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.netwww.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 Controls Set Policy Set Goals Assess- ment Air Quality

5. 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 Provider Push User Pull Flow of Data Flow of Control AQ DATA METEOROLOGY EMISSIONS DATA Informing Public AQ Compliance Status and Trends Network Assess. Tracking Progress Data to Knowledge Transformation Data Refining & Mediation Services

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_img_width src_img_height src_margin_rightsrc_margin_left src_margin_top src_margin_bottom src_lon_min src_lat_max src_lat_min src_lon_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 Transparent colors for overlays RGB(89,140,255) RGB(41,117,41) RGB(23,23,23) RGB(0,0,0)

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

11. Web Service Benefits: Creating a Custom View From Multiple Layers in a Page of XML Name & title the new view Identify each of 4 layers

12. 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 Data Sources Controls Displays I/O Layer Device Drivers Wrappers App State Data Flow Interpreter Core Web Services WSDL Ports

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.