Shai Agassi, a key executive in software maker SAP's campaign to expand its offerings and become a central player in the lucrative market for corporate middleware, will resign from the company on April 1, SAP said Wednesday.

Agassi, president of SAP's product and technology group, is leaving the company to devote more time to environmental causes, SAP said. "While we regret Shai's decision to leave, we congratulate him on his record of achievement," said SAP chairman Hasso Plattner, in a statement.

Agassi is widely seen as the architect of SAP's NetWeaver product -- middleware that can connect all of the disparate software applications and computer systems typically found in business computing environments. It's a key part of SAP's effort to expand beyond the ERP market, which it dominates, and compete more aggressively against Oracle and IBM in the broader business software market.

Agassi's stature in the company was such that he was seen as a possible successor to SAP CEO Henning Kagermann, who is under contract through 2009. Plattner said he shared with Agassi a plan to make him co-CEO with Kagermann, but Agassi "was not comfortable committing to a 10-15 year period."

His departure comes at a critical time in SAP's history. The company is fending off serious allegations brought by Oracle that its employees stole gigabytes of Oracle software as part of a scheme to provide cut-rate support to Oracle customers and ultimately lure them to SAP products.

Oracle sued SAP last week in U.S. District Court in California.

Agassi's pending departure has triggered a wider shakeup of SAP's executive offices. Among the changes: Doug Merritt has been named a corporate officer and will lead development of the company's business software; Jim Hagemann Snabe will lead development of the SAP Business Suite; and Michael Kleinemeier will head up collaboration and industry solutions.