Web GIS

Web GISMuhammad HarisLecturer GIS Center PUCIT1BasicsProgramming Desktop , Web , MobileSOA (Service Oriented Architecture)Client- Server 1 tier , 2 tier, 3 tier , n-tierhttp://blog.simcrest.com/what-is-3-tier-architecture-and-why-do-you-need-it/ Thick client vs Thin clientDesktop(thick/fat) (e.g. Yahoo Messenger, Google Earth)Web (thin) (e.g. web-browsers; IE, FireFox, Chrome, Facebook Chat)http://en.wikipedia.org/wiki/Thin_client http://en.wikipedia.org/wiki/Fat_client http://www.webopedia.com/DidYouKnow/Hardware_Software/2006/thin_client_applications.asp Miscellaneous Tier vs LayerWeb: LAN/WAN , Internet, Website, WebpagesProtocols: Internet => TCP/IP , Web => HTTP

2Todays Contents3 - Tier Client-Server Architecture Client (Front End, Presentation Tier) Server (Application or Business Tier) Database (Data source tier)

ConceptsBrowser, Server Software, URL (Static vs Dynamic)

Links open in Internet Explorer only !!!http://webgisdev.com/web2/web2_files/frame.htm (Dynamic and Static URL) http://webgisdev.com/webpro/web2/wpro2_files/frame.htm (Client-Server)

ClientServerDBHTML. CSS, Javascript, AJAX, JQueryPHP, JSP, ASPOrcale, MySQL, PostGres (SQL Language)3SOA and Web ServicesService Oriented ArchitectureExample: Viewing an online bank-statement, or placing an online booking or airline ticket order. Use defined protocols that describe how one or more services can "talk" to each other. AWeb serviceis a method of communications between two electronic devices over anetwork

Bank Providing Online Bank Statement Service

Clients Using the Bank ServiceWeb Service4Geospatial Web services are the services which deals with geographic information.

These web services can do the following:Provide access to geographic information stored in a database.Perform geographic computations, for example: find the area of land parcels Distance between two points on a path etc.

Geospatial Web Services5Open Geospatial Consortium (OGC) is an organization that helps in providing open standards for geospatial data and services.

Some basic and important standards provided by OGC are:Services:Web Mapping Services(WMS)Web Feature Services(WFS)Web Coverage Services(WCS)Web Processing Services (WPS)Data:Geographic Markup Language (GML)Keyhole Markup Language (KML)

Note: All these services part of Map Container and hence a Web Mapping Server.OGC Standards For Web GIS6Web Mapping ServerClientDBWeb ContainerMap ContainerBrowser (Chrome, Firefox)Web Server (Apache, IIS)Database Server(MySql, Postgres)Map Container ( GeoServer, ArcGIS server)7Mapping Concept

8An Open Geospatial Consortium Web Map Service (WMS) produces maps of spatially referenced data dynamically from geographic information.

This international standard defines a "map" to be a portrayal of geographic information as a digital image file suitable for display on a computer screen. WMS9WMS specifies a number of different request types, two of which are required by any WMS server:GetCapabilities - returns parameters about the WMS and the available layersGetMap - with parameters provided, returns a map imageRequest types that WMS providers may optionally support include:GetFeatureInfoDescribeLayerGetLegendGraphicFormat of Images returned by WMSJPEGGIFSVGPNGParameters of WMS Service10Parameters of GetMap RequestImportant ParametersRequestgetMapLayersOne or more layer name separated with commaBboxMinX, MinY, MaxX, MaxYFormatImage/jpegImage/gifImage/png Width & Height of ImageOptional ParametersSRSInput in EPSG codes like EPSG:4326 for WGS84 and EPSG:32643 for UTM Zone 43NExample:http://localhost:8080/geoserver/wms?bbox=-130,24,-66,50&styles=population&Format=image/png&request=GetMap&layers=topp:states&width=550&height=250&srs=EPSG:4326

11Parameters of GetLegendGraphicsImportant ParametersRequestGetLegendGraphicsFormatImage/gifImage/jpegImage/pngLayerLayernameWidth & HeightOptional ParametersVersion1.0.0Examplehttp://localhost:8080/geoserver/wms?REQUEST=GetLegendGraphic&VERSION=1.0.0&FORMAT=image/png&WIDTH=20&HEIGHT=20&LAYER=topp:states

12Parameters of Describe Layerhttp://localhost:8080/geoserver/wms?request=DescribeLayer&version=1.1.1&layers=topp:states13Parameters of Get Feature Infohttp://localhost:8080/geoserver/wms?bbox=-130,24,-66,50 & info_format=text/plain & request=GetFeatureInfo & layers=topp:states&query_layers=topp:states & width=550 &height=250&x=170&y=16014The Open Geospatial Consortium Web Feature Service Interface Standard (WFS) provides an interface allowing requests for geographical features across the web using platform-independent calls.The XML-based GML furnishes the default payload-encoding for transporting the geographic features, but other formats like shape files can also serve for transport. WFS15The WFS standard defines interfaces and operations for data access and manipulation on a set of geographic features, including:

Get or Query features based on spatial and non-spatial constraints Create a new feature instance Get a description of the properties of features Delete a feature instance Update a feature instance Lock a feature instance .WFS.16WFS RequestCommon RequestGetCapabilitiesGetFeatureGetFeatureMultiFilterGetFeatureIntersectsGetFeatureBBoxGetFeatureFidTransaction RequestTransactionDeleteTransactionInsertTransactionUpdate

17GetFeature without filterhttp://localhost:8080/geoserver/wfs?request=GetFeature&version=1.1.0&typeName=topp:states&formatName=GML218WFS With Filterhttp://localhost:8080/geoserver/wfs?request=GetFeature&version=1.1.0&typeName=topp:states&formatName=GML2&FILTER=MANUALWORKERS0.25

19The OpenGIS Web Coverage Service Interface Standard (WCS) defines a standard interface and operations that enables interoperable access to geospatial "coverages"

The term "grid coverages" typically refers to content such as satellite images, digital aerial photos, digital elevation data, and other phenomena represented by values at each measurement point. WCS20The basic Web Coverage Service allows querying and retrieval of coverages.

A WCS describes discovery, query, or data transformation operations. The client generates the request and posts it to a web feature server using HTTP. The web feature server then executes the request. The WCS specification uses HTTP as the distributed computing platform, although this is not a hard requirement..WCS.21provides an interface allowing requests for geographical coveragesThe coverages are objects (or images) in a geographical areaData may be available in several formats, such as DTED(Digital Terrain Elevation Data), Geo TIFF, HDF-EOS (Hierarchical Data Format), or NITF (National Imagery Transmission Format).

Several types of data layers are supported:series of points, such as locations of samples regular grid of pixels or points, which might represent a photo set of segmented curves, often used for road paths set of Thiessen polygons, used to analyse spatially distributed data such as rainfall measurements triangulated irregular network(TIN), often used for terrain models

WCS Data 22RequestGetCapabilitiesGetCoverageDescribeCoverage23HTML PracticeNote: These WebPages opens only in Internet Explorer

HTML Layoutshttp://www.w3schools.com/html/html_layout.asp

HTML Lecture 1: HTML Basicshttp://www.webgisdev.com/webpro/html1/index.htm

HTML Lecture 2: Using Tableshttp://www.webgisdev.com/webpro/html2/index.htm

HTML Lecture 3: Frameshttp://www.webgisdev.com/webpro/html4/index.htm

HTML Lecture 4: Formshttp://www.webgisdev.com/webpro/html4/index.htm

24Assignments

25CMS Interface

26JavaScript Practice Note: These WebPages opens only in Internet Explorer

JavaScript Lecture 1: Getting Startedhttp://www.webgisdev.com/webpro/js1/index.htm

JavaScript Lecture 2: Events(and Exercises)http://www.webgisdev.com/webpro/js2/index.htm

JavaScript Lecture 3: Document Object Modelhttp://www.webgisdev.com/webpro/js3/index.htm

JavaScript Events:http://webgisdev.com/webpro/js2/eventtbl.htm

HTML DOM (Complete Reference)http://webgisdev.com/webpro/js3/index.htm

Assignment JavaScript Calculatorhttp://webgisdev.com/webpro/3labb.htm

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