The World Wide Telescope a Digital Library Prototype.ppt

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1、The World Wide Telescope a Digital Library Prototype,Jim Gray, Microsoft Research Alex Szalay, Johns Hopkins University,Talk at OCLC Dublin, OH, 17 May 2004 http:/ Model of Library Science ,Alexandria Gutenberg(Melvil) Dewey Decimal MARC (Henriette Avram) Dublin Core,Yes, I know there have been othe

2、r things.,Dublin Core,Elements Title Creator Subject Description Publisher Contributor Date Type Format Identifier Source Language Coverage Rights,Elements+ Audience Alternative TableOfContents Abstract Created Valid Available Issued Modified Extent Medium IsVersionOf HasVersion IsReplacedBy Replace

3、s IsRequiredBy Requires IsPartOf HasPart IsReferencedBy References IsFormatOf HasFormat ConformsTo Spatial Temporal Mediator DateAccepted DateCopyrighted DateSubmitted EducationalLevel AccessRights BibliographicCitation,Encoding LCSH (Lb. Congress Subject Head) MESH (Medical Subject Head) DDC (Dewey

4、 Decimal Classification) LCC (Lb. Congress Classification) UDC (Universal Decimal Classification) DCMItype (Dublin Core Meta Type) IMT (Internet Media Type) ISO639-2 (ISO language names) RFC1766 (Internet Language tags) URI (Uniform Resource Locator) Point (DCMI spatial point) ISO3166 (ISO country c

5、odes) Box (DCMI rectangular area) TGN (Getty Thesaurus of Geo Names) Period (DCMI time interval) W3CDTF (W3C date/time) RFC3066 (Language dialects)Types Collection Dataset Event Image InteractiveResouce Service Software Sound Text PhysicalObject StillImage MovingImage,Thanks!,Whats Happening?,We are

6、 drowning in information Single fixed hierarchy is hopeless Cant organize/find things in a simple tree HOPE: “schematized storage” Objects have “Dublin-like” facets Most facets acquired automatically (email, photo, doc,) Users add annotations and relationships Librarians call this accession Automate

7、 accession as much as possible Folders/directories are standing queries Organization is “search based” demo sis. Interesting (public) research projects Stuff Ive Seen: http:/ MyLifebits: http:/ Longhorn product embraces & extends these ideas.,The World Wide Telescope a Digital Library Prototype,Jim

8、Gray, Microsoft Research Alex Szalay, Johns Hopkins University,Talk at OCLC Dublin, OH, 17 May 2004 http:/ what about the talk I promised you?,The Talk,Libraries morphing to integrated text + data (you know that) Dublin Core is bedrock, but many issues remain. (you know that) WWT: All Astronomy data

9、 and literature online and integrated Problems Librarians have grappled with for centuries: curation, preservation, indexing, access, summarization. Overview of the World-Wide Telescope as a digital library Focus on metadata, schema, curation, and preservation Candidly, we have more problems than so

10、lutions, but the data is arriving and we are doing the best we can.,New Science Paradigms,Thousand years ago: science was empiricaldescribing natural phenomena Last few hundred years: theoretical branchusing models, generalizations Last few decades: a computational branchsimulating complex phenomena

11、 Today: data exploration (eScience)synthesizing theory, experiment and computation with advanced data management and statistics,The Big Picture,Experiments & Instruments,Simulations,facts,facts,answers,questions,Data ingest Managing a petabyte Common schema How to organize it? How to reorganize it H

12、ow to coexist with others,Data Query and Visualization tools Support/training Performance Execute queries in a minute Batch (big) query scheduling,?,The Big Problems,Literature,Other Archives,facts,facts,The Virtual Observatory,Premise: most data is (or could be online) The Internet is the worlds be

13、st telescope: It has data on every part of the sky In every measured spectral band: optical, x-ray, radio As deep as the best instruments (2 years ago). It is up when you are up The “seeing” is always great Its a smart telescope: links objects and data to literature Software is the capital expense S

14、hare, standardize, reuse,Why Is Astronomy Special?,Almost all literature online and public ADS: http:/adswww.harvard.edu/ CDS: http:/cdsweb.u-strasbg.fr/Data has no commercial valueNo privacy concerns, freely share results with othersGreat for experimenting with algorithmsIt is real and well documen

15、tedHigh-dimensional (with confidence intervals)Spatial, temporalDiverse and distributedMany different instruments from many different places and many different timesThe community wants to share the dataThere is a lot of it (soon petabytes),IRAS 100m,ROSAT keV,DSS Optical,2MASS 2m,IRAS 25m,NVSS 20cm,

16、WENSS 92cm,GB 6cm,Like all sciences, Astronomy Faces an Information Avalanche,Astronomers have a few hundred TB now 1 pixel (byte) / sq arc second 4TB Multi-spectral, temporal, 1PB They mine it looking for new (kinds of) objects or more of interesting ones (quasars), density variations in 400-D spac

17、e correlations in 400-D space Data doubles every year Data is public after 1 year So, 50% of the data is public Same access for everyone,Publishing Data,Exponential growth: Projects last at least 3-5 years Data sent upwards only at the end of the project Data will never be centralized More responsib

18、ility on projects Becoming Publishers and Curators Data will reside with projects Analyses must be close to the data,How to Publish Data: Web Services,Web SERVER: Given a url + parameters Returns a web page (often dynamic) Web SERVICE: Given a XML document (soap msg) Returns an XML document (with sc

19、hema) Tools make this look like an RPC. F(x,y,z) returns (u, v, w) Distributed objects for the web. + naming, discovery, security, Internet-scale distributed computing,Your program,Data In your address space,Web Service,soap,object in xml,Your program,Web Server,http,Web page,The Core Problem: No Ec

20、onomic Model,The archive user has not yet been born. How can he pay you to curate the data? Q: The Scientist gathered data for his own purpose. Why should he pay (invest time) for your needs? A: thats the scientific method Curating data (documenting the design, the acquisition, and the processing) i

21、s very hard and there is no reward for doing it. Results are rewarded, not the process of getting them. Storage/archive NOT the problem (its almost free) Curating/Publishing is expensive. Better standards & tools lower costs,Data Inflation Data Pyramid,Level 1A Grows 5TB pixels/year growing to 25TB

22、2 TB/y compressed growing to 13TB 4 TB today (level 1A in NASA terms),Level 2 Derived data products 10x smaller But there are many catalogs. Publish new edition each year Fixes bugs in data. Must preserve old editions Creates data pyramid Store each edition 1, 2, 3, 4 N N2 bytes Net: Data Inflation:

23、 L2 L1,What SDSS is Doing: Capture the Bits,Best-effort documenting data and process. Publishing data: often by UPS ( 5TB today and so 5k$ for a copy) Replicating data on 3 continents. EVERYTHING online (tape data is dead data) Archiving all email, discussions, . Keeping all web-logs. Now we need to

24、 figure out how to organize/search all this metadata.,Making Discoveries,Where are discoveries made? At the edges and boundaries Going deeper, collecting more data, using more colors. Metcalfes law: quadratic benefit Utility of computer networks grows as the number of possible connections: O(N2) Dat

25、a Federation: quadratic benefit Federation of N archives has utility O(N2) Possibilities for new discoveries grow as O(N2) Current sky surveys have proven this Very early discoveries from SDSS, 2MASS, DPOSS,Federation,Global Federations,Massive datasets live near their owners: Near the instruments s

26、oftware pipeline Near the applications Near data knowledge and curation Each Archive publishes a (web) service Schema: documents the data Methods on objects (queries) Scientists get “personalized” extracts Uniform access to multiple Archives A common global schema,Schema (aka metadata),Everyone star

27、ts with the same schema Then the start arguing about semantics. Virtual Observatory: http:/ Metadata based on Dublin Core: http:/ Universal Content Descriptors (UCD): http:/vizier.u-strasbg.fr/doc/UCD.htx Captures quantitative concepts and their units Reduced from 100,000 tables in literature to 1,0

28、00 terms VOtable a schema for answers to questions http:/www.us-vo.org/VOTable/ Common Queries: Cone Search and Simple Image Access Protocol, SQL Registry: http:/ still a work in progress.,Data Access is Hitting a Wall,You can GREP 1 MB in a second You can GREP 1 GB in a minute You can GREP 1 TB in

29、2 days You can GREP 1 PB in 3 yearsOh!, and 1PB 4,000 disksAt some point you need indices to limit search parallel data search and analysis This is where databases can help,You can FTP 1 MB in 1 sec You can FTP 1 GB / min (= 1 $/GB) You can FTP 1 TB in 2 days and 1K$ You can FTP 1 PB in 3 years and

30、1M$,Current practice of data download (FTP/GREP) will not scale to petabyte datasets,Smart Data,Better Data Schemas There is too much data to move around Do data manipulations at database Build custom procedures and functions into DB Unify data Access & Analysis Examples Temporal and spatial indexin

31、g Pixel processing Automatic parallelism Auto (re)organize Scalable to Petabyte datasets,Move Mohamed to the mountain, not the mountain to Mohamed.,Next-Generation Data Analysis,Looking for Needles in haystacks the Higgs particle Haystacks: dark matter, dark energy, turbulence, ecosystem dynamics Ne

32、edles are easier than haystacks Global statistics have poor scaling Correlation functions are N2, likelihood techniques N3 As data and computers grow at Moores Law, we can only keep up with N logN A way out? Relax optimal notion (data is fuzzy, answers are approximate) Dont assume infinite computati

33、onal resources or memory Requires combination of statistics & computer science,The Sloan Digital Sky Survey,Goal Create the most detailed map of the Northern Sky to-date 2.5m telescope 3 degree field of view Two surveys in one 5-color images of of the sky Spectroscopic survey of a million galaxies a

34、nd quasars Very high data volume 40 Terabytes of raw data 10 Terabytes processed All data public,The University of Chicago Princeton University The Johns Hopkins University The University of Washington New Mexico State University University of Pittsburgh Fermi National Accelerator Laboratory US Nava

35、l Observatory The Japanese Participation Group The Institute for Advanced Study Max Planck Inst, HeidelbergSloan Foundation, NSF, DOE, NASA,SkyServer,A multi-terabyte database An educational website More than 50 hours of educational exercises Background on astronomy Tutorials and documentation Searc

36、hable web pages Easy astronomer access to SDSS data. Prototype eScience lab Interactive visual tools for data exploration,http:/skyserver.sdss.org/,Demo SkyServer,atlas education project Mouse in pixel space Explore an object (record space) Explore literature Explore a set Pose a new question,SkyQue

37、ry (http:/ Query tool using a set of web services Many astronomy archives from Pasadena, Chicago, Baltimore, Cambridge (England) Has grown from 4 to 15 archives, now becoming international standardAllows queries like:,SELECT o.objId, o.r, o.type, t.objIdFROM SDSS:PhotoPrimary o, TWOMASS:PhotoPrimary

38、 tWHERE XMATCH(o,t)2,Demo SkyQuery Structure,Each SkyNode publishes Schema Web Service Database Web Service,Portal is Plans Query (2 phase) Integrates answers Is itself a web service,MyDB: eScience Workbench,Prototype of bringing analysis to the data Everybody gets a workspace (database) Executes an

39、alysis at the data Store intermediate results there Long queries run in batch Results shared within groups Only fetch the final results Extremely successful matches work patterns,National Center Biotechnology Information (NCBI) A Better Example,Pubmed: Abstracts and books and Genbank: All Gene seque

40、nces deposited BLAST and other searches Website to explore data and literature Entrez: unifies many databases with literature (books, journals,) Organizes the data,The Big Picture,Experiments & Instruments,Simulations,facts,facts,answers,questions,Data ingest Managing a petabyte Common schema How to

41、 organize it? How to reorganize it How to coexist with others,Query and Vis tools Support/training Performance Execute queries in a minute Batch query scheduling,?,The Big Problems,Literature,Other Archives,facts,facts,The Talk,Libraries morphing to integrated text + data (you know that) Dublin Core

42、 is bedrock, but many issues remain. (you know that) WWT: All Astronomy data and literature online and integrated Problems Librarians have grappled with for centuries: curation, preservation, indexing, access, summarization. Overview of the World-Wide Telescope as a digital library Focus on metadata

43、, schema, curation, and preservation Candidly, we have more problems than solutions, but the data is arriving and we are doing the best we can.,Education,Educational Projects, aimed at advanced high school students, but covering middle school Teach how to analyze data, discover patterns, not just astronomy 3.7 million project hits, 1.25 million page views of educational content More than 4000 textbooks On the whole web site: 44 million web hits Largely a volunteer effort by many individuals Matches the 2020 curriculum,