deframed 0.2.3

Huh?

The basic idea of building web pages, these days, is to delegate as much as possible to the client. The problem is that if you don’t want to do that, but still like to offer a single-page site to your user, you’re on your own.

Why?

Well, maybe Javascript is a truly annoying language. To you, anyway. Maybe your site logic is Secret Sauce and shouldn’t end up in the browser. Maybe your API shouldn’t be exposed to the outside world. Maybe you want to tell the browser what to display. Maybe you just want to build a Web UI that behaves like any other UI, i.e. read events from the user and tell the screen what to display, period end of story.

Whatever your reason, DeFramed’s purpose is to make sure that you won’t have to deal with programming on the browser side. No more than absolutely necessary, anyway.

Client

DeFramed displays a generic initial page and starts a small Javascript handler that connects to a web socket on your server. It then proxies a handful of DOM manipulation functions and exports a few calls which your user-facing interface elements can use to send events or data to the server.

There’s also basic support for a client-side spinner, a simple way to show alerts if/when the connection breaks, templating (with Mustache) so you don’t need to send redundant data, and rudimentary access to local data to store the equivalent of a cookie and to stash templates on the client. Oh yes, and some rudimentary DOM manipulation, like adding a class to some element.

DeFramed also auto-adds “onclick” handlers to each button and “onsubmit”s to each form (assuming they have an ID and no existing handler), so you don’t have to.

Note the absence of anything that could be interpreted as client-side logic, which is why DeFramed is a non-framework.

Server

If there is zero client-side logic, the server needs to handle everything. (Which it has to do anyway.) Thus, DeFramed includes classes to support all of this.

The DeFramed server is based on Quart-Trio, thus it natively supports async operations. It uses Trio instead of asyncio: cleanly shutting down a complex asyncio application is a debugging exercise nobody should undergo. You can ignore the async stuff, but as soon as you call out to a database you probably don’t want to.

Each client’s events are processed sequentially, though it’s easy to run a background task – which is guaranteed to get terminated when the client disconnects or times out.