Imaging an arbitrary Mill module, which provides some language support, for example a fictivemill-rust plugin. To integrate nicely in the BSP server, it may need to provide something to it, e.g. each module (trait RustModule extends mill.scalalib.bsp.BspModule) want to provide some dependencies. It would be nice to use the dedicated classes from bsp4j (RustWorkspaceResult,RustDependency, ...), without forcing the transitive dependencies of bsp4j on the build classpath.

Of course, thismill-rust plugin may also provide some BSP server extension, which will assume the full current bsp4j classpath present. Let's consider this the implementation detail not of interest here.

My concern is to split the published bsp4j artifact into an artifact with only some Pojos (without dependencies on gson and guava), and one containing the actual server implementation.

• I opened issueSplit artifacts into absp4j.protocol and absp4j.server #668

@agluszak Maybe, I misunderstood you, but I though this issue should be fixed rather soon. Now, the bazel migration is done for some time, but I didn't receive any comments on#668.

Ah, sorry, we now have a busy time at JB. I'll try to handle it next week, okay?

Didn't manage to find time to do that this week and since next week I'm on vacation, perhaps it's best if I write instructions for you and you do it yourself. You don't need to have experience with bazel to do it.

1. Each library (bsp4s, bsp4j and also bsp4kt, bsp4rs and bsp4ts - which are not in this repository) has a corresponding generator which loads the smithy definition and emits source code in the respective language. In your case it will be easiest if you just copy the bsp4j generator and startremoving things. Seehttps://github.com/build-server-protocol/build-server-protocol/blob/master/codegen/src/main/kotlin/bsp/codegen/bsp4j/JavaRenderer.kt andhttps://github.com/build-server-protocol/build-server-protocol/blob/master/codegen/src/main/kotlin/bsp/codegen/bsp4j/Main.kt
2. Then you'll have to define the generator binary here:https://github.com/build-server-protocol/build-server-protocol/blob/master/codegen/BUILD
   It will look something like this:

kt_jvm_library(    name = "bsp4j-lite",    srcs = glob(["src/main/kotlin/bsp/codegen/bsp4j-lite/**/*.kt"]),    visibility = ["//visibility:public"],    deps = [        "@//codegen",        "@maven//:org_eclipse_xtend_org_eclipse_xtend_core",        "@maven//:org_eclipse_xtend_org_eclipse_xtend_lib",        "@maven//:org_eclipse_xtext_org_eclipse_xtext_xbase_lib",    ],)

(assuming that you still want to use xtend and write it in kotlin, like the current bsp4j generator).
3. Then you have to register the generator herehttps://github.com/build-server-protocol/build-server-protocol/blob/master/BUILD

java_binary(    name = "bsp4j-lite-generator",    main_class = "bsp.codegen.bsp4j.lite.Main",    visibility = ["//visibility:public"],    runtime_deps = [        "//codegen:bsp4j-lite",    ],)

4. Then you'll need to create a bsp4j-lite top level folder and put there a build file like this one:

load("@bazel_sonatype//:defs.bzl", "sonatype_java_export")load("//:version.bzl", "BSP_VERSION")load("//tools/rules/generator:generator.bzl", "library_generator")library_generator(    name = "generate-bsp4j-lite",    gen_tool = "//:bsp4j-lite-generator",    out_dir = "src",    visibility = ["//visibility:public"],)sonatype_java_export(    name = "bsp4j-lite",    srcs = glob(["src/**/*.java"]),    data = [        ":generate-bsp4j-lite",    ],    maven_coordinates = "ch.epfl.scala:bsp4j-lite:%s" % BSP_VERSION,    maven_profile = "ch.epfl.scala",    pom_template = "//tools/maven:pom.tpl",    visibility = ["//visibility:public"],)

5. Now you'll be able to generate the library by runningbazel run //bsp4j-lite:generate-bsp4j-lite (well, assuming you have bazel on your machine, ofc).

Cc@jastice@abrams27

@lefou did you make progress there?

No, I didn't try.