warren sack / film & digital media department / university of california, santa cruz

network protocols, addresses

and mark-up languages

fdm 20c introduction to digital media

lecture 21.10.2008

last time: free culture and open source

some key points (so far)

1. When technologies connect or separate people, they become media.

2. Technologies embody social, political, cultural, economic and philosophical ideas and relationships.

3. When a medium is new, it is often used to simulate old media.

4. New media do not replace old media, they displace them.

key point for today

• People make media and then media make people.

– This is another paraphrase from Marshall McLuhan’s book Understanding Media which was, in turn, a paraphrase of something Winston Churchill said about architecture.

outline for today

• the web as a technology

– who is tim berners-lee?

– an abbreviated reading of “the world-wide web” by berners-lee, et al.

– what are URIs, universal resource identifiers?

– what is HTML, the hypertext markup language?

– what is HTTP, the hypertext transfer protocol?

• the WWW is only a part of the Internet

• the web as an art form

– lisa jevbratt (1:1)

– mark napier (shredder)

– rsg collective (carnivore)

who is tim berners-lee?

tim berners-lee: cv

• education• b.a., physics, queen’s college, oxford university

• employment• senior research scientist, laboratory for computer science (lcs),

mit; and,– 3com founders chair, lcs, mit; and,

– director of the world-wide web consortium

• software engineer, cern, the european particle physics laboratory in geneva, switzerland

• fellowship at cern

• software engineer, image computer systems ltd.

• consultant at cern

• software engineer, d.j. nash ltd., dorsett, uk

• software engineer, plessey telecommunications ltd., poole/dorsett, uk

questions: the world-wide web

• what is the stated motivation of the research?– “The WWW was developed to be a pool of human

knowledge, which would allow collaborators in remote sites to share their ideas and all aspects of a common project.”

• what problem does this research address?– Originally the work was to provide a graphical

interface to a set of distributed files used in physics project management at CERN.

questions (continued)

• who funded this research? – Currently and/or previously supported by CERN,

DARPA, the European Commission, INRIA (Institut National de Recherche en Informatique et Automatique), Keio University of Japan (Shonan Fujisawa Campus), ERCIM (European Research Consortium in Informatics and Mathematics), MIT and the WWW Consortium.

• what is the economics of the work?– the economics of standards

• what is the stated genealogy of the technology?– (bush’s memex; nelson’s writings on hypertext;

berners-lee’s early implementations)

questions (continued)

• who is the intended audience? – Association for Computing Machinery (ACM)– Communications of the ACM; see www.acm.org

• who are the “dramatis personae” of the article? – humans, physicists, engineers

• what narrative strategies are employed in the article?– origin story, technical reference, how-to manual

• othering: who are “we”? who are “they”?– consider the competing standards (e.g., wais, gopher,

ftp) and the existing utopic writings (e.g., xanadu)

questions (continued)

• what is “thinking”/ “reading” / “writing” ?– see nelson and engelbart

• what other texts are cited?– definitions of various standards

what is the www?

answer 1:

a collaboratively authored hypertext

answer 2:

it is a standard

organizations and standards

• writing standards is a process of collaborative writing

• the practical politics of classifying and standardizing: There are two aspects of these politics: arriving at categories and standards, and, in the process, deciding what will be visible within the system (and of course what will thus then be invisible). The negotiated nature of standards and classifications follows from indeterminacy and multiplicity that whatever appears as universal or, indeed, standard, is the result of negotiations or conflict. How do these negotiations take place? Who determines the final outcome in preparing a formal classification? Visibility issues arise as one decides where to make the cuts in the system, for example, down to what level of detail one specifies a description of work, of an illness, of a setting. Because there are always advantages and disadvantages to being visible, this becomes crucial in the workability of the schema.Geoffrey C. Bowker and Susan Leigh Star, “How things (actor-net)work: Classification, magic and the ubiquity of standards,” http://weber.ucsd.edu/~gbowker/actnet.html

who wrote/influenced the www standards?

• what is the international standards organization (iso)?

• what is the internet engineering task force (ietf)?• what is a request for comments (rfc)?• who belongs to the world-wide web consortium?

iso: international standards organization

• ISO is a network of national standards institutes from 145 countries working in partnership with international organizations, governments, industry, business and consumer representatives. It acts as a bridge between public and private sector. It has created over 17,000 standards.

• ISO standards are developed according to the following principles:– Consensus: The views of all interests are taken into account:

manufacturers, vendors and users, consumer groups, testing laboratories, governments, engineering professions and research organizations.

– Industry-wide: Global solutions to satisfy industries and customers worldwide.

– Voluntary: International standardization is market-driven and therefore based on voluntary involvement of all interests in the market-place.

[from the ISO website www.iso.ch]

ietf: internet engineering task force

• The Internet Engineering Task Force (IETF) is a large open international community of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet. It is open to any interested individual.

• The actual technical work of the IETF is done in its working groups, which are organized by topic into several areas (e.g., routing, transport, security, etc.). Much of the work is handled via mailing lists. The IETF holds meetings three times per year.

rfc: request for comments

• Each distinct version of an Internet standards-related specification is published as part of the "Request for Comments" (RFC) document series. This archival series is the official publication channel for Internet standards documents and Internet community. RFCs can be obtained from a number of Internet hosts using anonymous FTP, gopher, World Wide Web, and other Internet document-retrieval systems [e.g., www.ietf.org/rfc]. The RFC series of documents on networking began in 1969 as part of the original ARPA wide-area networking (ARPANET) project.

• Some RFCs document Internet Standards. These RFCs form the 'STD’ subseries of the RFC series. When a specification has been adopted as an Internet Standard, it is given the additional label "STDxxx", but it keeps its RFC number and its place in the RFC series.

• Some RFCs standardize the results of community deliberations about statements of principle or conclusions about what is the best way to perform some operations or IETF process function. These RFCs form the specification has been adopted as a BCP, it is given the additional label "BCPxxx", but it keeps its RFC number and its place in the RFC series.

• Not all specifications of protocols or services for the Internet should or will become Internet Standards or BCPs. Such non-standards track specifications are not subject to the rules for Internet standardization. Non-standards track specifications may be published directly as "Experimental" or "Informational" RFCs at the discretion of the RFC Editor

w3c: world-wide web consortium

• As of 21 October 2008, the World Wide Web Consortium (W3C) has 413 Members

• 399 current members [2006] • 414 [2004]http://www.w3.org/Consortium/Member/List• Want to join? It is now a sliding scale:

– In order to promote a diverse Membership that represents the interests of organizations around the world, W3C fees vary depending on the annual revenues, type, and location of headquarters of an organization. For instance, as of 1 April 2007, a small company in India would pay 953 USD annually, a non-profit in the United States would pay 6,350 USD, and a very large company in France would pay 65,000 EUR.

• It used to be a fixed price– full membership: $57,500/year– affiliate membership: $5,750/year

uri: universal resource identifier

• examples:– http://ic.ucsc.edu/~wsack/fdm20c/fall2008/index.html– mailto:wsack@ucsc.edu– sftp://unix.ic.ucsc.edu

html: hypertext markup language

• try [view] --> [source] in your web browser• html is derived from sgml• sgml was created by charles goldfarb and

others originally as an ibm project on integrated law office information systems. sgml is intended to be a means to make explicit the content and structure of a document. compare this approach to the visual means of graphic design.

http: hypertext transfer protocol

– http is an internet protocol designed for transferring information for hypertext documents.

– what is a network protocol? a set of rules used when computers send information across the network

– compare this to ftp, smtp, nntp, etc.• for more on protocols and how they work see http://artstream.

ucsc.edu/film170a/Winter2003/notes-for-12-feb-03.html

How far is it from here to there?

• % traceroute google.com

traceroute visualized

http: experiments to try on your computer

– the simpliest web browser: from os x or your cats unix account, try fetching the front page of Google using telnet with the following sequence of commands:

• telnet www.google.com 80• get / http/1.0

– a trace of what the web server sees: examine the access_log of your apache web server: /private/var/log/httpd/access_log

– watching the traffic between the browser and he server: if you have mac os x, try running tcpdump:% sudo tcpdump -i en1 -vvv -n -s 0

[use en0 over Ethernet]

what is the www?

answer 3:

the www is a vast, heterogeneous network of people and machines

lisa jevbratt

• 1:1 • what is an IP address?• what is a URI?• what is a web crawler?• what is a search engine?

mark napier

• shredder• what is HTML?• what is a web client? a browser?

rsg collective

• carnivore• what is a packet sniffer?• what is a protocol?• what is HTTP?• who is watching you?

next time: midterm

• the midterm will be a closed-book, closed-note test and will take place in this room during our regular class meeting time