Delivery of Architectures for Tesco.com Direct Website (£200m)
Tesco wanted to compete in the global market as a market place rather than a retailer (ie hosting the sale of one's own and others goods rather than just ones own). This was scaled to Amazon and eBay sizes: 40m products, 160m listings. The solution incorporated a mixture of 40 COTS components (ATG, Sterling Commerce, Endeca, Adobe Web Analytics, Interwoven, Manhattan, Oracle PIM, Fraud tools, Silver Creek Data Cleansing, Rating, Review, Recommendation tools, Oracle Finance (x2) etc etc) with some bespoke pieces: Listing, Product Induction, Supplier Induction, Inventory Consumption, Inventory Presentation/Cohesion etc.
Due to the scale of the program, many of the components were at their (then) physical limit. Part of the fun was finding ways in which to be able to perform these processes within the design constraints of the tools themselves.
The major issues revolved around the size and complexity of the offering. Business requirements continued to change well into the 2nd year of delivery. The three big changes I'd make would be
1. Start much simpler - use native code rather than highly crafted business processes and grow the solution with the business
2. Freeze business requirements much earlier - it wasn't until the business recognised this that we has any chance of success
3. Make the business journeys much shorter and much wider - getting this amount of data into a system - especially where you are sharing inventory across multiple market places - is a nightmare in terms of consumption and validation. CQRS would be my preferred alternative approach.