On Sunday, 15 November 2015 5:37 AM, Dan Haywood
<[email protected]> wrote:
> Thanks for this James.
> My observation re: using the (relational) data model as the initial input
> though is that this is likely to lead to rather coupled code, ultimately
> not maintainable.
Couldn't agree more.
> So, while going from the database up to the domain is fine for a single
> module of 10 or so entities, any app that is bigger than this really should
> be modelled from the domain down to the database.
Quite right. Any business app that is non trivial should be domain modelled.
David.
> Dan
On 14 November 2015 at 15:00, James Agada <[email protected]> wrote:
> I actually tested out using Telosys to generate an isis app from database
> definition. It did work but of course it meant i did the ER first. I used
> MySQL, did the ER modelling on the workbench, forward engineered into the
> database and then used telosys scripts to generate a functional Isis
> application. Did it as a PoC but we will come back to it later.
> James Agada
> Chief Technology Officer
>
>
> On 14 Nov 2015, at 3:49 PM, Óscar Bou - GOVERTIS <[email protected]>
> wrote:
>
> Many thanks, Stephen for this detailed explanation.
>
> The problem I’m facing is that I intent to communicate the developers
> what’s the model to implement.
>
> And I usually don’t find big mistakes in action code, but what mostly
> forces us to refactor is miscommunication regarding the Domain Entities,
> attributes and actions names, including typos (think my team speak Spanish
> but they’re modeling in English) or wrong or missing relationships between
> those entities.
>
> All that could be avoided by firstly agree in a common UML Class Diagram.
>
> If it can potentially generate automatically the Java skeleton with Apache
> Isis annotations is a big plus, as it will avoid mistakes when moving from
> design to implementation.
>
> And if it could potentially reverse engineer Java (incl. Apache Isis
> idioms) a really good feature.
>
> Any ideas about what tools could best adapt to the workflow (that could be
> potentially customized to cover the last 2 whishes) ?
>
>
> Thanks,
>
> Oscar
>
>
>
>
> El 14 nov 2015, a las 2:03, Stephen Cameron <[email protected]>
> escribió:
>
> Hi Oscar,
>
> In a qualified way I think your idea has merit. I have never used UML for
> design, but a few years ago I decided to take a good look at it and see it
> if was useful. The idea of being able to draw a diagram and generate code
> from it seemed sensible, after all that is what is done by most other
> 'design' professions, such as building architects and engineers.
>
> To cut a long story short I realised after some reading that it was not
> that simple, and that OO languages themselves are really all that are
> needed for the process of designing a system. This is "the code is the
> design" school of thought, mainly attributed to Jack Reeves [1].
>
> I found that keeping code and UML diagrams in sync in a top-down 'UML to
> code' design process will always be problematic (maybe why there are
> apparently no open-source tools that claim to do this). Then I read about
> Domain Driven Design which seemed to agree with this premise, and from
> there found Apache Isis via Dan's book.
>
> So now for me UML class diagrams do have an after the fact use for
> documentation purposes and if a solution implement was capable of that
> reverse generation of diagrams from code it would be a good thing to have.
> Entity Framework can do this, its their "code first" approach.
>
> Given that the-code-is-the-design is true, I think that UML class diagrams
> real main value is as a data model, the question then is why not use a
> purely data-modeling tool and generate Java classes off it. Then the
> diagrams 'designed' could have a usefulness to programmers and to system
> users, something like those created SchemaSpy [2] for example.
>
> There are already useful and free Java class generation (binding) tools
> from off data-models, of one sort or another, such as JAXB, DataNucleus'
> schemaGen[3], even CAM [4].
>
> Here is my vision of what I think would be really useful: to have a design
> tool that can be used by non-programmers to create a simple data-model, and
> then to have that create a working Apache Isis based CRUD system. This
> could serve your purpose (I guess) and also find a wider use.
>
> The means of achieving this would I think, require something like the
> "dynamic classes" in available in the Moxy framework [5], that is, map
> based so that no Java class compilation is needed. Instead, a data-model
> configuration file (a schema) is read-in to configure the system. This is
> not a strange idea, in fact its the data-driven programming paradigm that
> is the basis of the original browser concept (before it was turned into OO
> application framework via addition of Javascript). In the browser the data
> is HTML that is turned into an in-memory Document Object Model (DOM) for
> rendering.
>
> As a blended solution between Apache Isis as it is currently (heavily
> influence by naked objects, an OO modelling based approach for creating
> custom *behavioural* applications) and this additional mainly data focused
> approach, I think a programmer developing a business application would
> start off with these dymanic classes and then in time 'harden' the design
> by generating and compiling real Java classes from off the model. [A
> non-programmer wouldn't get past the first design 'phase' usually, but
> still end up with a useable UI.]
>
> In addition, by having separate abstract model-generated classes, that can
> be overwritten if the data-model changes, and concrete implementation
> classes, where you put all your behavioural code and that are never
> overwritten, you get close to the 'round-tripping' that would seem to me to
> be the only valid way to use UML *for design*. I think this is how the
> Eclipse Ecore models work, that there are model classes and implementation
> classes that extend the model classes. The IDE will often warn you when
> these two sub-models have inconsistencies. This duality also offers an
> alternative means to achieving the goals of Lombok it would seem.
>
> Of course, sitting in the middle of all this is a meta-model, that creates
> the dynamic classes, generates and compiles the 'hardened' model classes
> (when used) and maps either of these means to a UI 'viewer'.
>
> For such data-management frameworks, the complicated aspect isn't so much
> going from the designed data-model to Java, there are lots of examples of
> that, instead its being able to have also, a dynamic query capability. So
> that a person unfamiliar with the dataset, can, via its data-model, start
> querying it (and also maybe integrating it in real-time with other online
> resources, the idea of a data-browser appeals!).
>
> In the science domain, where I worked for a few years building
> data-management infrastructure, there are highly advanced systems for
> online data access and querying e.g. [6], but at the same time a common
> tool used for small databases is still Microsoft Access. Access has many
> strengths as a desktop database, including form generation and also dynamic
> query-by-form, but the problems arise when you want to make such data
> publicly available, in the sense of being findable and searchable in real
> time. You might as well have used a web-based system from the start and
> then been able to easily open it to the world at the appropriate time.
>
> Having though about this problem for a number of years and spent alot of
> time working on a XForms based solution as well. I'd be very interested to
> see Apache Isis broaden its scope to offer what I have described, in fact
> its doesn't seem to need very much more than what is already present in the
> Isis meta-model and Wicket viewer. The Restful objects support already
> provides a generic 'generated' web programming interface.
>
> In summary I know that there are some Java projects that make very
> effective use of a Model Driven Architecture approach (e.g [7]), but I am
> now not sure that UML is the 'be-all-and-end-all' basis of that. Actually I
> think that data-models are the basis of most of MDAs efficiency dividends
> and that there are other approaches, specifically that conceptual models
> offer more versatility in terms of who and how you can make use of them.
> This thinking goes way back, such as Sowa's Conceptual Graphs [8] and even
> to Codd [9]. A modern expression of Sowa's thoughts (I gather) is the W3C
> semantic web, but he was thinking of database design and query way back.
>
> Apart from some additions to Isis, another interesting aspect is looking at
> the mapping to data-stores, using a graph database of one sort or another
> to avoid the complexity of ORM is a simple answer to that I feel. Again,
> the hardening of a design might mean manually adding a few overrides of
> default ORM mapping rules into some behavioural-model classes, that extend
> generated data-model classes (getters and setters only).
>
>
> [1]http://www.developerdotstar.com/mag/articles/reeves_design_main.html
> [2]http://schemaspy.sourceforge.net/sample/relationships.html
> [3]
>
> http://www.datanucleus.org/products/accessplatform_2_1/rdbms/schematool.html
> [4]http://camprocessor.sourceforge.net/wiki/index.php/Main_Page
> [5]https://wiki.eclipse.org/EclipseLink/Examples/MOXy/Dynamic
> [6]http://www.opendap.org/
> [7]http://www.opencrx.org/
> [8]https://en.wikipedia.org/wiki/Conceptual_graph
> [9]https://en.wikipedia.org/wiki/Relational_Model/Tasmania
>
>
>
> On Fri, Nov 13, 2015 at 8:45 PM, Óscar Bou - GOVERTIS <[email protected]>
> wrote:
>
>
> Hi all.
>
> I’m considering re-introducing UML Class diagrams in our workflow mainly
> for:
> - graphically design the domain entities.
> - modeling relationships.
> - agree with names of properties, collections and actions needed.
>
> It would be wonderful if the UML solution could also be “integrated” with
> Apache Isis or Java, automating at least the entities Java skeleton
> generation.
>
> I’ve worked extensively with Rational Rose and Sparx EnterpriseArchitect,
> but was thinking about an Eclipse-based solution that could “potentially”
> be adapted to generate the Java entities with Isis annotations.
>
> Before joining the Apache Isis community I developed [1] for Enterprise
> Architect for automatically generating Spring Roo-based classes, but Isis
> was better suited for our project and I abandoned it.
>
>
> Any ideas?
>
> Thanks,
>
> Oscar
>
>
> [1] http://roomodeler.com
>
>
>
>
>
>
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