Paul Coulton's Forum Nokia Blog

the joys of teaching with Python for S60

Wed, 12 Jul 2006 16:55:56 +0300

Today I ran a workshop on mobile phone programming as part of the scheme to encourage pre-university students to pursue degrees in computer science and engineering.

We took the through the development of a single player air hockey game through to a fully operational two player version in three hours. Although we had to give them much of the overall structure because of the time scale they were very quickly at the stage were they were changing the game physics and even adjusting the size of the goal to gain an advantage!

Single Player Version

Two Player Version

Once again I was impressed how easily students adapt to Python and how much enthusiasm you can generate very quickly.

I intend to develop this into a much more structured tutorial and post it for the community a soon as I can so stay tuned.

Oh yes and great to see the new version for S60 3rd edition so many thanks to those involved.

XML enabled payment scheme for mobile

Sun, 25 Jun 2006 15:31:53 +0300

Most new entrants into the mobile commerce marketplace are faced with a paradox; how can we attract users without merchants?, and how can we attract merchants without customers?

Without a huge investment in marketing to build consumer recognition, starting a new m-commerce service is risky. Many successful companies on the web have managed to create successful payment services by utilizing the brand recognition and ubiquity of the popular card networks. Attempts to marry credit cards and mobile phones are not new – encrypted phone wallet systems have been bundled with devices for a number of years. However, use of these wallet systems remains limited as the public failed to embrace shopping via WAP, frustrated by slow speeds and poor user interfaces. With mobile terminals more suited for browsing, and higher speeds from mobile data becoming the norm, we have developed a system to enable remote macro-purchases using existing credit card technology.

A number of banks use payment processing software from ClearCommerce Corp. to allow their customers who want to take credit card payments on-line to integrate payments into their e-commerce solution. ClearCommerce provides an XML payment API for e-commerce website builders to send complete information about a transaction to a capturing server at the associated financial institution. Typically an e-commerce web-server will generate an XML document associated with a transaction, including details about the products in the order, the delivery address, total price etc. This document is then sent to the bank’s processing servers, often via a HTTPS (Secure Sockets Layer-enabled) POST form. Merchants are able to define specific security rules that control a transaction, specifically using the Address Verification Service (AVS) to determine whether the delivery address matches the address registered with the card account. Further, advanced fraud detection rules can prevent transactions continuing given suspicious buying patterns such as a card being used to repeatedly buy high-value items.

The XEPS (XML-Enabled Payment System) project attempts to create a framework whereby developers could add this functionality to mobile applications and complete a transaction entirely from the device. This project used Python for Series 60 Nokia mobile phones in order to rapidly develop the concept on a mobile device. However, Python for Series 60 (PyS60) does not offer the complete XML package associated with standard Python releases. Fortunately, researchers at the Helsinki Institute for Information Technology have ported the pyexpat Python XML module from the full Python release for use with Python Series 60. This module enabled the generation of well-formed XML documents from the appropriate function calls.

The application was tested using the most verbose output XML that may be used to describe a transaction. This is quite a sizeable document for a device with only limited power to generate, approximately 200 lines of XML. In a real transaction, for something relatively simple, like a ticket for a train, the necessary XML describing the transaction may only be one-tenth of this length.

The generated XML feed is able to completely describe a transaction, including relevant shipping/billing addresses, recurrent order status, security features etc.

The full paper is being presented by one of our PhD students, Phil Garner,at the Mobile Business (ICMB 2006) conference today if anyone is attending the event and the XEPS software is available our research group website.

visualising blogs across time and space

Tue, 30 May 2006 21:58:22 +0300

I have been working on a Python application that allows users to create an on-line Blog of text and images from their phone, using location coordinates from a Bluetooth GPS unit ,and ultimately links through to Google maps to produce a representation of their journey. Python proved ideal and it enabled is to create the application very quickly (less than a week) as shown.

Having created the system I decided that 2-D (latitude and longditude)didnt really give me a feeling of what happened along the journeys in relation to time so I have been considering how best to represent data associated with both the temporal and spacial information . I came across a technique proposed by a human geographer in which we add time as a third (vertical) dimension as shown.This represents a walk around the campus at Lancaster University and as you can see you get a much richer representation of how I travelled rather than simply were I have been.

I would welcome any comments of users experiences trying to represent space-time movements and any other techniques that may have been encountered. I will also post the code to interface to Matlab to produce the 3-D plots if people are interested.