FYI: Issue with Windows 7 RC and VSTO…

mstehle — Tue, 02 Jun 2009 20:15:46 GMT

The VSTO team has a post which details an issue that you might see when trying to deploy a VSTO solution to Windows 7 RC. The error message would be…

“The required version of the .NET Framework is not installed on this computer”

As the blog post points out, the appropriate teams are aware of the issue and plan to address it by RTM of Windows 7. Additionally they provide a workaround in the meantime.

OOM.NET: Like a good standup comic – use scope and have good timing…

mstehle — Tue, 17 Feb 2009 18:55:16 GMT

Recently, I was helping someone with a Outlook item leak type issue involving a Task FormRegion. The symptom was that after opening a task, closing it, and reopening the item they were getting the infamous error message, “COM object that has been separated from its underlying RCW cannot be used.” They were familiar with some of the issues discussed here and knew to call ReleaseCOMObject() on objects as they were done with them. However, that is the only part of proper Outlook coding with .NET – you need to use scope and have good timing when you lay out .NET classes that handle events and use Outlook objects. The following class is a simple example of that scope and timing…

Scope

As I pointed out in my original OOM.NET post, you need to consider the scope of the objects whose events you listen to. The key is not to call ReleaseCOMObject() on an item while you are still listening to events from it. In the class below, notice that _task is defined at the module level so that as long as the instance of TaskRegion is alive and listening to the Write() event _task will not go out of scope and get garbage collected by the CLR.

Timing

It seems like there is a general understanding now that Outlook objects need to be released. Additionally, you must *always decrement the event handlers that you add*. However, the humor in a good joke is not just the punch line but also good timing – you have to be strategic about when to call ReleaseCOMObject() and when to decrement the event handler. Since this is a FormRegion class I’m utilizing the FormRegionShowing event to initialize _task and add the event handler and I use FormRegionClosed to remove the event handler and release _task. In a simple item wrapper class you might use the constructor and a dispose method in the same way. The goal is not call ReleaseCOMObject() until the events are unhooked, that way the COM object become separated from your RCW that is still trying to handle events.

…NOTE – I’m also employing Patrick’s fix in FormRegionInitializing for a FormRegion specific leak scenario…

partial class TaskRegion
{
    Outlook.TaskItem _task = null;

    #region Form Region Factory

    [Microsoft.Office.Tools.Outlook.FormRegionMessageClass
        (Microsoft.Office.Tools.Outlook.FormRegionMessageClassAttribute.Task)]
    [Microsoft.Office.Tools.Outlook.FormRegionName
        ("ReleaseTaskRegion.TaskRegion")]
    public partial class TaskRegionFactory
    {
        // Occurs before the form region is initialized.
        // To prevent the form region from appearing, set e.Cancel to true.
        // Use e.OutlookItem to get a reference to the current Outlook item.
        private void TaskRegionFactory_FormRegionInitializing(object sender,
            Microsoft.Office.Tools.Outlook.FormRegionInitializingEventArgs e)
        {
            Marshal.ReleaseComObject(e.OutlookItem);
        }
    }

    #endregion

    // Occurs before the form region is displayed.
    // Use this.OutlookItem to get a reference to the current Outlook item.
    // Use this.OutlookFormRegion to get a reference to the form region.
    private void TaskRegion_FormRegionShowing(object sender, System.EventArgs e)
    {
        _task = this.OutlookItem as Outlook.TaskItem;

        _task.Write += new Outlook.ItemEvents_10_WriteEventHandler(_task_Write);
    }

    private void _task_Write(ref bool Cancel)
    {
        System.Diagnostics.Debug.WriteLine("Write fired!");
    }

    // Occurs when the form region is closed.
    // Use this.OutlookItem to get a reference to the current Outlook item.
    // Use this.OutlookFormRegion to get a reference to the form region.
    private void TaskRegion_FormRegionClosed(object sender, System.EventArgs e)
    {
        _task.Write -= new Outlook.ItemEvents_10_WriteEventHandler(_task_Write);

        System.Runtime.InteropServices.Marshal.ReleaseComObject(_task);
    }
}

…This post is a continuation of my efforts to document common issues I’ve seen when .NET programmers write solutions with Outlook’s object model – be they separate executables, VSTO Add-ins, or Outlook FormRegions. To see all the posts in this series check out my posts with the OOM.NET tag…

…To check out more blog posts from Microsoft’s Messaging Developer Support team which supports Outlook, Exchange, and other email-related development using Microsoft APIs check out the DevMsgTeam tag across all MSDN blogs…

FYI: Want to build VSTO AddIns for Office 2007? VSTO 2005 SE Download Available Now!

mstehle — Tue, 07 Nov 2006 00:06:00 GMT

VSTO 2005 SE is a free download for Visual Studio 2005 Tools for Office AND Visual Studio 2005 Professional that will allow you to build VSTO AddIns for Office 2007 applications.

Note if you installed the CTP this summer...

"VSTO “v3” CTP users: If you previously installed any of the VSTO “v3” CTPs, you need to completely remove the CTP software from your computer before you install VSTO 2005 SE. Because the CTP’s ability to uninstall itself is very limited and unreliable, we strongly recommend that you restore your system in its entirety from a backup made before any VSTO “v3” CTP software was installed. This will require you to reinstall Visual Studio as well. If VSTO 2005 SE is installed on computers where VSTO “v3” CTP software is installed, or was installed but not removed properly, you may experience various error messages and failures. (If restoring a backup of your computer is not an option, you can try to uninstall Visual Studio 2005 and all related products from your computer, and then install them again. This is not guaranteed to completely remove the CTPs, but it has been reported to be sufficient to enable VSTO 2005 SE to work.) "

mstehle: The CDOs and CDONTS of Messaging Development : VSTO

FYI: Issue with Windows 7 RC and VSTO…

OOM.NET: Like a good standup comic – use scope and have good timing…

FYI: Want to build VSTO AddIns for Office 2007? VSTO 2005 SE Download Available Now!