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Re: [cinci-art] Next Meeting topic

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  • gerard sychay
    Could someone provide a quick 1-3 sentence summary of the difference between object modeling and data modeling. I feel that I already do one or the other, but
    Message 1 of 13 , Apr 24 9:22 AM
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      Could someone provide a quick 1-3 sentence summary of the difference between object modeling and data modeling.  I feel that I already do one or the other, but I'm not sure which one. :-)    

      Obviously, I'll look to the meeting for more details.

      On 4/18/2008 4:16 PM Mark Windholtz claimed:

      Edge Case will be presenting at the next C-ART meeting on May 6th, 2008

      Sit in like a fly on the wall with a development team as they wrestle
      with the issues of data modeling versus object modeling. This is not
      your standard slideshow and talk, but a dialogue presented in three
      acts in which we explore the themes of simplicity and modularity as an
      application is developed. Watch the sparks fly as old-school objects
      modelers meet the Rails generation.

    • Charles L Flatt
      I ll give it a shot. Data modeling consists of creating classes that represent the persisted data, and methods for creating, retrieving, updating and deleting
      Message 2 of 13 , Apr 24 9:48 AM
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        I'll give it a shot.  Data modeling consists of creating classes that represent the persisted data, and methods for creating, retrieving, updating and deleting that data.  A data model could contain classes that mirror customer, address and order tables.

        An object model is classes that represent the real-world entities a person thinks of.  So, a CustomerSummary object might include properties like CustomerName, FormattedAddress, TotalOrders.  It doesn't have a direct match in the database, and may just be read only.  An object model will often contain business rules.

        Data and object models are often closely related, but aren't required to be.  An object model could require no persisted data.  My own classes often mix the two, so that a Customer object also enforces business rules that aren't database constraints.

        That's more than 1-3 sentences.  :-)

        Charles


        gerard sychay wrote:

        Could someone provide a quick 1-3 sentence summary of the difference between object modeling and data modeling.  I feel that I already do one or the other, but I'm not sure which one. :-)    

        Obviously, I'll look to the meeting for more details.

        On 4/18/2008 4:16 PM Mark Windholtz claimed:

        Edge Case will be presenting at the next C-ART meeting on May 6th, 2008

        Sit in like a fly on the wall with a development team as they wrestle
        with the issues of data modeling versus object modeling. This is not
        your standard slideshow and talk, but a dialogue presented in three
        acts in which we explore the themes of simplicity and modularity as an
        application is developed. Watch the sparks fly as old-school objects
        modelers meet the Rails generation.

      • Charles L Flatt
        Funny that I m replying to my own response. Strictly speaking, modeling doesn t mean creating classes, even though I think that s normally the end result.
        Message 3 of 13 , Apr 24 9:57 AM
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          Funny that I'm replying to my own response.  Strictly speaking, modeling doesn't mean creating classes, even though I think that's normally the end result.  So, I could model the database using an entity-relationship diagram, then model the database using UML class diagrams, then create an object model in some other method, then create the code.

          I think my main point stays the same.  The "real world" objects don't have to match how their data is stored, and frequently shouldn't.

          Speaking of object modeling, I'll always remember fondly one of the few meetings I attended.  Ed had us all play his "object game", building an object model going around the table.  I later used that in an interview to determine how well the candidate understood object oriented programming!

          --clf


          Charles L Flatt wrote:

          I'll give it a shot.  Data modeling consists of creating classes that represent the persisted data, and methods for creating, retrieving, updating and deleting that data.  A data model could contain classes that mirror customer, address and order tables.

          An object model is classes that represent the real-world entities a person thinks of.  So, a CustomerSummary object might include properties like CustomerName, FormattedAddress, TotalOrders.  It doesn't have a direct match in the database, and may just be read only.  An object model will often contain business rules.

          Data and object models are often closely related, but aren't required to be.  An object model could require no persisted data.  My own classes often mix the two, so that a Customer object also enforces business rules that aren't database constraints.

          That's more than 1-3 sentences.  :-)

          Charles


          gerard sychay wrote:

          Could someone provide a quick 1-3 sentence summary of the difference between object modeling and data modeling.  I feel that I already do one or the other, but I'm not sure which one. :-)    

          Obviously, I'll look to the meeting for more details.

          On 4/18/2008 4:16 PM Mark Windholtz claimed:

          Edge Case will be presenting at the next C-ART meeting on May 6th, 2008

          Sit in like a fly on the wall with a development team as they wrestle
          with the issues of data modeling versus object modeling. This is not
          your standard slideshow and talk, but a dialogue presented in three
          acts in which we explore the themes of simplicity and modularity as an
          application is developed. Watch the sparks fly as old-school objects
          modelers meet the Rails generation.

        • Mark Windholtz
          The real-world is over rated. Often trying to model based on Real-World concepts is very limiting. The Real world is a good starting point but with Object
          Message 4 of 13 , Apr 24 10:05 AM
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            The "real-world" is over rated.

            Often trying to model based on "Real-World" concepts is very limiting.
            The Real world is a good starting point but with Object Modeling we can
            compose structures that solve the problem at hand but have no
            connection to the real world.

            Some of you might remember the Time Expressions we used in the ecal
            project.
            These solved a tricky problem, but were certainly not real world
            concepts.

            Description:
            http://www.martinfowler.com/apsupp/recurring.pdf
            Java Example:
            http://sourceforge.net/projects/ecal


            On Thu 24 Apr 08, at 12:48 PM, Charles L Flatt wrote:
            > I'll give it a shot. Data modeling consists of creating classes
            > that represent the persisted data, and methods for creating,
            > retrieving, updating and deleting that data. A data model could
            > contain classes that mirror customer, address and order tables.
            >
            > An object model is classes that represent the real-world entities a
            > person thinks of. So, a CustomerSummary object might include
            > properties like CustomerName, FormattedAddress, TotalOrders. It
            > doesn't have a direct match in the database, and may just be read
            > only. An object model will often contain business rules.
            >
            > Data and object models are often closely related, but aren't
            > required to be. An object model could require no persisted data.
            > My own classes often mix the two, so that a Customer object also
            > enforces business rules that aren't database constraints.
            >
            > That's more than 1-3 sentences. :-)
            >
            > Charles
            >
            >
            > gerard sychay wrote:
            >
            >> Could someone provide a quick 1-3 sentence summary of the
            >> difference between object modeling and data modeling. I feel that
            >> I already do one or the other, but I'm not sure which one. :-)
            >>
            >> Obviously, I'll look to the meeting for more details.
            >>
            >> On 4/18/2008 4:16 PM Mark Windholtz claimed:
            >>
            >>> Edge Case will be presenting at the next C-ART meeting on May 6th,
            >>> 2008
            >>>
            >>> Sit in like a fly on the wall with a development team as they
            >>> wrestle
            >>> with the issues of data modeling versus object modeling. This is not
            >>> your standard slideshow and talk, but a dialogue presented in three
            >>> acts in which we explore the themes of simplicity and modularity
            >>> as an
            >>> application is developed. Watch the sparks fly as old-school objects
            >>> modelers meet the Rails generation.
            >>>
            >
            >
          • Lari Kirby
            What is Ed s object game ? Lari Kirby ... From: Charles L Flatt To: cinci-art@yahoogroups.com Date: Thu, 24 Apr 2008 12:57:19
            Message 5 of 13 , Apr 24 10:21 AM
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              What is Ed's "object game"?


              Lari Kirby

              ----- Original message -----
              From: "Charles L Flatt" <charles@...>
              To: cinci-art@yahoogroups.com
              Date: Thu, 24 Apr 2008 12:57:19 -0400
              Subject: Re: [cinci-art] Next Meeting topic

              <snip>

              Speaking of object modeling, I'll always remember fondly one of the few
              meetings I attended. Ed had us all play his "object game", building an
              object model going around the table. I later used that in an interview
              to determine how well the candidate understood object oriented programming!

              --clf
            • Charles L Flatt
              Ed? Obviously you should describe it. --clf
              Message 6 of 13 , Apr 24 10:23 AM
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                Ed?  Obviously you should describe it.

                --clf

                Lari Kirby wrote:

                What is Ed's "object game"?

                Lari Kirby

                ----- Original message -----
                From: "Charles L Flatt" <charles@softwaremea dows.com>
                To: cinci-art@yahoogrou ps.com
                Date: Thu, 24 Apr 2008 12:57:19 -0400
                Subject: Re: [cinci-art] Next Meeting topic

                <snip>

                Speaking of object modeling, I'll always remember fondly one of the few
                meetings I attended. Ed had us all play his "object game", building an
                object model going around the table. I later used that in an interview
                to determine how well the candidate understood object oriented programming!

                --clf

              • Joe OBrien
                Sounds like a fun exercise for the beer portion of next months meeting :-)
                Message 7 of 13 , Apr 24 10:34 AM
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                  Sounds like a fun exercise for the beer portion of next months
                  meeting :-)
                • Bill Barnett
                  Perfect timing, Mark. I ll soon be needing to model recurrences in a new Rails project. Wonder if there s an acts_as_recurring gem/plugin? As I recall from
                  Message 8 of 13 , Apr 24 10:57 AM
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                    Perfect timing, Mark.

                    I'll soon be needing to model recurrences in a new Rails project. Wonder if there's an "acts_as_recurring" gem/plugin? As I recall from peeking at Martin's paper two years ago, it is a bit abstract (for me anyway...) but worth a look nonetheless.

                    BB

                    On Thu, Apr 24, 2008 at 1:05 PM, Mark Windholtz <windholtz@...> wrote:

                    The "real-world" is over rated.

                    Often trying to model based on "Real-World" concepts is very limiting.
                    The Real world is a good starting point but with Object Modeling we can
                    compose structures that solve the problem at hand but have no
                    connection to the real world.

                    Some of you might remember the Time Expressions we used in the ecal
                    project.
                    These solved a tricky problem, but were certainly not real world
                    concepts.

                    Description:
                    http://www.martinfowler.com/apsupp/recurring.pdf
                    Java Example:
                    http://sourceforge.net/projects/ecal



                    On Thu 24 Apr 08, at 12:48 PM, Charles L Flatt wrote:
                    > I'll give it a shot. Data modeling consists of creating classes
                    > that represent the persisted data, and methods for creating,
                    > retrieving, updating and deleting that data. A data model could
                    > contain classes that mirror customer, address and order tables.
                    >
                    > An object model is classes that represent the real-world entities a
                    > person thinks of. So, a CustomerSummary object might include
                    > properties like CustomerName, FormattedAddress, TotalOrders. It
                    > doesn't have a direct match in the database, and may just be read
                    > only. An object model will often contain business rules.
                    >
                    > Data and object models are often closely related, but aren't
                    > required to be. An object model could require no persisted data.
                    > My own classes often mix the two, so that a Customer object also
                    > enforces business rules that aren't database constraints.
                    >
                    > That's more than 1-3 sentences. :-)
                    >
                    > Charles
                    >
                    >
                    > gerard sychay wrote:
                    >
                    >> Could someone provide a quick 1-3 sentence summary of the
                    >> difference between object modeling and data modeling. I feel that
                    >> I already do one or the other, but I'm not sure which one. :-)
                    >>
                    >> Obviously, I'll look to the meeting for more details.
                    >>
                    >> On 4/18/2008 4:16 PM Mark Windholtz claimed:
                    >>
                    >>> Edge Case will be presenting at the next C-ART meeting on May 6th,
                    >>> 2008
                    >>>
                    >>> Sit in like a fly on the wall with a development team as they
                    >>> wrestle
                    >>> with the issues of data modeling versus object modeling. This is not
                    >>> your standard slideshow and talk, but a dialogue presented in three
                    >>> acts in which we explore the themes of simplicity and modularity
                    >>> as an
                    >>> application is developed. Watch the sparks fly as old-school objects
                    >>> modelers meet the Rails generation.
                    >>>
                    >
                    >


                  • Edward Sumerfield
                    You know that game where you sit in a circle and each say a word and has to be continued in a sentence by the next person. As you progress great stories are
                    Message 9 of 13 , Apr 24 11:04 AM
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                      You know that game where you sit in a circle and each say a word and
                      has to be continued in a sentence by the next person. As you progress
                      great stories are conceived.

                      The Domain Game (copyright Ed 2005) is similar in that each person
                      adds to an existing model allowing it to grown and morph as it goes.

                      I might say, Cat, leading to the next persons saying, "an associated
                      Leg", so now we can visualize a Cat class with a single association to
                      a Leg class. Well you know the next person is going to refactor that
                      association with some multiplicity so the Cat can have more than one
                      Leg. Very quickly the Cat has a massive Brain and is on a SpaceShip to
                      Mars.

                      Each person can refactor, add new classes, associations, inheritance
                      relationships or even start a whole new unrelated domain that may
                      eventually get related.

                      I find it works best when the domain is remembered because it forces
                      everyone to keep thinking about it. If it's written on a white board
                      you don't have to think as hard and it's the thinking hard about the
                      relationships that forces developers to think in objects.

                      Ideally, everyone is using the correct terms for these relationships
                      and if you are not then you will get challenged by "what the hell did
                      you just do our nice domain" or some such retort.

                      I use this game at work when working with teams on design problems to
                      get them thinking in the right way. Though in this real world scenario
                      I am usually writing stuff on the white board and we rarely end up
                      with Cats on Mars.


                      On Thu, Apr 24, 2008 at 1:34 PM, Joe OBrien <joe@...> wrote:
                      > Sounds like a fun exercise for the beer portion of next months
                      > meeting :-)
                      >
                      >
                    • Jim Weirich
                      ... Look at the TExp project on RubyForge. -- -- Jim Weirich -- jim.weirich@gmail.com
                      Message 10 of 13 , Apr 24 12:37 PM
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                        On Apr 24, 2008, at 1:57 PM, Bill Barnett wrote:
                        > I'll soon be needing to model recurrences in a new Rails project.
                        > Wonder if there's an "acts_as_recurring" gem/plugin? As I recall
                        > from peeking at Martin's paper two years ago, it is a bit abstract
                        > (for me anyway...) but worth a look nonetheless.
                        >

                        Look at the TExp project on RubyForge.

                        --
                        -- Jim Weirich
                        -- jim.weirich@...
                      • Bill Barnett
                        Temporal expressions! ARGH! I m hardly surprised you successfully implemented them when all we did in about 3-4 months of XPCinci meetings was discuss their
                        Message 11 of 13 , Apr 24 2:11 PM
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                          Temporal expressions! ARGH!

                          I'm hardly surprised you successfully implemented them when all we did in about 3-4 months of XPCinci meetings was discuss their implementation in Java and then toss them aside!

                          Thanks Jim. If there's a way I can stuff more Weirich goodness into this project I'll do it every time. Remind me to pick-up your tab at HabeƱero's the next 1,200 times!

                          BB

                          On Thu, Apr 24, 2008 at 3:37 PM, Jim Weirich <jim.weirich@...> wrote:
                          On Apr 24, 2008, at 1:57 PM, Bill Barnett wrote:
                          I'll soon be needing to model recurrences in a new Rails project. Wonder if there's an "acts_as_recurring" gem/plugin? As I recall from peeking at Martin's paper two years ago, it is a bit abstract (for me anyway...) but worth a look nonetheless.


                          Look at the TExp project on RubyForge.

                          --
                          -- Jim Weirich
                          -- jim.weirich@...


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