Re: Applause for ZODB! And a question: How do you get pending change info from a transaction object?

Correct me if I'm wrong, but isn't the _p_changed flag on the object 
itself? If I have the transaction object in hand and it's about to commit, 
I need to know just the objects that have changed, so wouldn't your 
suggestion mean that I have to traverse every object in the entire 
repository to look for _p_changed flags? I would expect that the 
transaction object maintains an internal list of objects that are getting 
ready to change so that it can efficiently commit them. I would simply want 
access to whatever enables the transaction to do that so that I can use it 
to inform sockets about the changes that they want to know about.

But again, my familiarity of ZODB internals is next to nothing. (That may 
change.) So there may be some hidden assumption that yanks the floor under 
everything that I'm saying. :D

I read that transactions are more than just ZODB and could also be combined 
with pretty much anything, so I have a general idea of the strategy you are 
talking about with MQTT, which I'll spend time looking into. Yes, that 
would be interesting.

One thing that interests me about Tornado, and perhaps this is true of MQTT 
as well, is that it can accept an http or https connection on port 80 or 
443 and then turn right around and establish a websocket connection on the 
same port. (And you can do that with almost no code, which is nifty, but 
not a requirement.) If MQTT can accomplish this, that would be interesting. 
I'll still take a look at it either way. GoLang has also been interesting 
to me (neat for MQTT), but not for high level business logic for my 
app--I'm glad it ties in to Python.

Subscribing to a tree of objects would be interesting, yes. As long as I 
can also get surgical and subscribe to specific objects if I want to.

I also want to be careful not to get lost. A clear path to what I'm trying 
to accomplish this time around may simply be to find a way to ask the 
transaction object what the pending object changes are without traversing 
the entire repository. At least as an alternative as I investigate your 
recommendations.

I will now check out all of the resources you provided. Thank you much!

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