Hi John,
Let me answer your questions:
1) What are the flag(s) that are used to decide that an exe is the same as
the one already running, is it just the GUID or are there other flags?
In Microsoft.VisualBasic.dll 8.0, the *Application Instance ID* is composed
of:
i. Assembly Typelib GUID
ii. Assembly Major Version Number
iii.Assembly Minor Version Number
The implementing code looks like this:
private string GetApplicationInstanceID(Assembly Entry)
{
PermissionSet set = new PermissionSet(PermissionState.None);
set.AddPermission(new FileIOPermission(PermissionState.Unrestricted));
set.AddPermission(new
SecurityPermission(SecurityPermissionFlag.UnmanagedCode));
set.Assert();
Guid typeLibGuidForAssembly = Marshal.GetTypeLibGuidForAssembly(Entry);
string[] strArray =
Entry.GetName().Version.ToString().Split(Conversions.ToCharArrayRankOne(".")
);
PermissionSet.RevertAssert();
return (typeLibGuidForAssembly.ToString() + strArray[0] + "." +
strArray[1]);
}
2) Is there a way I can get the same exe running from two (or more)
different directories to run separate single instances?
Yes. But not using the VisualBasic.ApplicationServices - because the logic
has been burnt into the code, as explained in answer 1).
In your case, you may consider implementing your own single instance
feature using Mutex. We can add Assembly Location info into the mutex name
so instances from different locations will not be considered as the same
app.
Here is a piece of sample code to proof the concept:
static void Main(string[] args)
{
bool mutexWasCreated = false;
string mutexName;
string asmLocHash;
Assembly execAsm = Assembly.GetExecutingAssembly();
SHA1Managed sha = new SHA1Managed();
Mutex m;
// The mutext name cannot be longer than 260 characters.
// So we use the hash value of the location instead of the real path,
// in case the Location string is too long for a mutex name.
asmLocHash =
Convert.ToBase64String(sha.ComputeHash(Encoding.UTF8.GetBytes(execAsm.Locati
on)));
// mutexName = GUID + Ver Major.Minor + Asm Location Hash
mutexName = Marshal.GetTypeLibGuidForAssembly(execAsm).ToString() +
string.Format("{0}.{1}", execAsm.GetName().Version.Major,
execAsm.GetName().Version.Minor) +
asmLocHash;
try
{
m = Mutex.OpenExisting(mutexName);
}
catch (WaitHandleCannotBeOpenedException)
{
m = new Mutex(true, mutexName, out mutexWasCreated);
}
if (mutexWasCreated)
{
Console.WriteLine("This is the first instance.\r\nWorking...");
Console.ReadLine();
}
else
{
Console.WriteLine("This is not the first instance.\r\nExiting...");
Console.ReadLine();
}
m.Close();
}
If you have any further questions regarding this issue, please feel free to
post here.
Regards,
Jie Wang (
[email protected], remove 'online.')
Microsoft Online Community Support
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