Under billionaire Larry Ellison, Oracle Corp. has been a proving ground for hard-driving executives who have gone on to run other technology companies. As Oracle now attempts to take over rival PeopleSoft Inc., Ellison is learning just how competitive his progeny can be.

Craig Conway, once head of marketing and sales at Oracle before joining PeopleSoft Inc. as chief executive in 1999, has matched Ellison step for step in the corporate tit for tat prompted by Oracle's decision to launch a hostile takeover earlier this month.

Oracle's surprise bid, only days after PeopleSoft announced plans to buy software maker J.D. Edwards & Co., disrupted Conway's friendly merger plans and threatened PeopleSoft's ability to sell software to new customers by creating tremendous uncertainty. To Conway, Ellison's aggressiveness seemed over the top. He called his former boss "diabolical."

"This is like having a wedding and Larry showing up with a shotgun trying to get someone to marry him," Conway told Dow Jones News Service.

Conway said he found the maneuver to be so "atrocious" that no price would be high enough for him to endorse the sale of PeopleSoft to its larger rival.

That assertion gave Ellison an opening to issue a stinging rebuke.

"In this new era of corporate governance, we would think management and the board of directors would be careful to put shareholder interests before their own," Ellison said in a written rejoinder.

Conway is among a small group of onetime Oracle executives who have succeeded elsewhere and find themselves bound by deep-seated animosity toward Ellison. In addition to Conway, its talented senior ranks have included Ray Lane, now a venture capitalist with Kleiner Perkins, Marc R. Benioff, now chief executive officer of SalesForce.com Inc., and Thomas M. Siebel, founder and head of software rival Siebel Systems Inc.

Benioff booted Ellison off of his board of directors a few years ago after discovering that his onetime mentor seemed to be laying the groundwork for Oracle to compete with SalesForce.com by copying aspects of its strategy. Ellison denied that he did anything wrong but agreed to leave the board.

Ellison engenders hostility among former protégés because he can be hard to work for and outspoken to a fault, according to Enzo Torresi, a technology entrepreneur who is close to Ellison. "Sometimes Larry doesn't give a lot of thought to his words," said Torresi, adding that Ellison can be cordial and friendly in a social setting, but is transformed into a "shark" once he goes to work.

"I never worked for him. Maybe that is big plus," Torresi quipped. "I find him generous and very smart, and find him a very pleasant friend to have."

Ellison has run Oracle since co-founding the company in 1977 with the goal of building software for big companies that would enable them to rapidly manage information and data in new, and valuable ways. Its products, often invisible to consumers, provide the technology backbone behind a wide array of secure commercial transactions for the nation's biggest banks, enabling millions of cardholders to access automated teller machines, for example, in addition to being used in labs by scientists analyzing DNA databases.

Along the way, Ellison has rubbed some people wrong.

Oracle chief executive Larry Ellison. File Photo/Paul Sakuma -- AP
"Larry Ellison has a big ego," said Jay Joseph, director of information technology at Bolinger Shipyards, an Oracle customer. "There are people out there like Conway who are not going to like it."

Conway was a successful sales executive at Oracle who eventually left the company after learning he would probably not be able to advance much higher up the corporate ladder. Conway took over an ailing PeopleSoft in 1999, turning a company that had been run like a mom-and-pop business -- with employees referred to as "PeoplePeople" -- into a corporation with an edge. He emphasizes accountability, competitiveness and results, while keenly watching customers and competitors. "I'm one of the most paranoid people there is," Conway once told an interviewer.

Ellison and Oracle have given him plenty to be paranoid about as they have sought to disrupt PeopleSoft's merger with J.D. Edwards. It doesn't help that Ellison sometimes has bad-mouthed PeopleSoft for competitive advantage.

"Some of it is gamesmanship," said Rick Lowrey, executive vice president of Deltek Systems Inc., which sells applications software to construction firms. "Many of the businesses that compete head-on daily [with Oracle] think it is just tactics to minimize their success in the software selling cycle."

In a takeover battle that has degenerated into a personal feud, Ellison frequently has punched back, rather than initiating verbal contact. "If you get attacked, you respond," Torresi explained.

While Ellison and Conway have been sniping at each other as competitors for years, tensions have risen to new heights amid the hostile takeover attempt. Conway is warning corporate software users that if Oracle buys PeopleSoft, they will have fewer choices, higher prices and be forced to buy Oracle software. Ellison has preached an entirely different message, telling commercial software users they can continue using PeopleSoft products for years, and urging them not to be scared by Conway's lies.

"They started blasting at each other prematurely," Torresi said. "That put Larry on the defensive. That put Conway on the defensive. Two big egos get on the defensive, and you get mass destruction."