Distributed Data Servers and Web Interface in the Climate Data Portal

1
Distributed Data Servers and Web Interface in
the Climate Data Portal

• Willa H. Zhu
• Joint Institute for the Study of Ocean and
  Atmosphere
• University of Washington
• (PMEL/NOAA)

2
Outline

• Climate Data Portal (CDP) Overview
• Distributed Object System (what, why, how)
• CDP System Architecture
• CORBA Client/Server Application
• CDP Data Servers
• CDP Client implementation
• CDP Client Web Interface
• Feature Plans

3
Climate Data Portal Overview

• It provides consistent and uniform access to
  geographically distributed in-situ data
  collections
• Use of CORBA and LDAP services provides
  instantaneous network awareness of the
  distributed data servers
• Sophisticated and customized Java tools
  facilitate collections typical of in-situ
  observations
• Selected data from distributed data servers can
  be plotted together for comparison
• Dual access
• Desktop Java application (with on-line help and
  tutorial)
• Web Interactive Interface
• Distributed Object System

4
What is Distributed Object System

• Objects are software units that encapsulate data
  and behavior
• Systems that feature these objects are termed
  distributed object systems
• Applications and interfaces are
• remotely accessible
• easily customized
• Software used to create distributed server
  objects are
• independent from the architecture
• independent from hardware platform used
• totally transparent to their clients

5
Why Distributed Object Systems

• Divide client/server applications into
  self-managing components that can interoperable
  across networks and operating systems
• Centralize data access and retain localized data
  management for heterogeneous data sets from
  different geophysical locations
• Require no data being transported to a central
  data repository

6
Distributed Object Technologies
CORBA (Common Object Request Broker Architecture)
CORBA provides a facility to establish the remote
communications with distributed objects and to
handle network interactions in passing data
between objects.

• complete distributed object platform
• operates across networks, languages, component
  boundaries, and operating systems
• network transparency
• automatic recognition of server
• supplements Java with a rich set of distributed
  services

7
Climate Data Portal Architecture
End Users
Web Browser
Java Application


CORBA Client
HTTP

Web Server
Java Servlet

Client support

CORBA Client

Distributed Object System
Object Request Broker (Internet Inter ORB
Protocol)

PMEL

UH

NODC

Data Servers
CORBA Server

CORBA Server

CORBA Server

TAO Data
In
-
situ Data
Sea Level Data
GTSPP Data

support

support

support

support





Data
Data
Data
Data
8
CDP Data Servers

• CORBA tool
• ORBacus
• fully compliant with the CORBA specification
• free for non-commercial use and available with
  complete source code http//www.ooc.com
• In-situ data collection presently available
• Global sea level data (realtime) University of
  Hawaii
• Global Temperature-Salinity Profile Program
  (GTSPP) NOAA/NODC, Silver Spring
• TAO El Nino buoy data (realtime) NOAA/PMEL,
  Seattle
• PMEL insitu data collections NOAA/PMEL, Seattle
• Data Supported
• NetCDF data format
• MySQL database maintaining meta-data

• Dual access from
• Java desktop application
• Web client interface

9
CORBA Client/Server Application
Development steps
(ORBacus, a CORBA tool, is used)
IDL File (interface specification)
IDL Interface Definition Language
IDL Compiler
ClientImplementation
Client Stub Files (Java)
Server Skeleton Files (Java)
ObjectImplementation
Object Request Broker
10
CDP Java Desktop Client Application

• Provides higher degree of interactivity
• Supported for most commonly used workstations and
  operating systems
• On-line help and tutorial
• Supported by other Java tools (Ndedit) for data
  sub-setting
• Easily download and installftp//www.epic.noaa.go
  v/java/CDPclient/install.html

11
CDP Client Web interactive interfacehttp//www.ep
ic.noaa.gov/cdp

• Java Servlets provide HTML front-end to the CORBA
  server
• Java Applet and JavaScript enhance the user
  interactivity
• Java Scientific Graphic Toolkit (SGT) is used to
  generate plots
• Result pages are dynamically created on-the-fly

12
CDP Web Client Interface Features

• Listing/Plotting options
• View data collection properties
• View data item properties
• Plot/Co-plot profile data
• Plot/Co-plot time series data
• Make section 2-D plot
• List data in ASCII format
• Download data in netCDF format

• Data search and access by choosing
• keywords
• data servers
• data collections
• data items
• geographic location
• depth range
• time range

13
CDP Web Data Selection
Locate data collections

• keywords
• geographic location
• time range

14
CDP Web Data Selection (continued)

• View Collection Properties
• Retrieve data items
• Specify data collections
• Location ranges (lon,lat,depth, time)

15
CDP Web Data Selection (continued)

• Select items from item list
• Specify access options

• View item properties

16
CDP Web Data Selection (continued)

• Select variable
• Select subset

17
CDP Web Results Pages (profile plot)
Profile Plot

• Showing co-plot of temperature data from two
  resources
• NODC GTSPP
• Silver Spring
• PMEL TAO
• Seattle

18
CDP Web Results Pages(Time Series Plot)
Time Series Plot
19
CDP Web Results Pages (Section Plot)
2-D Section Plot
20
CDP Web Results Pages (Data Listing)
Data Listing
21
CDP Web Results Pages(File Downloading)

• Select variables and subset
• Download netCDF file

22
Future Plans

• Include more data servers
• Intl. Pacific Research Center in-situ collection
  University of Hawaii
• WOCE hydrographic data Scripps Institution of
  Oceanography
• WOCE Time Series data NOCD, NOAA
• WOCE Acoustic Doppler Current Profiler data
  University of Hawaii
• In-situ data collection - Marine Environmental
  Data Service (MEDS) Canada
• Use LDAP (Lightweight Directory Access Protocol)
  directory server for CORBA data server registry
  for Web
• Add data sub-setting capabilities for Web access
• DODS proxy server - selected DODS datasets
• http//www.epic.noaa.gov/cdp
• Willa H. Zhu (willa.zhu_at_noaa.gov)