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Forget the empty "Web 2.0" buzzword! Web development, however, is changing. In this session, Bruce gives and overview of HTML5, its intelligent forms, scriptable images and native video. Together with CSS3 and SVG, it will change the way you work making it easier to develop exciting applications. The emergence of more and more Web-enabled devices presents headaches: do you write and test many sites for different devices, or make one site for all? Some simple techniques help you write one site to work everywhere, saving you time and grey hairs. Web development 2.0: Web workers of the world, relax!
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Web Development 2.0
Bruce Lawson / SparkUp! Poland / 24 May 2010
WEB STANDARDS, CROSS-DEVICE DEVELOPMENT AND THE WEB AS UBIQUITOUS PLATFORM
Web Evangelist at Opera
Opera – one browser on many devices
"Our goal is to take the one true Web and make it available to people on their terms."
Jon S. von Tetzchner, Opera Co-founder
"All I ask is access to the full Web, everywhere. And some more beer."Me
1. new web standards2. adaptive content3. browser as platform
1. new web standards2. adaptive content3. browser as platform
new technologies you can start using today
CSS 3font control, shadows, rounded corners,
basic animations
-moz-transition: all 0.5s ease-in-out;-ms-transition: all 0.5s ease-in-out;-o-transition: all 0.5s ease-in-out;-webkit-transition: all 0.5s ease-in-out;transition: all 0.5s ease-in-out;
HTML5<!DOCTYPE html>
HTML5 does not replace HTML 4.01
HTML5 has more bling!
“...extending the language to better support Web applications, since that is one of the directions the Web is going in and is one of the areas least well served by HTML so far. This puts HTML in direct competition with other technologies intended for applications deployed over the Web, in particular Flash and Silverlight.”
Ian Hickson, Editor of HTML5http://lists.w3.org/Archives/Public/public-html/2009Jan/0215.html
HTML5 is umbrella term:markup elements and JavaScript APIs
Webforms – more powerful form elements
standardise commonly-usedrich form elements – without JavaScript
built-in validation(of course you should still validate on the server)
Demonstration of webforms
<canvas>
canvas = “scriptable images”
canvas has standard API methods for drawing
ctx = canvas.getContext("2d");ctx.fillRect(x, y, width, height);ctx.beginPath();ctx.moveTo(x, y);ctx.lineTo(x, y);ctx.bezierCurveTo(x1, y1, x2, y2, c1, c2);
canvas mix with external graphics/ video
ctx = canvas.drawImage(…)
Demonstration of canvas
<svg> or
<canvas>?
Scalable Vector Graphics:
● Supported in 4 modern browsers, and IE9● Vector graphics, therefore infinitely scalable● XML so text-based - can be made accessible● Keeps a DOM● Can author with Adobe Illustrator or Inkscape
<video>
<object width="425" height="344"><param name="movie"
value="http://www.youtube.com/v/9sEI1AUFJKw&hl=en&fs=1&"></param>
<param name="allowFullScreen" value="true"></param>
<param name="allowscriptaccess" value="always"></param>
<embed src="http://www.youtube.com/v/9sEI1AUFJKw&hl=en&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>
<video src="video.ogv" controls autoplay poster="poster.jpg" width="320" height="240"> <a href="video.ogv">Download movie</a></video>
video format debates – Free formats vs MP4
<video controls autoplay poster="…" width="…" height="…"><source src="movie.ogv" type="video/ogg" /><source src="movie.mp4" type="video/mp4" /><!-- fallback content -->
</video>
still include fallback for old browsershttp://camendesign.com/code/video_for_everybody
video as native object...why is it important?
● “play nice” with rest of the page● keyboard accessibility built-in● API for controls
Demonstration of mark-up “fallback” video in Opera 10.53, scripted controls
geolocation
find out your location via JavaScript
navigator.geolocation.getCurrentPosition(success, error);function success(position) {
/* where's Waldo? */var lat = position.coords.latitude;var long = position.coords.longitude;...
}
offline support
detect if a browsers goes offline
window.addEventListener('online', function(){ … }, true);window.addEventListener('offline', function(){ … }, true);
storage
localStorage/sessionStoragelike cookies...
document.cookie = 'key=value; expires=Thu, 15 Feb 2010 23:59:59 UTC; path=/'…/* convoluted string operations go here … */
localStorage/sessionStoragelike cookies...on steroids!
localStorage.setItem(key, value);localStorage.getItem(key);localStorage.clear();localStorage.key = value;if (localStorage.key == '…') { … }…
Web Database – full relational DB / SQL
var db =openDatabase(dbName, version, displayName, expectedSize);db.transaction(function(tx) {
tx.executeSql(sqlStatement, [], function (tx, result) { /* do something with the results */
});});
application cache
cache UI/resource files for offline use
<html manifest=”blah.manifest”>CACHE MANIFEST# send this with correct text/cache-manifest MIMEimages/sprites.pngscripts/common.jsscripts/jquery.jsstyles/global.css
1. new web standards2. adaptive content3. browser as platform
Opera Mini: +140% users, +200% page views25.8 billion pages / month
3.6 petabytes of data were compressedMarch 2009 – 2010
www.opera.com/smw/2010/03
Top 10 sites in Poland
● google.com● nasza-klasa.pl● onet.pl● wikipedia.org● allegro.pl● youtube.com● wp.pl● sciaga.pl● fotka.pl● my.opera.com
Top 10 handsets in Poland
● Sony Ericsson K800i● Nokia 6300● Nokia 5130 XpressMusic● Sony Ericsson K550i● Sony Ericsson W890i● Nokia 5310 XpressMusic● Nokia E51● Nokia 6500s● LG KU990i● Sony Ericsson W910i
“One Web” is an uneven landscape:
● constrained browsers (WAP, …)● mobile “Full Web” (Android, Opera Mobile, …)● proxy-based (Opera Mini, …)● laptop, Netbook, Tablet PC, Desktop● games consoles, set-top boxes, TVs
Device capabilities also vary:
● screen size and resolution● input mechanism – touch, keypad, other?● memory and processing power● colour palettes● connection speed / quality
“One Web means making, as far as is reasonable, the same information and services available to users irrespective of the device they are using. However, it does not mean that exactly the same information is available in exactly the same representation across all devices.”W3C Mobile Web Best Practices http://www.w3.org/TR/mobile-bp/#OneWeb
Approaches to cross-device development:
● do nothing – use standards, defensive design● separate site (m.mysite.com, mysite.mobi)● single site, but optimised for cross-device
Server-side detection of devices:
● “browser sniffing” the User Agent stringOpera/9.80 (J2ME/MIDP; Opera Mini/5.0.2056/866; U; en) Presto/2.2
● offer users a way back (example of Orkut)
Tips for optimising for mobile/ devices:
● Use CSS3 Media Queries● Define size of images in HTML● Put JavaScript as far down as you can● Reduce HTTP requests
CSS 3 Media Queries:
@media screen and (max-device-width: 480px) { // insert CSS rules here
}http://www.w3.org/TR/css3-mediaqueries/
Demonstration of Media Queries
Images:
● Images take a long time to load, so tell the browser to leave a space for them● If you don't, when the image finally loads, the browser will redraw the page to fit the image in, perhaps scrolling off screen● Redrawing the screen wastes processor time (and battery life)● Some turn off images; design for accessibility
Images:
● Images take a long time to load, so tell the browser to leave a space for them● If you don't, when the image finally loads, the browser will redraw the page to fit the image in, perhaps scrolling off screen● Redrawing the screen wastes processor time (and battery life)● Some turn off images; design for accessibility
Put JS as far down the source as possible:
● Browsers wait for JS to load. If they're at the top, rendering pauses.● If your JS is at the bottom of the page, the user can read the content etc while she is waiting to interact with the page.
Minimise HTTP requests:
● Combine JS into one file. Same with CSS.● Use CSS sprites to combine decorative images● Consider encoding images directly in your page as data URLs● Use SVG or <canvas> for images
1. new web standards2. adaptive content3. browser as platform
“…the browser run-time is perfect…you’re out of writing for Windows Mobile, Android, S60, each of which require testing...we want to abstract that.
All the cool innovation is happening inside the browser – you don’t need to write to the native operating system anymore.”
Mobile Entertainment Market, June, 2009
W3C Widgets – application development filled with web standards goodness,
using browser engine as platform
Anatomy of a widget
index.html, assets + config.xml, zipped .wgt
1. new web standards2. adaptive content3. browser as platform
![Elefrant [ng-Poznan]](https://img.dokumen.tips/doc/110x75/559702181a28ab624f8b45b0/elefrant-ng-poznan.jpg)
