Generalization Web Services Moritz Neun University of Zurich
Jan 08, 2016
Generalization Web ServicesMoritz Neun
University of Zurich
Motivation
Generalization Web Services – Moritz Neun – 19. November 2007
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Motivation 1
Much progress of web cartography through OGC standards. WMS and WFS allow automated access and presentation of cartographic data Pre-calculation and usage of MRDB can support these services only partially
New requirements on delivering and generating on-demand and on-the-fly maps, containing more specific and tailor-made information
OGC (2002) has proposed Feature Generalisation Services, but no further developments yet
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Motivation 2
A large number of generalisation algorithms, auxiliary data structures, cartographic constraints and measures is developed and published
Isolated prototypes implemented with different programming languages
Integrated within closed monolithic systems(Clarity, ArcGIS, Genesys, ….)
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Motivation 2
Consequences: Benchmarks and comparison of algorithms difficult No reuse of available generalisation functionality
and support data structures - researchers have to start from scratch
Following that, rarely addressed “advanced questions” on the generalisation process such as combination of several operators, orchestration, …
Interoperable (research) platform for sharing of (generalization) functionalities needed
History
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History
Lehto and Kilpeläinen (2000, 2001)Edwardes et. al (2003)Badard and Braun (2003)Harrie and Johansson (2003)Sester et. al (2004),
Sarjakoski et. al (2005)Burghardt et. al (2005),
Neun et. al (2006, 2007)Regnauld (2006, 2007)Harrower and Bloch (2006)Lemmens et al. (2006),
Forster and Stoter (2006, 2007)
Open architectures based on distributed platforms have attracted significant interest in the generalisation community
•XSLT techniques are combined with Java programming for real-time generalisation
•Examples show two results of different XSLT processes with different generalisation functionality (selection and simplification)
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History
Lehto and Kilpeläinen (2000, 2001)Edwardes et. al (2003)Badard and Braun (2003)Harrie and Johansson (2003)Sester et. al (2004), Sarjakoski et. al (2005)Burghardt et. al (2005), Neun et. al (2006, 2007)Regnauld (2006, 2007)Harrower and Bloch (2006)Lemmens et al. (2006), Forster and Stoter (2006, 2007)
Open architectures based on distributed platforms have attracted significant interest in the generalisation community
• Need for a common research platform in the domain of map generalisation was expressed
• Requirements for an open generalisation system• Related OGC developments were presented
(WMS, SLD, SVG, WFS, GML, FES, SOAP, WSDL, …)
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History
Lehto and Kilpeläinen (2000, 2001)Edwardes et. al (2003)Badard and Braun (2003)Harrie and Johansson (2003)Sester et. al (2004), Sarjakoski et. al (2005)Burghardt et. al (2005), Neun et. al (2006, 2007)Regnauld (2006, 2007)Harrower and Bloch (2006)Lemmens et al. (2006), Forster and Stoter (2006, 2007)
Open architectures based on distributed platforms have attracted significant interest in the generalisation community
• OXYGENE platform developed at the COGIT laboratory of IGN
• Based on Java technology and different open source components
• Open source release in 2005
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History
Lehto and Kilpeläinen (2000, 2001)Edwardes et. al (2003)Badard and Braun (2003)Harrie and Johansson (2003)Sester et. al (2004), Sarjakoski et. al (2005)Burghardt et. al (2005), Neun et. al (2006, 2007)Regnauld (2006, 2007)Harrower and Bloch (2006)Lemmens et al. (2006), Forster and Stoter (2006, 2007)
Open architectures based on distributed platforms have attracted significant interest in the generalisation community
• GiMoDig services based on layer architecture • Layers encapsulating data integration, data
transformation into GML, data processing (generalisation) and device dependent styling (portal layer)
• Further development of the approach from Lehto and Kilpeläinen with XSLT processing
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History
Lehto and Kilpeläinen (2000, 2001)Edwardes et. al (2003)Badard and Braun (2003)Harrie and Johansson (2003)Sester et. al (2004), Sarjakoski et. al (2005)Burghardt et. al (2005), Neun et. al (2005, 2007)Regnauld (2006, 2007)Harrower and Bloch (2006)Lemmens et al. (2006), Forster and Stoter (2006, 2007)
Open architectures based on distributed platforms have attracted significant interest in the generalisation community
• WebGen platform • Accessible from different clients
(Web Browser, JUMP, …)• DEMO
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History
Lehto and Kilpeläinen (2000, 2001)Edwardes et. al (2003)Badard and Braun (2003)Harrie and Johansson (2003)Sester et. al (2004), Sarjakoski et. al (2005)Burghardt et. al (2005), Neun et. al (2005, 2007)Harrower and Bloch (2006)Regnauld (2006, 2007)Lemmens et al. (2006), Forster and Stoter (2006, 2007)
Open architectures based on distributed platforms have attracted significant interest in the generalisation community
• MapShaper for browser based generalisation• Aim on interactive user controlled generalisation, no platform-independent
coupling of generalisation services• Strong relation of user interface and generalisation functionality
(limited flexibility - new generalisation functions requires new client versions)
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History
Lehto and Kilpeläinen (2000, 2001)Edwardes et. al (2003)Badard and Braun (2003)Harrie and Johansson (2003)Sester et. al (2004), Sarjakoski et. al (2005)Burghardt et. al (2005), Neun et. al (2005, 2007)Harrower and Bloch (2006)Regnauld (2006, 2007)Lemmens et al. (2006), Forster and Stoter (2006, 2007)
Open architectures based on distributed platforms have attracted significant interest in the generalisation community
• Concept of system architecture for on-demand derivation systems• Usage of Geo-Ontologies to formalise input data, user requirements,
cartographic knowledge and service descriptions
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History
Lehto and Kilpeläinen (2000, 2001)Edwardes et. al (2003)Badard and Braun (2003)Harrie and Johansson (2003)Sester et. al (2004), Sarjakoski et. al (2005)Burghardt et. al (2005), Neun et. al (2005, 2007)Harrower and Bloch (2006)Regnauld (2006, 2007)Lemmens et al. (2006), Forster and Stoter (2006, 2007)
Open architectures based on distributed platforms have attracted significant interest in the generalisation community
• Implementation based on OGC Web Processing Services
• Usage of profiles to describe syntax and the semantics of the operation
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History
Lehto and Kilpeläinen (2000, 2001)Edwardes et. al (2003)Badard and Braun (2003)Harrie and Johansson (2003)Sester et. al (2004), Sarjakoski et. al (2005)Burghardt et. al (2005), Neun et. al (2005, 2007)Harrower and Bloch (2006)Regnauld (2006, 2007)Lemmens et al. (2006), Forster and Stoter (2006, 2007)
Open architectures based on distributed platforms have attracted significant interest in the generalisation community
Generalization Web Services – Moritz Neun – 19. November 2007
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History
M.F. Goodchild (2005). GIS and modeling overview. In D.J. Maguire, M. Batty, and M.F. Goodchild, editors, GIS, Spatial Analysis, and Modeling. Redlands, CA: ESRI Press, pp. 1–18.
“There is also increasing interest in providing basic GIS services, such as geocoding, as remotely invokable methods implemented on the Web. In the next few years, dramatic improvements are expected in the availability of techniques for sharing methods and models.”
Web Services
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Web Service Technology
Generalization Services are Web Services: Client-Server structure Component architecture:
- encapsulation of functionalities and resources - generic interfaces (interface description) - loosely coupled by contract Platform independence: usage of standard web protocols (HTTP and XML) Interoperable Remote Procedure Calls (RPC)
(remote processing instead of data delivery)
Web Services are enabling interoperability
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Middleware Generalization ServicesTypical on-demand or on-the-fly generalization service for web map services: Used in combination with data services (e.g. WFS) Translator or compiler for converting and
combining datasets in order to be displayed Usually bound to one or multiple
specific and predefined data delivery services
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Toolbox Generalization Services
Various processing services provide their functionalities as distributed toolbox Data to be processed is provided by the user Everybody can present own services Platform
independentservice access
Coupling of different generalizationsystems
research platform WebGen framework
State-of-the-Art Toolbox Services
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State-of-the-Art
• WebGen research platform• Web Processing Services
• ArcGIS Server (ESRI)• SerAx (Axes Systems)
Toolbox-like service approachesfor remote processing
open commercial
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WebGen
Our prototype of a generalisation toolbox service framework Different plug-ins Generic interface
descriptions Registry for
service discovery Servers for
hosting differentalgorithms
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WPS
WPS Concepts from Foerster (2006)
Web Processing Service (OGC Draft)
Intended for many purposes not only generalisation
Raster and vector data Very open (and vague)
definitions of interface descriptions and data formats
Currently rather aproposal than areal standard
More concrete profileneeded for generalization
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WPS
Foerster (2006) shows WPS implementation for generalisation(partially adopted from WebGen)
Intended for working together e.g. with a web map server like geoserver but not as middleware (geoserver calls the WPS)
Provides ready generalised maps to the requesting client
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axpand
Generalsation functionsas internal services
Adopts WebGen concepts(registry & interface descriptions)
possible use of external services
Management of service workflows
Data is not sent in the service calls (remains in central database, only references are passed)
Uses service concept but rather closed and proprietary
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ArcGIS Geoprocessing Services
Geoprocessing services for the ESRI ArcGIS Server
All types of geoprocessing tools can be served
Works only with ArcGIS products and algorithms
Rather closed and proprietary commercial system
The WebGen Framework
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The WebGen Framework
Implementation of the Toolbox Services Model: Various different distributed servers can provide
generalization services Generic interface
descriptions Registry for global
service discovery Services can use
other services(workflow)
Generalization Server
ServiceService
ServiceService
Generalization Server
ServiceService
ServiceService
Generalization Server
Registry Server
exec
ute
know
s
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The WebGen Framework
Client plug-ins for different platforms Remote processing (execute)
Generalization Server
ServiceService
ServiceService
Generalization Server
ServiceService
ServiceService
Generalization Server
JUMP GIS ClientPlug-in
Local data
AJAX Web ClientBrowser
Local data
Clarity Client
Plug-inLocal data
ArcGIS Client
Registry Server
query services
service descriptions
execute
execute
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WebGen Clients, Registry & Server
client server
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WebGen Registry
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WebGen Services
Large number of services available!
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WebGen Interface Descriptions
Generic XMLinterface descriptions: Nothing predefined
in the clients Dynamic adding of
new services Powerful also for
complex interfaces
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WebGen Client-Server Transfer
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Possible WebGen Scenario
LAN / InternetLAN / Internet
ServerJUMP
Server Plug-In
JUMP/JTSAlgorithms
ServerArcGIS
Server Plug-In
ArcGIS Toolbox
Workstation JUMP
local datasets
ToolboxPlug-In
Workstation ArcGIS
local datasets
ToolboxPlug-In
Workstation Clarity
local datasets
ToolboxPlug-In
ServerClarity
Server Plug-In
AGENTAlgorithms
Registry
coupling of systems for research or production
Generalization Service Categories
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MRDB
Generalization Service Categories
Gen
era
liza
tion
Serv
ices
Su
pp
ort
Serv
ices
Operator Services(simplification, aggregation, …)
service interface
interactive interface
Process Services(workflow control, evaluation)
service interface
interactive interface
Service Consumer(research, map production, …)
Support Services(attributes, triangulations …)
service interface
interactive interface
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Support Services
Provision of auxiliaryenriching information(data enrichment)
make structural knowledge explicit can be exploited by other services
differentiation by the output data type simple entities (geometries / attributes) complex relations (hierarchical / non-hierarchical)
Support Services
Entities(geometries, attributes)
Relations(hierarchical, non-
hierarchical)
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Operator Services
Operator services are implementing concrete generalization algorithms Perform geometrical and semantical transformations of map objects Can be context dependent by using structural knowledge (from support services)
Examples from building generalization:
RemovalSimplification Displacement
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Process Services
Workflow / orchestration of different services predefined batch workflows, adaptive workflows and fully automated systems: Selection of the appropriate algorithms
(operator services) for a situation Use of the right parameter values Application of operators in the proper sequence
simplifyinitial typify displace
Discussion
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Discussion
Strengths of the WebGen approach Provision of various functionalities as interoperable toolbox (research platform) Functional subdivision of generalization in
support, operator and process services Sharing, coupling and reuse of functionalities
at very different levels of granularity Provision of complex spatial data structures Central registry for service discovery Generic interfaces allow real interoperability Parallelization possible (clustering)
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Service Usage Scenarios
Keep in mind that different user types need different functionalities and levels of complexity: Novice user (planner wants to simplify a map) Expert user (NMA wants to couple systems) Researcher (wants to evaluate an algorithm) Data display (convert data from WFS on-the-fly)
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Where to start?
Challenges: Meet user scenarios Common generic (XML) service data model Generic syntactic and semantic interface descriptions needed (service capabilities and requirements) Granularity (especially of support services, stateless or stateful services)
Some work required (WebGen is still a prototype) Advance WebGen? Extend WPS with concrete profile?
Thank you!
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WebGen Registry