GIS 2096 Introduction to Web Mapping & The WWW Google Maps & Google Mashups

The World Wide Web Clients Servers Communication Networks Client Server

Applications that run on computers Rely on servers for – Files – Devices – Processing power Examples: – – Web Browser – FTP – ArcMap, QGIS Clients Clients are Applications

Servers Computers or processes that manage network resources – Disk drives (file servers) – Printers (print servers) – Web content (network servers) Example: Database Server – A computer system that processes database queries Servers Manage Resources

Client–Server Relationship Process takes place on the server and the client Servers – Store and protect data – Process requests from clients Clients – Make requests – Format data on the desktop Client-Server Computing Optimizes Computing Resources

What is a Google Map? Maps.google.com - interactive street, satellite, terrain maps and more.

What is Google Maps? An enormous amount of searchable geographic information (gazetteer) A way of organizing the worlds information geographically

What is a Google Map? Maps.google.com > MyMaps – create custom maps to share.

What is a Google Map? Google MyMaps – customize maps with user created enhancements.

Is Google Maps FOSS? No It is free of charge

What is Google Maps - summary A web mapping service, free for non-commercial use that contains: – Detailed global basemaps: streets, satellite imagery, and terrain. – Useful services such as address and place locating by searching against an information rich gazetteer. – Ability to overlay a wide variety of map layers, (weather, traffic) from static or dynamic sources. – Map layer creation and light customization through functionality through MyMaps. – An API that allows for embedding and extensive customization.

Application Programming Interface (API) API - An interface to a software program that allows users to interact and customize it. – Determines the vocabulary and calling conventions a programmer uses to employ the software services. – Usually based on an existing programming languages (C,.NET, VisualBasic, Java, javascript) – Many desktop and web software applications have API’s – Google Maps API uses javascript

Google Maps API Allows embedding of a Google map into one’s own web page using javascript. Free to use, on any website that is provided free of charge to others. Relatively gentle learning curve. Highly customizable and easily transferrable. Evolving - new functionality consistently being added.

What is a Mashup A web page or application that combines data or functionality from two or more external sources to create a new service. Therefore: MyWebPage + Google Map = mashup Even better: MyWebPage + Google Map + Other web service(s)

Google Map mashups examples: embeddable and customizable

Google Maps, Mashups, and Google Earth Differences and similarities Google Maps & MyMaps – A free web application (no software installation necessary) – 2 dimensional map view, with street, satellite, terrain basemaps – Data creation possible (points, lines, polygons), reads limited kml. – A selected set of map overlays and functions available. – Specific maps can be saved and shared easily on the web. Google Maps Mashups – A free service allowing one to embed a Google Map into a web page. – 2 dimensional map view, with street, satellite, terrain basemaps. – Highly customizable to include everything in MyMaps and more. – Customization requires using javascript and HTML. – Requires access to a web-server to publish to the web. Google Earth – A free desktop application (downloading and installation necessary). – 3 dimensional map view with satellite basemap, many map overlay layers, and a rich set of visualization tools. – Data creation possible (points, lines, polygons). – Complex kml creation is possible.

Google Maps, Mashups, and Google Earth Which one to use? Google Maps – Locating, measuring, or learning about the geography of a place. – If you want to share a map. – Communicate geographic information quickly. Google Maps Mashups – Used to embed a map into a new or existing website. – Create interactive web maps for your users. Google Earth – Visualizing terrain, 3d buildings, historical imagery, and access to many thematic map layers. – Virtual tour creation (movies) – Small amounts of data collection, geocoding, and image geo-referencing.

Axioms to follow for fledgling Google mappers If MyMaps or an existing mashup can be used to accomplish your web mapping goal, use it. In your internet browser, use “View > Page Source” to learn what code is used to produce a specific website. When coding, pay attention to every character. Comment your code thoroughly. Organize, document, and backup your maps and data. Other web map mashup API’s exist (Yahoo!, Microsoft, OpenLayers). If Google’s API doesn’t serve your needs, explore the others.

19 Web Mashup Definitions Mashup: A web application that performs browser- side integration of content or services from multiple sources Provider: site the provides content to the mashup

Markup languages Markup languages – Hyper Text Markup Language (HTML), Extensible Markup Language (XML), Keyhole Markup Language (KML), and many more… Text encoding schemes used to create and format a web document. Use tags contained within brackets <> to define formatting that web browsers read. Markup language code sample: This a new paragraph of text that is bold This text is new paragraph of text that is big This text is italic

HTML HyperText Markup Language What you create a web page in Consists of specific sections Content described by tags

HTML Tags Syntax content Standard Elements... Specifies the type of document... Title, Metadata, Scripts etc.... The main content of the page Comments

A Basic HTML Page favorites / bookmark title goes here My first page This is my first web page and I can say anything I want in here - I do that by putting text or images in the body section - where I'm typing right now :)

HTML Tags A Few Common HTML Tags … Web page title – Head section … Paragraph – basic text in Body section … Anchors – hyperlinks... To embed a script – e.g. javascript … Creates a table … Creates a table row … Creates and populates a table cell … Divide document into sections

Basics of an HTML page The Head section: Where you define the title of your web page Include metadata for your page so search engines like Google and Yahoo can find your page Style sheets (CSS) and scripts (javascript) Blah blah blah title …

Basics of an HTML page The Body section: Where you put most of your content

Javascript Javascript: Typically a “client side” programming language used primarily in web browsers Used to provide dynamic content to a web page Uses variables, loops, and functions to generate output on the web. Allows for the development of enhanced user interfaces and dynamic websites. Javascript code sample (Adds a placemark on a Google map) function createMarker(point,html) { var marker = new GMarker(point); GEvent.addListener(marker, "click", function() { marker.openInfoWindowHtml(html); }); return marker; } var point = new GLatLng( ,-106); var marker = createMarker(point,’Info in Window’); gmap.addOverlay(marker);

Javascript function message() { alert("This alert box was called with the onload event"); } //Comment We usually use the head section for functions (to be sure that the functions are loaded before they are called).

Explanations of the Basic Google Maps Code

Google Map Code This first javascript is a critical script element. It’s src attribute points to the location of the API on Google’s server, and your key is passed as a parameter. GoogleMaps use javascript to call the Google server and to provide specific parameters for your mashup

Google Map Code

Function calls in the element Onload=“load()” While an HTML page renders, the document object model (DOM) is built out, and any external images and scripts are received and incorporated into the document object. To ensure that our map is only placed on the page after the page has fully loaded, we only execute the function which constructs the GMap2 object once the element of the HTML page receives an onload event. Doing so avoids unpredictable behavior and gives us more control on how and when the map draws. The onload attribute is an example of an event handler. The Google Maps API also provides a number of events that you can "listen" for to determine state changes. Onunload=“Gunload() The GUnload() function is a utility function designed to prevent memory leaks. This just means that all running functions are cleaned up when you close the browser or leave the page.

Google Map Code The rest of the element The html created by Open Office with our text contained in paragraph tags A tag which defines divisions in a web document The start of a The “map” holding the map Closing tags

Google Resources Google Maps API Sign Up Google Maps API Documentation Google App Engine Google Map Books Map Builder

35 Mashup Examples housingmaps.com Wii Finder Clockr popurls.com Yahoo vs. Google Google Gadgets

Objectives: 1) In 2 hour, hands on, interactive session, learn how to create and customize a Google map mashup. 2) Learn a few fundamentals of programming, and gain insight into what skills and knowledge are required to be a successful Google map masher. 3) Learn the differences between Google MyMaps, mashups, and Google Earth and when to use each. Google Lab

Lab 6 Open Firefox Go to Click on Google Maps tutorials