[omniORB] newbie quick queries

[FountainB at switch.aust.com]

Ulf Stoermer wrote:
> even though CORBA and COM are conceptually very similar
> this is an area where they differ completely.
> CORBA doesn't provide for automatic server activation on ORB level.
> In this case you need the help of an implementation repository.

I don't think this is quite what Eric meant. He was asking whether
the servant object needed to be instantiated for the client to
make a request to it, not whether the server process had to be
running (which is where you want an implementation repository).

Yes, you can instantiate servants on demand. See the POA
chapters in H&V. An example of this might be where the
object reference includes a database ID. You don't want
to load the entire db table into memory, instead the POA
intercepts the request and instantiates the corresponding
servant if it hasn't already been loaded.

Alternatively, your server could expose an administrative
object which provides methods to resolve or create servants
(like a factory). This is a little simpler, but not transparent
to the client.

Bruce Fountain
Senior Software Engineer
Union Switch & Signal
Perth, Western Australia