java jacob

I'm using JACOB to do COM calls to PowerPoint and other Office applications from Java. On a particular Windows 7 box I'm getting the following message quite often, but not always:

Source: Microsoft Office PowerPoint 2007
Description: PowerPoint could not open the file.

From excel I get:

ERROR - Invoke of: Open
Source: Microsoft Office Excel
Description: Microsoft Office Excel cannot access the file 'c:\marchena\marchena10\work\marchena\batch_58288\input\content_1.xlsx'. There are several possible reasons:

? The file name or path does not exist.
? The file is being used by another program.
? The workbook you are trying to save has the same name as a currently open workbook.

The Word error is just:

VariantChangeType failed

The following is what I'm running, the error comes from the last line.

        ComThread.InitSTA();

        slideApp = new ActiveXComponent("PowerPoint.Application");

        Dispatch presentations = slideApp.getProperty("Presentations").toDispatch();

        Dispatch presentation = Dispatch.call(presentations, "Open", inputFile.getAbsolutePath(),
                MsoTriState.msoTrue.getInteger(), // ReadOnly
                MsoTriState.msoFalse.getInteger(), // Untitled The Untitled parameter is used to create a copy of the presentation.
                MsoTriState.msoFalse.getInteger()  // WithWindow
        ).toDispatch();

I've tried putting a breakpoint just before doing the Open call and the file is there, and I can actually open it with PowerPoint in the GUI but when I step the exception is thrown.

The annoying thing about this issue is that it seems to happen continuously to begin with, but after poking at it for a while (rerunning the same code), it eventually completes successfully, and after that never reoccurs.

Further research I've found this only happens with to .ppt, .doc and .xls files, not .pptx, .docx and .xlsx. And as far as I can tell it's not file system related (I've swapped out the mechanism that copies the files and tried putting the files on a different file system).

I've just noticed that this only happens when the Java application is running as a service, not when I runcatalina.bat start from command line.