q114/random_k2/random_2.md

Introduction to
Introduction to
WEBWEB--GISGIS

Chathura H Wickramasinghe
Chathura H Wickramasinghe

Geographic Information Systems
Geographic Information Systems

ÑÑ ““Mapping

Mapping”” is inventory and presentation of
is inventory and presentation of
spatial data.
spatial data.

Geographical Information
GIS means ““Geographical Information
ÑÑ GIS means
System””
System
Its called that because there is information
ÓÓ Its called that because there is information
behind the map.
behind the map.

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GIS vs CAD
GIS vs CAD

Difference between mapping software or CAD and GIS:
Difference between mapping software or CAD and GIS:

CAD
CAD

Mapping 2D or 3D geospatial data
ÓÓ Mapping 2D or 3D geospatial data

GISGIS
Three levels of GIS applications:
ÑÑThree levels of GIS applications:
Inventory (What is there?)
ÓÓ Inventory (What is there?)
Analysis (Answering questions)
ÓÓ Analysis (Answering questions)
Shortest distance
ÔÔ Shortest distance

Modeling (Making predictions)
ÓÓ Modeling (Making predictions)

CAD stands for Computer-Aided Design

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A GIS is a software system that connects map
layers with tables of information.

GIS MAP

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Image: ESRI course Learning ArcGIS Desktop  2007

Importance of Geographic Data
Importance of Geographic Data

GIS is different than most applications
ÑÑ GIS is different than most applications

Word processing, Spreadsheets…… are are
ÑÑ Word processing, Spreadsheets
entirely dependent on input of YOUR
entirely dependent on input of

YOUR datadata

GIS users nearly always require reference
ÑÑ GIS users nearly always require reference
map data (e.g., streets, boundaries) that are
map data (e.g., streets, boundaries) that are
by others
maintained by others
maintained

As GIS users, we rely heavily on
ÑÑ As GIS users, we rely heavily on
data sources
external”” data sources
““external

Data has to be shared

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Evolution of Data Sharing
Evolution of Data Sharing

Distributed GIS
Distributed GIS
(via web services)
(via web services)

Downloading
Downloading
DataData

y
t
i
r
u
t
a
M

Media
Media
Distribution
Distribution
((““ftpftp””))

Shared
Shared
Diskspace
Diskspace

Time

Issues with typical/traditional Data
Issues with typical/traditional Data
Sharing Methods
Sharing Methods

Getting all the data
ÑÑ Getting all the data
Vintage
ÑÑ Vintage
Format
ÑÑ Format
Coordinate System/Projection
ÑÑ Coordinate System/Projection
Media Compatibility
ÑÑ Media Compatibility
File Size
ÑÑ File Size
Bandwidth
ÑÑ Bandwidth
Metadata Distribution
ÑÑ Metadata Distribution

Typically requires data manipulation
prior to use (reformatting, reprojecting,
clipping, etc.)

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Distributed GIS Model
Distributed GIS Model
NYS DEC
NYS CSCIC
USGS

US EPA

DEM

Wetlands

Orthos

Real-time
access to
geographic
data and
services

Local
Data

Virtually Any Client

Mashup
Mashup

An application that combines data from multiple sources
ÑÑ An application that combines data from multiple sources
content aggregation””
Referred to as ““content aggregation
ÑÑ Referred to as
Combines similar
ÑÑ Combines
systems/services
different systems/services
different
Term originated from music industry when a new song
ÑÑ Term originated from music industry when a new song
was made from several existing tracks
was made from several existing tracks

types of data (e.g., maps,) from
similar types of data (e.g., maps,) from

+

=

Distributed GIS Advantages
Distributed GIS Advantages

Format is irrelevant
ÑÑ Format is irrelevant
Guarantees latest data
ÑÑ Guarantees latest data
No media involved
ÑÑ No media involved
Size is irrelevant (only requested
ÑÑ Size is irrelevant (only requested
data needed)
data needed)
Software independent
ÑÑ Software independent

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Distributed GIS Advantages
Distributed GIS Advantages

Device independent (PC, phone)
ÑÑ Device independent (PC, phone)
Saves Time!
ÑÑ Saves Time!
Data security
ÑÑ Data security
Only view data
ÓÓ Only view data
Download data
ÓÓ Download data
Data upload and editing
ÓÓ Data upload and editing

Distributed GIS Advantages
Distributed GIS Advantages
Desktop software's also support WMS
ÑÑ Desktop software's also support WMS
ÓÓ QGISQGIS
ArcGIS
ÓÓ ArcGIS

Advantages
ÓÓ Advantages
Carryout advance GIS operations on the data.
ÔÔ Carryout advance GIS operations on the data.
Use as source data for GIS analysis.
ÔÔ Use as source data for GIS analysis.
Easy to search and access data.
ÔÔ Easy to search and access data.

Distributed GIS Disadvantages
Distributed GIS Disadvantages

Dependent on server availability
ÑÑ Dependent on server availability
Dependent on internet availability
ÑÑ Dependent on internet availability
Users need to be aware of web service
ÑÑ Users need to be aware of web service

Service Oriented
Service Oriented
Architecture
Architecture

Architecture that is based on integrating
ÑÑ Architecture that is based on integrating
, interoperable services
loosely coupled””, interoperable services
““loosely coupled

Loosely coupled means NOT physically
ÑÑ Loosely coupled means NOT physically
bound or compiled like an EXE or DLL
bound or compiled like an EXE or DLL

These services can be invoked and
ÑÑ These services can be invoked and
consumed remotely over a network
consumed remotely over a network

Data and messages are exchanged
ÑÑ Data and messages are exchanged
between clients and services
between clients and services

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Basic Web Page Operation
Basic Web Page Operation

Request

Response
(HTML document)

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Web Service Operation
Web Service Operation

Client

Convert UTM To Lat/Long

Zone: 18
Longitude: -73.3456
Processing….
Easting: 623,456.3
Latitude: 42.2753
Northing: 4,745,342.3

1. Creates XML Request

2. Request sent to web
service

Web Server
(Listening for requests)

7. Receives response and parses

6. Response sent to client

3. Receives request and
parses XML

4. Calls the function

5. Creates response XML
with results

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Types of Geospatial Web Services
Types of Geospatial Web Services

Map/Data Oriented Services
ÑÑ Map/Data Oriented Services
Map Services (Image)
ÓÓ Map Services (Image)
Feature Services (Vector)
ÓÓ Feature Services (Vector)
Coverage Services (Grid)
ÓÓ Coverage Services (Grid)

Task Oriented Services
ÑÑ Task Oriented Services
Routing Services
ÓÓ Routing Services
Geoprocessing Services
ÓÓ Geoprocessing Services

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Map Services
Map Services

ÑÑ Client requests a map from a server for a specified geographic e

xtent
Client requests a map from a server for a specified geographic extent

Map Server renders the requested map internally and converts to an an
ÑÑ Map Server renders the requested map internally and converts to
image file (e.g., JPG, PNG, GIF) and returns the map image to the e
image file (e.g., JPG, PNG, GIF) and returns the map image to th
client for display
client for display

Fast map display is possible.
ÑÑ Fast map display is possible.

99% of current activity's in Web GIS Map/Image Serving

made way for WebGIS popularity
Google Map”” made way for WebGIS popularity
““Google Map

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Map Service Operation
Map Service Operation

Client

Web Server/Map Server

1. Creates XML Request

2. Request sent to web
service

8. Receives response,
parses to extract image
and updates map

7. Response sent to client

3. Receives request and
parses XML

4. Calls the map server to
request map

5. Map Server generates
map as image file

6. Creates response XML
with image file

Sample site
Sample site

http://www.wunderground.com/radar/map.as
ÑÑ http://www.wunderground.com/radar/map.as
pp
http://maps.eyesontheforest.or.id/
ÑÑ http://maps.eyesontheforest.or.id/
https://mapsengine.google.com/map
ÑÑ https://mapsengine.google.com/map

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Need for standardization
Need for standardization

Every one was creating own standards
ÑÑ Every one was creating own standards
Google maps
ÓÓ Google maps
Bing Maps
ÓÓ Bing Maps
USGS
ÓÓ USGS

Make universal data sharing possible.
ÑÑ Make universal data sharing possible.
Overcome technical chalengers.
ÑÑ Overcome technical chalengers.
Make way for rapid development in
ÑÑ Make way for rapid development in
WebGIS.
WebGIS.

OGC and Open Web Mapping
OGC and Open Web Mapping

ÑÑ The The Open Geospatial Consortium (OGC)
was founded in 1994
Open Geospatial Consortium (OGC) was founded in 1994
An international consortium of 346 organizations that lead the
ÑÑ An international consortium of 346 organizations that lead the
development of open standards and specifications to enable the
development of open standards and specifications to enable the
interoperability of geospatial and location based services
interoperability of geospatial and location based services

ÑÑ They have developed a series of open standards for geospatial we

They have developed a series of open standards for geospatial web b
services such as:
services such as:
Geography Markup Language (GML)
ÓÓ Geography Markup Language (GML)
Web Mapping Services (WMS)
ÓÓ Web Mapping Services (WMS)
Web Feature Services (WFS)
ÓÓ Web Feature Services (WFS)
Web Coverage Services (WCS)
ÓÓ Web Coverage Services (WCS)
Referrred to as ““OpenGIS

OpenGIS®®”” standards
standards

ÑÑ Referrred to as

OGC Web Services (OWS)
OGC Web Services (OWS)
Web Map Service (WMS)
ÑÑ Web Map Service (WMS)
ÓÓ Web Map Service  Interface Standard (WMS) provides  a simple HTTP

Web Map Service  Interface Standard (WMS) provides  a simple HTTP  interface for
interface for
requesting  geo--registered  map  images  from  one  or  more  distributed  geospatial
registered  map  images  from  one  or  more  distributed  geospatial
requesting  geo
databases. A WMS request defines the  geographic layer(s)  and  area  of interest  to
a  of interest  to
databases. A WMS request defines the  geographic layer(s)  and  are
be  processed.  The  response  to  the  request  is  one  or  more  geo--registered  map
registered  map
be  processed.  The  response  to  the  request  is  one  or  more  geo
rowser
images  (returned  as  JPEG,  PNG,  etc)  that  can  be  displayed  in  a  browser
images  (returned  as  JPEG,  PNG,  etc)  that  can  be  displayed  in  a  b
application.
application.

Web Feature Service (WFS)
ÑÑ Web Feature Service (WFS)
ÓÓ The  WFS  operations  support  INSERT,  UPDATE,  DELETE,  LOCK,  QUERY  a

The  WFS  operations  support  INSERT,  UPDATE,  DELETE,  LOCK,  QUERY  and nd
stributed
DISCOVERY  operations  on  geographic  features  using  HTTP  as  the  distributed
DISCOVERY  operations  on  geographic  features  using  HTTP  as  the  di
computing platform. It is the function of a web feature service, in its interaction with
in its interaction with
computing platform. It is the function of a web feature service,
ensure that changes
the data storage system used to persistently store features, to ensure that changes
the data storage system used to persistently store features, to
to data are consistent.
to data are consistent.

Web Coverage Service (WCS)
ÑÑ Web Coverage Service (WCS)
ÓÓ The  OpenGIS

The  OpenGIS®® Web  Coverage  Service  Interface  Standard  (WCS)  defines  a
Web  Coverage  Service  Interface  Standard  (WCS)  defines  a
standard  interface  and  operations  that  enables  interoperable  access  to  geospatial
ess  to  geospatial
standard  interface  and  operations  that  enables  interoperable  acc
"grid
term
[http://www.opengeospatial.org/ogc/glossary/c].  The
"coverages"
"coverages"
"grid
term
[http://www.opengeospatial.org/ogc/glossary/c].  The
digital aerial photos,
coverages" typically refers to content such as satellite images, digital aerial photos,
coverages" typically refers to content such as satellite images,
s  at  each
digital  elevation  data,  and  other  phenomena  represented  by  values  at  each
digital  elevation  data,  and  other  phenomena  represented  by  value
measurement point.
measurement point.

Web Mapping Services (WMS)
Web Mapping Services (WMS)

WMS is the OGC specification for
ÑÑ WMS is the OGC specification for
implementing a map (image) service
implementing a map (image) service

Does not allow for cached map services
ÑÑ Does not allow for cached map services

WMS provides 3 functions for clients to
ÑÑ WMS provides 3 functions for clients to
access functionality
access functionality

Two functions are mandatory to be
ÑÑ Two functions are mandatory to be
implemented, the third function is
implemented, the third function is
optional
optional

ÑÑ This results in two general

This results in two general ““types
WMS Services
WMS Services
ÓÓ BasicBasic
Queryable
ÓÓ Queryable

types”” of of

Web Mapping Services
Web Mapping Services
(WMS)
(WMS)

Basic WMS Service
Basic WMS Service
Every WMS service MUST support the following two functions:
Every WMS service MUST support the following two functions:

ÓÓ GetCapabilities

Describes the capabilities and available layers
GetCapabilities –– Describes the capabilities and available layers

ÓÓ GetMap

Generates a map image based on input parameters
GetMap –– Generates a map image based on input parameters

Queryable WMS Service
Queryable WMS Service
The following function is optional for WMS services:
The following function is optional for WMS services:

ÓÓ GetFeatureInfo

Gets the attributes for a specified feature
GetFeatureInfo –– Gets the attributes for a specified feature

http://www.opengeospatial.org/standards/wms
http://www.opengeospatial.org/standards/wms

What can be done with a
What can be done with a
WMS service?
WMS service?

ÑÑ Each client application (e.g., ArcView, MapInfo, Google Earth, e

Each client application (e.g., ArcView, MapInfo, Google Earth, etc.)
tc.)
handles WMS services differently
handles WMS services differently

However, generally the following functions are available:
ÑÑ However, generally the following functions are available:
Map Display and navigation
ÓÓ Map Display and navigation
Zoom to layer
ÓÓ Zoom to layer
Layer Control
ÓÓ Layer Control
Identify feature (only with Queryable Map services)
ÓÓ Identify feature (only with Queryable Map services)

Anything else is not available
ÑÑ Anything else is not available
No feature selection
ÓÓ No feature selection
No geoprocessing
ÓÓ No geoprocessing
No attribute table/browser display
ÓÓ No attribute table/browser display
Menus/Buttons are greyed out and disabled
ÓÓ Menus/Buttons are greyed out and disabled

WebGIS Components
WebGIS Components

Web GIS Components (Cont …………))
Web GIS Components (Cont

Internet Browser such as Internet Explore, Mozila firefox
Internet Browser such as Internet Explore, Mozila firefox

••Client:
Client:
––
etcetc
Internet Connection:
••Internet Connection:

––
Performance of a web mapping site largely depends on
Performance of a web mapping site largely depends on
bandwidth of the Internet connection
the  bandwidth of the Internet connection
the
Higher the bandwidth better the performance
––
Higher the bandwidth better the performance

Web server
••Web server

Handle the requests from Web Browser (user) and
Handle the requests from Web Browser (user) and

––
Return the web page
Return the web page
Apache,IIS
––
Apache,IIS

Meta Data
••Meta Data

––
––

data about data
data about data
Including Server URL, Owner etc
Including Server URL, Owner etc

Web GIS Components (Cont …………))
Web GIS Components (Cont

Map Server
••Map Server

––
page.
page.
––

TheMapServer is the engine behind the maps you see on a web
TheMapServer is the engine behind the maps you see on a web

The Map Server needs to be configured to communicate between
The Map Server needs to be configured to communicate between
the web server and assemble data layers into an appropriate
the web server and assemble data layers into an appropriate

image.
image.

Map viewer
••Map viewer

––
––

––
––

Renders the maps on the client side
Renders the maps on the client side
The relationships among Objects
The relationships among Objects
––Map Extent
Map Extent
Map Size
––Map Size
Reference Map (Key Map)
––Reference Map (Key Map)

Point Map Server where to locate data
Point Map Server where to locate data
Define how things are to be drawn
Define how things are to be drawn

Colors
––Colors
Labeling etc……
––Labeling etc

WEB GIS Software
WEB GIS Software

Category

Commercial

Operating Systems

Windows

Free

Linux

Database SW

ORACLE  , MSsql

Mysql , Postgresql

Spatial Database SW

ORACLE Spatial

MySQL Spatial, PostGIS

RS\GIS Applications

ArcGIS, ERDAS, ENVI

ILWIS, GRASS, QGIS

Web GIS Applications

ArcIMS

MapServer, GeoServer

ArcGIS Server/ ArcSDE

Mapbender, OpenLayers

GIS components
Open WEB--GIS components
Open WEB

Map Servers

Rendering spatial data (maps, images,

and vector data)   for the web

• Minnesota MapServer
• GeoServer

Map Viewer

http://mapserver.org/

http://geoserver.org

It provides a data model and web based
interfaces for displaying, navigating and
querying OGC compliant map services

www.mapbender.org/

• Mapbender
• OpenLayers

openlayers.org/

WebGIS using open source tools
WebGIS using open source tools

Example:  The following WebGIS application was developed using GeoServer &
OpenLayers

Open Web GIS solutions
Open Web GIS solutions

GeoNode
GeoNode
based application and platform for
GeoNode is a web--based application and platform for
ÑÑGeoNode is a web
developing geospatial information systems (GIS) and for
developing geospatial information systems (GIS) and for
deploying spatial data infrastructures (SDI).
deploying spatial data infrastructures (SDI).

geonode.org/

GeoNetwork opensource
GeoNetwork opensource
GeoNetwork is a catalog application to manage spatially
ÑÑGeoNetwork is a catalog application to manage spatially
referenced resources. It provides powerful metadata editing and
referenced resources. It provides powerful metadata editing and
search functions as well as an embedded interactive web map
search functions as well as an embedded interactive web map
viewer. It is currently used in numerous Spatial Data
viewer. It is currently used in numerous Spatial Data
Infrastructure initiatives across the world.
Infrastructure initiatives across the world.

http://geonetwork-opensource.org/

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Core components
Core components

• Upload Vector  & Raster data
• Metadata support.
• Create Maps
• Print maps as pdf

• Up- and downloading  data,

graphics, documents, pdf files

• Online editing of metadata
• Scheduled harvesting and

synchronization of metadata
• Support for OGC-CSW 2.0.2 ISO

Profile, OAI-PMH, Z39.50
protocols.

Web Server

Map Viewer

GeoEDGE
GeoEDGE

Compilation of Free Open source  Web GIS
Compilation of Free Open source  Web GIS
resources Powerful tool that support
resources Powerful tool that support

Map services
ÓÓ Map services
GIS spatial operations
ÓÓ GIS spatial operations
Map display
ÓÓ Map display
Advance Spatial analysis
ÓÓ Advance Spatial analysis
Automatic Geocoding
ÓÓ Automatic Geocoding
Geo reference map views
ÓÓ Geo reference map views
Interactive multi user digitizing
ÓÓ Interactive multi user digitizing

Web Processing Services

Web Processing Service
Web Processing Service

ÑÑ The OpenGIS

The OpenGIS®® Web Processing Service (WPS) Interface Standard provides
Web Processing Service (WPS) Interface Standard provides
ponses) for
rules for standardizing how inputs and outputs (requests and responses) for
rules for standardizing how inputs and outputs (requests and res
geospatial processing services, such as polygon overlay. .
geospatial processing services, such as polygon overlay

of a
The standard also defines how a client can request the execution of a
ÑÑ The standard also defines how a client can request the execution
nes an
process, and how the output from the process is handled. It defines an
process, and how the output from the process is handled. It defi
s and clients’’
interface that facilitates the publishing of geospatial processes and clients
interface that facilitates the publishing of geospatial processe
y the WPS
discovery of and binding to those processes. The data required by the WPS
discovery of and binding to those processes. The data required b
e server.
can be delivered across a network or they can be available at the server.
can be delivered across a network or they can be available at th

WPSWPS
Advantages
Advantages

GIS Operation online
ÓÓ GIS Operation online
No need of GIS applications
ÓÓ No need of GIS applications
Easy to use
ÓÓ Easy to use
No need of GIS knowledge
ÓÓ No need of GIS knowledge
Can be done on any device ( mobile / pc)
ÓÓ Can be done on any device ( mobile / pc)

Disadvantages
Disadvantages

Need powerful server
ÓÓ Need powerful server

Thank You
Thank You

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