IT BEWARE: Service-oriented architectures were supposed to be all about multivendor mashups and open standards, breaking applications up into services that can be easily stitched back together in new ways. But though SOA vendors still tout that path for applications, lately they're not practicing what they preach. It seems every one of them is buying up the competition or getting acquired, as they seek to build their offerings into suites that promise to fulfill all SOA needs at once.
It's an electrifying vision, but one that could force enterprises to buy more middleware to intermediate among different, competing middleware products. Moreover, despite pleas from users, Web services standards show no signs of stabilization.
Currently, the SOA intermediary software market is divided into four main product categories (see What Does What?" in the gallery). The most mature is the ESB (enterprise service bus), which shuttles data among services. In contrast, governance, a combination of catalog- and source-code management, is still in its adolescence. Both are always provided as software.
SOA-management systems and security gateways are equivalent to network-management frameworks and firewalls, respectively, and can be provided as hardware or software, sometimes even by the same vendor.