GO-ESSP 2008 1

The Earth System GridThe Challenges of Building Web Client Geo-Spatial Applications

Eric NienhouseNCAR

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Outline

A Case Study of UI Development

Brief Overview of the Earth System Grid Focus on User Interface for Visualization Present User Feedback and Technical Challenges Consider Next Steps in UI Development

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What is the Earth System Grid?

Distributed System of Gateways and Data Nodes

Access Control and User Management RDF Metadata Search Data Access and Download Collection Browsing Collection Tagging and Annotation Deep Storage Data Transfer and Monitoring Visualization and Data Products Model Comparison Use Metrics and Reporting

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User Interface for Visualization

Basic Requirements Provide ability to visually identify data of interest Usable by wide range of technical abilities Support future needs of comparison and sub-setting Integrate with gateway context and look and feel Flexible enough to adapt to new backend services Functional enough to generate feedback

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User Interface for Visualization

Alpha Process: How We Started

Lightweight client based on JavaScript/Ajax Use Live Access Server to deliver visualization OpenDAP and aggregation capabilities of TDS Develop within Java/Spring gateway framework Use known Google Maps API

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User Interface for Visualization

Initial Prototype:

Google Map API Custom selection overlay Dojo JavaScript Toolkit Tree based selection Ajax application with JSON Proxy client to access LAS LAS Armstrong v 0.4 TDS v 3.16

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LAS UI Proxy

Controller

ESG-CET Portal

HTTP (XML)

File I/O

HTTP (HTML)

HTTP (Subset Service)

HTTP (HTML)

HTTP (JSON)

HTTP

LAS

HTTP (JSON)

HTTP

SOAP

HTTP/ OpenDAP

Backend Service (Ferret)

XML Metadata (Configuration)

Local File(s) Thredds Data Server

LAS

Product Server

(Armstrong)

Client (web browser)

Google Map

Web Service

Component Communication

Proxy Client:

Request pass through to LAS Avoid browser security Augments LAS capabilities Preserves gateway context Allows Flexibility

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Initial Prototype:

Feedback and Lessons Learned:

Single page UI is an improvement over wizard Screen real estate must be used wisely Tree based UI tedious for some User reset of region is critical for usability Visualization tools excite people and yield feedback People look closely at dataset and variable names Visualization helps identify data problems Dojo toolkit is good but poorly documented TDS aggregations + LAS is a powerful combination Configuration of TDS and LAS must be automated

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User Interface for Visualization

Back to the Drawing Board:

Review of feedback Wire-frame drawings Basic formal specification

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User Interface for Visualization

Second Prototype:

YUI user interface Improved real estate use Improved state indication Pre initialized dataset and variable Ajax application with JSON Proxy client access to LAS Place holder for sub-setting UI LAS V7 Beta F-TDS v 3.16

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Second Prototype:

Feedback and Lessons Learned:

Differing communities have diverse abilities Modeling community prefers to access data directly Simplified work flows needed for some user groups Combine selection and presentation UI for efficiency Averaging and analysis functions are desired by many Plot legends, times and source data labels are important Variable names must be consistent TDS + NcML critical in making data “visualize-able” Delayed delivery is important consideration for UI Saving regions of interest and product result are desired Polar projections unlikely to be supported by Google Maps Firebug extremely useful debugging tool JavaScript frameworks produce browser incompatibilities

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Next Steps:

What will we do with these findings?

Collect more feedback from ESG test-bed deployment. Consider formalizing user studies and observations Expose more analysis features of LAS Add multi-variable selection for analysis, sub-setting, layering Integrate geographic selection with search tools Explore more “polar capable” UI components Explore WMS visualization capabilities Exploit more of the F-TDS analysis, sub-setting capabilities Continue to refine and improve quality of the UI Encourage community convergence on UI best practices

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Thank You!

In particular:

Ansley Manke, PMEL Roland Schweitzer, PMEL John Caron, UNIDATA Collaborators at ANL, LBNL, PCMDI and many others…

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Questions?