Cloud9 is a blog of everything that has to do with cloud computing at Microsoft.
It features a very good post on the comparison between SaaS and Software + Services. This is not to illustrate than one is better than the other, because this is not what Microsoft’s S+S strategy is about. Understanding the architectural differences will help organsiations / architects to choose the best scenario for their implementation ..
… Saas is an architectural paradigm where a solution architecture can benefit from the economies of scale of the data and behavior of that architecture being built and hosted in the cloud by a third party in a multitenant fashion.
Software + Services is an architectural paradigm where a solution architecture can achieve some of the same economies of scale as Saas while simultaneously benefiting from the synergies and efficiencies of the data and behavior of that
architecture being partly built on premises and partly built by third parties in a multitenant fashion, as well as, partly hosted on premises and partly hosted in the cloud in a multitenant fashion.
The cloud meaning, from an application standpoint, a set of applications or services with standards based interoperable interfaces that can be easily reachable and easily composed from any platforms in any locations with an internet connection. The cloud also meaning, from an infrastructure standpoint, a set of connected data centers providing elastic compute, elastic storage and other enterprise SLAs for those applications or services.
Multitenant meaning application routines, data and infrastructure meant to be built and hosted in a shared manner among multiple clients of the Saas organization.
In Software + Services the degree to which solution architecture is partly hosted on premesis or in the cloud, or, the degree to which the application is built from 3rd party services or software vs. homegrown software can be anywhere
along a spectrum of totally homegrown and hosted in house with small amount of 3rd party to almost totally a Saas model except for some code running on premises or close to the consumer of that data or behavior.
The "Software" in Software + Services alludes to data and routines executed or stored as close to the consumer as possible and/or on-premise inside corporate firewall. This could include everything from thick clients on desktops or
server software inside corporate firewalls to Silvelight web based applications to clients on roaming mobile phones. …
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