Server-side events as configuration

[ctrekker]

As discussed in the developer call on 1/27, here are a few changes related to server-side event listeners.

List of changes

• Move event listener to configuration
  • Had to add a MsgPack.to_msgpack for functions that returns null so Pluto doesn't try to serialize the event listener function
• Update Events.jl docstring with updated instructions
• Rename event_listener to on_event since its shorter and maybe more descriptive?
• Assign configuration port if none was provided (see comment below)

Example Usage

import Pluto

# catches unwanted events
function myfn(a::PlutoEvent)
    nothing
end
# catches the notebook `save` event
function myfn(a::FileSaveEvent)
    HTTP.post("https://my.service.com/count_saves")
end

Pluto.run(; on_event=myfn)

Backwards Compatibility

This PR would technically break backwards compatibility. I don't think refactoring everything to kwargs is too bad, but if others think otherwise we can add the following method definition for ServerSession and everything should (I didn't test it) be backwards compatible.

function ServerSession(; event_listener::Function, kwargs...)
    s = ServerSession(; kwargs...)
    s.options.server.on_event = event_listener
    s
end

TODO

• On server start event that sends port

[github-actions]

Try this Pull Request!

Open Julia and type:

julia> import Pkg
julia> Pkg.activate(temp=true)
julia> Pkg.add(url="https://github.com/fonsp/Pluto.jl", rev="cb/events-as-config")
julia> using Pluto

[ctrekker]

I added this because otherwise server-side event consumers would have no way of knowing what port Pluto is running on. This would only assign the configured port when it is not explicitly provided.