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Data Access Task Team - First Meeting

This is the agenda and proposal for the first meeting of the Data Services Task Team, discussing concepts and implementations for direct access to data in real-time. The purpose is to develop a conceptual model for accessing and manipulating Earth Observation data in a distributed computing environment.

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Data Access Task Team - First Meeting

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  1. Data Access Task Team- First Meeting - • George Percivall • Percivall@harp.gsfc.nasa.gov • March 1999

  2. Agenda - Wed, March 10 - • 1300 Background on Task Team - 30 minutes • 1330 Survey of Data Access Concepts - 30 minutes • 1400 Implementations • DIAL - Suresh, RSTX - 20 minutes • DODS - Richard Chinman, UCAR - 20 minutes 1440 (break 15 minutes) • OGDI - T. Fisher, CCRS - 20 minutes • Example of OGC Services - S. Shimada, Hitachi (Friday morning) • 1515 Open Discussion 40 minutes? • Revisit Purpose of Task Team • Potential Deliverables • Contributing Members • 1600 Adjourn

  3. Data Services Task Team - Proposal • Background • Users want direct access to the data in real time • Build on Access Subgroup methods to locate and order data • Build on Data Subgroup developments in data interoperability • Relate CEOS data services needs to ISO TC 211 and OGC activities • Draft Purpose Develop a conceptual model of EO needs for accessing and manipulating data in real time over a distributed computing environment. EO needs and technical feasibility determined through: review of existing implementations for direct access to data; review of existing and emerging standards; and the expertise of the task team. • Approach • Hold First meeting during the March 99 WGISS Subgroup meetings • First meeting to develop purpose and approach for task team • Submit pro forma for Task Team to WGISS

  4. Survey of Data Access Concepts • Scenario • Access Topics • Data Interchange • Services • Portrayal • Revenue Model for Access • Products/Implementations • http://sgt.sgt-inc.com/~george/CEOSacc/CEOSmain.html

  5. Reference Model Architecture with Three Tiers Web Browser Application Server Catalog Services Service Registry Portrayal Services Data Provider Data Provider Data Provider

  6. Data Access Scenario • User identified Landsat scenes of interest at a Data Provider using a Catalog Service 1. User interacts with Service Registry to find a land cover Classification Service and determines what parts of Landsat Data are needed 2. User reviews services available from the Landsat Data Provider: e.g., sub-selection on bands and compression 3. User requests Landsat data be subsetted on bands 1-5, compressed, and made available for on-line retrieval 4. User provides the Classification Service with a reference to data created in Step 3 5. Classification Service performs the classification and creates output available for on-line retrieval 6. User locates a USGS Quadrangle Map of the geographic area to use as base map 7. User provides Portrayal Service with references to Landsat images (step 3), Classification results (step 5) and USGS base map (step 6) 8. User provides Portrayal service with parameters for generation of image 9. Portrayal service creates the image, available for access by the User's browser.

  7. Topics in Data Access • Data Interchange • schema • encoding • Access Services • taxonomy • service request framework • Portrayal • Revenue Model

  8. System A System B Application schema I Internal schema A Internal schema B Internal database Internal database MAI MIB i i Encoding service R Encoding service R-1 d d File system Transfer services Transfer services File system Defines Data transfer Data flow System boundary System boundary Data Interchange

  9. Schema and Encoding • Application Schema built from Conceptual Schemas • Spatial Schema • Temporal Schema • Portrayal Schema • Quality Schema • Feature Catalog • Metadata Schema • Encoding of Schemas • All TC 211 Schema are defined using UML • All Schemas are transferred using XML • XML Metadata Interchange (XMI) under consideration • Encoding of Data • Encoded using XML? • Basic Data Types in TC 211 not sufficient for Gridded Data TC 211 Conceptual Schema

  10. Geospatial Information Access Services Feature Generalization Services Geospatial Catalog Services Geospatial Information Extraction Services Geospatial Coordinate Transformation Services Geospatial Annotation Services Imagery Manipulation Services Geospatial Manipulation Services Imagery Exploitation Services Geospatial Analysis Services “Exploits a Feature Collection to derive mission-oriented quantitative results. “ Geospatial Registration and Adjustment Services Geospatial Symbolization Management Services Geospatial Dissemination Services Image Map Generation Services Image Synthesis Services Image Understanding Services Geospatial Display Services TC 211 & OGC Services Taxonomy

  11. ECS Data Type Services (1 of 2) • Subsetting and Subsampling • by geographic location (x, y, z) based on a given 3- D polygon where the z- dimension is fixed. • based on complete rows of the swath. • based on parameter. • based on time • Mean, Median and Mode of like parameters with a data product • based on geographic location (x, y, z) (spatial with rectangular boundaries). • based on a given set of complete rows of the swath. • across time

  12. ECS Data Type Services (2 of 2) • Map projections from geographic latitude and longitude coordinates • to Universal Transverse Mercator map projection. • to Polar Stereographic map projection. • to Space Oblique Mercator map projection. • to Goodes Interrupted Homosoline map projection. • Display • time series plot browse data. • scatter plot browse data. • browse image data. • set of browse image data. • Data Dissemination • reformat the data set in ECS HDF format. • supply browse data for Data Dissemination • supply the data product for Data Dissemination. • metadata associated with the data product for Data Dissemination.

  13. Data Services by Doug Ilg

  14. Distributed Computing • Distributed Computing Platforms • CORBA- IIOP • COM • WWW - TCP direct • Service Request Framework • If everything is a Schema, then SQL answers all (??) • If SQL is not sufficient, then a general request model is is needed: • Abstractions of request types (which can be subclassed) • State diagram for long-running requests (long with respect to human interaction) • Synchrounous and asynchrounous communicaitons • Create and track service requests • Accept call backs (e.g. event notifications) • factories for creating server objects (and the client counter parts) dynamically.

  15. Portrayal Example from BBN OpenMap™ in context of OGC WWW Mapping

  16. Revenue Model for Access • Free to User • Demo version: ala translator on Alta Vista • Supported by Advertisement • Supported by an Agency • License problem: Renting an application typically not allowed • Charge the User • Micropayment: ecash, cybercash, cybercoin • Subscription service: Pay in advance • Credit Card

  17. Products/Implementation Examples • HDF API libraries • NetCDF API libraries • DIAL • DODS • OGDI • CubeWerx Inc. • ESRI SDE • Microsoft TerraServer • PCI EASI/PACE • Grid Analysis and Display System (GrADS) • Research Systems Inc, e.g., IDL • Environment for Visualizing Images (ENVI) • Khoros • NOAAServer Scientific Graphics Toolkit (SGT) Presentations today

  18. Recommendations • New Work Items in TC 211 • Imagery and Gridded Data • Coverages (based on OGC Coverages work) • Contribute Earth Observation (EO) needs to Schema and Encoding • Abstract data models for EO, e.g., grid, swath, point • Basic data types for EO data • Develop EO Services Taxonomy • Develop based on current services in EO Products • Submit to TC 211 and OGC as CEOS input • Review OGC Portrayal demo • Does Portrayal demo work for Earth Observation Data?

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