Monthly Archives: 2009-9

Cross-platform mobile application development and payments

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We have been piloting multi-platform mobile application development and payments in few client projects. Target platforms usually include iPhone, Android, Blackberry and Nokia Series 60. Also there are two notable usual cases which need to be specially handled

  • Image uploads
  • Payments for subscribed content

Sounds easy, right? Well it isn’t… Below are some notes for our due diligence work which you fellow developers might find interesting.

1. SDKs

Mobile phone vendors are jealously and don’t want to co-operate with each other. Building application which works in all handsets is major headache.

We found some reasonable candidates for cross-platform mobile development doing HTML and Javascript. HTML and Javascript pages are converted to native application using a wrapper technology (a.k.a. appaccelerator). Doing Flash Lite or Java ME can be pretty much forgotten nowadays as they won’t run on the most hyped platform, iPhone. Flash Lite has poor support for anything except content authoring due to primitive and limited APIs. Java ME provides horrible user experience.

(X)HTML is the only common language spoken by mobile phones. Thus, there has been a rise of “appaccelerators”, technologies which allow to create mobile applications with HTML(5) and Javascript.

  • Phonegap: iPhone, Android, Blackberry and possibly S60 in the future. Pluses: BSD license, very active community. Minuses: bad documentation, difficult deployment process.
  • Titanium: iPhone, Android. Pluses: Professional, Apache license. Minuses: Too tightly coupled with Appacclerator Inc. company.
  • Rhomobile: iPhone, Android, Blackberry, S60, Windows Mobile. Pluses: Professional, tries to build open source community, the widest platform support. Minuses: Dual licensing and tightly coupled with Rhomobile Inc.
  • Nokia Web-runtime: Nokia S60 and some other Symbian based phones. Pluses: Professional, good documentation. Minuses: Not open source, impossible to extend, Nokia has little interest to make this cross-platform, Nokia doesn’t like updating old models and web-runtime is useable only in the latest S60 5th edition models.
  • Palm Pre supports web applications natively. However Palm Pre application business is still taking a shape.

All these wrap the browser component (WebKit) and provide some extra Javascript APIs when your web pages as executed under the application mode.

  • Locationing
  • Contacts
  • SMS
  • Client-side database
  • and so on…

Rhomobile has little different use cases  from the rest of the bunch as it provides client-side programming using Ruby and less focuses on Javascript/web applications.

2. Payments and in-application purchases

There are four major way to do mobile payments “inside” the application for bought content and subscriptions. The price tag on the application itself is left out on this discussion as the application stores themselves take care of it.

  • Credit card
  • SMS
  • App Store payment (thus far Apple only)
  • Direct operator payments – you have a service provider (Bango) which can directly charge items to the operator phone bill based on handset identification.

App Store payment is the most attractive as it provides the best end user experience.  It allows you to use App Store payment mechanism inside the application. It is safe and no need to hassle with external payment providers. However, App Store payment can be used only for content consumed directly inside the application. You cannot use it e.g. for ordering a pizza. I think this might be related to recent EU legislation forbidding SMS payments for services not consumed in the phone itself.

SMS payment is ok for little payments. Operators take big cut of the revenue, generally 30% – 70% depending on the country. Short code fees usually start from 500€ set-up fee + 500€ / month. SMS cannot be often send as a background, but the user is presented the normal SMS editor which reduces the user experience somehow.

For credit card payments there exists several providers. Credit card has the cheapest entry fees, but the downside is that the user needs to have the credit card. This excludes teenager audience.

Direct operator payments are not very well supported yet globally. Most western operators support them. The operator also takes a big share and the fixed fee is pretty high.

My favorite payment provider thus far is Bango which provides credit card payment starting 9€ / mo. and scales up to worldwide SMS payments which cost few grannies per month.

In most cases, the payment experience will not be smooth. You need to open the phone main browser on the payment provider page to do the payment. This usually will close your own application. Rarely you can do the payment inside the application and support multiple platforms. After doing the payment most platforms allow you to close the browse and reopen your application using a special URL handler.

Wikipedia mobile payments page is also useful.

3. Image upload

<input type=”file”> won’t work on iPhone and some other platforms as those don’t have user browsable file system. Also the file dialog usually doens’t have image preview making it useless.

Phonegap has a branch which supports images picking using iPhone’s own gallery browser.

In any case, there is not yet cross-platform solution for this.

4. Future prospects

In some time-frame we will get rid of the need to wrap HTML applications natively as the web browser applications will support all HTML5 features without extensions and probably have some proprietary extensions for mobile specific features like SMS. We already have had some taste for this:

Building a mobile site and applications with Django and Python

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Recently we created a mobile site for an interactive bicycle tour. oulugo.mobi (you need to use mobile browser to access the site or you’ll get a redirect) is a multimedia enriched bicycle tour through the historic parts of the city of Oulu. All content is provided by OnGo.

The route, which you can bicycle through is drawn on Google Maps. There are nine  action points where the user can listen to streaming audio clips, with still images, in his/her mobile phone. This is sort of  augmented reality experience: The user sees the real world (where he/she is now bicycling) combined with the historic events (audio playback narrative). For example, at Linnansaari (a location on the route) you’ll see the actual 17th century castle ruins and the narrator tells how the castle exploded when fire, caused by a lighting, reached gunpowder warehouse… boom. The explosion caused stones fly over 400 meters.

Alternatively, the clips are available as podcasts from Oulu Tourism pages. You can download them into your iPod for offline listening and use in conjuction with a paper map. This demostrates interesting mix of multichannel publishing: paper, web, mobile and podcasts.

The tour is bilingual in Finnish and English.

There exists unreleased iPhone application, based on PhoneGap, which allows the user to track his/her location real-time on the web page. We didn’t see it worth of trouble to go through Apple iPhone application review process. When location based service support comes for the browser this feature is indended to be included as the standard HTML5 feature of the service.

There also exists Nokia Series 60 mobile application, based on PyS60 and Series 60 BrowserControl API, which allows the user to track his/her location in real-time. The application provides wrapper around Series 60 WebKit control and allows Javascript to access phone native functions (GPS) over localhost socket communication. Like with Apple, we didn’t see real-time tracking feature interesting enough to go through Symbian Signed process to get our application released. Also, BrowserControl had seriousquality problems and we didn’t consider it stable enough for the end users. Some work is available in PyS60 Community Edition repository.

The service is hosted on Python specific virtual server on Twinapex services server farm.

1. Features

  • Premium content tailored for audio listening
  • Dubbed in English and Finnish by a professional voice actor
  • Bilingual: English/Finnish
  • Adapts for smartphones (WebKit based browsers) and low end phones (XHTML mobile profile browsers)
  • Streaming video and audio (RTSP / progressive HTTP download forv iPhone). Different audio quality is provided on depending on the handset features.
  • Screen resolution detection based on user agent sniffing. Three different version of images are used.
  • Custom Google Maps component for mobile is used. The component adapts for different mobile phones based on sniffing. Features include zoom, show action point, show the current location, search street address name. This component can be published on a request.
  • Management interface features include video upload, video transcoding different mobile versions and editing bilingual content
  • Apex Vertex handset database is used to detect the user’s mobile phone capabilities
  • Apex Vertex logging and traffic analytics capabilities are used for the site statistics

2. Software stack

3. Development effort

Development time: Around 100 hours. Three different developers where involved. Used development tools: Eclipse, PyDev, Subclipse, Subversion. There were around five meetings between the content provider and the technology provider. Few beta testing rounds using iPhone application were performed by bicycling in -10 celcius degrees weather (north and so on…). No polar bears were harmed during the creation of this mobile service.

The service is linked in from Oulu Tourism pages and thousands of paper brochures printed for Oulu summer season 2009.

About the author Mikko Ohtamaa

Plone Developer Manual, take #0.1

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The first public version of  Plone developer manual is available here.

It is still very much draft, but I assure you will find it useful. You will find it even more useful after you put in the answers for your own problems.

In my previous Plone developer documentation rant my flow of though was little abstract and I couldn’t clearly explain how I want the community to maintain this crucial piece of documentation.  This time I made a comic.

* How to get support

** How to update Plone Developer Manual

Packing and copying Data.fs from production server for local development

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These instructions help you to copy and transfer production server  ZODB database (Data.fs) to your local computer for development and testing. This allows you to do the testing against the copy of real data and the production server Plone instance set up.

See the original tip by cguardia.

Data.fs is ZODB file storage for transactional database. Journal history takes quite a lot of disk space there. Packing, i.e. removing the journal history,  usually reduces the size file considerably, making the file lighter for wire transfer. Depending on the database age the packed copy is less than 10% of the original size.

These instructions apply for Ubuntu/Debian based Linux systems. Apply to your own system using the operating system best practices.

We need ZODB Python package to work with the database. To use it, we’ll create virtualenv Python installation in /tmp. In virtualenv installation, installed Python packages do not pollute or break the system wide setup. Note that you might use easy-install-2.4 depending on the OS. The latest stable ZODB can be picked from PyPi listing. Plone 3.x default is ZODB 3.7.x, which is not available as Python egg, but you can use ZODB 3.8.x.

sudo easy-install virtualenv


cd /tmp


virtualenv packer


/tmp/packer/bin/easy_install ZODB=3.8.3
Data.fs cannot be modified in-place. You must create a copy of it to work with it. Data.fs copy can be created from a running system without the fear of corrupting the database, since ZODB is append only database.


cp /yoursite/var/filestorage/Data.fs /tmp/Data.fs.copy


Then create the following script snippet /tmp/pack.py using your favorite terminal editor.


import time
import ZODB.FileStorage
import ZODB.serialize

storage=ZODB.FileStorage.FileStorage('/tmp/Data.fs.copy')
storage.pack(time.time(),ZODB.serialize.referencesf)


And run it using virtualenv’ed Python setup with ZODB installed:


/tmp/packer/bin/python /tmp/pack.py


Lots of patience here… packing may take a while, but it’s still definitely faster than your Internet connection transfer rate.


Verify that the file is succesfully packed:


ls -lh Data.fs.copy
-rw-r--r-- 1 user user 30M 2009-09-01 13:24 Data.fs.copy


Woohoo 1 GB was shrunk to 30 MB. Then copy the file to your local computer using scp and place it to your development buildout.


scp user@server:/tmp/Data.fs.copy ~/mybuildout/var/filestorage/Data.fs


You just saved about 30-90 minutes of waiting of file transfer.