Microsoft is backing away from its much-vaunted Common Object Model for a critical function: tying Java apps to Windows.

In its place is "@dll.import,'' a new technology for accessing Windows code that may replace the COM interfaces used today.

The @dll.import technology will debut in the next version of Microsoft's Java Software Development Kit (SDK), expected out in a month, said Kevin Miller, lead program manager in the applications and Internet client group at Microsoft. Microsoft said the tool has no larger implications for COM.

The key point of @dll.import is to link Java programs to non-COM-based Windows Dynamic Link Libraries (DLL), which are sets of compiled code that can be loaded and unloaded on demand.

``This will be easier than the COM way of doing things. It's hard to access native DLLs in some cases with COM, and in other cases, unimaginatively painful,'' Miller said.

COM, which Microsoft program manager Greg Dimescheli described as a framework for running components on multiple platforms, is a method of expressing interaction between distinct functional pieces.

However, COM does not effectively solve the software problem of getting what is known as C, C++ and Java ``types'' - the dictionary definitions of what component functions do - to work together, acknowledged Miller.

"The No. 1 cause of performance nightmares comes from marshalling to a new thread every time you cross from native code to Java.''

Microsoft's own internal tests have highlighted some severe COM-to-Java conversion problems. In addition, there are problems in the way Java's memory allocation mechanism, called the garbage collector, deals with objects written in COM.

Miller, who had been scheduled to present a talk entitled ``Effectively Using Java with COM and ActiveX'' at last week's Object Expo conference here, told his audience of programmers he was dumping the subject of the talk because Microsoft had just found a better way.

"The @dll.import will provide easy access to Win32 DLLs and third- party DLLs,'' Miller promised. "It answers a lot of the problems we've had in writing code in Java.''

The COM technique for accessing native Windows code in Java, called the Raw Native Interface (RNI), requires the programmer to manually manage the garbage collection, Miller said. ``But @dll.import automatically does the garbage collection for you, automatically moves the types across from one side to another,'' Miller said.

Sun Microsystems, Inc.'s JavaSoft division has urged companies to stick to "100% Pure Java'' and not use COM - which is the basis of ActiveX - since it renders an application platform-dependent. For instance, the Sun Java Virtual Machine, available in Sun's HotJava browser and its Java Development Kit, cannot import COM objects, although Microsoft's Java Virtual Machine can.

Sun claims @dll.import is no better. "This is sad,'' said JavaSoft senior staff engineer Larry Cable. "They've found a new way for people to lock themselves into the Windows environment.''

Source: Network World