mirror of
https://git.tuxpa.in/a/code-server.git
synced 2024-12-26 12:15:26 +00:00
48 lines
2.3 KiB
Markdown
48 lines
2.3 KiB
Markdown
|
# Protocol
|
||
|
|
|
||
|
|
This module provides a way for the browser to run Node modules like `fs`, `net`,
|
||
|
|
etc.
|
||
|
|
|
||
|
|
## Internals
|
||
|
|
|
||
|
|
### Server-side proxies
|
||
|
|
The server-side proxies are regular classes that call native Node functions. The
|
||
|
|
only thing special about them is that they must return promises and they must
|
||
|
|
return serializable values.
|
||
|
|
|
||
|
|
The only exception to the promise rule are event-related methods such as
|
||
|
|
`onEvent` and `onDone` (these are synchronous). The server will simply
|
||
|
|
immediately bind and push all events it can to the client. It doesn't wait for
|
||
|
|
the client to start listening. This prevents issues with the server not
|
||
|
|
receiving the client's request to start listening in time.
|
||
|
|
|
||
|
|
However, there is a way to specify events that should not bind immediately and
|
||
|
|
should wait for the client to request it, because some events (like `data` on a
|
||
|
|
stream) cannot be bound immediately (because doing so changes how the stream
|
||
|
|
behaves).
|
||
|
|
|
||
|
|
### Client-side proxies
|
||
|
|
Client-side proxies are `Proxy` instances. They simply make remote calls for any
|
||
|
|
method you call on it. The only exception is for events. Each client proxy has a
|
||
|
|
local emitter which it uses in place of a remote call (this allows the call to
|
||
|
|
be completed synchronously on the client). Then when an event is received from
|
||
|
|
the server, it gets emitted on that local emitter.
|
||
|
|
|
||
|
|
When an event is listened to, the proxy also notifies the server so it can start
|
||
|
|
listening in case it isn't already (see the `data` example above). This only
|
||
|
|
works for events that only fire after they are bound.
|
||
|
|
|
||
|
|
### Client-side fills
|
||
|
|
The client-side fills implement the Node API and make calls to the server-side
|
||
|
|
proxies using the client-side proxies.
|
||
|
|
|
||
|
|
When a proxy returns a proxy (for example `fs.createWriteStream`), that proxy is
|
||
|
|
a promise (since communicating with the server is asynchronous). We have to
|
||
|
|
return the fill from `fs.createWriteStream` synchronously, so that means the
|
||
|
|
fill has to contain a proxy promise. To eliminate the need for calling `then`
|
||
|
|
and to keep the code looking clean every time you use the proxy, the proxy is
|
||
|
|
itself wrapped in another proxy which just calls the method after a `then`. This
|
||
|
|
works since all the methods return promises (aside from the event methods, but
|
||
|
|
those are not used by the fills directly—they are only used internally to
|
||
|
|
forward events to the fill if it is an event emitter).
|