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Neonet A metadata application demonstrating SatCAST

Neonet A metadata application demonstrating SatCAST. Edwin Wisse & Rob van Swol National Aerospace Laboratory. Overview. History: Sawa and SatCAST demonstrations Neonet network The software Metadata gathering and distribution Using multicast to distribute metadata Demonstration.

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Neonet A metadata application demonstrating SatCAST

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  1. NeonetA metadata application demonstrating SatCAST Edwin Wisse & Rob van Swol National Aerospace Laboratory

  2. Overview • History: Sawa and SatCAST demonstrations • Neonet network • The software • Metadata gathering and distribution • Using multicast to distribute metadata • Demonstration

  3. 1998: Sawa demonstration • Demonstrated IP over satellite & caching, no multicast • Application: Neonet version 0 • No XML yet: HTML based • Built a single site combining and crosslinking pages from different sites about a common theme: remote sensing • Site was replicated on different UNEP sites by retrieving databases with HTML files.

  4. 2000: SatCAST demonstration • Multicast capability • Demonstration application: Neonet version 2 • Using structured metadata in XML • Network with nodes about different topics in remote sensing • Demonstration: • Neonet functionality • Database synchronisation by multicast over satellite link.

  5. Neonet: Background • Netherlands Earth Observation Network • Allow (Dutch) users of remote sensing data access to information in the Netherlands and abroad. • Keep information at the provider • Connect to other metadata infrastructures • CEOS IDN • CEO

  6. Neonet nodes A Neonet node is a website with supporting software. A node covers a self-chosen theme in remote sensing Users can search for and enter metadata in a fixed format. Format is derived from the CEO recommendation on metadata.

  7. Neonet network (1) • The network is a group of nodes running Neonet software • Node maintainer(s) decide what is appropiate information • A node servers a user community, example: • atmospheric chemistry • water management • Nodes are organised hierarchically • General node at top: APEX

  8. Neonet network (2)

  9. Metadata flow Node email Metadata entered at a specialised node is sent automatically to the nodes above. E-mail is available everywhere Even behind firewalls Node email Node metadata file Provider

  10. Neonet software • Retrieve metadata from provider by HTTP • Version 0: HTML pages • Version 1: metadata in XML pages (CEO like format) • Uses CEO standard for metadata • Status: version 2 released october (but used in SatCAST) • Available for interested institutes

  11. Software: elements • A Neonet node runs: • Webserver • Database • Servlet package • Java application for database sync and metadata retrieval • Nodes can be installed on systems running Windows and a number of Unix systems (SGI, Solaris, Linux).

  12. SatCAST setup • 3 top level nodes with local databases and no sub-nodes • Synchronisation: • Nodes synchronise their databases using HTTP requests • Added for SatCAST • Multicast aspect: • New or changed XML files get broadcasted to all nodes • Nodes retrieves files and records from local cache • No multicast for servlet results, only for database synchronisation

  13. Synchronisation Node Node SatCAST Multicast XML admin XML admin A node exports its database to a set of XML files, so it can be accessed using HTTP Node

  14. Demonstration • Three nodes were set up, all are Apex nodes. • Check each other every 10 minutes. • Metadata entered at 1 node is found and retrieved by the others • No instant result • Short demonstration of other Neonet features • Questions?

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