Friday, November 16, 2012

Virgo at the Core of SAP's Cloud

Congratulations to SAP on delivering Netweaver Cloud! The SAP committers have been a great asset to the Virgo team and it's good to see their hard work finally paying off for SAP.

Virgo is the core of SAP Netweaver Cloud or, less formally, Neo. More precisely, they are using the Virgo Nano Web deliverable which can be provisioned to their cloud VMs using p2 and which supports OSGi applications and applications written to the Java EE Web Profile. They've blogged about certifying Netweaver Cloud and now appear on the Java EE compatibility page.

Here's a short video where Harald Mueller, Chief Product Owner for SAP NetWeaver Cloud, mentions the use of Virgo and some of the benefits from his point of view - the section from 4:18 to 6:55 was of most interest to me: click here to watch.

Neo's business proposition is to encourage application developers to participate in the "SAP Store" by developing applications to run on Virgo in the cloud. They are emphasising open standards and open source to break out of SAP's proprietary image. Not only do they plan to attach a large number of application developers, they have a stretch goal of 1 billion users.

Neo's current architecture deploys each application to one or more virtual machines, each running one instance of Virgo Nano Web. AFAIK there is no support for multi-tenancy and popular applications will require load balancing across multiple Virgo instances, so the overall memory consumption looks pretty high. To scale up to large numbers of applications, not to speak of a billion users, multi-tenancy will be critical.

There are two clear options for multi-tenancy: multiple Virgo instances per virtual machine and multiple applications per Virgo instance. The former offers better failure isolation via operating system processes whereas the latter sacrifices strict isolation in order to share the overheads of JVM plus Virgo componentry. It will be interesting to see which approach they adopt. I'm particularly intrigued to see if they exploit the Virgo kernel's scoping mechanisms, regions, or OSGi subsystems to achieve multi-tenancy in a Virgo instance.

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