Interoperability ‘in-action’ – perspectives from UK academia

James Reid

GeoServices, EDINA

10 February 2005

Overview

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

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 servicee.g. Digimap, EMOL, etc

but also undertake r&D 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)

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

Services

Projects

Today

Services

Projects

1999

What we do - Some statistics

Digimap– Until 2002, largest online geospatial database in the UK

(300+m 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 > £1M

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!!)

The vision - a SDI for the UK academic community

© 2004 OpenGIS Consortium, Inc.

Data Data Data Data

Web Services

WFS Service

WAAS Service

WWW-Browser

WAAS Client

WFS ClientWMS Client

Go-Geo! Portal

WMS Service

Geo

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WMS ServiceG

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Services

Clients

Security Zone

EDINA Research Council Institute

JISC Data Centre

UserBased on R. Wagner 2002

WAAS Service

Data Access - a one-stop shop

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WGS ServiceCatalogue

Service

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.

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.

Project Outputs

• A range of OGC based web services (WMS;WFS;WCS)• 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

Data access demonstrator – Issues (1)

• Issues:– Identify what OGC web services available (estimated that

worldwide there are only c.250 public W*S 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 1:1 correspondence of portrayal and data) – ontology?

– Layer control and legend issues

e.g. Legend issuesGLOBE – Urban extents

GLOBE – Soil temperature

GLOBE – Snow height

GLOBE – Road classification

ICDES/GlobalMap – GetLegendGraphic

returns a 35*5 pixels – whiteimage!!

BUT

Example :

<Layer>      <Name>RIVERS</Name>      <Title>Rivers</Title>      <Abstract>Context layer: Rivers</Abstract>      <Style>        <Name>default</Name>        <Title>Default</Title>          <LegendURL width="180" height="50">            <Format>image/gif</Format>            <OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink"     xlink:href="http://globe.digitalearth.gov/globe/en/icons/colorbars/RIVERS.gif"/>          </LegendURL>      </Style>    </Layer>

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.

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?)

Differences between WFS and WMS capabilities (Nuke Goldstein Oct 2004)

http://www.directionsmag.com/article.php?article_id=686&trv=1

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-Security…longer 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…

Demo…

Data ‘browse & grab’ client

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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