Binary protocol channeling over HTTP

[1st1]

Requires the server to run with edgedb/edgedb#3682.

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@jaclarke James, I hope this would unblock you to implement querying from the admin panel.

Some notes:

1. I've only tested this running from the nodejs environment (not browser). The key limitation here is that node (pre 17.5) doesn't have native fetch(), so I'm using node-fetch to emulate it for testing purposes. When you run this in the browser, you might need to update FetchSocket.write() to properly cast emulated Buffer to something that browser's fetch() can understand (most likely ArrayBuffer).

2. Every HTTP request essentially creates a new (temporary) binary connection on the server. Which means that the typical [parse] [execute] message sequence doesn't work!

   • When you execute [parse] it creates an anonymous statement.
   • The subsequent [execute] message doesn't see that anonymous statement, because the connection is already different.
   • The way to fix this is to use the [parse] [optimisticExecute] sequence, essentially not relying on anonymous statements at all.
   • I've fixed (in a hacky way) the .query() method to do just that and it works. However, iirc the studio uses the rawExecute method that would have to be updated to also use optimistic execute.

3. Aside from the above it should work in the browser. I'll be completing some ToDos over the next couple of days, but you should be able to start playing with this.

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ToDo

• Proper state management in FetchSocket
• Think about the API -- do we want createClient to automatically detect the browser environment and try to use fetch()? (this decision can wait at least until we think about enabling this feature beyond admin panel)

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@jaclarke to test things from nodejs:

edgedb = require('./dist/index.node.js');

async function main() {
  con = edgedb.createFetchClient({host: 'localhost', port: 5656});
  console.log(await con.query('select 1'));
  console.log(await con.query('select {1, 2, 3}'));
}

main()

(don't forget to run yarn to install node-fetch@2)

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James, lastly, please commit and push directly to this branch when you make this work in the browser.

[1st1]

@jaclarke this should be ready for merge. Please review, push any changes you see necessary, and merge/release.