type: Structural metadata associated with digital data that indicates the digital format or the application used to process the data.

MIME type: A scheme for specifying the data type of digital material. Used in electronic mail and the web.

Examples: text/plain

image/tiff

video/mpeg

application/pdf

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Structural Types

Genre: Describes category of content, e.g.,

jazz, blues, rap, rock, ...

painting, fresco, mural, ...

operating system, compiler, interpreter, ...

Structural type: Describes structure of computer representation, e.g.,

scanned image

web page

marked-up text

digitized audio

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Readings for Wednesday

On the CS 502 web site, see the page "Readings and References."

Read the references for the Week 2 Discussion Class. Be prepared to discuss:

a) What are the differences between URLs and Uniform Resources Names?

b) What are the advantages and disadvantages of the approaches followed by the Handle (DOI) and PURL approaches?