The Frontier of GIS GIS Web Services Nadine Alameh, Global Science & Technology Next Generation of Community Statistical Systems Tampa, Florida March 14,

The Frontier of GISGIS Web Services

Nadine Alameh, Global Science & Technology

Next Generation of Community Statistical SystemsTampa, FloridaMarch 14, 2002

March 14, 2002

Evolution of GIS: From Stand-alone to Web Services

Stand-alone systems (workstations)

Data tightly integrated with system

Desktop mapping

Databases with spatial extensions, SDE

Embedabble GIS components

Web mapping

Unbundled GIS into autonomous services

Distributed and interoperable GIS

services

-Lower costs of PC-Faster processing

-Internet (html, cgi, java)-Client/Server-Middleware (Corba)

-Wireless and mobile computing-Internet technologies (eg.XML)-Role of GIS in Enterprises-Availability spatial data

March 14, 2002

Evolution of GIS: From Stand-alone to Web Services

Satellite imagery Variety of suppliers anddistributors

Availability of Spatial Data

Web mapping Push for interoperability

Internet

Integration of databases Push for components

Role of GIS in Enterprises

Location-basedwireless services Services for thin clientswith bandwidth constraints

Mobile & Wireless Techs

Push towards an infrastructureof distributed autonomousinteroperable GIS services

March 14, 2002

GIS Web Services

IWeb MappingService

Web FeatureService

PortrayalService

Web MappingService

BundledService

Address MatchService

Mobile Devices:Retrieve image

centered atcurrent location

Browsers:Retrieve several

overlayed imagesas one

Standardized Interfaces

Information Systems:Perform business analysis based

on customers’ geographicaldistribution

RegistryService

Web services are self-contained, self-describing, modular applications that can be published, located, and dynamically invoked across the web.

Applications can be dynamically assembled from multiple network-enabled web services for use by a variety of client applications.

March 14, 2002

GIS Web Services Architecture Lower the learning curve Share data and services more effectively

IWeb MappingService

Web FeatureService

PortrayalService

Web MappingService

BundledService

Address MatchService

Mobile Devices:Retrieve image

centered atcurrent location

Browsers:Retrieve several

overlayed imagesas one

Standardized Interfaces

Information Systems:Perform business analysis based

on customers’ geographicaldistribution

RegistryService

Cut system integration and deployment cost Learn, use/get and pay only for what you need

March 14, 2002

Service Chaining When a task needed by a client cannot be provided by a single service, but

rather by combining or pipelining results from several complementary services.

ReprojectionService

WebCoverage Service

Web

Coverage Service

PortrayalService

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 inputimage and the vector data and

sends the overlay to the client

To ClientWeb

Coverage Service

March 14, 2002

User-Defined Chaining Chaining is transparent: User defines and controls the order of execution of

the individual services.

Address Matching

OrthoImageryService

Re-projectionService

Client Catalog Service

Address Matching

OrthoImageryService

Re-projectionService

ClientCatalog Service

March 14, 2002

Aggregate Service Chaining is opaque: the services appear as a single service which

handles all coordination of the individual services behind the aggregate service. The user has no awareness that there is a set of services behind the aggregate service.

Address Matching

OrthoImageryService

Re-projectionService

Client

Catalog Service

Aggregate Service

March 14, 2002

Workflow-Managed Chaining Chaining is translucent (in between transparent and

opaque): execution of the chain is managed by a workflow service. User may select a chain of interest that is executed by the workflow service.

Client

Address Matching

OrthoImageryService

Re-projectionService

Workflow ServiceCatalog Service

March 14, 2002

Opportunities Portals for Community Statistics Field

Focus on providing specialized aggregate and workflow services Customize chains and combine services to meet community statistics

needs Sophisticated tools:

Tools for users to construct and customized their own chains Tools for finding the right services based on characteristics such as

service scope, performance, service/data quality, price Tools for constructing “optimal chains”: least expensive, minimum

number of constituent services, most accurate results, etc. Challenge

Sustainability of such a service-based architecture requires standards and well-defined interfaces for the underlying services

March 14, 2002

Current Status Web Services Technologies

WSDL for service description UDDI for service discovery SOAP for passing XML-encoded data IBM WSFL and MS XLANG for service composition and process

languages for orchestrating web services into larger-scale applications

OGC work Categorization of services: data services (WMS,WFS,WCS),

processing services, registry services Encodings: SLD, GML WMS/SLD/CPS set a precursor precedent for service chaining in

the web services environment