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Data Management with JavaFX and GraniteDS

11.30.2012
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JavaFX 2 is a new but very appealing technology for building client enterprise applications. Even more appealing that it is already bundled in the JRE since Java 1.7.0_07.

Following the release of GraniteDS for JavaFX 2, here is the version of the data management tutorial for JavaFX. What we call data management is a set of features that allow to work easily with data objects on the client and simplify the plumbing between client and server.

The project is hosted on GitHub at https://github.com/graniteds/shop-admin-javafx and requires Maven 3.x for building. It is also required to use a JDK 1.7.0_07 or better so JavaFX is already installed on your Java runtime. You may have to change your JAVA_HOME environment variable if you have many JDK installed.

It may be useful to follow the tutorial that you have an Eclipse installation, ideally with the Git and M2E plugins installed (to automatically update Maven dependencies). Spring Tool Suite is a good choice, all the more that we are going to use the Spring framework on both the server and the client.

For the impatient, you can simply clone the project and build it.

From a console, type the following:

git clone git://github.com/graniteds/shop-admin-javafx.git 
cd shop-admin-javafx 
mvn install

To start the embedded Jetty server, type this:

cd webapp
mvn jetty:run

To start the JavaFX client application, open a second console and type the following:

cd shop-admin-javafx/javafx
java -jar target/shop-admin-javafx.jar

When the application shows up, just logon as admin/admin. It’s a simple CRUD example which allows creating and modifying and searching for vineyards and the wines they produce.

The application has no fancy design and graphics but its goal is simply to demonstrate the following features :

  • Basic CRUD with a Spring Data JPA repository
  • Support for lazy-loading of JPA x-to-many associations
  • Dirty-checking / Undo
  • Client validation with Bean Validation API integration
  • Security (authentication, authorization)
  • Real-time data push

For the sake of simplicity, this tutorial has a few known limitations:

  • The search is case-sensitive
  • Validation errors are displayed as simple red borders without the corresponding message
  • The 'Save' button is incorrectly enabled when something is typed in the search input

Each step in the tutorial corresponds to a tag on the GitHub project so you can easily see what has been changed at each step.

So now let's start from scratch :

Step 1 : Create the Project from the Maven Archetype

If you have cloned the project from GitHub, just do this:

git checkout step1

This first step has been simply created by issuing the following command:

mvn archetype:generate
-DarchetypeGroupId=org.graniteds.archetypes
-DarchetypeArtifactId=org.graniteds-tide-spring-jpa
-DarchetypeVersion=2.0.0.M1
-DgroupId=com.wineshop
-DartifactId=shop-admin-javafx
-Dversion=1.0-SNAPSHOT
-Dpackage=com.wineshop

If you look at the result, the archetype has created a Maven project with three modules:

  • A Spring server module
  • A Webapp module
  • A JavaFX client module

The Spring server module generated by the archetype includes a suitable persistence.xml JPA descriptor and a basic domain model and service (Welcome + WelcomeService).

The Webapp module includes the necessary Spring configuration for JPA with a simple HSQL datasource, Spring Security and GraniteDS. It also includes a web.xml configured with a Spring dispatcher servlet, and GraniteDS Comet and WebSocket configurations for Jetty 8. The pom.xml of this module also includes the necessary configuration to run an embedded Jetty 8.

Finally the JavaFX module includes a pom.xml with the configuration to generate JavaFX client model from the JPA model with the GraniteDS gfx Ant task, and to package the application as an executable jar. It also includes a skeleton JavaFX client application with the necessary Spring and GraniteDS configurations.

The generated default application is basically a slighly improved Hello World where the names that are sent are stored in the database and pushed to all clients.

You can check the push by running many JavaFX clients simultaneously.

To start the embedded Jetty server, type this:

cd webapp
mvn jetty:run

To start a JavaFX client application, open another console and type the following:

cd shop-admin-javafx/javafx
java -jar target/shop-admin-javafx.jar

You can log in with admin/admin or user/user.

Before continuing, we will just remove some of this initially generated stuff from the project and eclipsify it.

The tag step1b contains a cleaned up version of the project that you can import in Eclipse (actually you will get 4 projects).

git checkout step1b

Step 2 : Implement Basic CRUD Functionality

This will be the longest step as we are now going to create most of the application.

The Server Application

First we have to build the server application. For convenience and because this is not a server tutorial, we are going to use the new support for Spring Data JPA repositories, and simply define a JPA model.

com/wineshop/entities/Vineyard.java:

@Entity
public class Vineyard extends AbstractEntity {
    private static final long serialVersionUID = 1L;
    @Basic
    private String name;
    @Embedded
    private Address address = new Address();
    @OneToMany(cascade=CascadeType.ALL, mappedBy="vineyard",
        orphanRemoval=true)
    private Set wines;
    public String getName() {
        return name;
    }
    public void setName(String nom) {
        this.name = nom;
    }
    public Address getAddress() {
        return address;
    }
    public void setAddress(Address address) {
        this.address = address;
    }
    public Set getWines() {
        return wines;
    }
    public void setWines(Set wines) {
        this.wines = wines;
    }
}

com/wineshop/entities/Wine.java:

@Entity
public class Wine extends AbstractEntity {
    private static final long serialVersionUID = 1L;
    public static enum Type {
        RED,
        WHITE,
        ROSE
    }
    @ManyToOne
    private Vineyard vineyard;
    @Basic
    private String name;
    @Basic
    private Integer year;
    @Enumerated(EnumType.STRING)
    private Type type;
    public Vineyard getVineyard() {
        return vineyard;
    }
    public void setVineyard(Vineyard vineyard) {
        this.vineyard = vineyard;
    }
    public Integer getYear() {
        return year;
    }
    public void setYear(Integer annee) {
        this.year = annee;
    }
    public String getName() {
        return name;
    }
    public void setName(String nom) {
        this.name = nom;
    }
    public Type getType() {
        return type;
    }
    public void setType(Type type) {
        this.type = type;
    }
}

com/wineshop/entities/Address.java:

@Embeddable
public class Address implements Serializable {
    private static final long serialVersionUID = 1L;
    @Basic
    private String address;
    public String getAddress() {
        return address;
    }
    public void setAddress(String adresse) {
        this.address = adresse;
    }
}

Note that our entities extend the AbstractEntity class provided by the archetype.  AbstractEntity simply has a Long id, a Long version field and a uid field.  We will mostly replace it by AbstractPersistable from Spring Data but we have to keep it because of the uid property.  The uid field is a global persistent identifier that is to be unique among all client and server layers, and is thus persisted in the database (but not necessarily a database key).  The GraniteDS data management framework can work without a specific uid field but with some restrictions (see the documentation for further explanation).

Next we are going to define the Spring Data repository, but first we have to add Spring Data in our dependencies in java/pom.xml.

<dependency>
  <groupId>org.springframework.data</groupId>
  <artifactId>spring-data-jpa</artifactId>
  <version>1.2.0.RELEASE</version>
</dependency>

We then change AbstractEntity so it extends AbstractPersistable (not necessary useful but more Spring Data-esque):

@MappedSuperclass
@EntityListeners({AbstractEntity.AbstractEntityListener.class, DataPublishListener.class})
public abstract class AbstractEntity extends AbstractPersistable {
    private static final long serialVersionUID = 1L;
  
    /* "UUID" and "UID" are Oracle reserved keywords -> "ENTITY_UID" */
    @Column(name="ENTITY_UID", unique=true, nullable=false, updatable=false, length=36)
    private String uid;
  
    @Version
    private Integer version;
  
    public Integer getVersion() {
        return version;
    }
  
    @Override
    public boolean equals(Object o) {
        return (o == this || (o instanceof AbstractEntity
            && uid().equals(((AbstractEntity)o).uid())));
    }
  
    @Override
    public int hashCode() {
        return uid().hashCode();
    }
  
    public static class AbstractEntityListener {
        @PrePersist
        public void onPrePersist(AbstractEntity abstractEntity) {
            abstractEntity.uid();
        }
    }
  
    private String uid() {
        if (uid == null)
            uid = UUID.randomUUID().toString();
        return uid;
    }
}

And define the repository interface :

com/wineshop/services/VineyardRepository.java

@RemoteDestination
@DataEnabled
public interface VineyardRepository extends FilterableJpaRepository {
}

As you can see, this repository extends the GraniteDS-specific FilterableJpaRepository  which is an extension of the default Spring JpaRepository that adds an extra finder method, findByFilter. This findByFilter is a kind of find by example implementation.  This is just for convenience and you can implement manually your own finder method if you don't want to rely on GraniteDS on the server (we might also consider contributing this code to Spring Data JPA or ditch it completely if Spring Data comes with something similar in a future release).

The @RemoteDestination annotation indicates that the repository is remote-enabled, that is will be accessible from our GraniteDS client. In general this is not what you would do for obvious security reasons (and for example create a Service in front of the repository) but we want to keep it simple here.

The @DataEnabled annotation indicates that GraniteDS should track JPA data updates happening during the execution of the service methods and propagate them to the client.

Finally we register our repository in webapp/src/main/webapp/WEB-INF/spring/app-jpa-config.xml:

<jpa:repositories
    base-package="com.wineshop.services"
    factory-class="org.granite.tide.spring.data.FilterableJpaRepositoryFactoryBean"/>

There is a tag step2a on the git project so you can see what has been changed since step 1.

git checkout step2a

Here the compare view on GitHub: https://github.com/graniteds/shop-admin-javafx/compare/step1b...step2a

Now you can rebuild and restart the Jetty server:

mvn install
cd webapp
mvn jetty:run

You may have noticed that the gfx generator is ran as part of the maven build.  If you have a look at the JavaFX module, you can see some newly generated classes for the client entities and a client proxy for the Spring Data repository,  in the packages com.wineshop.client.entities and com.wineshop.client.services.  That will be useful for the next part, that is developing the client.

The JavaFX Client

Now the most interesting part, the JavaFX client. To simplify things, we are going to keep some elements of the skeleton application, the Main and the Login screen.  We are mostly going to work on the Home.fxml screen and Home.java controller.

Our UI will be very basic, a table view to display the list of vineyards, and a form to create or modify them.

The Table View

First we add the table, here is the relevant part of Home.fxml:

<!-- Search Bar -->
<HBox spacing="10">
    <children>
        <TextField fx:id="fieldSearch" prefColumnCount="20"
            onAction="#search"/>
        <Button text="Search" onAction="#search"/>
    </children>
</HBox>




<TableView fx:id="tableVineyards" layoutX="10" layoutY="40"
    items="$vineyards">
    <columns>
        <TableColumn fx:id="columnName" text="Name" 
            prefWidth="320" sortable="true">
            <cellValueFactory>
                <PropertyValueFactory property="name"/>
            </cellValueFactory>
        </TableColumn> 
    </columns>
</TableView>

Nothing very fancy, we simply define a table view control with a single column mapped to the name property of our Vineyard entity, and a search bar with a search field and a search button.

The data source for the table view is defined as $vineyards, that would usually mean that we have to bind it to a collection in the controller.  If you look at the Main class coming from the archetype, it uses the custom TideFXMLLoader that automatically exposes all beans in the Spring context as FXML variables.  So we create a Spring bean named vineyards in the application configuration in Main.java:

@Bean
public PagedQuery vineyards(ServerSession serverSession) throws Exception {
    PagedQuery vineyards = new PagedQuery(serverSession);
    vineyards.setMethodName("findByFilter");
    vineyards.setMaxResults(25);
    vineyards.setRemoteComponentClass(VineyardRepository.class);
    vineyards.setElementClass(Vineyard.class);
    vineyards.setFilterClass(Vineyard.class);
    return vineyards;
}

We use the GraniteDS PagedQuery component which wires a client observable list (itself) to a server finder method, here the findByFilter method of the Spring Data repository.  This component also handles paging automatically so we can define a maxResults property which defines the maximum number of elements that will be retrieved from the server at each remote call. PagedQuery also handles remote filtering and sorting, so we next have to wire it to the view in the Home.java controller initialization:

@Inject
private PagedQuery vineyards;
The PagedQuery is a Spring bean, the Home controller too, so we can inject one into the other as needed.
@Override
public void initialize(URL url, ResourceBundle rb) {
    vineyards.getFilter().nameProperty().bindBidirectional(fieldSearch.textProperty());
    vineyards.setSort(new TableViewSort(tableVineyards, Vineyard.class));
    ...
}

These declarations bind the filter name property to the search field and define the sort adapter between the TableView control and the PagedQuery component. Finally we define the search action on the controller, it just has to call the method refresh on the PagedQuery component that will trigger a remote call to get an up-to-date dataset:

@FXML
private void search(ActionEvent event) {
    vineyards.refresh();
}

With this quite simple setup, we have a fully functional table view on our remote Vineyard entity.

The Edit Form

Here is the form description in Home.fxml:

<Label fx:id="labelFormVineyard" text="Create vineyard"/>
<GridPane fx:id="formVineyard" hgap="4" vgap="4">
    <children>
        <Label text="Name" 
            GridPane.columnIndex="1" GridPane.rowIndex="1"/>
        <TextField fx:id="fieldName" 
            GridPane.columnIndex="2" GridPane.rowIndex="1"/>
       
        <Label text="Address" 
            GridPane.columnIndex="1" GridPane.rowIndex="2"/>
        <TextField fx:id="fieldAddress" 
            GridPane.columnIndex="2" GridPane.rowIndex="2"/>
    </children>
</GridPane>
<!-- Button Bar -->
<HBox spacing="10">
    <children>
        <Button fx:id="buttonSave" text="Save" 
            onAction="#save"/>
        <Button fx:id="buttonDelete" text="Delete" 
            onAction="#delete" visible="false"/>
        <Button fx:id="buttonCancel" text="Cancel"
            onAction="#cancel" visible="false"/>
    </children>
</HBox>

Once again, nothing very spectacular. We now have to wire it to the controller, so we first add an instance variable vineyard that will hold the currently edited entity.

@FXML
private Vineyard vineyard;

We now have to manage this variable correctly. We will do this in a method that will bind the form to an existing instance or create a new instance:

private void select(Vineyard vineyard) {
    if (vineyard == this.vineyard && this.vineyard != null)
        return;
   
    if (this.vineyard != null) {
        fieldName.textProperty()
            .unbindBidirectional(this.vineyard.nameProperty());
        fieldAddress.textProperty()
            .unbindBidirectional(this.vineyard.getAddress().addressProperty());
    }
   
    if (vineyard != null)
        this.vineyard = vineyard;
    else {
        this.vineyard = new Vineyard();
        this.vineyard.setName("");
        this.vineyard.setAddress(new Address());
        this.vineyard.getAddress().setAddress("");
    }
   
    fieldName.textProperty()
        .bindBidirectional(this.vineyard.nameProperty());
    fieldAddress.textProperty()
        .bindBidirectional(this.vineyard.getAddress().addressProperty());
    labelFormVineyard.setText(vineyard != null
        ? "Edit vineyard" : "Create vineyard");
    buttonDelete.setVisible(vineyard != null);
    buttonCancel.setVisible(vineyard != null);
}

Additionally this method changes the title of the form to 'edit' or 'create' and makes the delete and cancel buttons visible when working on an existing instance. Not that we here make an extensive use of bidirectional data binding.

We will just call this method at the initialization of the screen and define a selection listener on the table to bind the selection to the form:

public void initialize(URL url, ResourceBundle rb) {
    ...
    select(null);
    tableVineyards.getSelectionModel().selectedItemProperty()
        .addListener(new ChangeListener() {
        @Override
        public void changed(ObservableValue<!--? extends Vineyard--> property,
            Vineyard oldSelection, Vineyard newSelection) {
            select(newSelection);
        }
    });
}

We're almost done, finally we have to define the actions of the three buttons:

@FXML
private void save(ActionEvent event) {
    final boolean isNew = vineyard.getId() == null;
    vineyardRepository.save(vineyard,
        new SimpleTideResponder() {
            @Override
            public void result(TideResultEvent tre) {
                if (isNew)
                    select(null);
                else
                    tableVineyards.getSelectionModel()
                        .clearSelection();
            }
           
            @Override
            public void fault(TideFaultEvent tfe) {
                System.out.println("Error: "
                    + tfe.getFault().getFaultDescription());
            }
        }
    );
}

Basically we save the entity by calling the remote Spring Data repository that we got injected by Spring.  Note that a suitable client has been generated for the repository and is defined as a Spring bean. On successful return, we either create a new empty entity with select(null) or simply clear the table selection,  which will consequently clear the form and reset it in creation mode.

You will probably notice that the remote call is handled asynchronously by a responder. This is very important so the UI thread is not handed while the server processes the action.

The delete action is quite similar:

@FXML
private void delete(ActionEvent event) {
    vineyardRepository.delete(vineyard.getId(),
        new SimpleTideResponder() {
            @Override
            public void result(TideResultEvent tre) {
                tableVineyards.getSelectionModel().clearSelection();
            }
        }
    );
}

The cancel operation is very basic for now:

@FXML
private void cancel(ActionEvent event) {
    tableVineyards.getSelectionModel().clearSelection();
}

You have maybe noticed that we call the remote repository and just don't do anything with  the actual result of the operation. Actually we don't have to because GraniteDS listens to the JPA persist/update/remove events  and propagates them to the client as Spring application events.  The PagedQuery automatically listens to these client events and refreshes itself when needed.  Of course if you need to access the result objects, you can still do it in the responder result handler.

The first step of the client application is now ready. You can get it with the tag step2 in the git repository:

git checkout step2

Here is the compare view on GitHub: https://github.com/graniteds/shop-admin-javafx/compare/step2a...step2

You can now build it and run it, assuming your Jetty server it still running in another console:

cd javafx
mvn clean install
java -jar target/shop-admin-javafx.jar

Step 3: Support for JPA lazy associations

If you have not yet fallen asleep, you have maybe noticed that we simply didn't take care of the wines  association. It is never populated, saved or rendered and that caused no problem at all to the application.  GraniteDS is indeed able to properly serialize and deserialize all lazy association so you simply don't have  to take care of them. What is lazy on the server stays lazy on the client.

However we now would like to edit the list of wines for our vineyards.  We first add a list view to the edit form:

<Label text="Wines" GridPane.columnIndex="1" GridPane.rowIndex="3" />
<HBox spacing="5" GridPane.columnIndex="2" GridPane.rowIndex="3">
    <children>
        <ListView fx:id="listWines" maxHeight="150"/>
       
        <VBox spacing="5">
            <children>
                <Button text="+" onAction="#addWine"/>
                <Button text="-" onAction="#removeWine"/>
            </children>
        </VBox>
    </children>
</HBox>

Now in the controller, we have to bind the list of wines of the current edited vineyard to this list:

@FXML
private ListView listWines;
private void select(Vineyard vineyard) {
    ...
    listWines.setItems(this.vineyard.getWines());
    ...
}

And add the actions to add and remove a wine from the list:

@FXML
private void addWine(ActionEvent event) {
    Wine wine = new Wine();
    wine.setVineyard(this.vineyard);
    wine.setName("");
    wine.setYear(Calendar.getInstance().get(Calendar.YEAR)-3);
    wine.setType(Wine$Type.RED);
    this.vineyard.getWines().add(wine);
}
@FXML
private void removeWine(ActionEvent event) {
    if (!listWines.getSelectionModel().isEmpty())
        this.vineyard.getWines().remove(listWines.getSelectionModel().getSelectedIndex());
}

Finally we have to setup the list to display and edit the properties of the Wine objects:

listWines.setCellFactory(new Callback, ListCell>() {
    public ListCell call(ListView listView) {
        return new WineListCell();
    }
});
private static class WineListCell extends ListCell {
    private ChoiceTypeListener choiceTypeListener = null;
    protected void updateItem(Wine wine, boolean empty) {
        Wine oldWine = getItem();
        if (oldWine != null && wine == null) {
            HBox hbox = (HBox)getGraphic();
            TextField fieldName = (TextField)hbox.getChildren().get(0);
            fieldName.textProperty()
                .unbindBidirectional(getItem().nameProperty());
            TextField fieldYear = (TextField)hbox.getChildren().get(1);
            fieldYear.textProperty()
                .unbindBidirectional(getItem().yearProperty());
            getItem().typeProperty().unbind();
            getItem().typeProperty().removeListener(choiceTypeListener);
            choiceTypeListener = null;
            setGraphic(null);
        }
        super.updateItem(wine, empty);
        if (wine != null && wine != oldWine) {
            TextField fieldName = new TextField();
            fieldName.textProperty()
                .bindBidirectional(wine.nameProperty());
            TextField fieldYear = new TextField();
            fieldYear.setPrefWidth(40);
            fieldYear.textProperty()
                .bindBidirectional(wine.yearProperty(), new IntegerStringConverter());
            ChoiceBox choiceType = new ChoiceBox(
                FXCollections.observableArrayList(Wine$Type.values())
            );
            choiceType.getSelectionModel()
                .select(getItem().getType());
            getItem().typeProperty()
                .bind(choiceType.getSelectionModel().selectedItemProperty());
            choiceTypeListener = new ChoiceTypeListener(choiceType);
            getItem().typeProperty()
                .addListener(choiceTypeListener);
            HBox hbox = new HBox();
            hbox.setSpacing(5.0);
            hbox.getChildren().add(fieldName);
            hbox.getChildren().add(fieldYear);
            hbox.getChildren().add(choiceType);
            setGraphic(hbox);
        }
    }
    private final static class ChoiceTypeListener
        implements ChangeListener {
        private ChoiceBox choiceBox;
        public ChoiceTypeListener(ChoiceBox choiceBox) {
            this.choiceBox = choiceBox;
        }
        @Override
        public void changed(ObservableValue<!--? extends Wine$Type--> property,
                Wine$Type oldValue, Wine$Type newValue) {
            choiceBox.getSelectionModel().select(newValue);
        }
    }
}

Ouch!

This cell implementation looks intimidating but in fact we simply create 3 text and choice fields for the values we want to edit in the Wine object.  Then we set bidirectional binding between each field and the corresponding property of the Wine class.  ChoiceBox is the most complex because we can't bind directly from the selectedItem property (?),  so we have to define a change listener to achieve the same result.

There is nothing else to change, this is purely client code.  The persistence on the server will be ensured by the cascading options we have defined on the JPA entity.

Interestingly we don't have to handle the loading of the collection,  Tide will lazily trigger a remote loading of the collection content when the content is first requested,  for example when a UI control tried to display the data.

As before, build and run:

git checkout step3

Compare view on GitHub: https://github.com/graniteds/shop-admin-javafx/compare/step2...step3

cd javafx
mvn clean install
java -jar target/shop-admin-javafx.jar

Step 4: Dirty Checking / Undo

If you have played with the application you may have noticed that using bidirectional bindings  leads to a weird behaviour. Even without saving your changes, the local objects are still modified  and keep the modifications made by the user.

To fix this, we can use the fact that GraniteDS tracks all updates made on the managed entities  and is able to easily restore the last known stable state of the objects (usually the last fetch  from the server).

We need to inject the local entity manager (EntityManager is a GraniteDS client component):

@Inject
private EntityManager entityManager;

And use it to restore the persistent state of the object when the user selects another element without saving:

private void select(Vineyard vineyard) {
    if (vineyard == this.vineyard && this.vineyard != null)
        return;
   
    if (this.vineyard != null) {
        fieldName.textProperty().unbindBidirectional(this.vineyard.nameProperty());
        fieldAddress.textProperty().unbindBidirectional(this.vineyard.getAddress().addressProperty());
        entityManager.resetEntity(this.vineyard);
    }
    ...
}

We can also enable or disable the ‘Save’ button depending on the fact that the user has modified  something or not. Tide provides the JavaFXDataManager component.

@Inject
private JavaFXDataManager dataManager;
buttonSave.disableProperty()
    .bind(Bindings.not(dataManager.dirtyProperty()));

If you try this, you will notice that it works fine when modifying existing data but not  with newly created elements. This is because these new elements are not known by the entity manager,  and thus not tracked by the dirty checking process.  To make this work, we have to merge the new entities in the client entity manager:

else {
    this.vineyard = new Vineyard();
    this.vineyard.setName("");
    this.vineyard.setAddress(new Address());
    this.vineyard.getAddress().setAddress("");
    entityManager.mergeExternalData(this.vineyard);
}

As before, there is a tag step4 on the git repository.

git checkout step4

Compare view on GitHub: https://github.com/graniteds/shop-admin-javafx/compare/step3...step4

cd javafx
mvn clean install
java -jar target/shop-admin-javafx.jar

Validation

We can now create, edit and search in our database.  We would now like to ensure that our data in consistent. The Bean Validation API is our friend and  as we are in Java on both sides we can use it on both the server JPA entities and on the client data objects.

Going back to the JPA model, we add a few validation annotations, here the Wine class:

@Basic
@Size(min=5, max=100,
    message="The name must contain between {min} and {max} characters")
private String name;




@Basic
@Min(value=1900,
    message="The year must be greater than {value}")
@Past
private Integer year;




@Enumerated(EnumType.STRING)
@NotNull
private Type type;

With these annotations we ensure that we cannot save incorrect values.  However we would also like to notify the user that something went wrong.  The brutal way would be to add a special handling of validation error in each and  every fault handler of the application.

A better way would be to define a global exception handler that will handle all validation faults.  Indeed GraniteDS already provides such a thing, and it takes server exceptions and propagates  them as events on the faulty property of the target data object.  We would then have to listen to these events and display some message or trigger  some notification to the user.

GraniteDS provides a special component, the FormValidator, that will further simplify our work.  We will simply bind it to the form containing the fields that we want to validate after  the entity to validate has been bound:

private FormValidator formValidator = new FormValidator();
...
private void select(Vineyard vineyard) {
    if (vineyard == this.vineyard && this.vineyard != null)
        return;
    formValidator.setForm(null);
    ...
    formValidator.setForm(formVineyard);
    ...
}

Finally we have to define a UI behaviour when a validation event occurs,  for example setting a red border on the faulty fields:

formVineyard.addEventHandler(ValidationResultEvent.ANY, new EventHandler() {
    @Override
    public void handle(ValidationResultEvent event) {
        if (event.getEventType() == ValidationResultEvent.INVALID)
            ((Node)event.getTarget()).setStyle("-fx-border-color: red");
        else if (event.getEventType() == ValidationResultEvent.VALID)
            ((Node)event.getTarget()).setStyle("-fx-border-color: null");
    }
});

Of course you could do whatever you want in this handler and apply a more suitable display,  for example display the error message in a tooltip or something.

If you test the application now, that should work fine, but the user is still able to submit  the save button even with invalid data. It's easy to block the remote call:

@FXML
private void save(ActionEvent event) {
    if (!formValidator.validate(this.vineyard))
        return;
    ...
}

Tag step5 on the git repository.

git checkout step5

Compare view on GitHub: https://github.com/graniteds/shop-admin-javafx/compare/step4...step5

cd javafx
mvn clean install
java -jar target/shop-admin-javafx.jar

Step 6: Security

The application already has a basic security with the login page.  If you look how this works, you will find the component Identity which acts a gateway  between the client and the Spring Security framework.

Just as an exercise, we can add a logout button to our application:

<Button text="Logout" onAction="identity.logout(null)"/>

With a tiny bit of JavaScript (but we could also use a Java method in the controller),  we can call the logout method of identity.  As we have defined a change listener on the property loggedIn of identity in the Main class,  the current view will be destroyed and replaced by the login screen.

The Identity component also handles authorizations, so we could also decide in the initialization  of the Home controller that only administrators are allowed to delete entities:

buttonDelete.disableProperty().bind(Bindings.not(identity.ifAllGranted("ROLE_ADMIN")));

identity.ifAllGranted(role) will issue a remote call to check the user rights on the first time and then cache the result so subsequent calls don't require access to the server. The security cache can be invalidated at any time to force a recheck on the server.

Tag step6 on the git repository.

git checkout step6
Compare view on GitHub: <a href="https://github.com/graniteds/shop-admin-javafx/compare/step5...step6">https://github.com/graniteds/shop-admin-javafx/compare/step5...step6</a>
cd javafx
mvn clean install
java -jar target/shop-admin-javafx.jar

Step 7: Real-time data push

Until now, we have used only one client at a time.  We are going to configure GraniteDS to push JPA data updates from the server to all connected clients.  We have almost already everything in place, the archetype has setup a complete configuration  with Jetty 8 websockets. When deploying on another container, you might need to change the  configuration to use the specific websocket support of Tomcat 7+ or GlassFish 3.1.2+,  or fallback to simple long-polling with the portable Servlet 3 implementation.

First we need to declare a messaging destination in the server configuration app-config.xml:

<graniteds:messaging-destination id="wineshopTopic" no-local="true" session-selector="true"/>

Declare the topic and enable automatic publishing on the Spring Data repository @DataEnabled annotation:

@RemoteDestination
@DataEnabled(topic="wineshopTopic", publish=PublishMode.ON_SUCCESS)
public interface VineyardRepository extends FilterableJpaRepository {
}

Declare a client DataObserver in the Spring configuration and subscribe this topic when the user logs in:

@Bean(initMethod="start", destroyMethod="stop")
public DataObserver wineshopTopic(ServerSession serverSession,
    EntityManager entityManager) {
    return new DataObserver("wineshopTopic", serverSession, entityManager);
}

We listen to the LOGIN and LOGOUT events in the Login controller to subscribe and unsubscribe the topic:

if (ServerSession.LOGIN.equals(event.getType())) {
    wineshopTopic.subscribe();
}
else if (ServerSession.LOGOUT.equals(event.getType())) {
    wineshopTopic.unsubscribe();
}
...

Now you can build the project and run two or more instances of the application in different consoles.  Changes made on a client should be propagated to all other subscribed clients.

Tag step7 on the git repository.

git checkout step7

Compare view on GitHub: https://github.com/graniteds/shop-admin-javafx/compare/step6...step7

cd javafx
mvn clean install
java -jar target/shop-admin-javafx.jar

Conclusion

This tutorial is now finished.

There are still a few more interesting features to show such as conflict detection and resolution  but the goal of this tutorial is to show the iterations needed to build a full featured  JavaFX application with the help of the GraniteDS JavaFX integration.

JavaFX is still a moving target and some parts of this tutorial might be simplified  with future releases of either JavaFX or GraniteDS, notably as the support for expression bindings in FXML improves.

Published at DZone with permission of its author, William Draï.

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