Rob Schneider (not the one from Deuce Bigalow) explains how SaaS (software-as-a-service), composite applications and SOA (service oriented architecture) all work together to make the enterprise more efficient.
Each has a key role to play and will continue to gain in importance. To begin, SOA design principles will increasingly serve as the standard by which well-run IT organizations measure themselves. These concepts will impact all areas of the IT lifecycle, from enterprise data modeling through application development and integration. Meanwhile, SaaS-based applications are on a meteoric rise. It's not too hard to envision a time when IT executives will be forced to justify why they are going through the time, expense and headache of self-hosting packaged enterprise software. Of course, there will still be a role to play for these comprehensive applications, but increasing numbers of enterprises are looking for the quick ROI sported by SaaS solutions. Finally, composite applications will progressively serve as the user interface-based glue that holds together data from silos both inside and outside the firewall.One missing item is the fact that SaaS, SOA and composite applications are largely driven by open source...you can't have control without the code.