When you wake up in the morning, turn on the light, switch on the television and start the coffee maker, your thoughts are likely on the day ahead and not whether you have enough capacity to power these items. You're free of these worries because the power company has created a reliable service, shared among the community, that scales to your individual, immediate demands. Since the service is metered and based on use, you pay only for your fair share.

The basic concept behind cloud computing is similar. Many companies are creating cloud services in a "pay as you go" scenario. These include sharing networks, computers, storage and even software applications.

Software as a Service, or SaaS, is the moniker for software applications delivered via the Internet from companies such as: Amazon, IBM, Salesforce.com, Microsoft, Google and others. SaaS is contrasted with the traditional "shrink wrapped" model for application delivery where the user installs and configures the software on a machine they own and maintain.

Growth trends for SaaS are strong: Gartner Inc. predicts the SaaS market will continue to grow more than 22 percent per year and that by 2011, 25 percent or more of new software systems will be delivered as SaaS applications.

So why is SaaS emerging as the dominant computing model today? The answer is the way in which the technology addresses the key needs and concerns of consumers, or what we call "the 5 C's:" Change, compliance, cost, continuity and coverage.

SaaS providers create multi-tenant software hosted in the cloud with the following basic attributes: All applications, databases and servers are hosted on the service provider's own infrastructure, typically at sophisticated outsourced data centers;

The public Internet is used as the communication path from the SaaS provider to users, with appropriate security measures in place;

Local users require no dedicated PCs or software applications, but gain access to the resources they need from a range of Internet-connected devices.

In the physical security world, the client/server model for delivery of applications has dominated most complex applications while an early precursor for SaaS, namely central station alarm monitoring, has dominated the less complex applications. Alarm monitoring is essentially a model for efficiently delivering pooled central resources to a group of users. The infrastructure, computers and personnel in today's central stations are shared among a group of clients. Each client pays a small fraction of the cost they would bear if they had their own dedicated central station.