Interoperability

1
Interoperability in-action perspectives from
UK academia
James Reid GeoServices, EDINA
10 February 2005
2
Overview

• Who we are
• What we do
• Why Interoperability?
• Interoperability in practice
• Concluding remarks/demo

3
EDINA - Who we are

• A National Data Centre for Tertiary Education
  since 1995
• based in the Data Library
• Our mission...
• to enhance the productivity of research,
  learning and teaching in UK higher and further
  education
• Focus is service
• e.g. Digimap, EMOL, etc
• but also undertake rD projects ? Services
• e.g. JORUM, SUNCAT, Shibboleth, Go-Geo!
• Until recently, main focus has been provision of
  services fund by the Joint Information Systems
  Committee (or JISC)

4
Research and geo-spatial data team

• Largest team within EDINA
• mixture of GIS specialists and software engineers
• Highly experienced and skilled team
• provides advice nationally and internationally
• active in standards development
• active in GI community nationally and
  internationally
• First online GI service, UKBORDERS, launched in
  1994
• Demands of the services offered means team has
  been at leading edge of GI service development in
  UK
• Strategic move toward interoperability

5
What we do - Some statistics

• Digimap
• Until 2002, largest online geospatial database in
  the UK (300m objects)
• in 1999, it took 70 days to load and convert the
  data
• 17,000 users (30,000 over 4½ years)
• Average 23,000 files downloaded per month,
  200,000 maps generated, 10,000 maps printed off
• In 2003, users downloaded over 6.5m worth of
  data
• UKBORDERS
• 300 boundary data sets
• 70 look up tables
• 1200 downloads per month
• Value to community of key downloads gt 1M

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Corollary of what we do - Service requirements

• Fast servicing of requests
• Scaleable
• accommodates steady or increasing demand
• Robust (our SLD aspires to 98 uptime!)
• Maintainable (see next point)
• Standardized
• Can easily substitute components for repair,
  upgrade, etc
• Rapid prototyping and rollout
• All above on tight budget ?
• (An aside whats the Business case for
  Interoperability Performance? Cost-reduction?
  Maintainability? RAD?
• recent OGC sponsored research suggests that
  saving money is not actually perceived as that
  important!!)

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OGC and interoperability

• Open Geospatial Consortium (OGC), a private
  sector initiative, formed in 1994
• aim is to develop software specifications to
  advance geo-processing interoperability across
  the GIS industry
• employing practical test-beds and a consensus
  specification development process to arrive at
  open specifications for standard interfaces and
  protocols
• defined web service implementation specifications
  for
• Map Services (WMS) Gazetteer Services
• Feature Services (WFS) Geoparser Services
• Coverage services (WCS) Catalog Services

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The vision - a SDI for the UK academic community
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Data Access - a one-stop shop
Based on R. Wagner 2002
User
WWW-Browser
Go-Geo! Portal
WFS Client
WMS Client
WAAS Client
Clients
Services
WAAS Service
WGS Service
Catalogue Service
WMS Service
WMS Service
WAAS Service
Athens
geoX walk
WFS Service
Geo-Data
Data set 2
Dataset 1
Geo-Data
Security Zone
Research Council Institute
EDINA
JISC Data Centre
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Perceived benefits of Interoperability

• Increases the value of existing and future
  investments in Information Systems.
• Allows portability of data.
• Expands choices for vendor alternatives no
  vendor lock-in.
• Enables vertical industry segments to unify
  trading practices.
• Decreases the long-term cost of ownership for
  applicable software investments.
• Enables leverage of existing skill-sets, i.e.,
  does not require proprietary training.
• Provides a benchmark for software design.

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Specific Project aims

• to prove the feasibility of delivering
  geo-spatial data using OGC standards
• to demonstrate ease of use and value added
• to build support and enthusiasm for further
  development
• to stimulate and advance further thinking and
• to identify major hurdles in full development.

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Project Outputs

• A range of OGC based web services (WMSWFSWCS)
• A basic annotation web service (XIMA) currently
  investigating IBM WBI development kit for Java to
  develop a Geoserver (WFS) plugin proxy server
  to translate requests
• A series of demonstrator clients to illustrate
• Access to data (see later)
• A teaching focussed use case (Metosat data in
  teaching weather forecasting)
• A research focussed use case (based on dynamic
  image registration using web services)
• A report on the utility and issues surrounding
  implementation of open standards for geospatial
  data within the JISC IIE, including an assessment
  of security and access authorisation issues

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Data access demonstrator Issues (1)

• Issues
• Identify what OGC web services available
  (estimated that worldwide there are only c.250
  public WS services and most of these serving
  only sample or test datasets) see
  www.refractions.net/ogcsurvey
• We identified c.20 WMS, 4 WFS, 2 WCS
• Ensure all conform to standards (scale hints
  missing, layer names cryptic SRS missing
  versioning dialogue issues)
• Need for local registry (meta-information)
• How to rationalise users view with disparate
  views afforded by different services (may not be
  a 11 correspondence of portrayal and data)
  ontology?
• Layer control and legend issues

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e.g. Legend issues
Example ltLayergt      ltNamegtRIVERSlt/Namegt     
ltTitlegtRiverslt/Titlegt      ltAbstractgtContext
layer Riverslt/Abstractgt      ltStylegt       
ltNamegtdefaultlt/Namegt        ltTitlegtDefaultlt/Title
gt          ltLegendURL width"180"
height"50"gt            ltFormatgtimage/giflt/Format
gt            ltOnlineResource xmlnsxlink"http//
www.w3.org/1999/xlink"     xlinkhref"http//glo
be.digitalearth.gov/globe/en/icons/colorbars/RIVER
S.gif"/gt          lt/LegendURLgt     
lt/Stylegt    lt/Layergt
As well as representing legends in different ways
in the capabilities file, the images themselves
can vary in size and style. Problems can also
arise from similarities between legends, where
the same colour is used to mean two or more
things depending on the layer viewed.
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Data access demonstrator Issues (2)

• Issues
• Latency and asynchronicity (especially if doing
  lots of round-tripping)
• Specification clarity e.g. exact definitions of
  some operations in Filter Spec, output schema for
  WMS GetFeatureInfo XIMA leaves a lot unspecified
  ?
• Specification harmonisation see next slide.
  Addressed under OWS Common?
• (04-016r5 e.g. WFS 1.1, Catalog 2.0)
• Metadata and sane names
• Variable quality e.g. granularity and precision
  of data
• (you pay for what you get?)

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Differences between WFS and WMS capabilities
(Nuke Goldstein Oct 2004)http//www.directionsmag
.com/article.php?article_id686trv1
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Preliminary conclusions

• More work required than possibly initially
  anticipated (though overheads with modern tools
  is less significant than was required previously
  e.g. MMS)
• Building the services as well as the clients!!
• Differences in underlying technologies may impact
  upon the degree of support for standards (open
  source vs commercial)
• Leading edge or bleeding edge?
• Security and DRM issues barely addressed how do
  OGC web services map into mainstream Web
  Serices what about WS-Securitylonger term
  where does e-Research and GGF approaches to
  security fit in?
• Interoperability by definition assumes a minimum
  of 2 endpoints providing the services
  themselves is only half the story! Still early
  days

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Demo

• Data browse grab client

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Interop servers

• ICEDS (http//iceds.ge.ucl.ac.uk/) - A
  demonstration service provided by University
  College London and ESYS plc, funded by the
  British National Space Centre, serving SRTM and
  Landsat data at full resolution for Africa, the
  Indian sub-continent and Europe.
• DEMIS (http//www.demis.nl/home/pages/home.htm)
  Company providing range of OGC products and
  services
• GLOBE (http//www.globe.gov/globe_html.html) - A
  worldwide hands-on, primary and secondary
  school-based education and science program.
  Provides access to datasets for download and a
  WMS server.
• EDINA (http//edina.ac.uk) National Data Centre
  serving UK higher and further education,
  delivering inter alia geospatial data and
  service, including OGC based ones
• IONIC (http//www.ionicsoft.com/) - Company
  providing range of OGC products and services.

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