[Pipet Devel] Could not contact the dl, it appears not to be started.

[Brad Chapman]

> I get the following error occasionally, for no apparent reason.  And 
it seems
> a little odd that the error says, "it appears not to be started", 
when Piper
> should take care of starting the DL automagically.

Okay, here's the gist of why you would get this error: The dl 
automatically "pings" all of the ui clients (well there is only one 
right now, but anyways...) to determine if they are still alive. When 
all of the clients either call close and shut down or die, the dl 
notices that it doesn't have any clients left, and shuts itself down. 
Right now I have the timeout for the dl set relatively quickly (10 
seconds or so) since that helps with development. So what you are 
seeing is this:

1. You shut down your ui. The dl is still waiting around and hasn't 
noticed all of the clients are shut down.

2. You go to start piper up again right after that. The dl is still 
running at this point, so the script doesn't start a new dl.

3. The old dl shuts itself down because it hasn't recieved a request 
from the new user interface to initiate contact yet.

4. Then the ui calls the dl, but the dl shut down, so the ui gets a 
CORBA communication error and reports the message that you see.

Eventually the dl will run for long periods of time and won't time out 
so rapidly, and so we shouldn't see this error any more. For now it is 
just an artifact of development. 

> jeff at dexter:jeff> ps -aux | grep python
> jeff     11279 18.6 10.3 10236 6528 pts/1    S    15:37   0:03 python
> startdl.py
> jeff     11282  0.0 10.3 10236 6528 pts/1    S    15:37   0:00 python
> startdl.py
> jeff     11283  0.0 10.3 10236 6528 pts/1    S    15:37   0:00 python
> startdl.py
> jeff     11284  0.0 10.3 10236 6528 pts/1    S    15:37   0:00 python
> startdl.py
> jeff     11285  0.0 10.3 10236 6528 pts/1    S    15:37   0:00 python
> startdl.py
> jeff     11291  0.0 10.3 10236 6528 pts/1    S    15:37   0:00 python
> startdl.py
> jeff     11292  0.0 10.3 10236 6528 pts/1    S    15:37   0:00 python
> startdl.py
> jeff     11293  0.0 10.3 10236 6528 pts/1    S    15:37   0:00 python
> startdl.py
> jeff     11294  0.0 10.3 10236 6528 pts/1    S    15:37   0:00 python
> startdl.py

Man, why the heck do you have 9 copies of the dl running? Kill some of 
those, for pete's sake! :-). Seriously, if the dl gets hung up because 
of a crash or error and doesn't close, you'll need to kill the old 
ones. They won't recieve any requests from new user interfaces because 
the string IOR that is written from newer dl's doesn't refer to them. 
So having them running doesn't mean they can recieve requests. From 
my experience coding the dl never gets hung up under "normal" 
circumstances, but you'll start seeing this during crashes/development.

Brad