SaaS and the packaged software appliance

Now that it's possible to package up an installation image of an application and ship it out as an executable download - a virtual software appliance - do we really need SaaS? Or does the software appliance model extend SaaS rather than replacing it?

Delivering software as an appliance brings many of the same benefits as delivering software as a service, as I've described in my previous posting about Socialtext's experience, Can the appliance put SaaS on-premise? For similar reasons to Socialtext, Zimbra, which provides a messaging platform that competes with Exchange, also likes the appliance model, but it prefers the virtual appliance format to a hardware appliance. President and CTO Scott Dietzen (pictured below) told me this week the company initially adopted the appliance model because some of its smaller customers in the education market didn't have Linux skills in-house. By using a prepackaged appliance, Zimbra effectively packages in all its own Linux implementation skills so that the customer can just get on with using the application.

Zimbra uses appliance technology from rPath to do the packaging. Because it only packages up the elements of the underlying Linux, Apache and mySQL platforms that the Zimbra application actually uses, another advantage is that it reduces the number of components to support and protect. "It's a really gifted technical group," said Dietzen, explaining that rPath's technology had cut the installation image for Zimbra from almost 2.5GB down to just 400MB in size. The rPath package also provides a Web console that customers use to configure the application.

Dietzen highlighted another benefit that makes the appliance model look even more like SaaS. Because the rPath product automatically includes the ability to package appliances for a number of target platforms, it provides an easy route to virtualization. In fact, said Dietzen, "We think this software appliance model works better for virtualized deployments than it does for the original use case." Using rPath's technology effectively decouples the software installation from the underlying virtualization layer, thus eliminating many of the versioning and patch management issues that would otherwise occur.

Put all of these considerations together and you can see that appliance packaging — especially of open-source platform components — is a way of eliminating a lot of the problems associated with conventional software; but without moving entirely to a vendor-hosted SaaS model. "This is independent of the delivery model," says Dietzen. "This is about cutting the cost of owning and running the software."

So there's a sense in which appliances are not so much a part of the SaaS model as competition for it. The appliance model provides many of the benefits of SaaS without forcing customers to store and access their data outside of the firewall. With a product like Zimbra, where the most intensive use is within the organization in any case, and where integration to other on-premise facilities such as telephony equipment is often important, it is often very difficult to argue for off-premise deployment anyway because that simply adds unnecessary cost and network latency. Maybe Google can afford to run a global network which means very few customers are more than a couple of hops away from its own routers, but smaller vendors like Zimbra can't.

On the other hand, there are many more applications that run much better off-premise because they involve a lot of interactions beyond the firewall anyway. So I think SaaS vendors shouldn't see software appliances as competition. Indeed, as I hinted at the outset of this article, managed appliances will probably become a part of most SaaS vendors' infrastructure, deployed where it makes sense to handle certain operations on customer sites or otherwise outside of the vendor's own data centers. This assertion is especially credible if you count client-side platforms such as Silverlight, Apollo, Google Gears and so on as part of the managed appliance spectrum.

Maybe some people will find it strange to be endorsing a form of on-premises deployment, but I have never been a big fan of seeing network-based computing as consisting solely of large computer installations in huge data centers. The network extends out to the edge and comprises all the connected devices within it. I think the most crucial element of the on-demand or SaaS model is not where the software resides so much as who takes responsibility for it and how effectively it connects into the rest of the network. If the vendors are managing the software, then where precisely it sits is less important — and indeed perhaps ultimately the software appliance model is the ideal mechanism for vendors to be able to put the software wherever it needs to be at any given moment to best serve the customer.

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