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I

HLA: Where We Are Today

Warren MillerTechnology Showcase 2007

15 March 2007

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IEnhanced Science Value from the HST Archive• Why HLA? And Why Now?

– Era of each scientist processing data from raw to finished product is past

– Scientists need access to fully processed data and high-level products (e.g., catalogs)

– Optimize community access to expertise developed by instrument teams and STScI development

– Upward trend in archival research using HST data• How will the HLA be different from other astronomical

services?– Products have added science value, beyond removal of

instrument signatures– Science products (images, spectra, catalogs) ready for

instant use– Science products served in seconds– Apply developments in browser technology and mind-set to

astronomical research

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IHubble Legacy Archive - Overall Concept

Archive User

Safe Store Core Archive

…

… … …

Extended Archive

Calibrated Data

Calibrated Data

Catalogs

Derived Products

• Process data from HST

• Re-process requested data for users

• All data are available

• Automatic updates from core

• Improved astrometry• Object catalogs• Space/time “footprint”

service• Cutouts• Other high-level-products

• Retrieval times: seconds to minutes

Archive User

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I Brief History

• Initial Study completed in May 2005– Cancellation of SM-4 prompted consideration of other

techniques for dramatically improving HST scientific return– Position paper presented to HST Mission Office

• Independent Project Team formed November 2005– Expertise from around the Institute and across the project

lifecycle brought together

• Prototyping and studies undertaken to explore key ideas– Rapid, agile explorations of science products, services, and

infrastructure elements

• Demonstrations and presentations made to HSTP– Study Report Presentation on February 22, 2007– Ready to proceed with preparing a release

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I HLA Team

• Faith Abney• Ken Anderson• Carol Christian• Alberto Conti• Niall Gaffney• Anne Gonnella• Gretchen Greene• Bob Hanisch• Steve Hulbert• Helmut Jenkner• Tim Kimball• Anton Koekemoer• Karen Levay

• Kevin Lindsay• Steve Lubow• Brian McLean• Warren Miller• Lee Quick• Fred Romelfanger• John Schultz• John Scott• Thomas Walker• Rick White• Brad Whitmore• CADC• ST-ECF

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I Technology and the HLA

• Science products, not S/W and technology, are the focus of the HLA

• However, technology will play an important role in delivering added science value– Help meet evolving user expectations of archive capabilities– Contributes to lower project labor costs

• Programmatic and architectural strategies broaden the types of technologies that might be applied to the HLA– IPT fosters agility and risk taking: can try out newer

technologies– HLA is decoupled from critical HST ground systems

• Highlights of some important technologies for the HLA follow– Search Google/Wikipedia for more information/links to these

topics

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I Web 2.0

• As it relates to web pages, generally refers to non-static content with rich user interaction

• Provides a standalone-application-like experience in the web browser

• Some common techniques– AJAX– CSS– XHTML / XSLT– Mashups

• Relevance to the HLA– Alternative to distributing a standalone UI application to

users• Reduces complexity (for us and the user)• Reduces number of different platforms to support

– Browser-side capabilities can mean less server-side loading (relative to legacy web)

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I Web Services / SOA

• Distributed computing is a useful approach to many situations– Well-designed interfaces, reusable components, and platform

independence are even better• Web services are a recent evolution of distributed

computing techniques– Making them conform to the principles of Service-Oriented

Architecture (SOA) further enhances their potential• Loosely-coupled, interoperable services based on a variety of

technologies woven together relatively quickly – Refers to machine-to-machine communications over the web

using (typically) XML-based messages and interface descriptions

• Relevance to the HLA– Virtual Observatory (VO) operates largely as a collection of web

services– SOA principles make web service paradigm applicable to the

server-side of the system

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IWeb Application Development/ Frameworks• Multi-tier architectures fit the web

services/SOA model well– Client/server systems, like the

browser/web server case, often are modeled this way

– Provides a good degree of independence to each tier

• Integrated Development Environments (IDEs) ease development in these frameworks

• Popular examples– MS’s ASP.NET– Sun’s J2EE

• Relevance to the HLA– Archive naturally resolves to this sort

of architecture (UI, archive logic, database)

– Development effort reduced with tight IDE/framework integration

– Simplifies (re)use of existing services– Rapid adaptation to changing

requirements

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I Metadata / Tags

• “Tag” or “Metadata” refers to a keyword or terms associated with some information– FITS header is a good example of tagging

• In the Web 2.0 context, tagging has taken on a degree of informality and dynamism– Tags not part of a formal metadata system– Tags on information change over time

• Value comes from information finding through searching of the indexed and associated tags

• Popular sites employing tagging– Gmail– Del.icio.us– Flickr– Youtube

• Relevance to the HLA– Means of generating a coordinate, object name/type, PI, … view of

a heretofore exposure-based HST data archive