> > The example case (reporting HAL groups as compound messages of several > HAL signals) is directed at a messaging model, though not request/reply; > I would think publish/subscribe is the more suitable pattern for status > reporting. I'm exploring a model where a 'HAL group name' becomes a > 'topic name' on the publish/subscribe level automatically, and > serialisation of HAL objects is derived from the group member list, with > the idea of having status messages generated by HAL-only configuration > and nothing else. I would think retrieving the names and types from HAL > at startup or on change is good enough; pounding the HAL locks and object > lists for every message would be a bit inefficient. > > For command input into a HAL instance, a request/reply type RPC would be > the better fit at the macroscopic level, I think. I'm still fiddling the > puzzle with respect to intra-HAL messaging to enable layering of > components at the command level (such that one component provides a > service, and another component can use it by sending a message; for > instance a homing component sending a 'feed move' or 'probe' command and > motion would execute it).
I still haven't wrapped my mind around your idea of messages in HAL and signal groups. My server/client thought was strictly thinking about halcmd type commands: newsig, setp, show pin, and similar. In that same category (but a little more buried) are the cases where halscope is about to present a dialog to the user to let them select the thing they want to probe. It needs a list of things, and gets that list by traversing the internal metadata lists. In this new case, it would get that list by asking the server for it. None of these commands actually relate to the operation of the machine control - they relate to configuring (and possibly troubleshooting) it. -- John Kasunich [email protected] ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
