What is a Web Service. or some relevant web services. (for) Developing Applications for Real-time Environmental Data Bryan Lawrence Head, NCAS British Atmospheric Data Centre P.I. The NERC DataGrid. Outline. Question: What is a Web Service? Answer: Acronym Soup! Fundamentals (XML+)
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or some relevant web services
(for) Developing Applications for
Real-time Environmental Data
Head, NCAS British Atmospheric Data Centre
P.I. The NERC DataGrid.
Question: What is a Web Service?
Answer: Acronym Soup!
OGC Web Services
NDG Web Services
Simple Object Access Protocol
Horrible looking XML specification, but lots of SOAP pacakges available which are (generally easy to use), eg:
from SOAPpy import SOAPproxy
Returns the temperature at U.S. zipcode 27502 (from Dive Into Python, Mark Pilgrim)
(One knew a priori that a method named getTEmp would return a float given an argument of a zip code, provided one used the right namespace – How?)
>>>for arg in callInfo.inparams:
. . . print arg.name, arg.type
. . .
Define expected messages for a service, and their (input or output parameters).
An interface will group together a number of messages (operations)
Bind an Interface via a definition to a specific transport (e.g. HTTP) and messaging (e.g. SOAP) protocol
The network location where the service is implemented , e.g. http://localhost:8080WSDL :Web Services Description Language
(Tim Ewald): “Today, I see three camps:
1) It's all about SOAP messages …,
2) It's all about WSDL,
3) It's all about XML/HTTP.
Microsoft is definitely in the first camp, focusing on doing things with SOAP whether or not they are ultimately represented as XML or a binary data rep.
IBM and Iona are in the second camp, focusing on describing in WSDL, whether or not they are ultimately represented as SOAP or a binary protocol.
Lots of developers and some big companies like Amazon are in the XML/HTTP camp, focusing on getting data from one place to another in a way they can consume it.
[Tim Ewald: http://pluralsight.com/blogs/tewald/archive/2004/10/18/2875.aspx]
[Open Geospatial Consortium (OGC): International consortium of nearly 300 companies, government agencies and universities participating in a consensus process to develop publicly available geoprocessing specifications]
eg, GLOBE program WMS server
globe.digitalearth.gov WMS server
OGC web services
Climate Science Modelling Language (CSML, a GML application schema)
Discovery Service (here now)
Data Extractor (next week)
Vocab Service (next month)
Attribute Authority (next couple of months)
Data Provider (next couple of months)
DeliveryBroker (later this year)
Browse Service (a long way off)
All Open Source, documented, clear APIs
Unidata (www.unidata.ucar.edu) provide data feeds using their Local Data Manager (LDM) technology to push data around the U.S. (and further afield) in the Internet Data Distribution system (IDD).