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Web Services Implementation Case Study: DataFed Air Quality Data & Services

Web Services Implementation Case Study: DataFed Air Quality Data & Services. Project Coordinators: Software Architecture: R. Husar Software Implementation: K. Höijärvi Data and Applications: S. Falke, R. Husar Center for Air Pollution Impact and Trend Analysis (CAPITA)

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Web Services Implementation Case Study: DataFed Air Quality Data & Services

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  1. Web Services Implementation Case Study:DataFed Air Quality Data & Services Project Coordinators: Software Architecture: R. Husar Software Implementation: K. Höijärvi Data and Applications: S. Falke, R. Husar Center for Air Pollution Impact and Trend Analysis (CAPITA) Washington University, St. Louis, MO 63130 April 2005, rhusar@me.wustl.edu

  2. Agenda • Project Overview • Motivation • Approach • Web Services Provided • WS Implementation Challenges • WS Benefits • Conclusion

  3. DataFed Overview • Vision • Better air quality management and science through effective use of relevant data • Goals • Facilitate flow of atmospheric data from provider to users • Support development of user-driven data processing value chains • Participate in specific application projects • Approach • Building WS-based data gateway & source wrapper utilities • Building WS-based browsers and analysis tools     • Data Provided • Air quality • Services Provided • Subsetting, fusion/layering • URL • www.datafed.net

  4. Motivation: Air Quality Management Requires a More Agile Information System • Challenges • Shift from primary to secondary pollutants • New regulatory approach based on ‘weight of evidence’ • Shift from command & control to participatory management • Broader user community • A richer set of data and analysis • Opportunities • Rich AQ data availability from EPA, NASA, NOAA available. • New information technologies Monitoring Set Policy Set Goals Assess-ment Air Quality Controls

  5. Informing Public AQ DATA AQ Compliance Data to Knowledge Transformation METEOROLOGY Network Assess. Status and Trends EMISSIONS DATA Tracking Progress Flow of Data Flow of Control Approach: Giving Users Control • Data are supplied by the provider and exposed on the ‘smorgasbord’ • Data selection and tailoring choices are made by the user Data Refining & Mediation Services Provider Push User Pull

  6. DataFed Services • Software for the User • Data catalog • Dataset Viewer/Editor • Web page collection of views (“console”) • Predefined web service chains (“mini-apps”) • Software for the Developer • *Dataset registration • *Data access • *Data processing • *Data rendering tasks • Web service chaining facility • Dataset wrapper generator * Available as a web service

  7. DataFed Services Example: Subsets/Views • Views are slices through a cube of data organized by lat, lon, altitude, and time (X,Y,Z,T)

  8. WS Implementation Challenges • Providing access via web services to data on web pages • Useful data is often embedded in web pages • Service interface to data source would be helpful • Developed wrapper to clip data from web pages • {List others here} • Need client/GUI to demonstrate WS benefits? • Reliability: Distributed computing issues: network reliability, bandwidth, etc • Chaining: Orchestrating distributed web services to act as a single application • Links: Linking users to providers and other federations (e.g. OGC, OPenDAP)

  9. Implementation Challenge: Providing Access via Web Services to Data on Web Pages • Short descriptor defines exact location of data on page • Wrapper software uses descriptor to present data on web page as a web service src_lon_min src_lat_max Image Description for Data Access: src_image_width=502 src_image_height=329 src_margin_bottom=105 src_margin_left=69 src_margin_right=69 src_margin_top=46 src_lat_min=-70 src_lat_max=70 src_lon_min=-180 src_lon_max=180 src_margin_top src_margin_left src_margin_right src_img_height Transparent colors for overlays RGB(89,140,255) RGB(41,117,41) RGB(23,23,23) RGB(0,0,0) src_img_width src_lat_min src_lon_max src_margin_bottom

  10. Web Service Benefits • Data from web services can be easily tailored and combined with other data Reflectance (SeaWiFS) Organics (IMPROVE) Air Trajectory (ATAD) Map Border (OGC)

  11. Web Service Benefits: Creating a Custom View From Multiple Layers in a Page of XML • <ServiceFlow> • <View> • <MapImageMargin ref="ws_margins" /> • <AnnotateImage ref="ws_title" icon_text="T" label="Title" execute="true" /> • <StockAnnotation ref="DATAFED" /> • <StockAnnotation ref="CIRA" /> • <AnnotateImage ref="ws_cursor_annotation" icon_text="C" label="Cursor" execute="true" /> • </View> • <Layers current="Traj_Grid" order="Traj_Grid Traj_Point Traj_Line MapImage_1"> • <Layer id="Traj_Line" dataset_abbr="VIEWS_OL" visible="false" visibility="1" click_target="true"> • <DataMapTimePoint ref="ws_data" label="Query Filter" /> • <DataMapTrajectory ref="ws_traj_render" show_data="false" icon_text="TR" /> • <AnnotateImage ref="ws_network_legend" icon_text="N" label="Network Legend" execute="true" execute_always="true" /> • </Layer> • <Layer id="Traj_Point" dataset_abbr="VIEWS_OL" visible="true" visibility="1" click_target="true"> • <DataMapPoint ref="ws_point_data" show_data="false" /> • <DataMapPoint ref="ws_store_cursor_value" /> • <RenderMapPoint ref="ws_point_render" icon_text="RP" label="point rendering" /> • <MapParamLocationAccessRender ref="ws_loc" execute_always="true" /> • <RenderLegend ref="ws_pntleg" icon_text="L" label="Point Legend" execute="true" execute_always="true" /> • </Layer> • <Layer id="Traj_Grid" dataset_abbr="VIEWS_OL" visible="true" visibility="1"> • <DataMapTimePoint ref="ws_ref_data" label="Reference Query Filter" /> • <DataMapTrajectory ref="ws_ref_traj_grid" icon_text="TG" /> • <DataMapTimePoint ref="ws_data" label="Query Filter" /> • <DataMapTrajectory ref="ws_traj_grid" icon_text="TG" /> • <MapGridOperator ref="ws_mgo" /> • <RenderMapGrid ref="ws_rg" /> • <RenderLegend ref="ws_rainbow" icon_text="L" label="Rainbow Legend" execute="true" execute_always="true" /> • </Layer> • <Layer id="MapImage_1" dataset_abbr="MapImage" visible="true" visibility="1"> • <MapImageAccessRender ref="ws_map_image" /> • </Layer> • </Layers> • </ServiceFlow> Name & title the new view Identify each of 4 layers

  12. Controls Ports Displays Data Sources App State Data Device Drivers Wrappers Flow Interpreter Core I/O Layer WSDL Web Services Implementation Challenge: Providing a GUI for WS Information • Core maintains the state and executes the data selection, access and render services • Wrappers encapsulate the heterogeneous external data sources • Device Drivers translate generic, abstract graphic objects to specific devices and formats • Ports connect the internal parameters of the program to external controls • WDSL web service description documents

  13. Conclusions • DatFed is an infrastructure for non-intrusively federating autonomous, distributed, heterogeneous datasets • Data are ‘wrapped’ for access through SOAP web services • Service chaining performs filtering, aggregation, fusion, overlay, rendering and other operations on data. • Several successful web-applications were built from the federated data and service components. • A key challenge is to link DataFed to other open data systems (e.g. OpenDAP, OGC) and to interoperate with other processing services.

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