Transcript NEONET Netherlands Earth Observation Network

Nationaal Lucht- en Ruimtevaartlaboratorium
National Aerospace Laboratory NLR
Neonet
A metadata application demonstrating SatCAST
Edwin Wisse & Rob van Swol
National Aerospace Laboratory
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Overview
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History: Sawa and SatCAST demonstrations
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Neonet network
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The software
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Metadata gathering and distribution
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Using multicast to distribute metadata
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Demonstration
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1998: Sawa demonstration
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Demonstrated IP over satellite & caching, no multicast
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Application: Neonet version 0
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No XML yet: HTML based
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Built a single site combining and crosslinking pages from
different sites about a common theme: remote sensing
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Site was replicated on different UNEP sites by retrieving
databases with HTML files.
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2000: SatCAST demonstration
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Multicast capability
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Demonstration application: Neonet version 2
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Using structured metadata in XML
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Network with nodes about different topics in remote
sensing
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Demonstration:
– Neonet functionality
– Database synchronisation by multicast over satellite link.
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Neonet: Background
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Netherlands Earth Observation Network
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Allow (Dutch) users of remote sensing data access to
information in the Netherlands and abroad.
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Keep information at the provider
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Connect to other metadata infrastructures
– CEOS IDN
– CEO
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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.
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Neonet network (1)
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The network is a group of nodes running Neonet software
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Node maintainer(s) decide what is appropiate information
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A node servers a user community, example:
– atmospheric chemistry
– water management
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Nodes are organised hierarchically
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General node at top: APEX
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Neonet network (2)
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Metadata flow
Node
email
Node
email
Node
metadata file
Provider
Metadata entered at a
specialised node is sent
automatically to the nodes
above.
E-mail is available everywhere
Even behind firewalls
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Neonet software
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Retrieve metadata from provider by HTTP
– Version 0: HTML pages
– Version 1: metadata in XML pages (CEO like format)
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Uses CEO standard for metadata
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Status: version 2 released october (but used in SatCAST)
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Available for interested institutes
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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).
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SatCAST setup
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3 top level nodes with local databases and no sub-nodes
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Synchronisation:
– Nodes synchronise their databases using HTTP requests
– Added for SatCAST
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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
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Synchronisation
Node
Node
admin
XML
SatCAST
Multicast
A node exports its database to a
set of XML files, so it can be accessed
using HTTP
admin
XML
Node
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Demonstration
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Three nodes were set up, all are Apex nodes.
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Check each other every 10 minutes.
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Metadata entered at 1 node is found and retrieved by the
others
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No instant result
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Short demonstration of other Neonet features
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Questions?
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