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[From Dave Farber's IPer list --BSA]
Begin forwarded message:
From: "Richard M. Smith" Date: June 27, 2004 10:21:19 AM EDT
To: [email protected]
Subject: Another example of holding back Internet innovation
Hi,
Innovation in Internet technologies continue to make people nervous.
The latest example comes from Slashdot (http://tinyurl.com/2kx8p). The U.S.
Weather Service has set up an experimental XML service to provide
Weather data on a NOAA Web site to the public, commercial services, and
researchers:
http://weather.gov/xml/
This move apparently has gotten the commercial weather industry all hot
And bothered:
http://www.weatherindustry.org/Comment-Letter-042204.doc
It appears that established players in the commercial weather industry
Feel threaten by the NOAA XML Web service and are joining together to
Restrict new entries into the market for weather services which would use
this XML Web service and similar Internet technologies.
Richard M. Smith
http://www.ComputerBytesMan.com
============================================================
Experimental National Digital Forecast Database XML Web Service
NOAA's National Weather Service offers several XML services
What is NDFD XML?
National Digital Forecast Database (NDFD) Extensible Markup Language (XML)
is a service providing the public, government agencies, and commercial
enterprises with data from the National Weather Service's (NWS) digital
forecast database. This service, which is defined in a Service Description
Document, provides NWS customers and partners the ability to request NDFD
data over the internet and receive the information back in an XML format.
The request/response process is made possible by the NDFD XML Simple Object
Access Protocol (SOAP) server. To see the details of the NDFD XML SOAP
service, go to the following URL and click on the NDFDgen link:
http://www.nws.noaa.gov/forecasts/xml/SOAP_server/ndfdXMLserver.php
If the web service description provided by the SOAP server does not meet
your needs, similar information is available in the following Web Service
Description Language (WSDL) document:
http://www.nws.noaa.gov/forecasts/xml/DWMLgen/wsdl/ndfdXML.wsdl
In addition to the SOAP technology, this service exploits XML to enhance the
ease with which NWS customers and partners can integrate NDFD data into
their computer applications. XML is a W3C standard that allows its users
to create languages with HTML-like tags and attributes. The NDFD XML
language is called Digital Weather Markup Language (DWML) and its schema can
be found at the following link:
http://www.nws.noaa.gov/forecasts/xml/DWMLgen/schema/DWML.xsd
The schema defines the XML language's vocabulary (available tags and
attributes) and syntax (expected order of tags). Knowing how NDFD XML is
constructed, users can write programs to process the XML document to get at
the data it contains.
To see a sample Digital Weather Markup Language document that conforms to
the DWML schema, click on the following link:
http://www.nws.noaa.gov/forecasts/xml/DWMLgen/schema/latest_DWML.txt
Why provide an Experimental NDFD XML service?
The National Weather Service is striving to serve society's needs for
weather information by evolving its services from a text-based paradigm to
one based on making NWS information available quickly, efficiently, and in
convenient and understandable forms. The NDFD is one example of this
transformation. NDFD XML takes yet another step towards a digital services
era by making NDFD data available for computer to computer transfer and
processing. NWS customers and partners can then enhance the value of NDFD
data through the creation of value added products.
This is an experimental service. NWS will be accepting comments on this
service until August 1, 2004. At the end of the period, comments will be
evaluated in order to decide if the service should become official or not.
How often is NDFD XML updated?
The NDFD is updated no more then hourly. We request developers using this
SOAP service for local applications only make a request for a specific point
no more than once an hour. The database is currently updated by 45 minutes
after the hour.
How is NDFD XML generated?
The first step to providing NDFD XML is the creation of the NDFD. For more
information on how NDFD is created, visit the NDFD home page. With NDFD
data available, a user application creates and sends a SOAP request to the
NDFD XML SOAP server. The SOAP request is processed, creating the DWML
document which is returned to the requesting application for processing.
Figure 1 provides a graphical view of the process.
Figure 1. NDFD XML SOAP Process
You can see an example of this process in action by visiting the following
URL:
http://www.nws.noaa.gov/forecasts/xml/sample_products/meteogram/DWML_graph.h
tm
By clicking the "submit" button, a script will request, retrieve, and parse
NDFD data and then display it in a graph.
You can download this sample application by clicking on the following links:
http://weather.gov/forecasts/xml/sample_products/ndfdXML.tar
NOTE: The PHP script, plotMeteogramDev.php, is an example only and will
not run as is. To run the script, you will need to install NuSOAP and VH
Graph. You can review the readme file for additional information on using
the sample clients.
What does NDFD XML contain?
NDFD XML contains forecasts for any combination of the following
meteorological parameters:
Maximum Temperature
Minimum Temperature
3 hourly Temperature
Dewpoint Temperature
12 hour Probability of Precipitation
Liquid Precipitation Amounts (Quantitative Precipitation Forecast)
Snowfall Amounts
Cloud Cover Amounts
Wind Direction
Wind Speed
Sensible Weather
Wave Heights
For additional information on NDFD parameter definitions and available time
projection, please see the NDFD technical page.
In addition to its meteorological content, NDFD XML contains meta data about
the product. A description of the meta data as well as data XML tags and
attributes can be found in the Digital Weather Markup Language
Specification.
How Do You Use the Web Service?
The first step to using the web service is to create a SOAP client. The
client creates and sends the SOAP request to the server. The request sent
by the client then invokes the server function NDFDgen(). NDFDgen()
requires the following user supplied input:
Input Name Type Example Description
Latitude Decimal 39.0000 The latitude of the point for which you want
NDFD data. North latitude is positive.
Longitude Decimal -77.0000 The longitude of the point for which you want
NDFD data. East longitude is negative.
Product String time-series There are two products. The "time-series"
product returns all data between the start and end times for the selected
weather parameters. The "glance" product returns all data between the
start and end times for the parameters maxt, mint, sky, wx, and icons
Start time XML Date String 2004-04-27T12:00 The beginning time for which
you want NDFD data. If the string is empty, the start time is assumed to
be the earliest available time in the database.
End time XML Date String 2004-04-30T12:00 The ending time for which you
want NDFD data. If the string is empty, the end time is assumed to be the
last available time in the database.
Parameters Array of Booleans maxt = TRUE The parameters that you want
data for. Valid parameters include the following:
You can view an example of how to invoke NDFDgen() in the following web page
and the SOAP client it uses.
http://www.nws.noaa.gov/forecasts/xml/SOAP_server/ndfdXML.htm
Once the SOAP server returns the XML document back to the client, you can
then parse the DWML using SAX, the DOM, or XSLT. The meteogramDev.php
script discussed above is an example of SAX processing.
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