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Re: ISSUE-2 (All processes are systems): All processes are systems [sensor ontology - http://mmisw.org/orr/#http://www.w3.org/2009/SSN-XG/Ontologies/SensorBasis.owl - 09.12.15 ]

From: Manfred Hauswirth <manfred.hauswirth@deri.org>
Date: Tue, 22 Dec 2009 19:34:47 +0000
Message-ID: <4B311F57.1040903@deri.org>
To: Michael Compton <Michael.Compton@csiro.au>
CC: Semantic Sensor Network Incubator Group WG <public-xg-ssn@w3.org>
I agree with Michael.

What about "A sensor implements a process"? The process may be 
implemented in hardware (=> device) or in software or a mix. Sensors can 
be components of more complex sensor.

Cheers,

Manfred

Michael Compton wrote:
> 
> Maybe I should just address the dot points.
> 
> 
>> - A process has inputs and outputs
> 
> ok
> 
>> - A system has components
> 
> ok
> 
> (1)
>> - A sensor is a process
> (2)
>> - *Some* devices are sensors 
>> - Some devices are sensors - because they have an output
> 
> are we saying that a sensor is a process or that sensing is a process. 
>  For example,  lets say:
> 
> * I have a device that measures wind chill (i.e. it measures temperature 
> and wind speed and does a calculation), by (2) above it's a device that 
> is-a sensor, and by (1) it must be a process (I'm uncomfortable with 
> this already because we have now said that a device is-a process, which 
> seems wrong to me.  I'd think a device might follow some process, but 
> this is-a relationship seems strange).
> 
> * Now what if I write down the wind speed and temperature measurements 
> myself and do the calculation myself.  What's the sensor here?  It can't 
> really be me, can it - it would seem strange to say that I am a process 
> and a sensor.  Seems more like I followed a process and thus calculated 
> wind chill. So maybe the sensor is the process I followed?  Or is it the 
> act of me following the process?  In either case we have a problem 
> because above we said a device is-a sensor and then here we are saying 
> something entirely different (a process or the act of following it) is-a 
> sensor.
> 
> I would say that a device cannot be a sensor (well not in the process 
> sense that we have been talking about) otherwise we are conflating an 
> abstract (a process) and a concrete thing (a device).  
> 
> Seems from all the discussions that we have had that sensing is-a 
> process - or that some processes result in sensing something, and that a 
> device or a person, or a regional observing system might act out such a 
> process and thus sense something.  
> 
> So I would be more comfortable with
> 
> - Sensing is a process
> - Some devices can act as sensors
> 
> And then that a device that senses something could be a 'sensing 
> device', which thus acts out some sensing process.
> 
> but I don't agree with (2) above
> 
> 
>> - *Some* devices are systems
> 
> Why aren't all devices systems?  Even if they only have one component or 
> we don't want to write down all their components?
> 
> 
>> *- Some systems are sensors*
> 
> It depends, is our definition "A system has components" or "All things 
> with components are systems"?  The question itself is silly, but my 
> point is why are we trying to use the same component relationship to 
> describe devices and processes?  
> 
> I'm having trouble seeing the example above with me calculating wind 
> chill as a system.
> 
> 
> Michael
> 
> 
> 
> 
> 
> 
> 
> 
> 
> On 20/12/2009, at 2:19 , Luis Bermudez wrote:
> 
>> Hi Michael,
>>  
>> The only thing we have said about systems is that it contains 
>> components...
>>
>>
>>  
>> On Fri, Dec 18, 2009 at 12:42 AM, Michael Compton 
>> <Michael.Compton@csiro.au <mailto:Michael.Compton@csiro.au>> wrote:
>>
>>     my conceptions/preconceptions/misconceptions are as follows.
>>
>>     - A sensor need not be a physical device.  Kevin's definition of
>>     "An entity capable of observing a phenomenon and returning an
>>     observed value." seems ok to me.
>>
>>  
>> agree !
>>  
>>
>>
>>     - A Sensor need not be a single entity - it can be composed of any
>>     number of sub sensors, each perhaps of their own identity, each
>>     perhaps measuring different things that get combined into the whole.
>>
>>  
>> This is why it can be a system . Maybe we need to add also:
>>  
>> *Some sensors are systems*
>> ** 
>>  
>>
>>
>>     - The following things 'are' sensors
>>     *a temperature sensor (i.e. a physical device) at location l
>>     *a program on a computer (far away from location l) that can read
>>     in the temperature at location l and a wind speed estimate for
>>     location l and calculate the windchill at l
>>
>>  
>>  
>> Yes.. Commonality is that a sensor has an output and therefore are 
>> processes.
>>  
>>
>>
>>     More correctly, in both cases something has acted as a sensor for
>>     a particular phenomenon: a device in the first instance, and the
>>     program in the second - if I wrote down the temperature and wind
>>     speed measurements on a piece of paper and calculated the wind
>>     chill myself, then I have acted as the sensor.
>>
>>     - The example of the wind chill sensor means that sensors can have
>>     multiple components, and I guess the components may themselves be
>>     interesting.
>>
>>     - A device (a physical piece of hardware) can also be broken down
>>     into components (presumably other devices, but perhaps also
>>     systems - software systems etc) but I don't see that as having
>>     anything to do with sensors or their decomposition into parts.
>>      For example, imagine a device that can measure wind speed and
>>     temperature, that has a small inbuilt chip that can calculate wind
>>     chill, round measurements, compute averages and a radio to
>>     communicate its readings.  It's physical decomposition into its
>>     components is different from its decomposition into the roles it
>>     can play as a sensor.  So the two sorts of decomposition may be
>>     related, but not equivalent.
>>
>>  
>>  
>> So I think this still holds  true:
>>  
>> - Some devices are sensors - because they have an output
>> - Some devices are systems - because they have components
>>  
>> But if you wnat to propose other statements which make the system 
>> composition more explict, please do so.
>>  
>>  
>>  
>>
>>
>>     - I'm also unsure about the word system and in particular it's
>>     relationship to process.
>>
>>  
>> We are separating them..
>>
>>
>>     - partly I see the problem as linguistic: i.e. we are using the
>>     word sensor in two different contexts.  We think of things in
>>     terms of 'ah this thing is a sensor', but we also say 'a sensor is
>>     a process'.  Is what we are really saying that to sense something
>>     is to follow a process that leads to a value as an estimate of a
>>     phenomenon.  In which case a sensor isn't a thing at all it's
>>     really a 'to sense do...' or 'was sensed by doing...'.  So if we
>>     take it that to sense something is to follow a process that
>>     estimates a value, then what is a system and why is a sensor one?
>>      To think of a system as a collection of components in some
>>     technical sense and then make sensor one of these is to take the
>>     'ah this thing is a sensor' approach, but then we also agree on 'a
>>     sensor is a process' which now seems to make a sensor not a
>>     system.  So is the biggest problem here simply that we (copying
>>     from SWE) have decided that systems have components and sensors
>>     are also made up of things, so it must be a system - where as
>>     there are actually two hierarchies here and we should represent
>>     them with different relationships?
>>
>>  
>>  
>> The only think we are saying about sensor is that it has an output !
>>  
>>
>>
>>     So how about....
>>
>>     a System is a device/computer system/software system that is made
>>     up of components
>>
>>  
>> I think we do not need to be explict about device/computer 
>> system/software.  For example, a regional observing system can also be 
>> a system.
>>
>>
>>     a Sensor is a process (a description of inputs/outputs, some steps
>>     and data flows) which may also be made up of sub sensors
>>
>>  
>> yes.
>>  
>>
>>
>>     a System may play the role of a sensor for phenomenon X.
>>
>>  
>> So is this OK ?
>>  
>> *- Some systems are sensors*
>>  
>>  
>> but I suggested before that *Some sensors are systems*
>> ** 
>> I think both are ok.. what do you think ?
>>  
>> -luis
>>  
>>
>>
>>
>>
>>     Michael
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>     On 17/12/2009, at 19:11 , John Graybeal 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 19:35:29 GMT

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