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CUAHSI WaterOneFlow
Web Services
By Tim Whiteaker
CE 394K.2 Hydrology
1 February 2007
Outline
• What are Web Services
• What is WaterOneFlow
• What is WaterML
• How do we use HIS Analyst to access
WaterOneFlow
Programs Use Functions
• Functions are pieces of code that perform
a specific task
What’s the
result
square root
= Math.SquareRoot(16)
of 16?
Functions:
16
Add
Multiply
4 SquareRoot
Math
library
Program
Web Services Let Computers
Share Functions
• Local programs take advantage of remote
resources
• Works just like local function
result = Service.SquareRoot(16)
Functions:
What’s the square root of 16
Add
Multiply
SquareRoot
Math
answer
Thelibrary is 4
Client Service
Program
How Do Web Services Work
• SOAP (Simple Object Access Protocol) is
a protocol for exchanging messages
over a network
• WSDL (Web Services Description
Language) is a language for describing
what a web service can do
How Do Web Services Work
Server
SOAP WSDL
(This is what I
can do)
Client SOAP is like speaking the same language
WSDL is like a contract
CUAHSI Web Services
(WaterOneFLow)
• Standard mechanism for flow of hydrologic
data between hydrologic data servers
(databases) and users.
• Provides data access to
– USGS NWIS
– EPA STORET
– NCEP North American Model (NAM)
– NASA MODIS
– Daymet
– NWS ASOS
http://water.sdsc.edu/waterOneFlow/
Water Data Web Sites
NWISWeb site output
# agency_cd Agency Code
# site_no USGS station number
# dv_dt date of daily mean streamflow
# dv_va daily mean streamflow value, in cubic-feet per-second
# dv_cd daily mean streamflow value qualification code
#
# Sites in this file include:
# USGS 02087500 NEUSE RIVER NEAR CLAYTON, NC
#
agency_cd site_no dv_dt dv_va dv_cd
USGS 02087500 2003-09-01 1190
USGS 02087500 2003-09-02 649 Time series of
USGS 02087500 2003-09-03 525 streamflow at a
USGS 02087500 2003-09-04 486
USGS 02087500 2003-09-05 733 gaging station
USGS 02087500 2003-09-06 585
USGS 02087500 2003-09-07 485
USGS 02087500 2003-09-08 463
USGS 02087500 2003-09-09 673
USGS 02087500 2003-09-10 517
USGS 02087500 2003-09-11 454
Observation Stations Map for the US
Ameriflux Towers (NASA & DOE) NOAA Automated Surface
Observing System
USGS National Water Information System NOAA Climate Reference Network
WaterOneFlow
• Consistent Query Format • Consistent Data Format
WaterOneFlow Methods
• (Almost) the same for all networks
• Methods
– GetSiteInfo – Give me info about a site
– GetVariableInfo – Give me info about a
variable
– GetValues – Give me a time series for a
variable at a site
GetSiteInfo
• Input • Output
– Network name and – Site name
site code – Site location
– Authorization token – Variables measured at
the site
• Variable code
• Period of record
where
response = service.GetSiteInfo("NWIS:08158000", "")
GetVariableInfo
• Input • Output
– Network name and – Variable name
variable code – Variable description
– Authorization token – Variable units
what
response = service.GetVariableInfo("NWIS:00060", "")
GetValues
• Input • Output
– Network name and – Site info
location (e.g., site – Variable info
code) – Time series
– Network name and
variable code
– Start datetime
– End datetime
– Authorization token where what
response = service.GetValues("NWIS:08158000", "NWIS:00060", _
"2006-12-31T01:00:00", "2006-12-31T08:00:00", "")
when
The “Where” in GetValues
• Works for sites, or geographic locations
• NetworkName:SiteCode
– NWIS:08158000
• GEOM:POINT(Longitude Latitude)
– GEOM:POINT(-113 35)
• GEOM:BOX(WLon SLat,ELon NLat)
– GEOM:BOX(-108 45,-107 46)
Extract – Transform – Load
Locations GetSiteInfo Data
STORET
GetVariableInfo
Variable Codes GetValues
Data
Date Ranges Data NAM
NWIS
WaterML
WaterOneFlow Data
Web Service Repositories
Client
TRANSFORM EXTRACT
LOAD
WaterML – The Output of
WaterOneFlow
• Standardized for all data sources
• Formats
– Object
– XML (for programs that can’t handle objects)
• Defined in XML
XML – A Primer
• The Extensible Markup Language (XML) is a
W3C-recommended general-purpose markup
language that supports a wide variety of
applications. – Wikipedia
• XML represents data
• XML is both human and machine readable
<site>
<name>Mansfield Dam</name>
</site>
XML Structure
• Example – Let’s describe a streamflow site
element
element name = “site”
<site></site>
start tag OR end tag
<site>
</site>
OR
<site />
Elements can have Children
child element
<site>
element <name>Mansfield Dam</name>
</site>
element text
Elements can have Attributes
<site>
<name>Mansfield Dam</name>
<siteCode network=“NWIS”>08154510</siteCode>
</site>
attribute name attribute value
XML Nesting
<site>
<name>Mansfield Dam</name>
<siteCode network=“NWIS”>08154510</siteCode>
<location>
<latitude>30.39</latitude>
<longitude>97.91</longitude>
</location>
</site>
WaterML
• XML for describing water data
• Defined at
http://water.sdsc.edu/waterOneFlow/documentation/schema/
• WaterOneFlow returns data in WaterML
format
Point Observations Information Model
http://www.cuahsi.org/his/webservices.html
USGS Data Source WaterML Response
Streamflow gages Network
SiteInfoResponseType
Neuse River near Clayton, NC Sites
Discharge, stage Variables VariablesResponseType
(Daily or instantaneous)
TimeSeriesResponseType
Values
206 cfs, 13 August 2006 {Value, Time, Qualifier}
• A data source operates an observation network
• A network is a set of observation sites
• A site is a point location where one or more variables are measured
• A variable is a property describing the flow or quality of water
• A value is an observation of a variable at a particular time
• A qualifier is a symbol that provides additional information about the value
WaterML Key Elements
• Response Types • Key Elements
– site
– SiteInfo – sourceInfo
GetSiteInfo
– seriesCatalog
– variable
– Variables
GetVariableInfo – timeSeries
• values
– queryInfo
– TimeSeries
GetValues
SiteInfoResponseType
• Namespaces Network
• queryInfo Sites
• site Variables
queryInfo
• Parameters sent to service
• URLs called (if external resource)
queryInfo – Another Example
user query URL
parameters
site
• siteInfo – info about the site
• seriesCatalog – catalogs of variables
measured
siteInfo
• Name
• Site Code
• Location
geoLocation
• geogLocation – geographic coordinates
– LatLon point
– LatLon box
• localSiteXY – projected coorindates
European Petroleum Survey Group
i.e., NAD 83, etc.
seriesCatalog
name web service location
series (variables)
original data source
series
• variable – what is measured
• valueCount – how many measurements
• variableTimeInterval – when is it measured
variable
• variableCode – global identifier
• variableName Sites
• units Variables
Values
variableTimeInterval
• TimeIntervalType – date range
• TimeSingleType – single measurement
• TimePeriodRealTimeType – last n days
ISO Time
• International Organization for Standardization
• 1998-03-01T14:30:00 =
March 1, 1998, at 2:30 in the afternoon
SiteInfo Response, Recap
queryInfo
name
code
location
site
seriesCatalog
what
how many
variables
when
VariablesResponseType
• variable – same as in series element
• Code, name, units Sites
Variables
Values
Additional variable Children
• variableDescription
• valueType (enumeration)
– Field Observation
– Sample
– Model Simulation Result
– Derived Value
• generalCategory – e.g., “water quality”
• sampleMedium – e.g., “water column”
-- Many are optional
TimeSeriesResponseType
• queryInfo
Sites
• timeSeries
Variables
– sourceInfo – “where”
– variable – “what” Values
– values
sourceInfo
• SiteInfoType
– Same as siteInfo element
– code, name, location
• DataSetInfoType
– For data continuous in space
– LatLonPointType
– LatLonBoxType
variable
• Same as previous variable element
• code, name, units, etc.
values
• Each time series value recorded in value
element
• Timestamp, plus metadata for the value,
recorded in element’s attributes
qualifier
ISO Time value
value Metadata Examples
• qualifiers
• censorCode (lt, gt, nc)
• qualityControlLevel (Raw, QC’d, etc.)
• methodID
• offset
– offsetValue
– offsetUnitsAbbreviation
– offsetDescription
– offsetUnitsCode
TimeSeries Response, Recap
queryInfo
location
variable
values
Conclusions about WaterML
• Consistent Format
• Includes lots of information
• How do I use it?
HIS Analyst
HIS Analyst
• Desktop apps that use WaterOneFlow
• Examples for various application
environments
• HydroObjects – for apps that aren’t web
service enabled
• Workbook available at:
http://www.cuahsi.org/his/docs/HIS-workbook-20061130.pdf
HIS Workbook
• Ingesting NWIS Data into Excel
• Ingesting STORET Data into Excel
• Ingesting Weather and Streamflow Data
into ArcGIS
• Plotting MODIS Data with Matlab
• Ingesting NWIS Data using VB.Net
• Ingesting NWIS Data Using Java
Excel Demo
Weather Downloader
Historical
Weather Data
Forecasted
Weather Data
Streamflow
Other
Recap
• Computers share functionality through
Web Services
GetSiteInfo
GetVariableInfo
HIS Analyst GetValues
WaterML
Time Series
Client WaterOneFlow Repository
Web Service
Related docs
