Rohit Khare 19 August 1999 Information

Rohit Khare 19 August 1999 Information & Computer Science 4 K Associates Internet Scale Namespaces: A Survey

What’s in a name? z. Any problem in Computer Science can be solved by another layer of indirection — David Wheeler (Chief EDSAC Programmer) z We name objects in order to: y. Abstract away details of location, access, user interface y. Interpose another layer of control, to allow relocation, e. g. z Naming is achoice y. To share a common name is to share trust in its 19 August 1999 Internet Scale Namespaces: A Survey meaning 2

What’s Internet Scale About, Anyway? z This workshop series is dedicated to the proposition that successful Internet applications require more than scalable algorithms: y. They must scale across time — longevity y. They must scale across space — latency y. They must scale across organizations — liability y. Economic, Political, and Social criteria are just as critical z Internet Scale is about more than large numbers. . . 19 August 1999 Internet Scale Namespaces: A Survey 3

1000 m 19 August 1999 Internet Scale Namespaces: A Survey 4

100 m 19 August 1999 Internet Scale Namespaces: A Survey 5

10 m 19 August 1999 Internet Scale Namespaces: A Survey 6

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Powers of Ten z Powers of Ten illustrates the different rules governing different scales of existence y Meteorology, Biology, Chemistry, Quantum Mechanics. . . y Geology, Astronomy, Cosmology. . . z Yet the same rules apply, too! y Physics is scaleinvariant z Let’s try ‘zooming in’ on an Internet-scale name… 19 August 1999 z A film from the office of Charles & Ray Eames, 1977, running time 8: 47 Internet Scale Namespaces: A Survey 8

http: //www. united. com/Itinerary/NQSS 5 A z z z z URI Uniform Resource Identifier Resolved by Web Browser Hierarchical Left-to-Right Format by IETF RFC 1630 (6/94) IETF RFC 2396 (8/98) Entries by Server Administrator Internationalization US-ASCII (UTF-8) Number 1010 + Lifetime 101 - 108 sec z Browsers resolve URIs to Web Pages z Replaced complex recipes for fetching network information with a single string z Composed from four namespaces y Scheme, domain, port, path z Can also have username, password 19 August 1999 Internet Scale Namespaces: A Survey 9

http: //www. united. com/Itinerary/NQSS 5 A z z z z URI Scheme Resolved by Web Browser Atomic ASCII string Format by IETF RFC 1738 Entries by IANA Registry Internationalization none Number 101+ Lifetime 108 - 109 sec z Web Browsers resolve URI Schemes into connection protocols and ports z Scheme Protocol RFC Port z FTP File Transfer Protocol 1738 21 z Telnet. Interactive Sessions 1738 23 z Gopher The Gopher Protocol z Quickly identifies information-access 1436 70 system which can resolve the URI z HTTP Hypertext Transfer 2616 path 80 z Resolves to IANA assigned port z NNTPNetnews Transfer 977 numbers 119 y Not injective: HTTP and IPP both at 80 z WAIS Wide Area Inf. Svc 1625 z Can be an address, too, as with data: 210 z Z 39. 50 s Z 39. 50 Session ANSI 19 August 1999 Internet Scale Namespaces: A Survey 10 210

http: //www. united. com/Itinerary/NQSS 5 A z z z z DNS Domain Name Resolved by DNS Protocol Hierarchical Right-to-Left Format by IETF RFC 883 (11/83) Entries by ICANN-delegated registrar Internationalization [A-Z][a-z][09]Number 108+ (63/254 char limit) Lifetime 107 - 108 sec z Composed of hierarchical namespaces y com (ICANN), united (NSI), www (United) z DNS Resolvers resolve Hostnames into Internet Addresses z National TLDs ISO-3166 two-letter codes y Iceland this. is/keyword y Monteserrat linux. versus. ms z Original TLD intentions: y. gov y. net providers y. int US Federal Gov’t Network service International treaty orgs z ‘Localhost’ is a reserved name z Reverse lookups y 213. 21. 195. 128. arpa. in-addr z Competing global trademark registries y Real. Names, WHOIS (RFC 2345) z Urgent need to expand number of z Uniqueness requirement forces roots political solutions: United Van Lines or 19 August 1999 Internet Scale Namespaces: A Survey several to masquerade as one 11 y Allow Air Lines?

http: //128. 192. 213/Itinerary/NQSS 5 A z z z IP Internet Protocol Address Resolved by TCP/IP Stack Hierarchical Right-to-Left Format by IETF RFC 791 (9/81) Entries by IANA-delegated IP registry z Internationalization none z Number 231 = 1010+ z Lifetime 101 - 107 sec z TCP/IP Stacks resolve Internet Addresses to MAC (physical) Addresses or next-hop Internet Addresses z Regional IP numbering registries y Europe - RIPE, Asia- APNIC, USARIN y Allocation Policy set by RFC 2050 z Reserved ranges y y z Composed of subnet and link numbers y Class A, B, C and CIDR net mask prefixes y Topological consistency of net ranges This network: 0. x. x. x Broadcast: 255. x. x (Class B) Multicast: 224. 0. 0. 0 and up Reserved loopback address: 127. 0. 0. 1 z Sample Netnumbers circa 1981 (RFC 790) z Internet Address z Also demuxed by 16 -bit TCP port z 001. rrr z 002. rrr number z 003. rrr z Network Address Translators (NATs) z 004. rrr z 005. rrr fudge injectivity – address collisions 19 August 1999 Internet Scale Namespaces: A Survey z 007. rrr poss. Name BBN-PR SF-PR-1 BBN-RCC SATNET SILL-PR CHAOS Network BBN Packet Radio Network SF Packet Radio Network BBN RCC Network Atlantic Satellite Net Ft. Sill Packet Radio 12 MIT CHAOS Network

http: //128. 192. 213/Itinerary/NQSS 5 A 90: ca: fe: de: ca: de z MAC Media/Multiple Access Control z Resolved by LAN Address Res. Protocol z Hierarchical Org. Unique ID + device ID z Format by IEEE 802. 3 &c z Entries by IEEE Registration Authority z Internationalization none z Number 248 = 1014 z Lifetime 108 - 1010 sec z ARP & RARP resolve Ethernet Addresses to/from Internet Addresses z Blocks of 4, 096 are sold to Ethernet adapter manufacturers for $500, after a $1, 250 “initiation” fee z What portions of this space are reserved? z Maps onto individual link endpoints (network stations) z Absolutely must be link-unique z Reverse ARP, RFC 903, June 1984 y Analogous MACs for ATM, Token Ring z Address Resolution Protocol, RFC 826, November 1982 y Announce own IP, request target IP’s MAC y Broadcast a request to get an IP address z ARP uses a simple lookup table 19 August 1999 Internet Scale Namespaces: A Survey 13

1 -800 -296 -3892 z PPPAddress Phone number z Resolved by Point-to-Point Prot. + modem z Hierarchical Left-to-right z Format by ITU E. 164 (Bell, 1947) z Entries by N. Am. Numbering Plan z Internationalization country codes z Number 1010 z Lifetime 105 - 109 sec z PPP Link driver itself operates over a phone circuit z Phone numbers hierarchically assigned z Telephonesresolve phone numbersinto circuits z Networks can be countries, too: Iridium satellite phone subscribers get +8816 z Phone numbers are represented in many common forms y ITU form: +1 -(626)-806 -7574 y DNS form: 4. 7. 5. 7. 6. 0. 8. 6. 2. 6. 1. tpc. int y URI form: phone: //16268067574/ x Tel: , fax: and modem: proposals, too y Geocoded: MAdison 437 (archaic) z Reserved portions y 555 testing & information services y 800 -855 -xxx Teletype toll-free info (TDD) z Caller-ID (ANI) reveals source address z Reverse lookup possible too y Nation, Area, Exchange, Subscriber 19 August 1999 Internet Scale Namespaces: A Survey z Absolutely must be world-unique 14

http: //www. united. com/Itinerary/NQSS 5 A z z z URL Pathname Resolved by Web Server Hierarchical Left-to-right Format by IETF RFC 2396 Entries by Server Administrator Internationalization US-ASCII (UTF-8) z Number 1010 + z Lifetime 101 - 108 sec z Web Servers resolve. Pathnamesinto HTTP Representations(replies) z Becomes BASE for resolving relative URLs z Maps onto individual resources z Can have properties (DAV) y But representation on the wire may still depend on content language, media type, authorization, &c. y This resource identifier resolves to the HTML outline of a page that is completed with several subsidiary resources (graphics, sounds, style sheets) z Can be a collection resource (DAV) y Supports enumeration, searching of directories y Such as Author, Words, Cost… x Which come from yet other property namespaces. . . z Must be server-unique; may be aliased z No versioning by default; can rot 19 August 1999 Internet Scale Namespaces: A Survey 15

http: //www. united. com/Itinerary/NQSS 5 A /usr/local/www/db/reservations. msql z z z z Filename Resolved by Web Server Hierarchical Left-to-right Format by Operating System Entries by Content Administrator Internationalization ad-hoc Number 1 - 106 Lifetime 101 - 108 sec z Web Servers resolve path components into filenames z Operating Systems resolve filenames into inodes z Disk Drivers resolve inode into track+sector addresses z Disk Controllers resolve track+sector addresses into data blocks z Maps onto individual files or processes z Server typically rewrites the URL by substituting root, user directory, extension z Security and accounting controlled by OS, not necc. the web server’s control 19 August 1999 Internet Scale Namespaces: A Survey 16

http: //www. united. com/Itinerary/NQSS 5 A z PNR Passenger Name Record z Resolved by Airline Distribution System z Atomic Alphanumeric picture string z Format by Length, pattern vary by GDS z Entries by Airline z Internationalization none z Number 108 + z Lifetime 101 - 107 sec z A Reservation Database Process resolves PNR keys into Reservation records z Talking to a process, not a bag of bits. z Interoperability standards are crucial for interline ticketing, but still fragmented by each GDS (Sabre, Apollo, Amadeus, etc). z Maps onto individual reservations y Every booking and confirmation is kept until flight time z Resolves to an IATA+Airline ticket number z GDS = Global Distribution System y Permanent identifier lasts. Internet Scale Namespaces: A Survey for years 19 August 1999 z Must be unique over itsdesign lifetime 17

Anatomy of a URI 19 August 1999 Internet Scale Namespaces: A Survey 18

A URI resolves to an HTTP Message z Zooming further in, an HTTP response message uses several more namespaces z Method Standards-track RFC z Reply Code RFC; new. IANA Registry z Content-Type IANA Media-Type z Content-Language ISO language codes z Character-set IANA ref to ISO Charset z ETag Uniquely identify the resource z PICS label URI pointing to schema z Digital Signature z z GET /PICS/DSig/Overview HTTP/1. 1 Host: www. w 3. org HTTP/1. 1 200 OK Date: Wed, 18 Aug 1999 21: 22: 41 GMT Server: Apache/1. 3. 6 (Unix) PHP/3. 0. 11 Content-Location: Overview. html Vary: negotiate Last-Modified: Mon, 06 Apr 1998 20: 24: 44 GMT ETag: "2 def 30 -a 2 e-35293 a 0 c; 35293 a 2 f” Accept-Ranges: bytes Content-Length: 2606 Content-Type: text/html; charset=iso-8859 -1 … <\/a>") //-->