Dune RPC¶
Starting from dune 3.0, dune’s watch mode also runs an RPC server. This is a general mechanism introduced to integrate with various dune functionality. Some use cases we have in mind are:
Text editors that would like to receive dune’s error reporting
In the future, custom actions that need to communicate with dune
There’s no fixed scope for RPC, and we encourage users to submit requests to cover more functionality.
The purpose of this documentation is to explain how RPC works, and how to connect to it as a client. More concrete information such as what requests are available is in Dune_rpc
dune-rpc library¶
We provide a client library dune-rpc
to make it easy to write clients. The
library has a versioned interface and we guarantee to maintain its stability.
The library documentation describes the guarantees in more detail.
RPC clients written with this library are guaranteed to work for all versions of
the RPC server greater than it. In other words, a client using version X
will work with all servers >= X
. However, it will not work with any servers
< X
.
The library contains a client implementation parameterised over a concurrency
monad. The dune-rpc-lwt
package provides an instantiation of the RPC client
defined in dune-rpc
using lwt to implement the concurrency monad.
It is of course possible to instantiate the dune RPC client using alternative
concurrency implementations.
The dune-rpc
library provides an API to do the following:
Initialise an RPC session over a channel
Send RPC requests and notifications
Handle notifications received from the server
Definitions of available requests, notifications, and their associated types.
Subscribe to streams of build progress events
Here is an example of a simple Dune RPC client that
uses the dune-rpc
and dune-rpc-lwt
packages.
Connecting¶
To connect to Dune’s RPC server, it needs to be started in watch mode. It is
possible to use dune build --passive-watch-mode
to start an RPC server which
will listen for requests without starting a build by itself. Then dune rpc
build .
will connect to it, trigger a build, and report status.