1. 1 CS 502: Computing Methods for Digital Libraries Lecture 2 The Nomadic Computing Experiment Object Models

2. 2 Administration COM 440 and CS 502 Knowledge of html

3. 3 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?

4. 4 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?

5. 5 URL Resolution WWW browser HTTP server URL Resource

6. 6 Proxy Resolution WWW browser Proxy server HTTP server Log database URL Resource URL

7. 7 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.

8. 8 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

9. 9 The Wireless Network

10. 10 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 program Dean Eckstrom and others at CS CIT for network installation

11. 11 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.

12. 12 Collecting your Laptop Read and understand the online instructions Pick-up is from 311 Upson Hall January 27th, 1:30 to 4:30 February 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

13. 13 Object Models

14. 14 General Architecture Repositories Identification services Search services User interface

15. 15 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.

16. 16 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.

17. 17 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

18. 18 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]

19. 19 Object Model Set of Digitized Page Images Data Each page: separate image may have several representations Metadata Structure of work: page sequence page numbers special pages

20. 20 Data Structure Identifier Data Metadata page 3 gif loc.ndlp/amrlp.13579 page 1 gif page 2 gif doc1 page map object-md

21. 21 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]

22. 22 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

23. 23 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

24. 24 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?