Servants needing proxies to themselves

dougmeredith

I’m a newbie to Ice, but I’ve searched both the manual and the forums for this, with no real help. I guess this is more of a best practices question than anything.

I have a servant that represents an electrical light, which can be either on or off. The servant is to use IceStorm to broadcast changes to it’s state. I toyed with one topic per light, but decided on a single topic for all light changes. That means that the monitor interface method becomes “void levelChanged(Light* theLight, int level)” rather than just “void levelChanged(int level)”. I could have used an identity rather than the proxy, but this seemed more convenient for the clients.

The difficulty arises with the servant needing to have (or create) a proxy to itself in order to broadcast update messages. Servants don’t have any knowledge of their identity, so I would need to construct the servant with some extra information, or set it after construction. I can think of ways to do this, but nothing that seems graceful.

I’d appreciate any advice, both on my specific problem, or on my entire approach.

benoit

Hi,

If the light IceStorm updates are only invoked from light servant dispatch, you can construct the proxy from Ice::Current, for example:

// C++
void 
LightI::levelChanged(int level, const Ice::Current& current)
{
     LightPrx self = LightPrx::uncheckedCast(current.adapter.createProxy(current.id));
     _publisher->levelChanged(self, level);
}

Otherwise, if updates can be sent form methods which aren't servant dispatch and where you don't have an Ice::Current, you will need to cache the light proxy with the light servant at construction time.

Cheers,
Benoit.