Ooui

Ooui (pronounced weeee!) is a small cross-platform UI library for .NET that uses web technologies.

It presents a classic object-oriented UI API that controls a dumb browser. With Ooui, you get the full power of your favorite .NET programming language plus the ability to interact with your app using any device.

Try the Samples

git clone git@github.com:praeclarum/Ooui.git
cd Ooui

dotnet restore
dotnet run --project Samples/Samples.csproj

Now point your browser at http://localhost:8080/shared-button

You should see a button that tracks the number of times it was clicked. The source code for that button is shown in the example below.

Example

Here is the complete source code to a fully collaborative button clicking app.

using System;
using Ooui;

class Program
{
    static void Main(string[] args)
    {
        // Create the UI
        var button = new Button("Click me!");

        // Add some logic to it
        var count = 0;
        button.Clicked += (s, e) => {
            count++;
            button.Text = $"Clicked {count} times";
        };

        // Publishing makes an object available at a given URL
        // The user should be directed to http://localhost:8080/button
        UI.Publish ("/shared-button", button);

        // Don't exit the app until someone hits return
        Console.ReadLine ();
    }
}

Make sure to add a reference to Ooui before you try running!

dotnet add package Ooui

With just that code, the user will be presented with a silly counting button.

In fact, any number of users can hit that URL and start interacting with the same button. That's right, automatic collaboration!

If you want each user to get their own button, then you will instead Publish a function to create it:

Button MakeButton()
{
    var button = new Button("Click me!");
    var count = 0;
    button.Clicked += (s, e) => {
        count++;
        button.Text = $"Clicked {count} times";
    };
    return button;
}

UI.Publish("/button", MakeButton);

Now every user (well, every load of the page) will get their own button.

How it works

When the user requests a page, Ooui will connect to the client using a Web Socket. This socket is used to keep an in-memory model of the UI (the one you work with as a programmer) in sync with the actual UI shown to the user in their browser. This is done using a simple messaging protocol with JSON packets.

When the user clicks or otherwise interacts with the UI, those events are sent back over the web socket so that your code can deal with them.

Comparison

UI Library	Ooui	Xamarin.Forms	ASP.NET MVC
How big is it?	25 KB	650 KB	1,300 KB
Where does it run?	Everywhere	iOS, Android, Mac, Windows	Windows, Linux, Mac
How do I make a button?	new Button()	new Button()	<button />
Does it use native controls?	No, HTML5 controls	Yes!	HTML5 controls
What controls are available?	All of those in HTML5	Xamarin.Forms controls	All of those in HTML5
Which architecture will you force me to use?	None, you're free	MVVM	MVC/MVVM
What's the templating language?	C#	XAML	Razor
How do I style things?	CSS baby!	XAML resources	CSS
Is there databinding?	No :-(	Yes!	Debatable
Do I need to run a server?	Nope	Heck no	Yes
Is it web scale?	How much money do you have?	What's the web?	Sure