There’s a lot of media buzz right now about cloud computing – which encompasses both “web 2.0” and Software as a Service (SaaS). Whilst it’s undeniable that web services are becoming increasingly more important, I’ll stand by my comments from a couple of years ago that the “webtop” will not be in mainstream use any time soon and those who are writing about the the death of Microsoft Windows and Office are more than a little premature.

Even so, I was interested to hear Microsoft’s Kevin Sangwell explain the differences between SaaS and the Microsoft idea of software plus services (S+S) during the recent MCS Talks session on infrastructure architecture.

I’ve heard Microsoft executives talk about software plus services but Kevin’s explanation cut’s through the marketing to look at what S+S really means in the context of traditional (on premise) computing and SaaS:

Kevin made the point that there is actually a continuum between on premise and SaaS solutions:

• We all understand the traditional software element – where software is installed an operated in-house (or possibly using a managed service provider).
• Building block services are about using web services to provide an API to build applications “in the cloud” – so Amazon’s simple storage service (S3) is an example. This gives developers something to hook into and onto which to deliver a solution – for example, Jungle Disk uses the Amazon S3 platform to provide online storage and backup services.
• Attached services provide self-contained functionality – for example anti-spam filtering of e-mail as it enters (or exits) an organisation.
• Finished services are those that operate entirely as a web service – with salesforce.com being one, often quoted, example – Google Apps would be another (not that Microsoft are ever likely to promote that one…).

S+S is about creating a real-world hybrid – not just traditional or cloud computing but a combination of software and services – for example an organisation may use a hosted Exchange Server service but they probably still use Microsoft Outlook (or equivalent software) on a PC.

So, would moving IT services off to the cloud make all the associated IT challenges disappear? Almost certainly not! All this would lead to is a disjointed service and lots of unhappy business users. SaaS and S+S do not usually remove IT challenges altogether but they replace them with new ones – typically around service delivery (e.g. managing service level agreements, integrating various operational teams, etc.) and service support (e.g. presenting a coherent service desk with appropriate escalation between multiple service providers and the ability to assess whether a problem relates to internal IT or the hosted service) but also in relation to security (e.g. identity lifecycle management and information rights management).

Kevin has written an article for The [MSDN] Architecture Journal on the implications of software plus services consumption for enterprise IT and, for those who are interested in learning more about S+S, it’s worth a read.