re-enable backend functionalities #40

Including in particular poly.pizza caching and processing through containers.

Could rely on testing via fetch() if a backend is available then clarify why related capabilities (functions and interface) are unavailable.

Consider also new functionalities e.g

save change on top with optionally reload (as before with sseSend(data))
as this is risky (can end up in a broken state) be able to restore from past working state

So overall might have to consider saving changes in a repository, e.g git managed by the server. See https://twitter.com/utopiah/status/1642788355648675842 providing Gitea on device.

See https://fabien.benetou.fr/pub/home/future_of_text_demo/engine/index.js

Basic example on device (using Termux) to save locally as new.html file

const fs = require('fs');
const express = require('express')
const path = require('path')

const app = express()

app.get('/', function(req, res){
        res.redirect("engine/index.html")
});

app.use('/', express.static(path.join(__dirname, '.')))

const port = 7777
app.listen(port, () =>
  console.log('listening on port', port)
);

app.use(express.json({limit: '50mb'}));
app.use(express.urlencoded({limit: '50mb', extended: true, parameterLimit: 50000}));

// queried as fetch("/",{ method: "POST",  headers: { 'Accept': 'application/json', 'Content-Type': 'application/json' },body: JSON.stringify({number:42})})
app.post("/", (req, res) => {
    res.send(req.body)
    fs.writeFileSync('engine/new.html', String(req.body.number) )
})

Itself can be queried as


fetch("/engine/index.html")
.then( r => r.text() )
.then( t =>  fetch("/",{ method: "POST",  headers: { 'Accept': 'application/json', 'Content-Type': 'application/json' },body: JSON.stringify({number:
    t.replaceAll("jxr", "OK")})}) )

which for examples replace all instances of jxr by OK (and surprisingly doesn't seem to break the code).

See https://factsheet-permanence.glitch.me as remixable Express based examples saving (parsimoniously) and loading all entities with a target component.

See instead https://glitch.com/edit/#!/jxr-permanence with generic content

As container with usual setup, i.e Lets Encrypt subdomain and nginx reverse proxy :

See companion.js in the fot-sloan-companion branch as the most complete version.