Download Metadata database

The Metadata System of
China Mete. Data Service System
WANG Guofu
[email protected]
National Meteorological Information Centre, CMA
Metadata Workshop 27-29 Sept. 2005
What’s the data service system?

First, it’s a distributed service system (distributed in physical existence
and unified in logics). Every data centre maintains and manages its XML
metadata data base

Second, the system is jointly constituted by national data service web site,
and provincial special topic data service web sites.

Third, it makes up:

Web sites (for data access)

Metadata system (for data discovery)

Security identity authentication system
National Meteorological Information Centre, CMA
Main Server
Observing data service web site
Low temp. data service
Satellite data service web site
Scientific research data service web site
Drought data service web site
Meiyu data service web site
Qinghai-Tibet data web site
Torrential rain and flood data service web site
National Meteorological Information Centre, CMA
What’s the metadata system?
Includes:


metadata publish servers:

publish, metadata management,
interface

metadata gateway:

proxy server, node management

metadata databases

XML metadata editor
Metadata
Publish
Server
Metadata
Database
Metadata
Gateway
Metadata
Editor
Monitor and control node
National Meteorological Information Centre, CMA
Infrastructure of Metadata System
Register
Metadata Server
Web Server
Gateway
HTTP protocol
Z39.50 protocol
Metadata
Database
Monitor and node control
gateway
interne
t
Metadata server
Metadata
database -A
Metadata
database -B
Metadata
server
Metadata
server
Metadata
database
Metadata
database
Metadata
database -C
National Meteorological Information Centre, CMA
Monitor and node control
Gateway
interne
t
Metadata
server
Metadata
server
Metadata
server
Metadata
database
Metadata
database
Metadata
database
National Meteorological Information Centre, CMA
Edit metadata
Web Server
Gateway
database
register
Metadata
server
documents
Metadata Editor
Metadata
database
XML database
others
National Meteorological Information Centre, CMA
Besides metadata database, …
Catalogue?
• Sub- WMO Core: Title(search),
Data category(navigation),
Keywords(search), On-line
Gateway
source(location), Abstract(search),
useLimitation etc
• Node information
• Location of Metadata Database
•Update every day
 
Metadata
Server
Metadata
Database
Metadata
Server
Metadata
Database

…….
Metadata
Server
Metadata
Database
National Meteorological Information Centre, CMA
Where we used the metadata ?

Discovery of data
By Metadata system, user can locate the datasets from the catalogues quickly
first, then go to the XML metadata database and get it.

Determining data fitness for use
Users can determine if the dataset meets their needs by understanding the
metadata elements.

Data access
After locating and determining if a dataset meet their needs, users may do query
or download data (need registration).

Data application
Metadata elements have been selected, so that users know how to process,
apply, merge a particular dataset with others, as well as understanding the
limitations of the data.
National Meteorological Information Centre, CMA
Data Discovery
Client
App.
Server
User send
request
using web
interface
Determining
data fitness
for use
Transform
the results
to web
pages
Web Server
Gateway
Metadata
Server
creates SQL
by request and
sent to
gateway
Assemble
message and
locating, then
send to the
located web
site
Do XML
query and
extract
information
Metadata
DB
Assemble the
query results
as message
National Meteorological Information Centre, CMA
Data Access
Client
App Server
If meet the
needs, get the
location of
dataset (for
example,
through a URL)
Identification
of user
WebServer
Exe. HTTP or
FTP download
Do SQL
Datasets
File system
Database system
National Meteorological Information Centre, CMA
Summery

Distinguish the “metadata” into:

Metadata for data set– WMO Core is good to use

Metadata for data access (Query)– design as your system
developing

Metadata for data– go with the data set, for example “data
dictionary”, station information

Maintain and manage the metadata in every centre, need the
update mechanism
National Meteorological Information Centre, CMA
Welcome to
http://cdc.cma.gov.cn
http://data.cma.gov.cn