Uberfire – The Unanswered Questions: Part 1

Uber…what now?

Yes, I know it sounds like an unfortunate incident on a California freeway, but Uberfire is actually a Rich Client Platform for building web applications. Based on the Google Web Toolkit (GWT) and JBoss Errai, Uberfire allows you to build workbench-style applications entirely (or rather, mostly) in Java. Think of HTML meets Java with a little Javascript thrown in for good measure. Uberfire is currently used for the KIE Workbench, which has been a driving force in Uberfire’s development. BTW, this actually happened to me in college – engine fires were simply accepted as part of the VW Beetle owner experience.

Disclaimer:

Uberfire has a steep learning curve and I’m still climbing that hill. The information in these blogs is my understanding of the software and may or may not be correct. I’m asking my readers to help me out and correct errors or misunderstandings here – thank you 🙂 So with that said, please take heed of my disclaimer*.

Building on UF Tasks

If you haven’t realized it by now, Uberfire is huge as far as application frameworks go, and it tries very hard to hide many of the complexities of web app development.

While the original UFTasks tutorial does a good job of presenting some of the major UI framework concepts, there are many aspects of Uberfire which, in my mind at least, were still a mystery and left me wanting more. Some of the unanswered questions that I was thinking about while working through the tutorial were:

  • How does the VFS work, and what are my options for using the client and server side file system? I would have liked to be able to persist the Project/Folder/Task hierarchy that was developed by the UFTasks tutorial. I assume that since the tutorial web app requires a user login, how about a personal task list for each user? How do I get the currently logged-in user’s information?
  • What is this CDI thing you speak of? Even though I’ve been a java developer for years (I come from a C++ background) I have never really dug very deeply into CDI nor understood all of its complexities. Uberfire depends very heavily on using CDI for intra-app communication, so I was going to have to study up on it.
  • Views, shmiews…what I really want is an Editor. Editors are a big part of the Uberfire user experience, but what exactly is a @WorkbenchEditor and how is it different from a @WorkbenchPartView?
I’m only scratching the surface of my “unanswered questions” in part 1 of this blog. As I become more familiar with Uberfire, I’m sure I’ll find more unanswered questions along the way.

Rethinking the Model

Thinking about what a task or to-do list really is, the UFTasks demo left me wanting more than just a task name. What about priorities? Start and completion dates? Maybe a more detailed description? I can probably come up with several other things I would want in my task manager, but let’s not lose sight of the goal, which is to learn about Uberfire, and not to design the World’s Greatest Freaking To-Do  App.

The first thing that struck me about the UFTasks tutorial was that the Model part of the MVP pattern was scattered through some of the Presenter and View bits. This was a little infuriating because of, well… MVP! The Model should be contained in Model classes, not View or controller classes.

Also, if I was going to persist the model, I would need the ability to quickly and easily navigate it and gather up all the related bits for serialization. So without further ado, here are my model classes:

TreeNode.java

package org.uberfire.shared.model;

import java.util.ArrayList;
import java.util.List;

public abstract class TreeNode< PARENT extends TreeNode, CHILD extends TreeNode > {
    private PARENT parent;
    private List< CHILD > children;

    public TreeNode() {
        parent = null;
    }

    abstract public String getName();

    public PARENT getParent() {
        return (PARENT) parent;
    }

    protected void setParent(PARENT parent) {
        this.parent = parent;
    }

    public List< CHILD > getChildren() {
        if (children == null)
            children = new ArrayList< CHILD >();
        return children;
    }

    public void addChild(CHILD child) {
        getChildren().add(child);
        child.setParent(this);
    }

    public void removeChild(TreeNode child) {
        getChildren().remove(child);
        child.setParent(null);
    }
}

Task.java

package org.uberfire.shared.model;

public class Task extends TreeNode< Folder, TreeNode > {
    private String name;
    private boolean done;

    public Task(String name) {
        this.name = name;
        this.done = false;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
    
    public boolean isDone() {
        return done;
    }

    public void setDone(boolean done) {
        this.done = done;
    }
}

Folder.java

package org.uberfire.shared.model;

public class Folder extends TreeNode< Folder, Task > {

    private final String name;

    public Folder(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }
}

Project.java

package org.uberfire.shared.model;

public class Project extends TreeNode< Project, Folder > {

    private final String name;
    private boolean selected;

    public Project(String name) {
        // this is the root of the tree so it has no parent
        this.name = name;
        this.selected = false;
    }

    public String getName() {
        return name;
    }

    public boolean isSelected() {
        return selected;
    }

    public void setSelected(boolean selected) {
        this.selected = selected;
    }
    
    public int countDoneTasks() {
        int doneTasks = 0;
        for (Folder folder : getChildren()) {
            for (Task task : folder.getChildren()) {
                if (task.isDone()) {
                    ++doneTasks;
                }
            }
        }
        return doneTasks;
    }
    
    public int countTotalTasks() {
        int totalTasks = 0;
        for (Folder folder : getChildren()) {
            totalTasks += folder.getChildren().size();
        }
        return totalTasks;
    }
}

TasksRoot.java

package org.uberfire.shared.model;

import java.util.ArrayList;
import java.util.List;

public class TasksRoot {
    private List< Project > projects = new ArrayList< Project >();
    
    public List< Project > getProjects() {
        return projects;
    }
}

No surprises here. The only things worth mentioning are:

  • TreeNode – a generic tree node class which takes PARENT and CHILD type parameters. Note that Project does not have a parent and Task does not have any children and we could have written TreeRootNode, TreeInternalNode and TreeLeafNode classes, but…meh.
  • TasksRoot – a root object to contain the list of Projects. This will become important during serialization. The instance of this thing is also made available to other beans by way of the @Produces CDI annotation. More about this in Part 2.
  • Project – this includes two convenience functions for counting the total number of tasks and the number of completed tasks. We’ll use this in the Dashboard later on.
Obviously these are some drastic changes here, not to mention the addition of an actual Task model object which was conspicuously missing from the original tutorial. In Part 2 of this blog, I’ll describe the changes in the Presenter and View components. Surprisingly, these model changes actually simplified the handling in the “P” and “V” bits so we can concentrate on Uberfire functionality instead of littering the code with “M” bits. Stay tuned…

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