BackWeb Technologies Ltd has sued Microsoft for patent infringement, alleging that Microsoft's Background Intelligent Transfer Service, otherwise known as BITS, introduced in 2001 in Windows XP and now in Vista, Windows Server 2003 and Windows Server 2008, treads on four of its patents.

Throwing a wide lasso, BackWeb charges Microsoft with inducing others to infringe its patents since BITS is used by companies developing applications on Windows.

The suit, filed in San Francisco district court last Friday, claims the trespass has been willful and so demands treble damages along with the usual injunction and jury trial.

BackWeb's earliest patent for transmitting digital information in background over a network to a client that throttles down the transfer speed so there's minimal interference with other network activity dates back to June of 1999.

The others build on that, culminating with one granted in April 2002 for distributing data packages across a hybrid P2P network that the Israeli company claims Microsoft has messed with since it started distributing BITS 3.0 in 2007.

The eight-page suit filed by Hosie Rice LLP makes no mention of BackWeb asking Microsoft to license its technology.

The U.S. patents at issue are 5,913,040 (1999) and two continuation patents, 6,317,789 (2001) and 6,539,429 (2003), and the P2P patent 6,374,289.

BackWeb's stock in trade is data transfer, web distribution, updating and synchronization.