Developer Pitfalls & Strategies for Improving Mobile Web Developer Experience

Mobile 2.0 Conference 2009

Developer Pitfalls and Strategies for Improving
Mobile Web Developer Experience

Tasneem Sayeed
Mobile Technologist
October 16, 2009

Outline
 Definition of Mobile Web
 Mobile Device Constraints
 Mobile Development Challenges
 Tools and Trends
 Performance Rules and Web Development Strategies
 Bridging the Mobile Web Tools Gap
 Conclusion

Copyright © 2009 Symbian Foundation. 2

Definition of the Mobile Web
“Mobile Web”
 W3C pushing the idea of “One Web”
 Making the same information and services available
to users irrespective of the device they are using
 Does not mean exactly the same information is
available in exactly the same representation across
all devices
 The context of mobile use, device capability variations,
bandwidth issues and mobile network capabilities all
affect the representation
 Some services and information better suited for and
targeted at particular user contexts

Source: W3C Mobile best practices „One Web‟ page


Mobile Device Constraints

• Screen Size/Resolution
• Keep Layout as simple and
fluid as possible
• Keep your page contents
all in a single column
stacked on top of each
other so regardless of
screen size/resolution,
information simply wraps
• Test with and without CSS
and JavaScript


Mobile Device Constraints

• Limited Memory
• Limits amount of
processing that can be
handled
• Limited battery power
• Limits implementations of
JavaScript, Flash and other
technologies
• Drains battery
• Creates a slower user
experience
• Increases the bandwidth
(i.e. can be more costly to
download web content)


Mobile Web Development Challenges


Mobile Web Development Challenges

• “Code once, run anywhere” is a foreign concept
• Many browser and device types to accommodate
• Unresolved connectivity and caching issues to contend
• On our 5th Generation of HTML with WML, XHTML, and
cHTML still alive
• Constellation of mobile platforms
• Symbian (Symbian OS-based)
• Java ME
• BREW
• Windows Mobile
• Blackberry
• iPhone (Objective-C based)
• Linux-based Android
• Palm Web OS
• and more on the way!


Tools and Trends


Tools and Trends
• Issues that are gradually finding resolution in the mobile
Web world either via ingeniuty of the developer community
or market drivers
• Device and Platform Proliferation
• Coding Standards
• Testing Ubiquity
• Caching Capabilities
• Mobile Web development has more tools available today
• J2ME Polish
• .NET Compact Framework for Windows Mobile devices
• PhoneGap (Cross platform mobile framework)
• Rhomobile (open mobile framework)
• Titanium Appcelerator and many others
• Mobile Complete (remote handset testing)
• iLoop (resolves device compatibility by doing heavy lifting
for identifying device profile information to enable device
detection and automatically serving the right data and format


Tools and Trends
• W3C Mobile Web initiative continues to drive best practices &
standards
• HTML5
• Web Forms 2.0, and is expected to be a game-changer
in Web application development, making obsolete
such plug-in based rich internet application (RIA) technologies
such as Adobe Flash, Microsoft Silverlight and Sun JavaFX
• New caching capabilities and so on


Performance Rules


14 Performance Rules (Yahoo)

content
1. Make Fewer HTTP Requests
2. Use a Content Delivery Network server
server
3. Add an Expires Header (or Cache-control)
server
4. GZip Components
CSS
5. Put CSS (Stylesheets) at the Top
javascript
6. Move Scripts to the Bottom (inline too)
CSS
7. Avoid CSS Expressions
CSS Javascript
8. Make JavaScript and CSS External
content
9. Reduce DNS Lookups
10. Minify JavaScript and CSS (inline too) CSS Javascript

11. Avoid Redirects content
Javascript
12. Remove Duplicate Scripts
sserver
13. Configure ETags
content
14. Make AJAX Cacheable
 Source: http://developer.yahoo.com/performance/rules.html


Performance Rules: Make Fewer HTTP Requests

• Less components = fast page
• HTTP Request overhead
• Combine scripts
• Combine CSS stylesheets
• Combine images into CSS sprites


Performance Rules: GZip Components
• When you send zipped content over the
internet, the browser unpacks it
• Modern browsers understand
compressed content
• Request header
Accept-Encoding:gzip,deflate
• Response header
Content-Encoding: gzip
• All text components should be sent
gzipped: html (php), js, css, xml, txt…


Performance Rules: Put CSS at the Top

• Firefox and IE will not render anything until
the last piece of CSS reaches the wire
• Place stylesheets as early as possible in
the document
<head>
<title>Your page here</title>
<link href=“styles.css” …>
</head>
<body>
<!– content -->
</body>


Performance Rules: Move Scripts to the Bottom
(inline too)
• Scripts block downloads
• Since the script can do
location.href or document.write at
any time, browser blocks rather than
downloading possibly useless components
• Inline scripts too
<body>
<!– content -->
<script src=“script.js” …/>
</body>
</html>


Performance Rules: Avoid CSS Expressions
CSS expression
#content {
position: absolute;
left:
expression(document.body.offsetWidth +
„px‟);
}
• In IE, this is the only way to have Javascript in
CSS
• CSS expressions tend to get executed more
often than was intended, think about
onmousemove
• Smart expressions overwrite
themselves


Performance Rules:
Make Javascript and CSS External

• Helps with caching, “never expire” policy
• Share with other pages
• However, this is two more HTTP requests
• May want to consider inlining for homepages


Performance Rules: Minify JavaScript and CSS (inline
too)

• Minify, but still Gzip
• JSMin (Written in Javascript, but has a PHP port)
• YUI compressor – minifies CSS too
• Inline styles and scripts should also be minified
• Minification
• Removes unnecessary characters from code to reduce its size, thus improving
load times
• When JS/CSS code is minified, all comments are usually removed as well as
unnecessary “white space” characters like <space>, <newline>, and <tab>
• With respect to JavaScript, this improves load time performance because the
size of the file downloaded is often significantly reduced
• Two Popular Tools for Minifying JavaScript code are:
• JSMin
• YUI Compressor

To learn more on Minification tools, see MinifyJS.com and MinifyCSS.com


Performance Rules

• Avoid Redirects
• A wasted HTTP Request
• Causes a Restart
• Remove Duplicate Scripts
• IE may decide to download them again


Performance Rules: Make AJAX Cacheable

• Content returned from XMLHttpRequest
is like any other component
• Returned content must be Gzipped
• Could be cached
• Cache-control: max-age=?


Newer Performance Rules


20 New Performance Rules for Faster Web Pages (Yahoo)
1. Flush the buffer early
2. Use GET for AJAX requests
3. Post-load components
4. Preload components
5. Reduce the number of DOM elements
6. Split components across domains
7. Minimize the number of iframes
8. No 404s
9. Reduce cookie size
10. Use cookie-free domains for components
11. Minimize DOM access
12. Develop smart event handlers
13. Choose <link> over @import
14. Avoid filters
15. Optimize images
16. Optimize CSS sprites
17. Don‟t scale images in HTML
18. Make favicon.ico small and cacheable
19. Keep components under 25K
20. Pack components into a multipart document
Source: http://developer.yahoo.com/performance/rules.html


Performance Rules:Use GET for AJAX Requests

• GET is for retrieving data
• POST is a two-step process (send headers, send data)
• GET request is one TCP packet, except in the case you
have a lot of cookies
• Max URL length is 2K (because of IE)
• POST without actually posting data is the same as GET


Yahoo!Mail Research)


Performance Rules: Post-Load Components

• Determine the components absolutely required initially to
render the page.
• Rest of the components (i.e. drag and drop, animations,
hidden content, images below the fold) can all wait
• JavaScript is ideal candidate for splitting

YUI Image Loader
YUI Get Utility


Performance Rules: Minimize DOM Access

• DOM access is the slowest
• Cache
• Update nodes “offline” and then add them to the tree
• Avoid fixing layout with JavaScript



Performance Rules:Optimize Images

• GIF – don‟t use a bigger palette than you will need
• Use PNGs instead of GIFs
• Use pngcrush tool (or optipng or pngoptimizer)
• Remove gamma chunks which helps with cross-
browser colors
• Strip comments
• jpegtran – lossless JPEG operations can be used to
optimize and remove comments


Performance Rules: Optimize CSS Sprites

• Choose horizontal over vertical sprites whenever possible
• Combine similar colors
• Keep color count low (<256) to fit in a PNG8
• “Be mobile-friendly” – don‟t leave big gaps
• Filesize doesn‟t increase much, but the image needs to be
decompressed into a pixel map


Performance Rules: Do not scale images in HTML

• Scaling images in HTML downloads unnecessary bytes
• If you need
<img width=“200” height=“200” src=“myPic.jpg” />
• Better to just have myPic.jpg 200x200 not 1000x1000


Performance Rules: Keep components under 25K

• Because mobile phones may generally not cache them
• Uncompressed size under 25K
• Minify HTML in addition to JavaScript and CSS


Performance Rules:
Pack components into a multipart document

• For UAs that support it
• For example,
• Email with attachments
• MMS


Web Technologies for Symbian


Web Technologies
• Web Runtime (WRT) for S60 devices
• A set of componenets based on the WebKit architecture
that enables you to apply your skills at creating web
content – to createfull mobile web applications that are
simple, powerful and optimized for mobile devices
• Widget development is simplified with plug-ins for Aptana
Studio, Adobe Dreamweaver, and Microsoft Visual Studio
• The plug-ins enable developers to create, edit, test, package
and deploy widgets all from within their web development
tool of their choice

For more information::
http://www.forum.nokia.com/Technology_Topics/Web_Technologies/Web_Runtime/ /
See Mobile 2.0 Developer Talk on “Developing Web Runtime Widgets with Aptana”


Case Study: Twitter mobile client
• Design methodologies
• Prototype Twitter client for basic twitter functionality using
standard Web Services
• Download XAMPP (LAMP stack)
• Configure Apache Server and PHP (.ini )
• Implement PHP script using cURL and test for
• Getting tweets
• Updating status
• Download Prototype JavaScript standard-compliant library for
enabling interactive Web 2.0 development
• AJAX.Request() for „get‟ requests
• AJAX.Updater() (to make an AJAX request and use
the returned data to update a Form element)

Due to security constraints, AJAX XMLHttpRequest API's usage is limited by the “same-origin” policy, which means that the hostname
of the url you are sending the XMLHttpRequest cannot be different from the hostname of the web server. In order to bypass this AJAX llmitation
was necessary to interpose a PHP proxy between the mobile twitter client and the Twitter Server

XAMPP: http://www.apachefriends.org/en/xampp.html
Prototype.js: http://www.prototypejs.org/
cURL: http://curl.haxx.se/


Case Study: Lessons Learned

• Mobile Web Development Tools could be further enhanced to
enable a better mobile Web development experience
• Mobile Web UI challenges
• AJAX cross-domain limitations
• JSLint Plugin for JavaScript code validation is helpful
• Better debugging capabilities needed


Bridging the Mobile Web Tools Gap

• Develop an Eclipse Plug-in for Web Development on
Symbian to support Nokia‟s Web Runtime (WRT)
• Open Source Eclipse Plug-in Alpha with the below
features to enable tool developer collaboration by
December 2009
• Based on JSDT (part of Eclipse Web Tools Project)
• Incremental Project Builder
• Creates built state based on project contents,
and keeps it synchronized to project changes
• Integrated Debugger with basic debugging capabilities


Join the Symbian Community
Silicon Valley Symbian Programming SIG
http://www.meetup.com/Silicon-Valley-Symbian-Developers-Meetup/
Symbian SIG Mailing List
Silicon-Valley-Symbian-Developers-Meetup-list@meetup.com
Symbian Developer Group
http://developer.symbian.org
Symbian Exchange & Exposition (SEE 2009) (Oct 27-28), London, UK
http://www.see2009.org/


Summary

• Make the experience feel like a native application
• Take advantage of the enhanced features
• Don‟t simply release a hybrid version of the mobile web site
• Optimize performance
• Collaborate with the developer community to further
enhance the mobile Web development experience!


More Information

My Blog
http://mymobilecorner.blogspot.com

Follow me on Twitter
http://www.twitter.com/twitmymobile

Symbian Developer Group
http://developer.symbian.org

Copyright © 2009 Symbian Foundation.

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