James Duncan Davidson is an American software developer and photographer. He's currently the Technology Advisor to Tobias Lütke, CEO of Shopify. While a software engineer at Sun Microsystems (1997–2001), Davidson created Tomcat, a Java-based webserver application and the Ant Java-based build tool. Davidson is the author or co-author of several books on both using and writing software, including Learning Cocoa with Objective-C, Cocoa in a Nutshell, Running Mac OS X Panther, and Mac OS X Panther Hacks, all published by O’Reilly Media. He also contributed to Agile Web Development with Rails, published by The Pragmatic Programmers.