By Richard Waters in San Francisco

IBM's business from "service- oriented architecture", which many experts believe will be the "Next Big Thing" in enterprise software, has doubled over the past year. SOA, which promises to bring a deeper level of integration to today's fragmented corporate IT systems, is finally taking root, though it remains only a "modest percentage of our revenues," according to IBM's head of software, Steve Mills. Enterprise software makers such as IBM, SAP and BEA Systems, which sell to large companies and governments, have looked to SOA to spur the biggest new wave of spending since the rise of the internet in the late 1990s. Like the advent of the internet and, before it, the emergence of clientserver computing, it is seen as a fundamental architectural shift that will pull the industry out of its post-bubble slump.