Generalization Web Services Moritz Neun University of Zurich

Motivation

Generalization Web Services – Moritz Neun – 19. November 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

Generalization Web Services – Moritz Neun – 19. November 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, ….)

Generalization Web Services – Moritz Neun – 19. November 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

Generalization Web Services – Moritz Neun – 19. November 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)

Generalization Web Services – Moritz Neun – 19. November 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, …)

Generalization Web Services – Moritz Neun – 19. November 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

Generalization Web Services – Moritz Neun – 19. November 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

Generalization Web Services – Moritz Neun – 19. November 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

Generalization Web Services – Moritz Neun – 19. November 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)

Generalization Web Services – Moritz Neun – 19. November 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

Generalization Web Services – Moritz Neun – 19. November 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

Generalization Web Services – Moritz Neun – 19. November 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 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

Generalization Web Services – Moritz Neun – 19. November 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

Generalization Web Services – Moritz Neun – 19. November Middleware Generalization Services Typical 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

Generalization Web Services – Moritz Neun – 19. November 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 independent service access  Coupling of different generalization systems  research platform  WebGen framework

State-of-the-Art Toolbox Services

Generalization Web Services – Moritz Neun – 19. November State-of-the-Art WebGen research platform Web Processing Services ArcGIS Server (ESRI) SerAx (Axes Systems) Toolbox-like service approaches for remote processing opencommercial

Generalization Web Services – Moritz Neun – 19. November WebGen  Our prototype of a generalisation toolbox service framework  Different plug-ins  Generic interface descriptions  Registry for service discovery  Servers for hosting different algorithms

Generalization Web Services – Moritz Neun – 19. November 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 a proposal than a real standard  More concrete profile needed for generalization

Generalization Web Services – Moritz Neun – 19. November 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

Generalization Web Services – Moritz Neun – 19. November axpand  Generalsation functions as 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

Generalization Web Services – Moritz Neun – 19. November 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

Generalization Web Services – Moritz Neun – 19. November 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 Service Generalization Server Service Generalization Server Registry Server execute knows

Generalization Web Services – Moritz Neun – 19. November The WebGen Framework Client plug-ins for different platforms  Remote processing (execute) Generalization Server Service Generalization Server Service Generalization Server JUMP GIS Client Plug-in Local data AJAX Web Client Browser Local data Clarity Client Plug-in Local data ArcGIS Client Registry Server query services service descriptions execute

Generalization Web Services – Moritz Neun – 19. November WebGen Clients, Registry & Server clientserver

Generalization Web Services – Moritz Neun – 19. November WebGen Registry

Generalization Web Services – Moritz Neun – 19. November WebGen Services Large number of services available!

Generalization Web Services – Moritz Neun – 19. November WebGen Interface Descriptions Generic XML interface descriptions:  Nothing predefined in the clients  Dynamic adding of new services  Powerful also for complex interfaces

Generalization Web Services – Moritz Neun – 19. November WebGen Client-Server Transfer

Generalization Web Services – Moritz Neun – 19. November Possible WebGen Scenario LAN / Internet Server JUMP Server Plug-In JUMP/JTS Algorithms Server ArcGIS Server Plug-In ArcGIS Toolbox Workstation JUMP local datasets Toolbox Plug-In Workstation ArcGIS local datasets Toolbox Plug-In Workstation Clarity local datasets Toolbox Plug-In Server Clarity Server Plug-In AGENT Algorithms Registry  coupling of systems for research or production

Generalization Service Categories

Generalization Web Services – Moritz Neun – 19. November MRDB Generalization Service Categories Generalization Services Support Services 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

Generalization Web Services – Moritz Neun – 19. November Support Services Provision of auxiliary enriching 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)

Generalization Web Services – Moritz Neun – 19. November 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: Removal Simplification Displacement

Generalization Web Services – Moritz Neun – 19. November 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 simplifyinitialtypify displace

Discussion

Generalization Web Services – Moritz Neun – 19. November 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)

Generalization Web Services – Moritz Neun – 19. November 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)

Generalization Web Services – Moritz Neun – 19. November 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!

Generalization Web Services – Moritz Neun – 19. November WebGen Registry