C# Signature:

[DllImport("Kernel32.dll", SetLastError=true)]
[return: MarshalAs(UnmanagedType.Bool)]
private static extern bool ActivateActCtx(IntPtr hActCtx, out IntPtr lpCookie);

VB Signature:

Private Declare Function ActivateActCtx Lib "Kernel32" (ByVal hActCtx As IntPtr, _
                    <Out()> ByVal lpCookie As IntPtr) As Boolean

User-Defined Types:

None.

Alternative Managed API:

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Notes:

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Tips & Tricks:

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Sample Code:

MFC automatically manages activation context switching for fusion/winsxs support.

Interop dll's don't. I had to add support for this in our application. To do so, define

these adt's and values:

[StructLayout(LayoutKind.Sequential)]

    private struct ACTCTX
    {
    public int cbSize;
    public uint dwFlags;
    public string lpSource;
    public ushort wProcessorArchitecture;
    public ushort wLangId;
    public string lpAssemblyDirectory;
    public UInt16 lpResourceName;
    public string lpApplicationName;
    }

    private const uint ACTCTX_FLAG_PROCESSOR_ARCHITECTURE_VALID = 0x001;
    private const uint ACTCTX_FLAG_LANGID_VALID = 0x002;
    private const uint ACTCTX_FLAG_ASSEMBLY_DIRECTORY_VALID = 0x004;
    private const uint ACTCTX_FLAG_RESOURCE_NAME_VALID = 0x008;
    private const uint ACTCTX_FLAG_SET_PROCESS_DEFAULT = 0x010;
    private const uint ACTCTX_FLAG_APPLICATION_NAME_VALID = 0x020;
    private const uint ACTCTX_FLAG_HMODULE_VALID = 0x080;

    private const uint RT_MANIFEST = 24;
    private const uint CREATEPROCESS_MANIFEST_RESOURCE_ID = 1;
    private const uint ISOLATIONAWARE_MANIFEST_RESOURCE_ID = 2;
    private const uint ISOLATIONAWARE_NOSTATICIMPORT_MANIFEST_RESOURCE_ID = 3;

To create the context:

private bool EnsureActivateContextCreated()
    {
    string rgchFullModulePath = null;
    rgchFullModulePath = System.Reflection.Assembly.GetExecutingAssembly().Location;

    actCtx = new ACTCTX();
    actCtx.cbSize = Marshal.SizeOf(typeof(ACTCTX));
    actCtx.dwFlags = ACTCTX_FLAG_RESOURCE_NAME_VALID;
    actCtx.lpSource = rgchFullModulePath;
    actCtx.lpResourceName = ISOLATIONAWARE_MANIFEST_RESOURCE_ID;

    hActCtx = CreateActCtx(ref actCtx);
    contextCreationSucceeded = (hActCtx != new IntPtr(-1));

    if (!contextCreationSucceeded)
    {
        actCtx.lpResourceName = ISOLATIONAWARE_NOSTATICIMPORT_MANIFEST_RESOURCE_ID;
        hActCtx = CreateActCtx(ref actCtx);
        contextCreationSucceeded = (hActCtx != new IntPtr(-1));
    }
    if (!contextCreationSucceeded)
    {
        actCtx.lpResourceName = CREATEPROCESS_MANIFEST_RESOURCE_ID;
        hActCtx = CreateActCtx(ref actCtx);
        contextCreationSucceeded = (hActCtx != new IntPtr(-1));
    }

    return contextCreationSucceeded;
    }

Now, in all your function calls, call Activate and Deactivate to get the fusion manifest of you file!

Read up on the "Programming the Context Activation API" at msdn for more info.

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