INTERNATIONAL INSTITUTE FOR GEO-INFORMATION SCIENCE AND EARTH OBSERVATION

Towards quality-aware Infrastructures for Geographic

Information Services

Richard Onchaga M.onchaga[at]itc.nl

Outline:

Background Geographic information Exploiting location to create value GI market dynamics

Towards open access to GI Motivation Objective Approach

Background: Geographic information

[…] information that references a geographic location e.g. topographic maps, census data, zip codes, and street addresses.

Used for managing environment, resource allocation, navigation, military applications, etc.

Background: Exploiting location to create value

[…] integrate information from different sources to create new information for new applications […]

Background: GI Market dynamics

Market pull Increased awareness of

“positive externalities” of GI

More integration of GI across domains/applications

Increased demand for GI Growing non-expert GI

market e.g. location based services

Technology push Earth observation, GPS,

Aerial Mapping technologies & GIS, Image processing systems: Less costly & more efficient data collection & processing

Internet/Web: Improved chances for information sharing => SDI

SOC, Web services, Wireless & mobile technologies: New opportunities for location based services & information integration => GI services

Towards Open Access to GI (TOAG)

Two paradigms: Spatial data infrastructure (SDI Geographic information web services

(GI services) and GI service composition:

TOAG: Spatial data infrastructure /1

[…] “a relevant collection of technologies, policies and institutional arrangements that facilitate the availability of and access to geographic data” [….]

TOAG: Spatial data Infrastructure /2

Local, Provincial &National Government

User Communities

Transportation,Utilities & Infrastructure

Management

Research Groups

Security & Emergency

Data Producers

Commercial &Professional Users

SDI

Local data

sub-nationaldata

Project specificdata

???

Citizens

• Standardized data descriptions• Search engine• Communication network• Exchange agreements

Clearing house

Search

Publish

Access

Maintain

Geographic Data

DataMetadata

Data user

Data provider

Create / Maintain

TOAG: Spatial data infrastructure /3

TOAG: GI services

[…..] geoprocessing services which are published, and can be located and invoked over the web to access and process geographic data from different sources …. and can be composed to create and deliver sophisticated services & customized information

Extends the SDI Based on open industry and IT standards Standardization led by the Open

Geospatial Consortium (OGC)

Application service

Registry service

Data service

Portrayal service

Processing service

Search Publish

Invoke

Maintain

Hold

Render

Process

Metadata

Geographic data

invoke

TOAG: GI services architecture

Motivation: Composition of GI services (Example)

Reprojection

Service

Web

Coverage Service

Web

Coverage Service

Portrayal

Service

Portrayal service assembles

orthoimage from several imagery

services

Reprojection service reprojects

the image from one coordinate

system to another one

Vector Data

Provider Service

Vector data provider service

returns a certain layer at the

extent specified

Overlay

Service

Overlay service overlays the input

image and the vector data and

sends the overlay to the client

To Client

Web

Coverage Service

(Adopted from (Alameh, 2001))

User(Application)

Registry service

GI service

Locate GI services

Publish

Orchestrate Services GI service

GI service

Motivation: Conventional GI service composition architecture/1

Motivation: Conventional GI service composition architecture/2

Service composition “intelligence” on client side

Simple mediator (registry) – query & search

Not quality-aware Costly & complex process of GI

service composition/developing GI applications

Motivation: Proposal for GI Middleware

GI middleware to provide dedicated functionality for quality-aware composition of GI services

Functionality to be exposed as generic services to application components

Motivation: Positioning the GI middleware

Distribution Middleware

GI Applications & services

Distributed Resources

GI Middleware

Motivation: Benefits of GI Middleware

Business justification Flexible & efficient business processes – easy,

fast, & reliable re-use of existing resources; Mass customization or service-differentiation

Design benefits: Less complex & less costly GI application

design process in the long run as a result of: Quality-aware composition transparencies; Re-useable GI middleware services; Extensible GI middleware

Objective: General objective

To design and validate an architecture for the GI middleware system which facilitates quality-aware composition of GI services

Objective: Specific objectives

1. To define concepts for quality in distributed service-oriented processing of geographic information

2. To derive requirements that will guide the design of the GI middleware system

3. To define an architecture for the GI middleware system

4. To validate the architecture by using typical use cases

Review of state of art in distributed geoprocessing

Review of state of art in web service composition

Requirements analysis

System design

Design Validation

Define quality concepts

Approach: General Approach

Thank you !