Edwin Wisse

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?