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Commit 9013a8b6 authored by Kai-Holger Brassel's avatar Kai-Holger Brassel
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Next version usable until "Modeling Data Catalogs for ..." inclusively

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Data Catalogs Documentation/DataCatalogs1Overview.adoc
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== Overview
== Introduction
[IMPORTANT]
====
This overview talks about the work of the author and others, but without bibliographic references. Currently, it is just meant as background to better understand the technical documentation in the sections to follow.
This introduction talks about the work of the author and others, but without bibliographic references. Currently, it is just meant as background to better understand the technical documentation in the sections to follow.
Maybe it could be developed into a more serious paper later.
====
......@@ -27,10 +27,10 @@ This very short history on technologies for development of software in general,
* formal textual domain specific languages (DSLs) dedicated to solve specific tasks with ease
* formal graphical DSLs.
****
====
Note that DSLs more tend to describe _what_ shall be achieved by a computation instead of describing in detail, _how_ to achieve it.
Therefore, DSLs usually look more like a model than like an algorithm.
****
====
Now back to the task at hand.
......@@ -67,14 +67,14 @@ Instead, we decided to use a DSL for data modeling and use code generation whene
Since SimStadt was developed within the Java eco-system we followed this standard approach:footnote:[A similar approach is in use to standardize extensions to CityGML via so called application domain extensions (ADE) like the energy ADE for exchanging energy related data.]
. Developer and domain expert create a first version of the data model as XML Schema Definition (our DSL).
. For plausibility checks any standard XML editor can be used to create example data conforming to the XSD.
. For plausibility checks use any standard XML editor to create example data conforming to the XSD.
. With JAXB, the Java Architecture for XML Binding, Java code is generated to read our XML catalogs into Java objects that, in turn, can be accessed by SimStadt workflows to generate and parameterize simulations.
. If required, developer and domain expert go back to step one to refine data model and catalog data
. If required, developer and domain expert go back to step one to refine data model and catalog data.
After the data model for building physics catalogs had matured, we developed an extra application for convenient creation and maintenance of building physics data catalogs separate from SimStadt.
It was developed in Java with a user interface written in JavaFX and was well received by domain expert users.
However, as a different catalog for building usages had to be created, it was quite difficult to reuse the XML schema and application code from the building physics catalog: The usage catalog data model was "pressed" into a form similar to the building physics catalog data model, and the UI code was "over-engineered" to accommodate both catalog's requirements.
However, as a different catalog -- this time for building usages -- had to be created, it was quite difficult to reuse the XML schema and application code from the building physics catalog: The usage catalog data model was "pressed" into a form similar to the building physics catalog data model, and the UI code was "over-engineered" to accommodate both catalog's requirements.
=== Low-Code-Development of Data Catalogs
......@@ -90,23 +90,32 @@ On the other hand, user interfaces and generation and parameterization of simula
Now, in 2020, several developments in different projects provide an opportunity to re-think the topic of data catalogs for simulations, namely:
. Plans for a new Urban Simulation Platform at Concordia University, Montreal
. New implementation of INSEL front-end based on the Eclipse application framework and Eclipse-Sirius diagram editors
. Enhancement of existing building physics and usage catalogs from SimStadt and their adaptation to new regions
. Plans for a new Urban Simulation Platform at Concordia University, Montreal.
. New implementation of INSEL user interface based on the Eclipse application framework and Eclipse-Sirius diagram editors.
. Enhancement of existing building physics and usage catalogs from SimStadt and their adaptation to new regions.
. Development of a new comprehensive catalog of electric systems components to be used in SimStadt as well as in Concordia's Urban Simulation Platform.
====
In what follows, the new technology stack used to implement (4) is documented in detail.
Plans are to use the same approach also for implementation of (3).
It uses four technologies to replace manual coding by code generation from models:
* _Ecore_ to model the catalog's data and generate Java classes and persistence layer from it.
* _EMF Forms_ for modeling and generating tables, forms and buttons to **c**reate, **r**ead, **u**pdate, and **d**elete data (CRUD).
* _E4_, the Eclipse way of modeling the application user interface itself, e.g. the placement and behavior of views, editors, toolbars, menus, and more.
* A template engine called _Handlebars_ to generate fully parameterized simulation models from textual templates without programming.
The new technology stack is rooted in the Eclipse application framework and eco-system.footnote:[A comparable, but completely different approach would be to combine several web applications and services via portal software in web browsers.]
Its main advantage is the possibility to implement CRUD (Create, Read, Update, Delete) applications like data catalogs and their underlying data models with no or very view lines of handwritten code (_low-code-development_).
Its main advantage is the possibility to implement CRUD applications like data catalogs and their underlying data models with no or very view lines of handwritten code (_low-code-development_).
====
Plans are to use the same approach also for implementation of (3).
Since task (2) and maybe (1) will use Eclipse, too, close integration of data catalogs and simulation environments seems feasible.
E.g., a user could drag an electric system component from a catalog onto an INSEL block for parametrization.
The Eclipse application framework offers:
* OSGI plug-in mechanism and UI framework for integrating applications and services
* _E4_ application model to declaratively describe user interface's structure
* General notion of _project_ with specific file types, help system, preferences etc.
* IDE support for important general purpose languages like Java, https://marketplace.eclipse.org/content/pydev-python-ide-eclipse[Python], Ruby, C, Fortran, C++
* Support for creating textual and graphical DSLs (https://www.eclipse.org/Xtext[XText], https://www.eclipse.org/sirius[Sirius])
......@@ -114,7 +123,7 @@ The Eclipse application framework offers:
* Industry proven DSLs and code generators for data models and form based UIs via the https://www.eclipse.org/modeling/emf[_Eclipse Modeling Framework_] (EMF) providing:
** https://www.eclipse.org/ecoretools[_Ecore_] for model driven generation of Java classes and persistence layers for XML or data bases
** https://eclipsesource.com/blogs/tutorials/emf-forms-view-model-elements[_EMF Forms_] for describing and generating form based UIs
** Mechanisms to adapt or extend data models and forms to special needs (e.g., we added a quantities -- that is numbers _with_ units -- to Ecore and EMF Forms, a feature very important for data catalogs)
** Mechanisms to adapt or extend data models and forms to special needs (e.g., we added quantities -- that is numbers _with_ units -- to Ecore and EMF Forms, a feature very important for data catalogs)
* Rich open source eco-system with lots of plugins and projects important for an urban simulation platform:
** model server for distributed access and work on Ecore models, including model comparison and migration (https://projects.eclipse.org/projects/modeling.emf.cdo[CDO], https://www.eclipse.org/emf/compare[EMFCompare])
......
Data Catalogs Documentation/DataCatalogs2Creation.adoc
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== How to Implement Data Catalogs with Eclipse
:imagesdir: DataCatalogs2Images
To build a new data catalog from scratch, we first have to understand some basics about Eclipse, and then install the correct Eclipse package and add some plug-ins to it.
To build a new data catalog from scratch, we first have to understand some basics about Eclipse, and then install the correct Eclipse package.
Thereafter, we can model our data with Ecore considering some best practices, followed by the generation of Java classes and user interface (UI).
Some hints on versioning data catalogs conclude this how-to-section.
We, then, will add some plug-ins to "pimp" our Eclipse installation, (a) to enable deployment of data catalog applications, and (b) to add units and quantities to the mix.
Some hints on special modeling problems and versioning data catalogs conclude this how-to guide.
=== Eclipse Basics
......@@ -15,6 +16,7 @@ Eclipse RCP is foundation of a plethora of general-purpose applications, too.
First time users of Eclipse better understand the following concepts.
.Eclipse Packages
An Eclipse package is an Eclipse distribution dedicated to a specific type of task.footnote:[The notion of an Eclipse package has nothing to do with Java packages.]
A list of packages is available at https://www.eclipse.org/downloads/packages/[eclipse.org].
Beside others it contains _Eclipse IDE for Java Developers_, _Eclipse IDE for Scientific Computing_, and the package we will use: _Eclipse Modeling Tools_.
......@@ -22,24 +24,27 @@ Note that third parties offer many other packages, e.g. _GAMA_ for multi-agent-s
[NOTE]
====
Several Eclipse packages can be installed side by side, even different releases of the same package. Multiple Eclipse installations can run at the same time, each on its own workspace (see below).
Several Eclipse packages can be installed side by side, even different releases of the same package. Multiple Eclipse installations can run at the same time, each on its own _workspace_ (see below).
====
.Plug-ins / Features
An installed Eclipse package consists of a runtime core and a bunch of additional plug-ins.
Technically, a plug-in is just a special kind of Java archive (JAR) that uses and can be used by other plug-ins with regard to OSGi specifications.
Technically, a plug-in is just a special kind of Java archive (JAR file) that uses and can be used by other plug-ins with regard to OSGi specifications.
Groups of plug-ins that belong together are called a _feature_.
Often, a user will add further plug-ins or features to an Eclipse installation to add new capabilities.
Often, a user will add plug-ins or features to an Eclipse installation to add new capabilities.
E.g. writing this documentation within my Eclipse IDE is facilitated by the plug-in https://marketplace.eclipse.org/content/asciidoctor-editor[Asciidoctor Editor].
Plug-ins can easily be installed via main menu command `Help → Eclipse Marketplace...`. Some plug-ins may be self-made like our plug-in `de.hftstuttgart.units` that enables Ecore to deal with quantities.
Plug-ins can easily be installed via main menu command `Help → Eclipse Marketplace...` or `Help → Install New Software...`.
Some plug-ins may be self-made like our plug-in `de.hftstuttgart.units` that enables Ecore to deal with quantities.
These may be provided via _Git_ or as download and have to be added to an Eclipse installation manually.
.Git
Today https://git-scm.com[Git] is the industry standard for collaborative work on, and versioning of, source code and any other kind of textual data. Collaborative development of data catalogs benefits massively from using Git, and Git support is built into _Eclipse Modeling Tools_, the Eclipse package we will use.
https://git-scm.com[Git] is the industry standard for collaborative work on, and versioning of, source code and any other kind of textual data. Collaborative development of data catalogs benefits massively from using Git, and Git support is built into _Eclipse Modeling Tools_, the Eclipse package we will use.
However, if Eclipse needs to connect to a Git server that uses SSH protocol (not HTTPS with password), access configuration is more involved and may be dependent on your operating system.
Some users, anyway, prefer to use Git from the command line or with on of the client application listed https://git-scm.com/downloads/guis[here], e.g. https://tortoisegit.org[TortoiseGit] for Windows.
Some users, anyway, prefer to use Git from the command line or with one of the client application listed https://git-scm.com/downloads/guis[here], e.g. https://tortoisegit.org[TortoiseGit] for Windows.
While it is required to get Git working at some point, we won't refer to it in this document and, for now, do not cover the installation of Git on your machine or configuration of Git in Eclipse.
......@@ -47,22 +52,25 @@ While it is required to get Git working at some point, we won't refer to it in t
When you start a new Eclipse installation for the first time, you are asked to designate a new directory in your file system to store an _Eclipse workspace_.
Eclipse is always running with exact one workspace open.
As the name implies, a workspace stores everything needed in a given context of work, that is a set of related projects the user is working on as well as meta-data like preference settings, the current status of projects, to do lists, and more. In case a user wants to work in different contexts, e.g. on different tasks, command `File -> Switch Workspace` allows to create additional workspaces and switch between them.
As the name implies, a workspace stores everything needed in a given context of work, that is a set of related projects the user is working on as well as meta-data like preference settings, the current status of projects, to do lists, and more.
In case a user wants to work in different contexts, e.g. on different tasks, command `File -> Switch Workspace` allows to create additional workspaces and to switch between them.
[NOTE]
====
Any plug-in from the original Eclipse package or installed by the user later will be copied into the Eclipse installation directory, *not* in any workspace. Configuration and current state of plug-ins, on the other hand, are stored in workspaces.
Any plug-in from the original Eclipse package or installed by the user later will be copied into the Eclipse installation directory, *not* in any workspace.
Configuration and current state of plug-ins, on the other hand, are stored in workspaces.
====
.Projects
An Eclipse project is a technical term for a directory that often contains:
* files of specific types for source code, scripts, XML files or other data
* build settings, configurations
* dependency definitions (remember the dependencies between plug-ins above?)
* other Eclipse projects
* other Eclipse projects.
Depending on the plug-ins installed, `File -> New -> Project...` offers many different types of projects that the user can choose from, e.g. Java projects to create Java programs, model projects to work with Ecore data models, or general projects, that simple hold some arbitrary files.footnote:[Projects possess one or more _natures_ used to define a project's principal type.]
Depending on the plug-ins installed, `File -> New -> Project...` offers many different types of projects that the user can choose from, e.g. Java projects to create Java programs, Ecore modeling projects, or general projects, that simple hold some arbitrary files.footnote:[Projects possess one or more _natures_ used to define a project's principal type.]
[WARNING]
====
......@@ -83,11 +91,14 @@ That way, we can follow the convention that local Git repositories should all be
.Install Java
As a Java application, Eclipse runs on 64-bit versions of Windows, Linux, and macOS and requires a 64-bit Java runtime, version 1.8 (aka version 8) or higher, to be installed on your machine.
If not already there, download the latest version of OpenJDK (currently 14) for your operating system from https://adoptopenjdk.net[AdoptOpenJDK].footnote:[AdoptOpenJDK recently joined the Eclipse founation and soon will change its name to _Adoptium_ for legal reasons.]
As a Java IDE, Eclipse runs on 64-bit versions of Windows, Linux, and macOS and requires an according Java Development Kit (JDK), version 1.8 (aka version 8) or higher, to be installed on your machine.
If no such JDK already exists, please download version *11* of OpenJDK for your operating system from https://adoptopenjdk.net[AdoptOpenJDK].
footnote:[AdoptOpenJDK recently joined the Eclipse foundation and soon will change its name to _Adoptium_ for legal reasons.]
Choose `HotSpot` as Java Virtual Machine.
Installation process is straight forward, but you can also find links to exhaustive instructions for your operating system. Note that different versions of Java can peacefully coexist.
New Java versions appear every six months, so the actual version at the time of writing is 14. Since we stick with an older Eclipse version (see below), install version 11 as advertised! Also, this one is the latest LTE version (long time support).
.Install Eclipse Modeling Tools
Now its time to download and install the correct Eclipse package.
......@@ -107,7 +118,7 @@ To do so, click the link depicted by the red arrow below.
.Eclipse packages download page with links to older releases
image::EclipseDownloadPage1.gif[EclipseDownloadPage1, role="thumb"]
A similar download page for all the packages appears but this time for version `2019-12`. Now look for package _Eclipse Modeling Tools_ and follow the link of your operating system on the right:
A similar download page for all the packages appears, but this time for version `2019-12`. Now look for package _Eclipse Modeling Tools_ and follow the link for your operating system on the right:
.Download links for Eclipse Modeling Tools package
image::EclipseDownloadPage2.gif[EclipseDownloadPage2, role="thumb"]
......@@ -115,7 +126,6 @@ image::EclipseDownloadPage2.gif[EclipseDownloadPage2, role="thumb"]
Finally, you can click on `Download` and wait for the 400 something MB package to arrive.
[NOTE]
====
Depending on the operating system, several security dialogs have to be acknowledged during installation and first launch of Eclipse.
====
......@@ -123,12 +133,12 @@ Depending on the operating system, several security dialogs have to be acknowled
The downloaded installation file contains the application simply named `Eclipse` ready to be copied into `Applications` on macOS or be installed in `Programs` on Windows.
Since you may add other Eclipse packages later, I suggest to rename the application to something more significant like `EclipseModeling`.
After installation has finished launch Eclipse for the first time and see the dialog for choosing a new empty directory as its workspace pop up.
After installation has finished launch Eclipse for the first time and you will see the dialog for choosing a new empty directory as its workspace pop up.
.Initial Dialog to Choose a Workspace Directory
image::SelectWorkspaceDirectory.gif[SelectWorkspaceDirectory, 500, role="thumb"]
Again, more workspaces might come into existence later, so replace the proposed generic directory name with a more specific one, e.g.`EclipseModelingWS`.
Again, more workspaces might come into existence later, so replace the proposed generic directory path and name with a more specific one, e.g.`EclipseModelingWS`.
The Eclipse main window appears with a Welcome Screen open.
It contains links to exhaustive documentation on concept, features and usage of Eclipse that might be of interest later, especially:
......@@ -144,31 +154,44 @@ It contains links to exhaustive documentation on concept, features and usage of
For now, you can dismiss the welcome screen. It can be opened anytime by executing `Help -> Welcome`
.Add Support for Units and Quantities
=== Modeling Data Catalogs for Simulation with Ecore
Now you should see the initial layout of Eclipse with _Model Explorer_ and _Outline_ on the left and a big empty editing area with _Properties_ view below to the right.
As mentioned before, data catalogs for simulations should be able to represent quantities, not just bare integer and real numbers.
To this end, the author has created two Eclipse plug-in projects providing this feature to be used by Ecore and EMF Forms later.
Since we will use Ecore diagrams for data modeling, create your first Ecore modeling project now:
Currently, the projects are not distributed as plug-ins.
Instead, we compile them from source code, simply by importing the projects.
These two projects will be the first to populate the yet empty workspace:
. Execute `File -> New -> Ecore Modeling Project` from main menu -- not `Modeling Project`!
. Name it `project.first` and click `Next >`
. Uncheck `Use Default Location` so that the new project is *not* stored in the workspace, but a different directory you choose, then click `Next >`
. Provide `datacatalog` as main Java package name and click `Finish`.
. Copy to file system ...
. Import project but *not* copying it in the workspace (just linking)
Eclipse should look like below with an new empty graphical Ecore diagram editor opened.
The diagram is automatically named `datacatalog` after the package name for the Java classes that will be generated from it (provided above).
The _Model Explorer_ shows the contents of the new Ecore modeling project.
Text
=== Modeling Data Catalogs for Simulation with Ecore
.New Ecore Modeling Project
image::ProjectFirst1.png[ProjectFirst1, role="thumb"]
Now domain experts can start modeling the data that the projected catalog shall contain.
To get your feet wet, do this:
. Drag a _Class_ from the palette on the right onto the editor's canvas: it will materialize as a rectangle labeled `NewEClass1`.
. The class symbol was selected initially, so you can see its attributes in the _Properties_ view.
. In there replace `NewEClass1` by `EnergyComponentsCatalog` to rename the class.
. Click anywhere on the canvas and notice that the class symbol is deselected and the toolbar at the top adapts accordingly.
. In the toolbar change `100%` to `75%` to scale the diagram
. Execute `File -> Save` and model and diagram are saved.
. Close diagram editor `datacatalog` by closing its tab.
. Reopen saved diagram by double click on entry `datacatalog` in the _Model Explorer_.
Technically, everything is in place now to begin modeling the data that the projected catalog shall contain.
Except ... understanding the basics of object-oriented modeling would be helpful.
This is why developers should support domain experts at this stage.
.Model Data with Class Diagrams
We will use Ecore diagramsfor data modeling below.
Ecore diagrams are simplified UML class diagrams.
Here some resources about what this is all about:
Here some resources on what this is all about:
* http://www.cs.toronto.edu/~sme/CSC340F/slides/11-objects.pdf[Toronto Lecture on Object Oriented Modeling]
* http://agilemodeling.com/artifacts/classDiagram.htm[UML 2 Class Diagrams: An Agile Introduction]
......@@ -176,47 +199,362 @@ Here some resources about what this is all about:
[TIP]
====
Beginners are strongly encouraged to read the first two resources. The first one contains a gentle introduction, especially suited for domain experts. The second one also serves as a reference.
Beginners are strongly encouraged to read the first two resources. The first one contains a gentle introduction, especially suited for domain experts. The second one can also serve as reference.
====
We will touch central object oriented concepts _Class_, _Object_, _Attribute_, _Association_, _Composition_, and _Multiplicity_ in an example below, but work through above sources to get a deeper understanding and enhance your modeling skills.
Note that the sources differentiate between _conceptual_ and _detailed_ models.
In principle we go for detailed models, since only these contain enough information to generate code.
Having said this, it is usually a good idea to have two or three conceptual iterations at a white board to agree on the broad approach before going too much into detail.
But even if one starts with Ecore models right away, these also can be adapted any time to follow a new train of thought.
See here the essential and typical structure of a data catalog in a class diagram.
Instead of artificial example classes like _Foo_ and _Bar_ it shows classes from an existing catalog, albeit in a very condensed form.
.Principle Structure of a Data Catalog
[plantuml, role="thumb"]
----
together {
class SolarPanel
class Inverter
}
class EnergyComponentsCatalog {
author: String
}
abstract class EnergyComponent {
modelName: String
revisionYear: int
}
abstract class ChemicalEnergyDevice {
installedThermalPower: double
}
class Boiler {
type : BoilerType
}
class CombinedHeatPower {
thermalEfficiency : double
electricalEfficiency : double
}
class Manufacturer {
name : String
}
enum BoilerType {
LowTemperature
Condensing
}
class SolarPanel {
nominalPower : double
mppVoltage : double
mppCurrent : double
}
class Inverter {
nominalPower : double
maxDCVoltage : double
maxDCCurrent : double
}
BoilerType -[hidden]- Boiler
SolarPanel --|> EnergyComponent
Inverter --|> EnergyComponent
ChemicalEnergyDevice --|> EnergyComponent
Boiler --|> ChemicalEnergyDevice
CombinedHeatPower --|> ChemicalEnergyDevice
EnergyComponentsCatalog *-- "0..*" Inverter: inverters
EnergyComponentsCatalog *-- "0..*" SolarPanel: solarPanels
EnergyComponentsCatalog *-- "0..*" Boiler: boilers
EnergyComponentsCatalog *-- "0..*" CombinedHeatPower: chps
EnergyComponentsCatalog *-- "0..*" Manufacturer: manufacturers
EnergyComponent -up-> "1..1" Manufacturer: producedBy
----
The diagram models four types of technical components whose data shall be stored in the catalog for later use, e.g. for parameterization of simulation models: _Boiler_, _CombinedHeatPower_, _SolarPanel_, and _Inverter_.
The catalog itself is represented by class _EnergyComponentsCatalog_.
Unlike dozens, hundreds, or even thousands of objects to be cataloged -- Boilers, Inverters etc. -- there will be just exactly *one* catalog object in the data representing the catalog itself.
Its "singularity" is not visible in the class diagram, but an _Ecore_ convention requires that all objects must form a composition hierarchy with only one root object.
.Composition
If, in the domain, one object is composed of others, this is expressed by a special kind of association called _composition_.
Compositions are depicted as a link with a diamond shape attached to the containing object. In the _Boiler_ case said link translates to: The _EnergyComponentsCatalog_ contains -- or is composed of -- zero or more (`0..*`) boiler objects stored in a list named `boilers`.
[IMPORTANT]
====
Note that class names -- despite the fact that they model a set of similar objects -- are always written in _singular_! They are written in https://en.wikipedia.org/wiki/Camel_case[Camel case notation] starting with an upper case letter. Associations and attributes are written the same way, but starting with a lower case letter. Names for list-like associations and attributes usually are written in plural form.
====
In what follows, a principle understanding of concepts _Class_, _Object_, _Attribute_, _Association_, _Composition_, and _Multiplicity_ is taken for granted.
.Inheritance
Besides composition of *objects*, the model above shows another completely different kind of hierarchy: the inheritance hierarchy between *classes*.
Whenever classes of objects share the same attributes or associations, we don't like to repeat ourselves by adding that attribute or relation to all classes again and again.
Instead, we create a _super class_ to define common attributes and associations and connect it to _sub classes_ that will automatically _inherit_ all the features of their super class.
Note that the sources above differenciate between conceptual and detailed models. While the first work very well on a white board, the latter can be used for code generation.
In our example above, common to all four energy components are attributes `modelName` and `revisionYear`, thus these are modeled by class `EnergyComponent` that is directly or indirectly a super class of _Boiler_, _CombinedHeatPower_, _SolarPanel_, and _Inverter_.
Similar, _Boiler_ and _CombinedHeatPower_ share attribute `installedThermalPower` factored out by class _ChemicalEnergyDevice_.
.Principle Structure
<Use PlantUML?>
.Associations
You probably noticed a fifth type of objects contained in the catalog, namely `Manufacturer` objects stored in list `manufactureres`.
How come? Ok, here is the story:
Hierarchic, main catalog with several lists of objects of the same type using attributes, primitive types, references and enums
.Domain Expert Meets Developer
****
_Exp_: "`I'd like to store a component's manufacturer. Shall I add a String attribute `manufacturerName` to all classes like _Boiler_, _Inverter_ and so on to store the manufacturer's name?`"
Ids?
_Dev_ shudders: "`Well, what do you mean by "... and so on"?`"
.Add Units to the Mix
_Exp_: "`Basically, I mean all energy components.`"
using Indrya, the reference implementation for Units of Measurement in Java (JSR 385)
_Dev_: "`Fine. We already have a class representing all those energy components, brilliantly named _EnergyComponent_. Thus, we can define `manfacturerName` there, following one of Developer's holy principles: "_DRY_ -- Don't repeat yourself!"
By the way: Is the name all you want to know about manufacturers?`"
.Represent (Parameterized) Functions:
_Exp_: "`Mhm, maybe we need to know if they are still in business ...`"
Text
_Dev_: "`... or even since when they were out of business, if at all ...`"
.Derived References and Attributes
_Exp_: "`... and the country or region they are active.`"
There are no derived references or attributes by now. But if one has to implement some by providing a getter, it is necessary to return an unmodifiable list like BasicEList.UnmodifiableEList or EcoreUtil.unmodifiableList(...) instead of EList as described here: https://www.ntnu.no/wiki/plugins/servlet/mobile?contentId=112269388#content/view/112269388 .
_Dev_: "`Ok, so it's not just the name -- we need a class `Manufacturer` to model all these information.`"
_Exp_ sighs.
=== Generation of Java code and persistence layer
_Dev_: "`Come on, its not that hard to add a class to our data model, isn't it?`"
Custom code marked with `@generated NOT` in `de.hftstuttgart.energycomponents.provider` in project `de.hftstuttgart.energycomponents.edit`
_Exp_: "`Ok, but how can we express what components a manufacturer produces?`"
_Dev_: "`Wasn't it the other way around? I thought, you just wanted to know the manufacturer of a component?`"
_Exp_: "`What is the difference?`"
_Dev_: "`In data modeling, it is the difference between a uni-directional and a bi-directional association.`"
_Exp_: "`...?`"
_Dev_: "`Let's put it that way: The difference between a link with an arrow on one side or on both sides.`"
_Exp_: "`Ok. We don't need a list of components per manufacturer, but simply a reference from the component to its manufacturer.`"
_Dev_: "`Fine, then in Ecore please create a simple reference from class `EnergyComponent` to class `Manufacturer`, maybe named `producedBy`.`"
_Exp_: "`I will try this and get back to you.`"
_Dev_: "`Fine ... good meeting.`"
****
Observe in our data model, reference `producedBy` points _from_ `EnergyComponent` _to_ `Manufacturer` making it uni-directional reference.
One can simply query the manufacturer of a product, but not so the other way around.
With a bi-directional reference both queries would be available.
Observe also the annotations `0..*` and `1..1` near class `Manufacturer`.
These are _multiplicities_ of associations: An `EnergyComponentsCatalog` contains zero, one, or many objects of class `Manufacturer` and an `EnergyComponent` must reference exactly one manufacturer -- not less, not more.
[.float-group]
--
.Ecore Relations
image::EcoreRelations.gif[EcoreRelations, 200, float="right", role="thumb"]
To recapitulate: Our example data catalog already exhibits all four types of relations provided by Ecore.
You find these in the Ecore editor's palette shown here.
To create a relation between a sub class and a super class use tool `SuperType`.
Use the other tools to create an association between classes, may it be a simple (uni-directional) reference, a bi-directional reference, or a composition.
--
.Attributes and Enumerations
Obviously, attributes are central in data modeling.
Create one by dragging it from the palette onto our one and only class so far: `EnergyComponentsCatalog`.
The class symbol will turn red to indicate an error.
Hover with the mouse pointer over the new attribute and a tooltip with a more or less helpful error message will appear.
The error is caused in that no data type was set for the new attribute.
Data types for attributes can be integer or float numbers, strings, dates, booleans, and more.
To get rid of the error:
. If not already selected, select new attribute by clicking at it in the editor.
. In view _Properties_ find `EType` and click button `...` to see a quite long list of available data types.
. Choose `EString [java.lang:String]` from the list and the error is gone.
[.float-group]
--
.Class with Attribute
image::EcoreClassWithAttribute.png[EcoreClassWithAttribute, 200, float="right", role="thumb"]
Change the attribute's name to `author` and the class should look like shown here.
Most data types to choose from begin with an *E* like in **E**core. These are simply Ecore enabled variants of the respective Java types, thus, choose EInt for an int, EFloat for a 32 bit floating point number, EDouble for a 64 bit one, and so on.
Ecore allows to introduce new data types. We employ this feature later to enable data model with physical units and quantities.
--
There exists one other means to define the values an attribute can take, namely enumerations of distinct names. Take _Monday_, _Tuesday_, _Wednesday_, ... as a typical example for representing weekdays.
In our example data model you'll find one _Enumeration_ named `BoilerType` with values `LowTemperature` and `Condensing`.
.Homework
The next section deals with generation of Java code from data models. To have more to play with, please implement our example model in Ecore now.
[.float-group]
--
.Abstract Class
image::EcoreClassifier.png[EcoreClassifier, 200, float="right", role="thumb"]
To do this, there is one more thing to know about classes: the difference between ordinary classes and abstract classes.
'Ordinary class' doesn't sound nice, therefore, classes that are not abstract are called _concrete_ classes.
Our example diagram depicts abstract classes with letter *A* while concrete classes are labeled with *C*. You add abstract classes to a model with a special palette tool shown here.
The thing is: Objects can be created for concrete classes only!
In our example, it makes no sense to create an object from class _EnergyComponent_, because there is not such a thing like an energy component _per se_.
Therefore, this class is _abstract_.
It is true that an inverter _is_ an energy component, thus inheriting all its features, but it was _created_ as _Inverter_, not as _EnergyComponent_.
Super classes will be abstract most of the time.
So my advice is: Model a super class as abstract class unless you convince yourself that there are real objects in the domain that belong to the super class but, at the same time, do not belong to any of its sub classes.
In the Ecore editor properties view, you can specify if a class is abstract or not, simply by toggling check box `Abstract`.
--
[TIP]
====
An exhaustive user manual for Ecore diagram editor is available. Execute `Help -> Welcome` and follow link `Learn how to use the diagram editor`.
====
[TIP]
====
If Ecore models get bigger, you may find it more convenient to work with a form based UI instead of, or in addition to, the diagram editor.
Open this kind of editor via command `Open With -> Ecore Editor` from the context menu over entry `datacatalog.ecore` in the _Model Explorer_ view.
Note that Eclipse synchronizes different editors of the same content automatically.
====
=== Generation of Java Code from Data Model
TBD
Let us bring the data model to life, that is, generate program code from it that can be used to create, edit and delete concrete data objects of the classes modeled in computers.
I would like to tell you that this is done with one click but, actually, you need two or three:
. Make sure, all files are saved by ..
. Open the context menu of Ecore editor showing the model and perform `Gerenerate -> Model Code`
. `Gerenerate -> Edit Code` (Do not execute `Gerenerate ->Editor Code` -- we do not need this).
.Development Cycle
Creation -- Recreation
Custom code marked with `@generated NOT` in `de.hftstuttgart.energycomponents.provider` in project `de.hftstuttgart.energycomponents.edit`
=== Generation and Tweaking of UI
If there are many types of entities, their tables may be ordered hierarchical in the user interface to simplify user access. Probably, this hierarchy will be different from aggregation and inheritance hierarchies present in the Ecore model. We get to this later when we create a UI model for the data catalog.
Table columns sequence and width.
for creating custom UI labels:
* `ExponentialFunctionItemProvider.java`
* `LinearFunctionItemProvider.java`
* `TableFunctionItemProvider.java`
=== Run and Deploy the Demo Data Catalog Application
.Run from Eclipse IDE
TBD
.Install Maven Support
We are going to create a complete Eclipse desktop application from generated code.
We also want to deploy this application for Linux, macOS and Windows operating systems.
Eclipse offers several approaches for compiling and deploying such an application, traditionally with _Ant_ scripts.
Creation and maintenance of these scripts turned out to be tedious and error prone.
For quite some years now, the proposed -- and mostly supported -- method for building Eclipse applications is to use _Maven_ build system, more specifically, a couple of Maven plug-ins, subsumed under the name _Tycho_.
Many Eclipse platforms have Maven support https://www.eclipse.org/m2e/[_M2Eclipse_] already built in, not so our _Eclipse Modeling Tools_.
But don't worry: Installation of required Eclipse feature is easy and straight forward.
And, by the way, you will acquire the indispensable skill of how to install new plug-ins/features to Eclipse.
First, tell your Eclipse installation where to look for the new software.
Execute `Help -> Install new Software...` to invoke dialog _Available Software_ and press `Add...`.
Sub-dialog `Add Repository` pops up.
.Add update site m2e
image::InstallMaven1.gif[InstallMaven1, role="thumb"]
In there provide `m2e` as name and
http://download.eclipse.org/technology/m2e/releases
as location.
After confirmation with `Add`, Eclipse now looks up the site for available software.
.Choose features to install
image::InstallMaven2.gif[InstallMaven2, role="thumb"]
Check the items to install like shown above and confirm all following questions about licenses and security concerns.
After download is complete -- it can take a few minutes -- restart Eclipse.
Verify that Maven version 3.6.3 or above is now installed in `Window -> Preferences...` (or `Eclipse -> Preferences...` on macOS) under `Maven -> Installations`.
.Check Maven installation
image::InstallMaven3.gif[InstallMaven3, 400, role="thumb"]
."Mavenize" our Projects for Deployment
*TBD*
=== Add Units to the Mix
*TBD*
As mentioned earlier, data catalogs for simulations should be able to represent quantities, not just bare integer and real numbers.
using Indrya, the reference implementation for Units of Measurement in Java (JSR 385)
To this end, the author has created two Eclipse plug-in projects providing this feature to be used by Ecore and EMF Forms.
Third-party libraries like Indrya, usually, are not distributed as plug-ins, but _Tycho_ can wrap them automatically as OSGi plug-ins that can added directly to our application.
Another plug-in, created by the author connects the Ecore and Indrya. We will compile it from source code, simply by importing the projects.
. Copy to file system ...
. Import project but *not* copying it in the workspace (just linking)
=== Ecore Solutions for Specific Modeling Problems
. How to Represent Parameterized Functions
*TBD*
. How to Model Derived References and Attributes
*TBD*
We haven't used derived references or attributes by now. But if one has to implement some by providing a getter, it is necessary to return an unmodifiable list like BasicEList.UnmodifiableEList or EcoreUtil.unmodifiableList(...) instead of EList as described here: https://www.ntnu.no/wiki/plugins/servlet/mobile?contentId=112269388#content/view/112269388 .
=== Versioning and Collaboration
Text
*TBD*
=== Summary
*TBD*
Three hierarchies: Composition of objects, Inheritance of classes, Trees in user interface.
Data Catalogs Documentation/DataCatalogs3Usage.adoc
View file @ 9013a8b6
== Accessing and Using Data Catalogs
=== Accessing XML-Catalogs
Add JAR file or plugin with Ecore data model
Load an XML catalog and access corresponding Java-Objects in code
.Add Ecore data model to a third-party Java application
TBD: Access from Python?
*TBD*
=== Java template engine Handlebars for creating Insel models in SimStadt
Parameterization of blocks
.Load XML Data Catalog and Access Corresponding Java Objects in Code
*TBD*
.Access from Python?
*TBD*
=== Create Insel Models with Handlebars Templates
Handlebar templates to access data catalogs and create/parameterize textual simulation models.
.Parameterization of blocks
*TBD*
Creation of submodels, e.g. for parameterized functions
Access of catalogs / Integration into simulation models:
.Creation of submodels, e.g. computing parameterized functions
*TBD*
* Template Engine Handlebars to access catalogs and create/parameterize textual simulation models
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