neonet a metadata application demonstrating satcast

Nationaal Lucht- en RuimtevaartlaboratoriumNational Aerospace Laboratory NLR

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Edwin Wisse & Rob van SwolEdwin Wisse & Rob van Swol

National Aerospace LaboratoryNational Aerospace Laboratory

NeonetNeonetA metadata application demonstrating SatCASTA metadata application demonstrating SatCAST


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Overview History: Sawa and SatCAST demonstrations

Neonet network

The software

Metadata gathering and distribution

Using multicast to distribute metadata

Demonstration


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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.


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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.


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Neonet: BackgroundNeonet: Background Netherlands Earth Observation NetworkNetherlands Earth Observation Network

Allow (Dutch) users of remote sensing data access to Allow (Dutch) users of remote sensing data access to information in the Netherlands and abroad.information in the Netherlands and abroad.

Keep information at the providerKeep information at the provider

Connect to other metadata infrastructuresConnect to other metadata infrastructures– CEOS IDNCEOS IDN– CEOCEO


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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 CEOrecommendation on metadata.


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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


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Neonet network (2)


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Metadata flow

Node

Provider

metadata file

Node

Node

email

emailMetadata entered at a specialised node is sentautomatically to the nodesabove.

E-mail is available everywhereEven behind firewalls


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Neonet software Retrieve metadata from provider by HTTPRetrieve metadata from provider by HTTP

– Version 0: HTML pagesVersion 0: HTML pages– Version 1: metadata in XML pages (CEO like format)Version 1: metadata in XML pages (CEO like format)

Uses CEO standard for metadataUses CEO standard for metadata

Status: version 2 released october (but used in SatCAST) Status: version 2 released october (but used in SatCAST)

Available for interested institutesAvailable 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 setupSatCAST 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


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Synchronisation

Node

XMLadmin

Node

XMLadmin

SatCASTMulticast

NodeA node exports its database to aset of XML files, so it can be accessedusing HTTP


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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?

neonet a metadata application demonstrating satcast

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