IBM has called Microsoft's recent attacks on the open source business model "arrogance", blasting them as futile and counterproductive. In recent weeks, Microsoft executives have launched an all-out propaganda war against open source software, based on the GNU Public Licence (GPL). Open source allows free access to the programming code that makes up operating systems and applications, but also requires that any source code modifications also be made available. Microsoft's comments have branded this way of working anti-American and destructive to intellectual property, but IBM, which has recently become an outspoken proponent of open source, says Microsoft is swimming against the tide. "Microsoft is trying to shore up its defences as the tide is coming in," Adam Jollans, marketing manager for IBM Software for Linux in the European region. "They're trying to stop the tide, but the tide comes in whether you want it to or not." IBM executives were are in London this week showing Linux-based products at Linux Expo 2001, which runs until Thursday. The recent marketing push from Redmond has been around .Net, a nebulous initiative designed to turn software into a service that can be billed like gas or water. But many observers fear that .Net is a way of turning the open standards-based Internet into yet another Microsoft proprietary format. "We don't think [the proprietary model] is viable any more," Jollans said. "The world has changed irrevocably with the Internet, and Microsoft's single-platform approach won't work. You have to be able to connect to things." Andy Hoiles, IBM's Linux business manager for IBM's European Enterprise Systems Group, believes Microsoft's anti-open source, pro-.Net strategy is the arrogance of a company that has succeeded in conquering markets more often than it has failed. "We had that arrogance a few years ago," he said. "Then we nearly went out of business. You learn from that." Jollans also disagrees with Microsoft's argument that the GPL and intellectual property are incompatible. "That is a false argument," he said. "Both [open source and intellectual property] innovate in their own ways, and you can combine them in different ways. You can take the best of breed from both." Microsoft's remarks have drawn criticism from Linux advocates but also from legal experts, many of whom say that Bill Gates' portrayal of the GPL as a "PacMan-like" force is inaccurate. IBM has pledged to spend $1bn (about £700m) this year pushing open source and particularly the GNU/Linux operating system. It has recently scored public-relations points by signing up large companies such as Shell, Western GeCo and Danish ISP Telia to install large clusters of Linux machines for core business tasks. Find out how the open source movement is revolutionising the high-tech world at ZDNet UK's Linux Lounge. Have your say instantly, and see what others have said. Click on the TalkBack button and go to the Linux lounge forum Let the editors know what you think in the Mailroom. And read other letters.