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Re: [usage-centered] Character based notations (was Patterns cum UCD vs. XP)

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  • Nuno J. Nunes
    on 4/28/01 21:52, Hallvard Tratteberg at hal@idi.ntnu.no wrote: Tony, David and Hallvard, ... I ll have to agree with Hallvard on this one. ... XMI is the
    Message 1 of 44 , Apr 29, 2001
      on 4/28/01 21:52, Hallvard Tratteberg at hal@... wrote:

      Tony, David and Hallvard,

      >> I really like Tony's suggestion for using character-based UI notations for
      >> both applications and fragments and enhancing them with pattern mappings.
      >> Three reasons stand out to me:
      >> 1. Most UI designers will have some development experience, and the
      >> pseuodocode-type expression will leverage off that prior experience.
      >> 2. The textual notation is clearer than current graphical ones, unless the
      >> ideographs and spacial arrangement were much clearer than most used today.
      >> 3. The textual notation is easily machine translatable into graphical
      >> notations or lo- or hi-fidelity prototypes, or even generate code for
      >> language/platform specific development environments.
      > I would argue against all these. First, what has pseudocode with development
      > experience. Do you mean coding experience? If 2 is correct, why do we have
      > UML? In addition, most modelling language distinguish between abstract
      > syntax and surface syntax, and usually support a textual notation for file
      > exchange, while using a graphical one for editing. Why? For 3 I would say
      > that it is very difficult to generate good graphical diagrams from text,
      > since they usually utilise size and layout for focus and grouping of
      > concepts.

      I'll have to agree with Hallvard on this one.

      Regarding David question:

      >1. Can anybody tell us how much of this, if any, is present in the UML
      >(XMI?) std's?

      XMI is the OMG's streaming format for model interchange between MOF
      compliant metamodels (such as the UML, EJB, SWM, CORBA and so on). XMI is
      specifically indented to be a machine readable format that enables several
      levels of validity checking (syntactic and some level of semantic
      correctness). XMI is not something you'll use to communicate models between
      people (at least regular people). The great power of XMI is that it enables
      tools to perform loss-less interchange of data and metadata, even when one
      tool doesn't fully understand the information in the stream. Another good
      thing about the XMI is that the semantics are precisely defined (contrary to
      the UML 1.x spec which is recognized to be a real mess).

      I'm particularly interested in the UML (and trying to push it for UI
      purposes) mainly because I believe the potential of interchanging models can
      highly benefit UI design. The UML has many drawbacks, but the good thing
      about it is the underlying infrastructure (MOF, XMI...). For instance the
      UML notation needs improvements but if we have precise semantics (and a
      proper abstract syntax) we can change the concrete syntax at will, but still
      be able to interchange the models with other tools and leverage existing
      tool support.

      For instance, David proposes to create a text-based UI notation for UsageCD
      canonical prototypes... That's OK, but the UI field is already plagued with
      literally hundreds of UI description languages that support one tool,
      model-based environment or method. My point is that if we're trying to build
      a good UI description language why not build it over the existing metamodel
      that everybody else is using (or at least says so) in the SE field? If we're
      able to do that we can still develop tools that take the semantics and
      abstract syntax of those models and depict them using different concrete

      Nuno Jardim Nunes
      University of Madeira - Teaching Assistant
      Mathematics Dep. - Computer Science Unit
      phone: +351 291 705160 (direct) 705150 (secretary)
      fax: +351 291 705199
      URL: http://www.math.uma.pt/njn/
      Address: Campus Universitário da Penteada
      9000 - Funchal - Portugal
    • Nuno J. Nunes
      on 30/04/01 08:40, Hallvard Trtteberg at hal@idi.ntnu.no wrote: Hallvard, ... I m familiar with Paternò s interactors. That approach is very close to the
      Message 44 of 44 , Apr 30, 2001
        on 30/04/01 08:40, Hallvard Trtteberg at hal@... wrote:


        > The abstraction is close to the "York/Piza" interactors, which in short
        > introduces a basic UI building block called "interactor" which mediates
        > information in two directions, user to system and system to user, through
        > four "gates". In my notation, the interactor is a rectangular box with
        > title, triangular gates and a resource interface. I've introduced functions
        > and merged these with gates, to provide domain specific computations.
        > Interactors are put together a bit like lego-bricks, by connecting the gates
        > and can be nested into a hierarchical graph, similar to a process network. I
        > formalise part of this using Statecharts, while the process algebra LOTOS
        > has been used by others. If anyone is particularly interested, I can send
        > him/her parts of my thesis, where this is discussed in relation to concrete
        > interface elements.

        I'm familiar with Paternò's interactors. That approach is very close to the
        model-based tradition, which was popular years ago but failed to gain
        widespread support mainly because model-based environments (including
        back-to-back automatic generation) never proved to be effective in practice.

        I'm not saying this approach is wrong or flawed, it surely is sound from a
        theoretical perspective. The main problem is that "pure" model-based
        approaches (in the sense that they attempt to fully automate the UID
        process) have not proved to be flexible enough for modern UIs. There are
        other successful examples of automatic generation techniques, mainly the web
        - where UIs described in markup are rendered in different platforms.
        However, those successful examples are very limited in terms of the extent
        to which they support the UID process.

        Times are changing though. Today we're moving away from the stable desktop
        paradigm and there is an increasing number of target platforms that differ
        substantially in terms of the devices we use to interact, and the related
        interaction styles and techniques.

        My point is that model-based techniques will inevitably come into play
        again. It will be very difficult to deploy software systems over a series of
        different platforms (just think of desktop, web, palm, cellular phone, and
        interactive TV) without effective model-based techniques. It's not a matter
        of whether we like them or not... We just can't cope with the increasing
        complexity without model-based approaches.

        > I want this to be a practical tool and have experimented with a runtime
        > system for this. I'm also working on a mapping to UML through stereotypes,
        > which I guess you're particularly interested in.

        Sounds interesting... Can you send more info on that UML adaptation? Is the
        runtime environment available?

        > I like to call the UID patters, i.e. both user interface and design. If we
        > omit "design" these may wrongly regarded as software patterns.

        I prefer a different distinction:
        Software patterns - all patterns that have to do with software
        Design patterns - patterns that have to do with OO design
        Analysis patterns - same for OO analysis
        UI patterns - patterns that have to do with UIs - interaction patterns,
        UID patterns, etc. are different classes of UI patterns.

        Nuno Jardim Nunes
        University of Madeira - Teaching Assistant
        Mathematics Dep. - Computer Science Unit
        phone: +351 291 705160 (direct) 705150 (secretary)
        fax: +351 291 705199
        URL: http://math.uma.pt/njn/
        Address: Campus Universitário da Penteada
        9000 - Funchal - Portugal
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