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WDBWeather and Water Database

19th EGOWS Meeting,Ljubljana, June 9-12, 2008.

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Outline

• Introduction• Background of WDB• Overview of WDB• WDB Components• Future of WDB

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Who are we?

• Michael Akinde– Ph.D., Database Architect, IT, Met.no – Systems architect on ROAD system at

SMHI(2003-2006)

• Vegard Bønes– M.Sc., Senior Engineer, IT, Met.no

• Børge Moe– M.Sc., Senior Engineer, IT, Met.no

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Who are you?

• Survey: please raise your hands...– Who has coded programs?– Who has written SQL queries?– Who has worked with database APIs

(JDBC,ODBC,etc)?– Who knows what database normalization is?– Who knows what a database index is?– Who has written database extensions?

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What is this about?

• We need to store weather/water data• We need indexed (fast) access to time

series retrieved from multiple files or sources

• We need access from a variety of applications

• We need products to be consistent• We want to be able to track changes• We want programs to be independent of

the data format• We have limited ressources

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What is WDB?

• WDB is a storage system for meteorological, hydrological, and oceanographic data– Developed by the PROFF program at met.no– Based on the ROAD (SMHI) architecture

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History of ROAD

• Operational meteorological database, developed in the late 90’s at SMHI; operational since 2001

• Responsible for 90% of SMHI’s automatic production

• One of the world’s fastest meteorological databases

• Mature and well-established production system; 3rd generation in development 2006-2008

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Problems of ROAD

• Like most met systems, ROAD is a legacy system– Prior to ROAD3G, the loading chain of the ROAD

system included Fortran code developed in the 1970s

• SMHI is in the process of a major rehaul of the production systems in terms of migrating software from OpenVMS to Linux

• IBM Informix platform– Geodetic datablade (geospatial extension)– Licenses are expensive

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WDB is…

• Open source collaboration between met.no and SMHI

• Can be considered the 4th generation of the ROAD system– Built from the ground up without legacy code– Developed at met.no

• Released under the GNU GPL2 license

Fast, Free, Flexible

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WDB: Open Source Alternative

• Should be robust enough to handle high volume, high availability production– e.g., as the backend engine of yr.no

• Should be flexible– e.g., to easily handle new types of data

• Should support quality and consistency of data

• Should be simple to use• Should be easy to maintain and operate

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WDB provides...

• Quick and easy to deploy data storage system

• Modular loading programs– Easy to add more…

• Data-independent application programmers interface (API)– Usable, in theory, from any environment

• Fast performance on queries

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WDB Overview

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Installing WDB

• Download the tar package, and...

• Or request the debian package

server:wdb-x.x% ./configure --prefix=/home/myuser/localserver:wdb-x.x% makeserver:wdb-x.x% make install

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Putting WDB through its paces

• WDB implements all the standard GNU targets

• “make check” runs the WDB unit tests– tests that can be run without being installed

• “make installcheck” runs the WDB install tests– tests that require an installed database

• 300+ tests and counting– CPPunit and TAP protocol– Fully automated test framework on

CruiseControl

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Enabling Technology

• Linux (Debian, Fedora Core 5)• PostgreSQL version 8.1.x or later• PostGIS version 1.1.x or later• Proj.4 version 4.6.0• ECMWF GRIB API• GNU Autotools• C++ open source libraries

– Boost Std Libraries, log4cpp, cppunit, etc.

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WDB Overview

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Loading forecast data

• Loading data into the database, is as simple as:

server:mydata% gribLoad myforecast.grib server:mydata% server:mydata% gribLoad /opdata/hirlam10/*.grib server:mydata%

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Loading Programs

• GRIBLoad is the design pattern for the WDB loading programs

• Loads one or more GRIB1 files into the database– Uses ECMWF GRIB API, so theoretically, GRIB2

works as well– Stand-alone client program that connects to any

WDB database

• Loaders for other grid formats are easily built in the same way by reusing code

• Loading of BUFR will be ported from ROAD

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WDB Overview

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WDB Call Interface (WCI)

• WCI is the data retrieval API for WDB• Based on a function interface in SQL

Why not stick to “simple” SQL?- SQL isn't really that simple- Requires knowledge of the underlying data model (tables/views)- Lacks useful functionality; e.g., interpolation, point-in-field, etc.

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WCI versus pure SQL

• SQL results in tight coupling between application and database– Table names– Table structure

(attributes)– Really strange

database queries

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WDB Call Interface (WCI)

• WCI is the data retrieval API for WDB• Based on a function interface in SQL

Why not a lib file?- Changes in a library require that the applications using the library are recompiled- New libraries need to be pushed to the user (application)- Each operating system, machine and language = its own library

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WCI versus compiled software library• How many combinations do we need?

Java C C++ Perl Fortran Python

Debian

Fedora

Ubuntu

Sun Solaris

Windows XP

Windows Vista

Don't forget 32 vs 64 bit architectures...

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WDB Call Interface Features

• Stable Interface

• Performance– 100-1000 values/s in single point retrieval (to be

improved) – 10 million floating points/s in field retrieval (about 100

fields/s)

• Functionality: – Pointwise, Timeseries, 2d-volumes, Quality information– Coming: Paths, Interpolation in space and time, 3D

volumes?

• Easy to program– 1/2 page of code to retrieve MHO-data

• Platforms: C/C++, Java, Perl, Python, Fortran, ODBC…

• Operating systems: Pretty much anything...

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WCI functions

• wci.begin• wci.end• wci.read• wci.write• wci.browse• wci.info

– Programmer doesn’t need any knowledge of the data format or the database model

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The WCI Data Model

Data ProviderData Value

Place

Time (Ref)

Time (Valid) Parameter

Level

Version

Quality

Value ID??

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WDB Overview

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WDB2TS

• TS2XML for WDB• Web service to retrieve time series of data

from a WDB database– delivers data as csv or xml– REST-like interface

http://host/path?lat=10;lon=10;parameterspec

(parameterspec = data specification)

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The Road ahead for WDB

• WDB version 0.6.0– First production version of WDB – Hindcast archive (12 TBs of grids)

• WDB version 0.7.4– To be released next week– We currently release a new version about once

a month– Implements a new loading program

• FELT: met.no field format• Approximate time to develop: 2 weeks x 2 persons

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WDB Roadmap

• Version 0.8.0 is scheduled for July 2008– Official beta version of WDB– Limited scale real-time production

• Version 0.9.0 is scheduled for October 2008– Release candidate version (full-scale testing)

• Version 1.0 scheduled for December 2008– Full-scale production version

• WDB is a part of the PROFF framework; minimum expected life-time is at least15 years

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Future thoughts?

• Complete integration with Diana• More data types

– Fields (NetCDF, GRIB2, etc.)– Observations (BUFR, XML)

• Better administration tools• Verified Stability

– 24x7 hands-free operation (have this in ROAD…)

• Improved Performance– We have not started optimizations

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Future thoughts?

• Scalability and fail-over– Want more load? Add another server– Want to guarantee up-time? Add more servers

• Consistency– Easy on one server; we want multiple servers– Distributed data/replication is a well-known

problem in the database community– Problems: huge data, geographically distant

regions

• Tracking of changes– Metadata can be used to track history…

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Recommended Reading

• WDB website (wdb.met.no)– WDB User Manual– WCI User Manual– Man Pages for all WDB utilities– Source code browser (SVN repository and

doxygen)– Developer documentation (design docs)– Eclipse setup instructions

• Subscribe to WDB project on Freshmeat.net

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Summary

• WDB is designed as a generic weather/water database system– Perspective: one core system that can be

leveraged for many different uses– Functionality that isn't implemented can

probably be added– For users: fast access to data– For developers: a simple, generic interface to all

kinds of different data– For operators: a system that is easy to maintain

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Concluding thoughts…

• Many, many more WDB systems in the future– WDB is intended as the backbone of the

production systems at met.no and SMHI

• Open source is a different model of collaboration which can be of great benefit to meteorological institutions– We all require broadly the same functionality– Good communications = better systems– Free as in Freedom

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THANK YOU !Questions?

E-mail: michael.akinde@met.no