Creating a Seaside “Hello World”, localhost

Table of Contents:

Note: This section assumes that you’ve mastered the basics of creating new classes and methods in Pharo Smalltalk. If not, I recommend you glance through the Paro By Example, or my own previous post on Creating Classes and Methods in Pharo.

Note 2: See also the Getting Started (Pharo and Squeak) section of Dynamic Web Development with Seaside for a similar “getting started” tutorial, with screenshots.

Time to create our first “Hello World” app in Smalltalk/Seaside. Here’s the plan:

  1. Create a new Category and component (read: class) for our app.
  2. Create a method to output ‘Hello World’
  3. Register the component with Seaside, so it can start routing requests
  4. Profit! (That is, load up the page in the browser, and behold Hello World)

1.a. Creating a Seaside Component – The How

Creating a Seaside component is easy. First, create a Category for this tutorial – something like ‘RHelloWorld-Core’. Now, inside it, create a class (a subclass of WAComponent) called, for example, RHelloWorldComponent. Like this:

WAComponent subclass: #RHelloWorldComponent
	instanceVariableNames: ''
	classVariableNames: ''
	poolDictionaries: ''
	category: 'RHelloWorld-Core'

That’s it. You’re a third of the way done (now we just need to create a method to output ‘Hello World’, and register the component with the framework, so it can start routing).

1.b. Creating a Seaside Component – The Why

So, what is a component? A Seaside component is a subclass of WAComponent (the “WA” stands for “Web Application”, incidentally). Great, but what is it really? To answer that, we need to briefly discuss how you write web apps in Seaside.

Think of a component as a “smart view”. What about Models, though? And Controllers? Well, components that are complex enough to need models, have models. That is, Models are also a concept that Seaside uses. Since we’re just writing a static “Hello World” app, we don’t need a model, we’re just going to output a literal string directly. What about Controllers, though? Don’t we need a Controller? Well, no. Not as such. Part of the answer is – Seaside (and the programming language itself) IS the Controller. It takes on the traditional role of the controller (routing requests, calling the right objects and methods, managing sessions and marshalling parameters). Seaside also has Tasks (subclasses of WATask), which are view-less control and routing objects that manipulate other components, a job traditionally reserved for Controllers in the MVC paradigm. But again, we don’t need Tasks for a Hello World tutorial.

The easiest way to understand Seaside web development is to think of it in terms of traditional desktop GUI development. Say you open up a desktop application, like Firefox or Outlook Express. You see a window, and within it, panes and toolbars, and within those, buttons and lists and other GUI widgets. In Seaside, the application/”window” is a top-level Component, which displays sub-components (toolbars, navigation menus, panes). In a desktop app, the components keep track of their own states (and have models if need be), and have Events/Actions defined for when you interact with them (click on a button, scroll the scrollbar, and so on). Same thing in Seaside. So a Seaside app is “just” a nested collection of components, which keep track of their own states, and which register events or actions that are performed when a user clicks on a link or selects a value from a pulldown, and so on.

If that’s too confusing, or if you haven’t done desktop GUI programming, don’t worry about it. In Seaside, you’ll be dealing with Views, Models when you need them, and occasionally view-less controller-like Tasks.

2. Create a method to output ‘Hello World’

Ok, let’s create a method in our RHelloWorldComponent class. (You can either put it in the default --all-- method category, or, more correctly, create a rendering method category, and add the method there).

renderContentOn: html
	html text: 'Hello World!'.

3. Register RHelloWorldComponent with Seaside

Lastly, we need to register our component with Seaside (specifically, the Web Application Admin class), so it can start routing requests to it.

Execute the following snippet of code:

WAAdmin register: RHelloWorldComponent 
	asApplicationAt: 'helloworld'

Hold up. How do I execute code in Squeak/Pharo?
You can execute code from any code editor or workspace in the Pharo image. Traditionally, snippets of code (or “incantations”) are executed from a Workspace window, which just looks like a blank text editor window. To open one, click anywhere in the background of the Pharo window to bring the the World Menu, and select Workspace. You’ll see a blank text window. Now you can type arbitrary code in here, select it with your mouse, right-click on it and select Do It (d). The keyboard shortcut is Meta-d, of course.

Ok! Now, when you access the /helloworld url on your web server (in our case, running it by default on the desktop, it will be http://localhost:8080/helloworld), Seaside is going to locate the RHelloWorldComponent (since that’s what we registered as the top-level component of our application up above) and execute the renderContentOn: method.

Test it out – load it up in your browser, and you should see

Hello World!

displayed on a plain white html page.

Coming up next: Obtaining access to a remote server, installing Pharo on it, and packaging up your app for deployment.

A Secret: Passion and Your Choice of Web Framework

I will tell you a secret. I am passionate about Smalltalk and the Seaside web app framework. Not just on an intellectual level, “oh hey this is pretty cool, it’s got some good ideas”. But on a fire-in-my-heart level, “this is profound and important technology” kind of stuff.

Why? Good god, why? Why should a choice of language, or especially a choice of which web app framework to use, matter? Because, I believe that:

Your choice of app framework deeply affects your development speed, and your overall level of courage.

Choosing the right framework means you will finish your projects faster, and you will dare to include better and more audacious features in it.

Life is very short. You have a limited amount of time in which to realize your dreams, in which to do your projects. If you’re like me, you probably have dozens and dozens of ideas for apps, sites, portals, that you want to implement. Most of those ideas will suck. But you don’t know which ones, you won’t know until you try them. Your goal, in this life, is to iterate faster. To fail more, to fail quicker, until you get to the brilliant ideas and brilliant projects that can change the world, or at least make you a dollar or two.

I want to be able to code at the speed of thought. At the speed of dreaming. Or rather, at the speed of essential complexity, without the overhead of the accidental. See, there is a notion in computer science of Essential complexity versus Accidental complexity. Essential complexity is “Hmm, I’m trying to solve a difficult real-world problem that is complex and messy”, and accidental complexity is “why the hell can’t I easily do this simple thing in my framework?!”. And I believe that while the first will never go away, there is still too much of the second, of the overhead, of cruft, in the world of web frameworks.

Based on my experience, I believe that the Seaside framework is the most powerful and flexible one, that has the potential to come closest to “development at the speed of dreaming”. It is not quite there yet. But it can be, with not too much more effort.

Now it’s time for a confession: the fastest-to-develop in, most prototype-friendly framework that I’ve had the pleasure to work with so far is not Seaside, nor is it Ruby on Rails (which has other reasons to recommend it). It’s a relatively unknown (dare I say underdog?) Python framework called web2py, headed by Massimo Di Pierro. Its ease of use, quality of documentation and community support, and the amount (and integration) of out-of-the-box features made (on large project with a small team) development quick, easy and secure. I am seriously grateful to Massimo and the web2py community for raising my standards of what a web app framework should do.

Then what am I doing here? Why isn’t this blog called “web2py Zen”? Because, I believe that the features that make web2py fantastic (like comprehensive documentation, out-of-the-box authentication and user management, ease of use and diversity of persistence options, amazing error logging capabilities, etc) can be added to Seaside – with some effort, but it’s not impossible. Whereas the key features of Seaside (the continuations, the reuse and embedding of components, Halos and the debugging process) cannot be easily (or at all) added to web2py. Smalltalk (and Seaside) is fundamentally “upstream” to Python, in the sense that Paul Graham writes about.

So, Seaside could be my ideal web app framework. It is built on some amazing technology, and has features unsurpassed by any other framework at the moment (and has plenty of drawbacks, sure, but none unfixable). It’s going to take some work (and that’s part of what starting this blog has been about, for me), but it also has a vibrant community around it that I think is up to the task.

One more thing. While I believe that the choice of frameworks is important, and that some are, objectively, better than others (for certain goals), I don’t want the arguments over which one is better to be based solely on personal opinion. I want the frameworks to prove themselves, to pull their own weight. What I really want to see is studies, and competitions between frameworks. I want web framework olympics, of the kind that Plat-Forms is trying to do (only that’s in Germany – I would love to see more US-based ones). I want to see evidence, and experimentation. And will strive to provide some of my own.

Am I advocating that you choose one framework (that you think is best) and really focus on it, practice the hell out of it? Yes. But also: You have to try all the other frameworks. You have to periodically re-evaluate your choice. If some other framework is doing something fundamentally right, and you can easily add it to your framework, do it. If not, if they’re doing something right and profound and you can’t add it to your framework (perhaps because of language limitations), perhaps you need to reconsider your allegiance.

In any case, whatever your favorite language: Choose the right app framework. Love it, improve it, practice the hell out of it. Re-evaluate your choices periodically. And iterate faster.