Building apps with similar sets of features is universal across software development. Integrating app features such as renders, routers, and state managers can be cumbersome, so developers tend to find solutions to avoid doing it more than once. In this article, we are going to be considering frameworks, how we make them today, and how we can make them better and more feature-rich. While the concept of a framework is not tied to a particular programming language, we will be focusing on Node.js based applications and tooling.
Now, when you hear the word framework, you might be thinking, “I don’t like frameworks, they’re too restrictive.” Or maybe, “Frameworks are too bulky. I don’t need the whole kitchen sink and its features for my apps. Just give me libraries and let me piece together my apps the way I want.”
So let’s say that you decide to build an app without a framework, and you have gone through the process of determining which features your app needs. You have selected libraries for the features, and you are ready to stitch those pieces together to build your app. After tediously integrating these, you can finally implement the contents of the app itself. Now, you have a pretty good app! You continue to iterate on it, tweak some things for performance, improve some code here and there, but now your manager or client asks you to build another app quite similar to this one.
What do you do? Do you start this process over again? Can you take your current work and build from it? Likely you’ll copy the first project, gut the pieces that are specific to that app, and refit it with content for the next app. So, guess what you just did? You made a framework! By copying your previous app, you found a way to develop multiple apps using common patterns and feature sets. Or put another way, a framework upon which to build more apps.
Since you already know how to make a framework, why should you keep reading? Because, quite simply, there is a better way to make a framework. Let’s look at some of the approaches and problems of building frameworks with what is available to us today.
To avoid gutting one app every time you need to make another, you can build a trimmed-down starter app and push it to a repository (repo). You can now clone your starter repo and jump right into building your new app. Starter kit boilerplate repos are a typical pattern which GitHub is littered with.
Yet, even when cloning an app repo, there is still a decent amount of fixup to do. You need to untie it from the original repo, or wipe the old repo files and re-init it. Or, install and use degit to copy the repo without commit history. And still, you likely need to change the app name and some defaults in several places to truly get started.
Alternatively, you can create an app generator. Something like create-react-app can save a few steps when spinning up new apps, but an existing generator may limit the features in your framework unless you build one yourself. If you decide to trudge through the depths of making an app generator, there is also Yeoman, which provides a more composable approach.
However, whether copying repos to create new apps or generating them, these approaches will present a few cascading maintenance problems as the number of apps you develop grows.
Problems with apps from mere starter repos or generators may not present themselves until you are a few apps into it. Say one of the libraries you use has a new release with some cool new features, but the API has changed. You can’t just upgrade your apps with the latest version of the package, as you also have to update the integration code that lives within your apps. What do you do? If there aren’t too many apps and the change is relatively simple, maybe you can make the change along with the package upgrade. If there are other teams building apps off of your starter kit, perhaps you submit PRs to their repos too. Otherwise, you will need to write up a guide on how to upgrade that library and hope they update their app accordingly.
Either way, this can be a big chore for you and anyone who utilized your starter app. Wouldn’t it be better if your integration code did not have to be updated directly in each specific app?
To reduce the amount of library integration code residing in your apps, you can extract it to a separate package. This approach allows you to centralize your library integrations into a distinct package so that you don’t have all that integration code sitting in your apps (where you have to maintain it). When it’s time for an important library to be upgraded, it can be done in your integration package, then consuming apps only need to upgrade your package.
Using packages can also help with code organization in your app, drawing a finer line between where the framework code ends and the app code begins. However, this approach is not without caveats.
By extracting library integrations into separate packages, you create a sort of black box for consuming developers. This forces app developers towards the package’s specific integrations, making it difficult to tie in new features, and near impossible to remove or change existing ones. While that may be suitable for some frameworks and teams, if you want to support experimentation and differentiation for apps using your framework, you should leave the door open for at least some app-specific configurations.
Avoiding a fixed amount of features can be managed by limiting the scope of your integration package and/or by providing integration package choices, which can then be composited into apps.
To allow choices or options in your framework, you might consider a more configurable approach. By providing a way to configure your framework, developers using your framework can adjust it in expected ways. If you know up front that there are a few integration choices for a feature, you could even provide those as turnkey plugins. Maybe the whole kitchen sink is available as plugins, but now developers can pick and choose as they need for their apps.
There are some common difficulties encountered when developing a plugins system, like in determining where plugins can tie into the framework. The framework should provide enough configurable parts to be useful without being overly complicated, but that largely depends on the scope of your framework. This can be a tricky balance.
For example, Next.js is a fantastic framework package that does a great job integrating React with routing and server-side rendering solutions along with Webpack. It supports configuration, but really only ties into the build and start settings and Webpack config. For instance, Next.js doesn’t dictate what server engine or state management libraries you can use, nor does it provide a pluggable way to integrate them. You have to implement these yourself, as that decision is outside the framework’s scope.
Another factor to consider in framework configurability is the runtime aspects of applications. With mere configuration, how can apps tie in various actions or events that your framework may perform during the life of a running app’s process? This can be done with an event system, allowing your app to subscribe to events emitted during various points in the app’s life. An event system can also allow for different layers of an app to communicate in flexible ways.
Now, you may be thinking, “This is a lot of work for a framework. Instead of just copying an app and refitting it, you’re asking me to generate my scaffolding, implement integrations in separate packages, allow for configurations, and now support an event system?”
Well, yes, but fortunately, there is something that can help. Something that can make frameworks more fully-featured beyond what we’ve discussed so far, and that makes frameworks easier to assemble than a simple starter app.
At GoDaddy, we created tooling to help facilitate the development of the Node.js frameworks we use internally, and the good news is: we will be open-sourcing this tooling we call Gasket!
Gasket helps teams and communities compose frameworks to deliver apps of various shapes and sizes. It provides all the elements you need to make a robust framework meeting the needs from what we have discussed so far.
To begin with, Gasket has a command-line interface that you can use to generate an app and to interact with it upon creation. The Gasket CLI is the foundation to build your framework on and to run your apps. Different commands exist to run apps as you would expect, such as ‘build’ and ‘start’. You can also create new apps using the ‘create’ command.
Commands can do anything you want with your app. For example, you can run a command to analyze a web app’s bundle size or run a command that displays docs. Commands are what initiate various lifecycles within apps. Since we have been discussing the use of frameworks for starting new apps, we will look more closely at Gasket’s built-in ‘create’ command from here on.
When running the ‘create’ command, the create lifecycle is executed. When lifecycles are executed, they can be hooked by plugins.
Plugins can hook various lifecycles issued by commands, execute additional lifecycles, and even introduce additional commands. Plugins are the composable packages that integrate libraries and provide features for apps.
By hooking the create lifecycle, plugins can install libraries and generate the necessary scaffolding code where needed. Gasket plugins provide a composable approach to generating apps. Somewhat like composable generators from the aforementioned Yeoman. However, Gasket plugins are not merely for generating, but also stick around in the app for runtime uses.
So, if a framework is a common set of patterns and features upon which you can build apps, how does all this tooling constitute a framework?
As we have discussed, Gasket gives you the foundation to generate an app, run it, and tie into or introduce various lifecycles by way of plugins. Upon determining what plugins you wish to reuse across your apps, these can be stamped into a preset. The known set of features upon which you can build your apps are now in the reusable preset, effectively, the framework.
By specifying the preset when using the Gasket create command to generate a new app, the app will be created with all the features from the plugins you have selected for the preset!
And now we are back to where we began, with a feature set we would like to build our apps from. However, what was once just a copied-around app with some glued together libraries, is now a preset of plugins using Gasket. Making your framework with Gasket plugins in a composable way allows code to be easily maintained and versioned. Establishing plugins into presets allows them to be easily shared to benefit other app and framework developers. Gasket’s modular approach also enables development collaboration, allowing plugins and presets to be contributed to and improved by others.
Whether you utilize Node.js to build web apps, services, CLI tools, or otherwise, you can now use Gasket to quickly compose your reusable features to make your frameworks!
Get started and involved! Stay tuned for more details as we announce our open source release of Gasket soon at Node+JS Interactive 2019. If you are attending the conference, I hope to see you at my talk, Gasket: Framework Maker!