Mobile-Web Integration
with Open Source Tools (1)
Lukhnos D. Liu
Principal, Lithoglyph Inc.

Agenda
Client Side
Server Side

Client-Side Agenda
What to put on client, what on server
Mobile app design constraints
Case study: TapExpense
Open source tools you can use
Demo

Mobile Internet is finally
there!

Ubiquitous computing for
consumers

But mobile web is not the
answer to everything...

Server-side pro’s and con’s
Server is good for LARGE data
But network is slower than you think
Mobile web = just ok to use
But you don’t want to use it every day
Native mobile app FTW

Perspective
Mobile computers that happen can make calls
Telephony is not important
Data terminal, data presentation
Limited device versus cloud

Client-side problems
Device is limited in every aspect
Display, memory, CPU speed
But response is very fast
Suitable code: UI, data collection, simple computation

Mobile app constraints
Slow CPU
Low memory: 64 MB of heap, no swap
So design you app as if you were in 1996 (seriously)

Integration considerations
Use lightweight data structure
XML parsing is usually a bad idea (no SOAP, e.g.!)
Stream-able or partially readable format is good
(JSON, CSV, etc.)

Wacky connections
Internet should be assumed but not taken for granted
Power management policy is a pain
3G handover
Intermittent connection
Design early: Offline plan, caching policy, resume
mechanism

UIRequiresPersistentWiFi UIRequiresPersistentWiFi
<true/> <false/>
Always on, but
idleTimerDisalbed Always on, always
wifi/3G off after 30
YES connected
min
3G/wifi off when
Wifi on when app
idleTimerDisalbed device wants to
is on, but 3G off
NO even when app is
when screen off
on

Still with us? Good.

Case Study: TapExpense
iPhone expense tracker
Requirement: Excel spreadsheet export
Data analytics
Internet strategy: “Shoot and Forget”

“XLS is complicated...”
“Let’s use CSV”
“But...”

CSV is not simple at all!
Originally: Email to user
Common format, but tons of pain (saving, exporting)
Usability = 0
No way to handle multi-line text
Variants!
Not all spreadsheet app is created equal
Excel, Numbers, OpenOffice

You thought that is all...
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Parlez-vous français?
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30.4.2009:Food:1.000.000,00
Ich spreche Deutsch, aber...

Sprechen Sie...
Schwyzerdütsch?
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Two Provisions
Pure-text CSV: Matches user’s international settings
(language and locale)—backward compatible
XLS: Use server-side solution

Making HTTP Requests
Everyone has her favorite wrapper on iPhone
Our favorite: LFHTTPRequest

LFHTTPRequest
Part of the ObjectiveFlickr project
http://github.com/lukhnos/objectiveflickr/
Targeting both Mac 10.4/10.5/[Redacted], iPhone OS
2.x/[Redacted], 32-bit, 64-bit
Lightweight and robust

Other Open Source Libs
Three20
http://github.com/joehewitt/three20
Erica Sadun’s code
http://ericasadun.com/
And more

Client-side demo