Enterprise Application Architecture
Enterprise Application Architecture by Martin Fowler: A fantastic book on Object Oriented patterns and how they can be applied to large software projects. The book is available on the web as a work-in-progress and I can safely say I’ve never found an online resource that has taught me more about software design. Literally 24 hours after finding it my head is swimming with design patterns, domain models and relational database mapping techniques, and I’ve already started using some of the patterns in my latest project. A big thanks to Captain Proton on the SitePoint forums for pointing it out (and also for helping me understand PHP references a few days ago). I thoroughly recommend this to anyone who is serious about learning Object Oriented design, or indeed any OO-capable language.