SaaS provider Workday has bought Cape Clear, one of the last remaining independent ESB (enterprise service bus) vendors. It isn't surprising that Cape Clear would disappear. Even as ESBs grow more popular, the market for standalone products is shrinking thanks to consolidation and commoditization. But Workday is an unusual acquirer: Rather than another player in the SOA space, Workday is a Cape Clear customer, using the Cape Clear ESB within its hosted ERP application.

Workday plans to use the Cape Clear technology as the foundation of what it calls Integration on Demand: hosted services for interconnecting different enterprise applications. This is essentially SOA as a service, similar to what Microsoft and Salesforce.com have talked about.

Workday is aiming at a slightly different market from Microsoft, though. It's targeting intranet-type applications, with a set of 10 to 15 prebuilt integrations between common systems like HR and CRM as well as a development environment. In this, it competes with enterprise mashup providers like Serena Software. Microsoft's vision is more about extranet-type Web services between business partners, which are a lot easier to integrate if they're all hosted in the same place. Microsoft also promises a radically simplified development environment (code-named Oslo), but this is currently vaporware and unlikely to ship for at least a year.

Workday will no longer be selling the Cape Clear ESB as software for local installation, though says that it will continue to support existing customers. This means that most of its customers will likely want to start looking elsewhere, as it's clear that the product will no longer be actively developed outside of the Workday SaaS infrastructure. Cape Clear had previously claimed to have about 300 customers, mostly SaaS providers, though that meant total lifetime sales. Its current customer base is probably a lot smaller.