- From: Manfred Hauswirth <manfred.hauswirth@deri.org>
- Date: Tue, 22 Dec 2009 19:10:40 +0000
- To: Luis Bermudez <bermudez@sura.org>
- CC: John Graybeal <jbgraybeal@mindspring.com>, Semantic Sensor Network Incubator Group WG <public-xg-ssn@w3.org>
Looks fine to me. The only item I am really having trouble with is "a sensor is a process". Since I wanted to test, if I am the only person who could not understand this, I tested it around here: 100% had the proverbial question marks written on their faces (mostly CS people, some with a science back ground - physics). Just wanted to flag this. Seems a pretty strong indicator to me though. However, If this is the consensus of the group it to go with it, I am OK with it (still feels strange for me though). Cheers, Manfredd Luis Bermudez wrote: > Can we make some conclusions, in particular those of you discussing this > thread ? > > I agree with all of these: > > - A process has inputs and outputs > - A system has components > - A sensor is a process > - *Some* devices are sensors > - *Some* devices are systems > > > -luis > > On Thu, Dec 17, 2009 at 3:11 AM, John Graybeal > <jbgraybeal@mindspring.com <mailto:jbgraybeal@mindspring.com>> wrote: > > > On Dec 16, 2009, at 12:00, Manfred Hauswirth wrote: > > Hi John, > > thanks for your insightful comments. Some more comments from my > side. > > John Graybeal wrote: > > > Regarding "all systems are processes": Honestly, I would > not > understand this (I stated this at the F2F). For me, > you have systems > which include one ore more processes. If > systems are processes, why > have systems at all. My notion > of systems would informally consist > of processes, > scenarios, deployments, etc. > The question "why have systems at all?" is the crux here. > Can we state clearly when a process is not a system? Or in > other words, how is a system more narrow than a process? > Incidentally, my notion of processes would informally > consist of the same list. I am also having trouble drawing > the distinction. > > > Interesting! I think this may be due to our different background > (I assume your are not a computer scientist like myself - > without evidence I may add). > > > Computer Science and Statistics. 30 years software and systems > support. (No worries!) > > > In my area (computer science, information systems) systems would > be defined as I do and a system would consist of software and > hardware and the processes would clearly be "inside" the system > as part of the software, so there is a clear distinction between > "system" and "process" (other CS/IS people - please feel free to > contradict me), whereas you seem to define this more from the > viewpoint of an experiment which is being observed (?) where > processes come into play as part of the observation process > (please correct me - I am guessing here). > > > I'm using one of the general meanings of the word 'process', which > applies not just to what's happening in side the computer or > component, but what happens as all the software and components > interact with each other. There are local processes and there are > external processes. > > It isn't driven by experiment orientation but by broader CS > orientation -- dealing with engineering systems of systems, and > including the human component in those systems, and modeling all the > above as processes (which may, or may not, then be computerized in > the new version of the system). Anyway, just a different viewpoint, > neither right nor wrong. > > > The problem here seems to lie in different conceptualizations in > different communities - all of which done according to the > specific needs of a community. Now, while this may complicate > things, I think it is also a useful and actually mandatory > exercise. While I may claim, that I need to understand the > conceptualization because as an CS/IS person I will have to > build (software/hardware) systems (sorry! no other term comes to > mind) which need to manage information coming out of > observations, you may claim exactly the same from you point of > view (and rightfully so). The question now for me is: Who are > our users and how to serve them best? Where's the sweet spot? > > > Concur. I presumed from the start that the group was interested in > modeling hardware elements, but I have found it useful to consider > those hardware components as processes in a larger system of > systems. They take data in and transform it to other data that is > spit out. This is one useful definition of a process, as Luis notes. > > Oops, got off track there! But our agreed point is to agree on which > type of devices (= which group of users) we want to make the > ontology for. My assumption/preference was the group that used > physical devices to transform measurable phenomena into digital data > (because that's the easiest to model and the most immediately > useful). But I can go with whatever on this, as long as we all > understand. > > > > PhysicalSystem: I don't remember the exact reason for > this. Did we > mean deployment? > I assume this is to distinguish it from a software system. > > Sensor as subclass of Device: I think this is too narrow. > I can > think of sensors which are not devices at all, > e.g., human "sensors" > in the context of social sensing > (which is an accepted concept in > many domains including > CS by now). Making sensors a subclass of > device limits us > to purely technical systems in hardware, IMHO. Is > an RSS > feed a device? I can clearly use it as a sensor. I think > that > Device should be a subclass of Sensor. Even in > existing middelware > systems like our GSN we followed that > path (without having an > ontology in mind at all). > This gets to purpose of the ontology. As I understood it, > the group was originally constructed to model hardware > sensors. (May have just been a wrong assumption on my part. > More precisely, what we clearly were not doing is modeling > samplers, that is, devices that return a physical sample.) > > > Agreed. But "sensors" do not necessarily manifest themselves as > hardware. If I want to detect user activity / inactivity on a > computer in an experiment, one of my sensors may be a the > keyboard, another one running processes (not waiting for user > input), etc. It is very hard to draw the line here. My question: > Do I have to have this distinction at all? Essentially I convert > an X into a Y and Y should be usable in a computer. Whether X a > is a physical phenomenon or not depends on the domain, IMHO. > > > Sure, that works for me too. If you make a sensor too general, > though, it can have components. What do we call those components -- > are not at least some of them sensors? So now, what is different > from the sensor that can have sensors, and a device, which has the > same recursion into smaller devices; and a system, which can have > systems (and a process, that can have processes)? > > I'm being a little silly of course. All I mean to do is call > attention to the need to define the terms according to what makes > them different from each other, not just whether they are higher or > lower in a hierarchy. I think we haven't done that well enough yet. > > > So using one definition of sensor ("anything that senses") > makes Sensor very broad, and other things would subclass to > it. (Since some devices (a hammer) don't sense things, we'll > have to define Device narrowly to make it a subclass > Sensor.) Using another definition of sensor ("a component > that detects (measures) a physical phenomenon, converting it > into a digital representation that can be output to other > components"), a Sensor is clearly a specific type of Device, > and is also a component of any sensing device. > > > If you see software as a Device, I would agree to it, but then > again Device has the connotation of hardware. > > > Ah, I said a Sensor was hardware in my original world, so I didn't > have any problem here -- since my Sensor was hardware and my Device > had a sensor, I was already on board with Device being hardware. > > > Do we have a set of definitions by any chance, so we can all > use these (or some) terms the same way? > > > I don't think we have. > > > Why is a Device a subclass of a Process? A Process can > use Sensors > which are manifested as Devices to do/measure > something, IMHO. Again > this is a quite narrow notion of > the concepts. > I'm not following your argument here. Yes, a Process can > use Sensors as you say. So can a Device. There is no > inconsistency that I can see. This suggests a Device is in > fact a type of Process. > > > Sorry, but I don't understand how a Device can be a Process. > > > The "Process: something that receives an input and produces an > output" is not a sufficient explanation or model of that? > > John > > > Best regards, > > Manfred > > > > > > > -- > Luis Bermudez Ph.D. > Coastal Research Technical Manager > Southeastern Universities Research Association (SURA) > bermudez@sura.org <mailto:bermudez@sura.org> - Office: (202) 408-8211 > 1201 New York Ave. NW Suite 430, Washington DC 20005 -- Prof. Manfred Hauswirth Digital Enterprise Research Institute (DERI) National University of Ireland, Galway (NUIG) http://www.manfredhauswirth.org/
Received on Tuesday, 22 December 2009 19:11:22 UTC