On Thu, 7 Mar 2013 11:52:50 +0100 Michael Haberler <[email protected]> wrote:
> a) is HAL the right place to do persistence as opposed to the current > ad-hack way EMC and later linuxcnc have always had a Model/View/Controller architecture. The _only place_ where state information is supposed to be saved is in the Model. Looking at the source right now, I can't seem to find the big structure where the Model was stored, but suffice it to say that the overriding idea was "only one place where data is stored". This is why UI elements are of the 'momentary' or stateless type. As to the HAL components, they mimic small to medium scale logic ICs in their concept. This means that upon 'power up' they initialize to a known state, or even a random state according to their maker's wishes, but none preserve their state across subsequent runs of the system. One could argue that a HAL component designed to mimic an EEPROM _would_ have to save it's state, but that's a rather unique case :) I know there are probably a million and one exceptions to this which have probably crept in over the years, and I also acknowledge that the implementation may sometimes fail to make the state information available as it was needed, or to store all the data that could be used, or to fail in some other way prompting exceptions to this rule to be created. I don't however feel that the idea of a single, central data store is a bad architectural idea. What happened to all the really cool ideas about redis and 0MQ? I was pretty jazzed about those things, and I think the answer to some of the issues you raise (persistence) could be addressed in redis with a messaging system to transport the state information to where it is needed. Thanks, Matt ------------------------------------------------------------------------------ Symantec Endpoint Protection 12 positioned as A LEADER in The Forrester Wave(TM): Endpoint Security, Q1 2013 and "remains a good choice" in the endpoint security space. For insight on selecting the right partner to tackle endpoint security challenges, access the full report. http://p.sf.net/sfu/symantec-dev2dev _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
