Archive for SqueakJS

browser-to-browser websocket tunnels with Caffeine and livecoded NodeJS

Posted in Appsterdam, consulting, Context, Smalltalk, SqueakJS with tags , , , , , , , , on 4 July 2017 by Craig Latta

network

In our previous look at livecoding NodeJS from Caffeine, we implemented tweetcoding. Now let’s try another exercise, creating WebSockets that tunnel between web browsers. This gives us a very simple version of peer-to-peer networking, similar to WebRTC.

Once again we’ll start with Caffeine running in a web browser, and a NodeJS server running the node-livecode package. Our approach will be to use the NodeJS server as a relay. Web browsers that want to establish a publicly-available server can register there, and browser that want to use such a server can connect there. We’ll implement the following node-livecode instructions:

  • initialize, to initialize the structures we’ll need for the other instructions
  • create server credential, which creates a credential that a server browser can use to register a WebSocket as a server
  • install server, which registers a WebSocket as a server
  • connect to server, which a client browser can use to connect to a registered server
  • forward to client, which forwards data from a server to a client
  • forward to server, which forwards data from a client to a server

In Smalltalk, we’ll make a subclass of NodeJSLivecodingClient called NodeJSTunnelingClient, and give it an overriding implementation of configureServerAt:withCredential:, for injecting new instructions into our NodeJS server:

configureServerAt: url withCredential: credential
  "Add JavaScript functions as protocol instructions to the
node-livecoding server at url, using the given credential."

  ^(super configureServerAt: url withCredential: credential)
    addInstruction: 'initialize'
    from: '
      function () {
        global.servers = []
        global.clients = []
        global.serverCredentials = []
        global.delimiter = ''', Delimiter, '''
        return ''initialized tunnel relay''}';
    invoke: 'initialize';
    addInstruction: 'create server credential'
    from: '
      function () {
        var credential = Math.floor(Math.random() * 10000)
        serverCredentials.push(credential)
        this.send((serverCredentials.length - 1) + '' '' + credential)
        return ''created server credential''}';
    addInstruction: 'install server'
    from: '
      function (serverID, credential) {
        if (serverCredentials[serverID] == credential) {
          servers[serverID] = this
          this.send(''1'')
          return ''installed server''}
      else {
        debugger;
        this.send(''0'')
        return ''bad credential''}}';
    addInstruction: 'connect to server'
    from: '
      function (serverID, port, req) {
        if (servers[serverID]) {
          clients.push(this)
          servers[serverID].send(''connected:atPort:for: '' + (clients.length - 1) + delimiter + port + delimiter + req.connection.remoteAddress.toString())
          this.send(''1'')
          return ''connected client''}
        else {
          this.send(''0'')
          return ''server not connected''}}';
    addInstruction: 'forward to client'
    from: '
      function (channel, data) {
        if (clients[channel]) {
          clients[channel].send(''from:data: '' + servers.indexOf(this) + delimiter + data)
          this.send(''1'')
          return ''sent data to client''}
        else {
          this.send(''0'')
          return ''no such client channel''}}';
    addInstruction: 'forward to server'
    from: '
      function (channel, data) {
        if (servers[channel]) {
          servers[channel].send(''from:data: '' + clients.indexOf(this) + delimiter + data)
          this.send(''1'')
          return (''sent data to server'')}
        else {
          this.send(''0'')
          return ''no such server channel''}}'

We’ll send that message immediately, configuring our NodeJS server:

NodeJSTunnelingClient
  configureServerAt: 'wss://yourserver:8087'
  withCredential: 'shared secret';
  closeConfigurator

On the NodeJS console, we see the following messages:

server: received command 'add instruction'
server: adding instruction 'initialize'
server: received command 'initialize'
server: evaluating added instruction 'initialize'
server: initialized tunnel relay
server: received command 'add instruction'
server: adding instruction 'create server credential'
server: received command 'add instruction'
server: adding instruction 'install server'
server: received command 'add instruction'
server: adding instruction 'connect to server'
server: received command 'add instruction'
server: adding instruction 'forward to client'
server: received command 'add instruction'
server: adding instruction 'forward to server'

Now our NodeJS server is a tunneling relay, and we can connect servers and clients through it. We’ll make a new ForwardingWebSocket class hierarchy:

Object
  ForwardingWebSocket
    ForwardingClientWebSocket
    ForwardingServerWebSocket

Instances of ForwardingClientWebSocket and ForwardingServerWebSocket use a NodeJSTunnelingClient to invoke our tunneling instructions.

We create a new ForwardingServerWebSocket with newThrough:, which requests new server credentials from the tunneling relay, and uses them to install a new server. Another new class, PeerToPeerWebSocket, provides the public message interface for the framework. There are two instantiation messages:

  • toPort:atServerWithID:throughURL: creates an outgoing client that uses a ForwardingClientWebSocket to connect to a server and exchange data
  • throughChannel:of: creates an incoming client that uses a ForwardingServerWebSocket to exchange data with a remote outgoing client.

Incoming clients are used by ForwardingServerWebSockets to represent their incoming connections. Each ForwardingServerWebSocket can provide services over a range of ports, as a normal IP server would. To connect, a client needs the websocket URL of the tunneling relay, a port, and the server ID assigned by the relay.

As usual, you can examine and try out this code by clearing your browser’s caches for caffeine.js.org (including IndexedDB), and visiting https://caffeine.js.org/. With browsers able to communicate directly, there are many interesting things we can build, including games, chat applications, and team development tools. What would you like to build?

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retrofitting Squeak Morphic for the web

Posted in Appsterdam, consulting, Context, Smalltalk, Spoon, SqueakJS with tags , , , , , , , , on 30 June 2017 by Craig Latta

Google ChromeScreenSnapz022

Last time, we explored a way to improve SqueakJS UI responsiveness by replacing Squeak Morphic entirely, with morphic.js. Now let’s look at a technique that reuses all the Squeak Morphic code we already have.

many worlds, many canvases

Traditionally, Squeak Morphic has a single “world” where morphs draw themselves. To be a coherent GUI, Morphic must provide all the top-level effects we’ve come to expect, like dragging windows and redrawing them in their new positions, and redrawing occluded windows when they are brought to the top. Today, this comes at an acceptable but noticeable cost. Until WebAssembly changes the equation again, we want to do all we can to shift UI work from Squeak Morphic to the HTML5 environment hosting it. This will also make the experience of using SqueakJS components more consistent with that of the other elements on the page.

Just as we created an HTML5 canvas for morphic.js to use in the last post, we can do so for individual morphs. This means we’ll need a new Canvas subclass, called HTML5FormCanvas:

Object
  ...
    Canvas
       FormCanvas
         HTML5FormCanvas

An HTML5FormCanvas draws onto a Form, as instances of its parent class do, but instead of flushing damage rectangle from the Form onto the Display, it flushes them to an HTML5 canvas. This is enabled by a primitive I added to the SqueakJS virtual machine, which reuses the normal canvas drawing code path.

Accompanying HTML5FormCanvas are new subclasses of PasteUpMorph and WorldState:

Object
  Morph
    ...
      PasteUpMorph
        HTML5PasteUpMorph

Object
  WorldState
    HTML5WorldState

HTML5PasteUpMorph provides a message interface for other Smalltalk objects to create HTML5 worlds, and access the HMTL5FormCanvas of each world and the underlying HTML5 canvas DOM element. An HTML5WorldState works on behalf of an HTML5PasteUpMorph, to establish event handlers for the HTML5 canvas (such as for keyboard and mouse events).

HTML5 Morphic in action

You don’t need to know all of that just to create an HTML5 Morphic world. You only need to know about HTML5PasteUpMorph. In particular, (HTML5PasteUpMorph class)>>newWorld. All of the traditional Squeak Morphic tools can use HTML5PasteUpMorph as a drop-in replacement for the usual PasteUpMorph class.

There are two examples of single-window Morphic worlds in the current Caffeine release, for a workspace and classes browser. I consider these two tools to be the “hello world” exercise for UI framework experimentation, since you can use them to implement all the other tools.

We get an immediate benefit from the web browser handling window movement and clipping for us, with opaque window moves rendering at 60+ frames per second. We can also interleave Squeak Morphic windows with other DOM elements on the page, which enables a more natural workflow when creating hybrid webpages. We can also style our Squeak Morphic windows with CSS, as we would any other DOM element, since as far as the web browser is concerned they are just HTML5 canvases. This makes effects like the rounded corners and window buttons trays that Caffeine uses very easy.

Now, we have flexible access to the traditional Morphic tools while we progress with adapting them to new worlds like morphic.js. What shall we build next?

Pharo comes to Caffeine and SqueakJS

Posted in Appsterdam, consulting, Context, GLASS, Naiad, Seaside, Smalltalk, Spoon, SqueakJS with tags , , , , , , , , , on 29 June 2017 by Craig Latta

Google ChromeScreenSnapz025

The Caffeine web livecoding project has added Pharo to the list of Smalltalk distributions it runs with SqueakJS. Bert Freudenberg and I spent some time getting SqueakJS to run Pharo at ESUG 2016 in Prague last summer, and it mostly worked. I think Bert got a lot further since then, because now there are just a few Pharo primitives that need implementing. All I’ve had to do so far this time is a minor fix to the input event loop and add the JavaScript bridge. The bridge now works from Pharo, and it’s the first time I’ve seen that.

Next steps include getting the Tether remote messaging protocol and Snowglobe app streaming working between Pharo and Squeak, all running in SqueakJS. Of course, I’d like to see fluid code-sharing of all kinds between Squeak, Pharo, and all the other Smalltalk implementations.

So, let the bugfixing begin! :)  You can run it at https://caffeine.js.org/pharo/. Please do get in touch if you find and fix things. Thanks!

a faster Morphic with morphic.js

Posted in Appsterdam, consulting, Context, Naiad, Smalltalk, Spoon, SqueakJS with tags , , , , , , , , , , on 28 June 2017 by Craig Latta

Google ChromeScreenSnapz017

Caffeine is powered by SqueakJS. The performance of SqueakJS is amazingly good, thanks in large part to its dynamic translation of Smalltalk compiled methods to JavaScript functions (which are in turn translated to machine code by your web browser’s JS engine). In the HTML5 environment where SqueakJS finds itself, there are several other tactics we can use to further improve user interface performance.

Delegate!

In a useful twist of fate, SqueakJS emerges into a GUI ecosystem descended from Smalltalk, now brimming with JavaScript frameworks to which SqueakJS can delegate much of its work. To make Caffeine an attractive environment for live exploration, I’m addressing each distraction I see.

The most prominent one is user interface responsiveness. SqueakJS is quite usable, even with large object memories, but its Morphic UI hasn’t reached the level of snappiness that we expect from today’s web apps. Squeak is a virtual machine, cranking away to support what is essentially an entire operating system, with a process scheduler, window system, compiler, and many other facilities. Since, with SqueakJS, that OS has access to a multitude of similar behavior in the JavaScript world, we should take advantage.

Of course, the UI design goals of the web are different than those of other operating systems. Today’s web apps are still firmly rooted in the web’s original “page” metaphor. “Single Page Applications” that scroll down for meters are the norm. While there are many frameworks for building SPAs, support for open-ended GUIs is uncommon. There are a few, though; one very good one is morphic.js.

morphic.js

Morphic.js is the work of Jens Mönig, and part of the Snap! project at UC Berkeley, a Scratch-like environment which teaches advanced computer science concepts. It’s a standalone JavaScript implementation of the Morphic UI framework. By using morphic.js, Squeak can save its cycles for other things, interacting with it only when necessary.

To use morphic.js in Caffeine, we need to give morphic.js an HTML5 canvas for drawing. The Webpage class can create new DOM elements, and use jQuery UI to give them effects like dragging and rotation. With one line we create a draggable canvas with window decorations:

canvas := Webpage createWindowOfKind: 'MorphicJS'

Now, after loading morphic.js, we can create a morphic.js WorldMorph object that uses the canvas:

world := (JS top at: #WorldMorph) newWithParameters: {canvas. false}

Finally, we need to create a rendering loop that regularly gets the world to draw itself on the canvas:

(JS top)
  at: #world
  put: world;
  at: #morphicJSRenderingLoop
  put: (
    (JS Function) new: '
      requestAnimationFrame(morphicJSRenderingLoop)
      world.doOneCycle()').

JS top morphicJSRenderingLoop

Now we have an empty morphic.js world to play with. The first thing to know about morphic.js is that you can get a world menu by control-clicking:

Google ChromeScreenSnapz018

Things are a lot more interesting if you choose development mode:

Google ChromeScreenSnapz019.png

Take some time to play around with the world menu, creating some morphs and modifying them. Note that you can also control-click on morphs to get morph-specific menus, and that you can inspect any morph.

Google ChromeScreenSnapz020.png

Also notice that this user interface is noticeably snappier than the current SqueakJS Morphic. MorphicJS isn’t trying to do all of the OS-level stuff that Squeak does, it’s just animating morphs, using a rendering loop that is runs as machine code in your web browser’s JavaScript engine.

Smalltalk tools in another world, with Hex

The inspector gives us an example of a useful morphic.js tool. Since we can pass Smalltalk blocks to JavaScript as callback functions, we have two-way communication between Smalltalk and JavaScript, and we can build morphic.js tools that mimic the traditional Squeak tools.

I’ve built two such tools so far, a workspace and a classes browser. You can try them out with these expressions:

HexMorphicJSWorkspace open.
HexMorphicJSClassesBrowser open

“Hex” refers to a user interface framework I wrote called Hex, which aggregates several JavaScript UI frameworks. HexMorphicJSWorkspace and HexMorphicJSClassesBrowser are subclasses of HexMorphicJSWindow. Each instance of every subclass of HexMorphicJSWindow can be used either as a standalone morphic.js window, or as a component in a more complex window. This is the case with these first two tools; a HexMorphicJSClassesBrowser uses a HexMorphicJSWorkspace as a pane for live code evaluation, and you can also use a HexMorphicJSWorkspace by itself as a workspace.

With a small amount of work, we get much snappier versions of the traditional Smalltalk tools. When using them, SqueakJS only has to do work when the tools request information from them. For example, when a workspace wants to print the result of evaluating some Smalltalk code, it asks SqueakJS to compile and evaluate it.

coming up…

It would be a shame not to reuse all the UI construction effort that went into the original Squeak Morphic tools, though. What if we were to put each Morphic window onto its own canvas, so that SqueakJS didn’t have to support moving windows, clipping and so on? Perhaps just doing that would yield a performance improvement. I’ll write about that next time.

Caffeine :: Livecode the Web!

Posted in Appsterdam, consulting, Context, Naiad, Smalltalk, Spoon, SqueakJS with tags , , , , , , , , , , , , , , on 22 June 2017 by Craig Latta

CaffeineFor the impatient… here it is.

Back to the Future, Again

With the arrival of Bert Freudenberg’s SqueakJS, it was finally time for me to revisit the weird and wonderful world of JavaScript and web development. My previous experiences with it, in my consulting work, were marked by awkward development tools, chaotic frameworks, and scattered documentation. Since I ultimately rely on debuggers to make sense of things, my first question when evaluating a development environment is “What is debugging like?”

Since I’m a livecoder, I want my debugger to run in the web browser I’m using to view the site I’m debugging. The best in-browser debugger I’ve found, Chrome DevTools (CDT), is decent if you’re used to a command-line interface, but lacking as a GUI. With Smalltalk, I can open new windows to inspect objects, and keep them around as those objects evolve. CDT has an object explorer integrated into its read-eval-print loop (REPL), and a separate tab for inspecting DOM trees, but using them extensively means a lot of scrolling in the REPL (since asynchronous console messages show up there as well) and switching between tabs. CDT can fit compactly onto the screen with the subject website, but doesn’t make good use of real estate when it has more. This interrupts the flow of debugging and slows down development.

The Pieces Are All Here

With SqueakJS, and its JavaScript bridge, we can make something better. We can make an in-browser development environment that compares favorably with external environments like WebStorm. I started from a page like try.squeak.org. The first thing we need is a way to move the main SqueakJS HTML5 canvas around the page. I found jQuery UI to be good for this, with its “draggable” effect. While we’re at it, we can also put each of Squeak‘s Morphic windows onto a separate draggable canvas. This moves a lot of the computation burden from SqueakJS to the web browser, since SqueakJS no longer has to do window management. This is a big deal, since Morphic window management is the main thing making modern Squeak UIs feel slow in SqueakJS today.

SqueakJS provides a basic proxy class for JavaScript objects, called JSObjectProxy. Caffeine has an additional proxy class called JSObject, which provides additional reflection features, like enumerating the subject JS object’s properties. It’s also a good place for documenting the behavior of the JS objects you’re using. Rather than always hunting down the docs for HTMLCanvasElement.getContext on MDN, you can summarize things in a normal method comment, in your HTMLCanvasElement class in Smalltalk.

Multiple Worlds

With a basic window system based on HTML5 canvases, we can draw whatever we like on those canvases, using the SqueakJS bridge and whatever other JS frameworks we care to load. I’ve started integrating a few frameworks, including React (for single-page-app development), three.js (for WebGL 3D graphics development), and morphic.js (a standalone implementation of Morphic which is faster than what’s currently in Squeak). I’ll write about using them from Caffeine in future blog posts.

Another framework I’ve integrated into Caffeine is Snowglobe (for Smalltalk app streaming and other remote GUI access), which I wrote about here previously. I think the Snowglobe demo is a lot more compelling when run from Caffeine, since it can co-exist with other web apps in the same page. You can also run multiple Snowglobes easily, and drag things between them. I’ll write more about that, too.

Fitting Into the JavaScript Ecosystem

To get the full-featured debugger UI I wanted, I wrote a Chrome extension called Caffeine Helper, currently available on the Chrome Web Store. It exposes the Chrome Debugging Protocol (CDP) support in the web browser to SqueakJS, letting it do whatever the CDT can do (CDT, like SqueakJS, is just another JavaScript-powered web app). The support for CDP that I wrote about previously uses a WebSocket-based CDP API that requires Chrome to be started in a special way. The Caffeine Helper extension provides a JavaScript API, without that requirement.

I also wrote support for generating Smalltalk code from JavaScript, using the esprima parsing framework, and vice-versa. With my debugger and code generation, I’m going to try developing for some file-based JS projects, using Smalltalk behind the scenes and converting to and from JavaScript when necessary. I think JS web development might actually not drive me crazy this way. :)

Please Try It Out!

So, please check out Caffeine, at caffeine.js.org! I would very much appreciate your feedback. I’m particularly interested to hear your use cases, as I plan the next development steps. I would love to have collaborators, too. Let’s build!

App streaming with Snowglobe

Posted in Appsterdam, consulting, Context, Naiad, Smalltalk, Spoon with tags , , , , , , , , on 31 October 2016 by Craig Latta

Now that we’ve seen how to run Smalltalk in a web browser, clone web Smalltalk as a desktop app, and send remote messages between Smalltalks, let’s look at an application of these technologies.

app streaming

App streaming is a way of delivering the user experience of an app without actually running the app on the user’s machine. The name is an allusion to music and video streaming; you get to experience the asset immediately, without waiting for it to download completely. Streaming an app also has the benefit of avoiding installation, something which can be problematic to do (and to undo). This is nice when you just want to demo an app, before deciding to install it.

Another advantage of app streaming is that the app can run on a much faster machine than the user’s, or even on a network of machines. Social networks are a crude example of app streaming; there are massive backends working behind your web browser, crunching away on all that graph data. Typically, though, app streaming involves an explicit visual component, with the user’s display and input devices standing in for the normal ones. The goal is to make using a new app as simple as playing an online video.

distributing Smalltalk user interface components

Everything in Smalltalk happens by objects sending messages to each other. With a remote messaging framework like Tether, we can put some of the objects in a user interface on a remote machine. Snowglobe is an adaptation of Squeak‘s Morphic user interface framework which runs Squeak on a server, but uses SqueakJS in a client web browser as the display. This is an easy way to recast a Smalltalk application as a web app, while retaining the processing speed and host platform access of the original.

Morphic is built around a display loop, where drawable components (morphs) are “stepped” at some frequency, like a flipbook animation. Normally, drawing is done on a single morph that corresponds to the display of the machine where Squeak is running. Snowglobe adds a second display morph which is Tether-aware. When drawing to this tethered display morph, the app server translates every display operation into a compact remote message.

To maximize speed, Morphic already tries to do its drawing with as few operations as possible (e.g., avoiding unnecessary redrawing). This is especially important when display operations become remote, since network transmission is orders of magnitude slower than local drawing. Since the tethered display morph also lives in a Smalltalk object memory, we can optimize drawing operations involving graphics that are known to both sides of the connection. For example, when changing the mouse cursor to a resize icon when hovering over the corner of a window, there’s no need to send the icon over the wire, since the displaying system already has it. Instead, we can send a much smaller message requesting that the icon be shown.

For full interaction, we also need to handle user input events going back the other way. Snowglobe co-opts Morphic’s user input handling as well. With user input and display forwarded appropriately together, we achieve the seamless illusion that our app is running locally, either as a single morph amongst other local morphs, or using the entire screen.

going beyond screen-sharing

Protocols like VNC do the remote display and user input handling we’ve discussed, although they are typically more complicated to start than clicking a link in a web browser. But since both systems in a Snowglobe session are Smalltalk, we can go beyond simple screen sharing. We can use Tether to send any remote messages we want, so either side can modify the app-streaming behavior in response to user actions. For example, the user might decide to go full-screen in the web browser displaying the app, prompting SqueakJS to notify the remote app, which could change the way the app displays itself.

try it for yourself

I’ve set up an AWS server running the Squeak IDE, reachable from SqueakJS in your web browser. Be gentle… there’s only one instance running (actually two, one in Europe and one in North America, chosen for you automatically by Amazon). Please check it out and let me know what you think!

 

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