Impacts of web services web services Impacts of web services. P. Bogaert Ph. De Maeyer

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web services

Impacts of web services

. P. Bogaert Ph. De Maeyer

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AM/FM-GIS Belux - 08 november 2005 - Grimbergen.

Approaches

Human thinking pattern

Technologic aspects

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DBMS - 1

DBMS - 2

CAD - 1

CAD - 2

vector GIS - 1 raster GIS - 1

GIS - 2

GIS - 3

GIS - 4

matricial maps

imageprocessing

intranet and internet

knowledge andexpertsystems

main frames'70

mini'80

micro'90

2000 ...

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History of GIS computing

Accessibility

Time

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Evolution of the Internet

Arpanet

TCP-IP:communication

protocol

Tim Brenners-Lee and the WWW

applicationHigh Perfomance Act

+ Webbrowsers

1969 1993-1995 1989 1978

Number of users

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How many people use the WWW

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Source :CyberAtlas 2005

Relative number of users0 - 5.315.31 - 15.3115.31 - 29.6529.65 - 50.8150.81 - 68.51No Data

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Alsolute number of users200 - 37200003720001 - 1388000013880001 - 4188000041880001 - 9980000099800001 - 185550000No Data

Source :CyberAtlas 2005

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How many people use the WWW?

Source :CyberAtlas

0

200000000

400000000

600000000

800000000

1000000000

1200000000

1995 1998 2000 2005

1 000 000 000

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Impact?

Advantages of webcartography:

• facilities for actualisation of data;• large diffusion (and quick (!?) diffusion) of the information;• interactivity;• zooming facilities and multi-window approach;• possibilities for creating personalised maps using personal selections of information and

map layers and using personalised symbolisations;• facilities to integrate multimedia, including sound, animations, …;• less limitations of diffusion of large amounts of maps and accompanying information;• possibility to deliver a product that is free for customer (all times wished?);• ….• accessibility

– Available worldwide– All you need is a PC and a connection– GSM / Pocket PC– …

• actuality– Almost real-time– But!! Keep information up to date!!

• interoperability

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Impact ?

Disadvantages of webcartography:

• limited image resolution, but …;• limitation in overview and limitation in the covered surface , but …;• difficulties for mental mapping;• disappearance of copyright concept (fuzzy copyright interpretations by users); • legal issues (law and directives for privacy, databases, software, …) • language (choice, globalisation)• data quality? (origin, completeness, actuality, scale, precision, accuracy and consistency: geometric and semantic) •

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Due to Accessibility of Data

A distributed system is an application that runs on different computers, with different operating systems, at different locations and different connections but for the user it seems to be one system only

Distributed GI-System

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Client/Server architecture applied to a GIS

• Partitioning in software

Presentatie Verwerking Gegevens

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• Partitioning in software: Division point

Presentatie Verwerking Gegevens

Remote presentation

Distributed Presentation

Distributed function

Remote Data Access

Distributed database

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Presentation Logical data

Distributed PresentationInteractivity

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Distributed function

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Remote Data Acces

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Distributed database

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Thin Thick

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• Two, three, n-tier systems

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Exchange standards

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Exchange standards

• GML• Geography Markup Language

• is an XML grammar written in XML Schema for the modelling transport, and storage of geographic information.

– ISO standard (commision TC211)

– Developed by OGC (Open Geospactial Consortium)

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Exchange standards

• GML• Geography Markup Language

• GML 2.0– Simple features: point, line polygon, no curves

– 2D

• GML 3.0– GML 2.0

– + 3D

– + Topology

– + complex features

– + temporal aspects

– + reference systems + …

– 8 times as big

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Exchange standards

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Exchange standards

• WMS (Web Map Service)

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Exchange standards

• WMS (Web Map Service)

– Exchange of geographic information via images

+ =+ …

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Exchange standards• WMS (Web Map Service)

– Operations

• GetCapabilities

• GetMap

• (GetFeatureInfo)

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Exchange standards

• WFS (Web Feature Service)

– Instead of an image, features are send

– Allows operations

– Answer in GML

– Basic WFS vs. Transition WFS

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Exchange standards• WFS (Web Feature Service)

– Operations

• GetCapabilities

• DescribeFeature

• GetFeature

• Transaction

• LockFeature

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Exchange standards

• Others:

– Catalog Service for the Web (Metadata)

– Web Coverage Surface (Coverages)

– …

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Considerations concerning the medium

• Client-Server Architecture.

Browser(Internet Explore,

Netscape, ...)

Webserver(IIS, Apache,...)

Client Server

Communication

Request

Answer

Client Computer

The connectionServing Computer

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• Client Computer:– Screen resolution (800x600 of 1024x768 …)

• Keep maps small

• Interactive maps can adapt to the users screen resolution

– Colours (256 colours or more?)• Use with web save colours only (256 standard colours)

– Plug-ins (available / installed?)• Avoid Plug-ins

– Browsers (Netscape, Internet Explorer, Opera, … ?)• Use Standards (HTML / DHTML)

• Online validation of the code via W3C

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• The communication

– Does the client/server have a broadband/smallband connection

– How long does it take to view the map (5 seconds)

World Wide Web <> World Wide Wait !!!

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• The connection

– Keep the information to be sent as small possible

– Compression!

– Use interactivity!• Send only the information which is asked for

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• The serving computer:

– Do all systems that generate maps work on my system?(Windows, Unix, Linux, …)

– Do I have a strong enough computer to cope with:• Number of visitors

– Memory

– Connection

• Maps to be generated– Storage

– Memory

– …

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Thanks

Philippe De Maeyer | Peter Bogaert{philippe.demaeyer , peter.bogaert}@ugent.be

Universiteit Gentwww.geoweb.ugent.be

Documents

Impacts of web services web services Impacts of web services. P. Bogaert Ph. De Maeyer