"Good SaaS companies have built their apps on a Web-services based architecture," he says. "It's less proprietary, and as such it's easier for SaaS apps to share data with one another."

As an example, for Ingres's sales and marketing needs, Ingres uses Salesforce.com, the CRM software often credited with kicking off the enterprise SaaS movement,. They also needed an app that dealt with financials, and he picked Intacct because the two applications talked well with one another. For instance, Harr explained, when you're ready to launch a sales order in Salesforce.com, the end user has a window that opens up and allows her to punch financial data in Intacct.

Harr looks for such features when he chooses software for Ingres and its IT group. "We give preference to companies that can provide that kind of integration, with tools that were built with these kinds of integrations in mind," he says.

Other notable SaaS apps Ingres adopted include ADP for his human resources and xactly for sales performance management, all of which he said brought integration to the table.

Harr won't disclose specific dollar amounts on what he's saved from implementing SaaS with its "per user per month/year" rates, but says he has estimated what it would have cost to install the equilvalent software on premise. Based on his experience, he says, the purchase and installation would cost more than using a SaaS app for five years.

His advice for CIOs?

"Get on the bus and be part of the solution," he says. "I read a Forrester report recently that said departments are going around IT and implementing SaaS without them. I find that sad. Maybe it's due to the fact IT held all the cards back in the 90s and they told [rather than asked] departments what software they'd use. But now I think it's wrong to go completely in the other direction to say a department is just going to get these tools and not have IT involved. You need to have a partnership."