fetch-event-source VS vrite

* `text/event-stream` relies on a modified version of [Azure's fetch-event-source](https://github.com/Azure/fetch-event-source). They handle errors and chunking better than I was. New version has been tested out to 4 billion fragments rendered on a single page with no errors.

The EventSource Web API for handling SSEs (built into most modern browsers) unfortunately supports only GET requests, which was quite limiting when a POST request with larger body JSON data was required. As an alternative, you can use the Fetch API or a ready library like Microsoft’s Fetch Event Source.

Aforementioned limitations are taken care with a specialised SSE client (inspired by the awesome @microsoft/fetch-event-source) and two separate connection modes: the HTTP/1 safe "single connection mode" that uses a single SSE connection for receiving events with separate HTTP requests dictating the behaviour, and the HTTP/2+ "distinct connections mode" that uses distinct SSE connections for each GraphQL operation, accommodating the parameters in the request itself.

These reasons (and many others) are why I decided to create Vrite - an open-source developer content platform.

Vrite is an open-source developer content platform, featuring extensible editing experience, content management tools, and powerful APIs. It’s intended as an all-in-one, collaborative solution for product documentation, technical blogs, and knowledge bases.

So, I've been building Vrite as an open-source project for a while now, and I'm happy to finally share it here - with v0.2.0 now having official self-hosting support.

Let’s start by getting into Vrite. You can use the hosted version (free while Vrite is in Beta) or self-host Vrite from the source code (with better self-hosting support coming soon)

You can use Vrite via the hosted version (that’s free while in Beta) or self-host it from the open-source repo (though good support for self-hosting is still in the works).

Since Vrite (and Vrite Editor for that matter) is currently in Public Beta, new features and improvements are in active development. The best way to try it out right now is through the hosted version at app.vrite.io (free while in Beta) with better self-hosting support in the works.

The editor itself is a standalone app, extracted from the larger Vrite CMS project (https://github.com/vriteio/vrite) which you can also test out (only with sign-in) here: https://app.vrite.io/

The main output is JSON ProseMirror format. Other formats are processed from this JSON using Transformers and Vrite SDK: https://github.com/vriteio/vrite/tree/main/packages/sdk/java...

In the GFM transformer I try to follow GitHub Flavored Markdown spec, which technically doesn't support embeds. Since I didn't find any "common" syntax to use for the embeds, I just left them out. They're still there in JSON and HTML outputs.

That's one of the drawbacks of MD. That said, I plan to add an option like Markdoc, which has clearly defined spec for implementing custom blocks like embeds.

That said, for now, if you sign up for the full Vrite CMS, you can create a custom Transformer and process the output so that embeds are included in your desired format. That's what I'm doing for auto-publishing extensions for platforms like Dev.to and Hashnode. I don't know what your use-case is, but I thought it's worth noting.

The process basically came down to figuring out the position and size of the block node, given a selection of an entire top-level node or just its child node (source code):