The easiest way to build a bridge between private and public clouds is to own both ends of the bridge, which is exactly what VMware is proposing to do with a scheme it calls vCloud Express.

VMware figures it’s got the internal private cloud covered with its vSphere widgetry.

Now it’s started building from the other side and has recruited a bunch of services providers to build external or public clouds that instantly connect with VMware-based widgetry, rapidly provisioning the stuff on-demand and asking users only to pay for what they use by the hour with a credit card à la Amazon, all managed by the same tools like, say, RightScale’s migration skills.

Poof! It’s nominally solved the interoperability and portable issues associated with clouds – though not the proprietary lock-in – and dodged the problem of making it necessary for an application to be written specifically for a particular cloud.

The external cloud widgetry is also supposed to be cheaper than Amazon – like cheaper by half – and support more operating systems though no more hypervisors.

The company has Terremark, the managed hoster where VMware has some money parked, BlueLock and Hosting.com in the US, Logica in EMEA and Melbourne IT in APAC beta testing its vCloud Express public cloud widgetry and their own services. Some will have production-grade SLAs; initially most are thinking prototyping and development.

VMware claims to have amassed a following of a thousand service providers in the last year, which would appear to put it ahead of the eight ball, but most of them don’t have an infrastructure-as-a-service platform, according to Forrester.

vCloud Express depends on a REST-based API for application vendors, service providers and enterprise IT that VMware means to have standardized.

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