[RESOLVED] ActiveX server and DCOM

OK, I have quite a tangle.

I have created an ActiveX exe out-of-process server (the class is called Locator.Locator), which implements an interface I've invented and called ILocator. The Locator object currently has an instancing type of MultiUse (with 1 thread in its thread pool, if that makes a difference).

I have a Standard exe that accesses this server using a CreateObject call

VB Code:

Dim IL As ILocator
Set IL= CreateObject("Locator.Locator")

Even though this call is sometimes repeated several times during the course of the program's execution, it always connects to the same object, as long as something doesn't kill the ActiveX exe process.

That's what's happening when I'm running both on the same computer, which is exactly what we want to happen.

I want to run the server process on several machines in the network, with each of them communicating with each other, sharing information. The purpose behind this, by the way, is graceful failure, so that if any of them goes down, the rest of the networked computers can allow for this, and recover. Therefore I've put a function onto the ILocator interface whose implementation looks like this:

VB Code:

Private Sub ILocator_Connect(Machine As String)
    Dim IL As ILocator
    'Some code here to make sure Machine is a valid name
    Set IL=CreateObject("Locator.Locator",Machine)
    If Err Or IL Is Nothing Then
            MsgBox "Could not connect to " & Machine & ": (" & Err & ") " & Err.Description, , "Connection Error"
            Err.Clear
            Exit Sub
    End If
    'Some code here to add IL to a collection for later access
End Sub

Ideally, this function would connect to the server process running on Machine, and return its ILocator interface. I would like it to behave exactly like all the other CreateObject calls, so that it won't create multiple copies of the server process.

Here's where I seem to start running into DCOM issues. Right now, my DCOM settings (on both computers) are set this way:
Default Authentication Level: None
Default Impersonation Leve: Anonymous
Default Security allows launch and access to Everyone, Interactive, and System
Locator.Locator settings:
Authentication Level: Default
Location: Run on this Computer
Security: Default Launch and Access
Identity: The launching user

When I set it up this way, the CreateObject call works properly as long as the same user is logged on to both computers. If different users are signed on, and the user on the other machine is already running the process server, I get a new copy of the process server. Once I looked into it, I found that this was expected behavior for Identity: the launching user, because the two processes belong to different people.

If I change the identity option to "The interactive user", which is supposed to use the security scope of the person logged on, the connect process causes the process to stop responding (apparently because it is getting no answer). And anyway, we don't want to use this option because you have to have somebody constantly logged on to the other computers in order to run using this option.

If I change the identity option to "This user:" and supply my own username and password, the Standard EXE can no longer correctly access the Locator on the same computer with it, even when I'm the one logged on (and I can't even try connecting to another computer, because my Locator object doesn't have a user interface--I need to get at the Connect function through my standard exe in order to even attempt connecting to the other computer). The error that I'm getting is extremely strange because, apparently, the CreateObject("Locator.Locator") call returns an (apparently) valid ILocator object (and doesn't throw an error), but any attempt to call the functions of the ILocator object causes error 462, "The remote server machine does not exist or is unavailable."

Does anyone out there have any insight into what I should change in the projects or the DCOM settings to make it possible to run an out-of-process server on several machines, some of which might have different users or not have anyone logged in, and have the processes communicate properly?

--roo2d2

Search my name and Singleton. Your post is rather long-winded so it's hard to determine exactly what you need but it may help.

What I am trying to do is make the ActiveX server do across computers (through DCOM) what it is already doing on one computer.

It is already a singleton, if I'm understanding the term correctly. I can have several different copies of my standard exe running, and they all connect to the same object. Only one copy of my Locator.exe (the ActiveX server) program is running at any given time, according to Task Manager.

In fact, it is sort-of working across computers, as long as the same person is logged into both, and the DCOM identity settings are set to "the launching user". While this situation was all right while I was debugging the communication between two copies of the server running on different machines, it is not a good situation for my finished product. I'm asking what I should change to allow different people to be logged on, or for nobody to be logged on, and have the server programs correctly connect to each other. These changes might be in the DCOM settings or I might have to change the ActiveX exe project settings. I'm just not familiar enough with what all the options do to know.

If you can point me to a particular post that you've made that you think addresses this problem, I'd be extremely happy, because I couldn't find it.

--roo2d2

I think I see where you are going with this. Maybe I can help by offering my general DCOM settings. These 4 users are required to both Launch, and Access each DCOM component:

- Everyone
- Interactive
- Network
- System
- (Anonymous is sometimes required)

Identity should be the Interactive user

The Default Properties should be:

- Connect
- Identify

To remove any chance of auth. failures, use:

- None
- Anonymous

OK, thanks. That works, as long as someone is logged in. They're correctly connecting to each other and communicating. I'm not sure yet how much of hassle it'll be to have to log in to every connected computer to get it to work, so I might need some advice on how to do a remote login later on in the project.

The weird thing is I thought I tried the above setup last week and it didn't work, but I'm not going to complain because it's working now!

--roo2d2

I recommend using VNC server/viewer to do remote configurations. It will not "log out" the currently logged in user, runs as a service, and it's free. Glad to hear you are up and running.