[EclipseCon France 2017] Language Server Protocol in action
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The document discusses the Language Server Protocol (LSP) and its importance for integrating language support within various IDEs and editors. It highlights the challenges of integrating multiple languages and tools and presents LSP as a solution that facilitates easier communication between clients and language servers. The document outlines current capabilities, future improvements, and invites contributions to the LSP project.
![[EclipseCon France 2017] Language Server Protocol in action](https://image.slidesharecdn.com/lspecon-170623085927/85/EclipseCon-France-2017-Language-Server-Protocol-in-action-3-320.jpg)
![Example of communication
● Request for hover
{
"jsonrpc": "2.0",
"id": "27",
"method":
"textDocument/hover",
"params": {
"textDocument": {
"uri":
"file:///home/mistria/runtime-
demoLSP/mess/style.css"
},
"uri":
"file:///home/mistria/runtime-
demoLSP/mess/style.css",
"position": {
"line": 1,
"character": 2
}
}
}
● Response for hover
{
"jsonrpc": "2.0",
"id": "27",
"result": {
"contents": [
"Sets the background color of an
element."
],
"range": {
"start": {
"line": 1,
"character": 2
},
"end": {
"line": 1,
"character": 26
}
}
}
}](https://image.slidesharecdn.com/lspecon-170623085927/85/EclipseCon-France-2017-Language-Server-Protocol-in-action-12-320.jpg)
[EclipseCon France 2017] Language Server Protocol in action
- 1. Hey language, please add support to the hypest IDE/editor of this day! Hey IDE/Editor, please add support for the hypest language of this day in your IDE/Editor ! DONE !DONE ! Language Server Protocol in action ...15 minutes later…
- 2. About... Mickael Istria @mickaelistria Eclipse contributor and committer Focused on IDE technologies ❤ Eclipse IDE and Eclipse community
- 4. Hey language, please add support to the hypest IDE/editor of this day! Hey IDE/Editor, please add support for the hypest language of this day in your IDE/Editor ! DONE !DONE ! Language Server Protocol in action ...15 minutes later…
- 5. Preamble - Lexic ● By language we only mean Textual Language (ie any text with constraints) – at the moment... ● Ad-hoc languages (without constraints pre- defined, but with constraints we can learn from the language) are valid languages ● A server is any application that provide a service. It can be local or remote, using transport of its choice (not only Web nor remote).
- 6. Integrating edition support for one language in one tool ● Requires good knowledge of the language and its technical stack – How to parse it – How to do semantic analysis – Usually a type system – … ● Requires good knowledge of the tool and its technical stack – What are the usual workflows and UX – What is the development style, what are the APIs? – … Difficulty: Tool and language experts
- 7. Java JS TS C# Yaml JSon Ceylon Go ... Eclipse IDE 3 3 3 3 ... ... ... ... ... VSCode 3 3 ... ... ... ... ... ... ... EclipseCh e 3 3 ... ... ... ... ... ... ... Emacs 3 ... ... ... ... ... ... ... ... NeoVim ... ... ... ... ... ... ... ... ... Gnome- Builder ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... M languages N IDEs/Editors Total cost: • O(M*N) difficult integrations • Not usually designed for separation nor reusability as technology differ a lot → can drive to inconsistencies in tools 120
- 8. Enters the Language Server Protocol Language Server Protocol Difficulty: Difficulty: Tool Language/Framework Logic consumes implements <<interface>> Tool experts Language/Framework experts
- 9. Protocol insights ● Initiated as part of VSCode, by emeritus Eclipse IDE contributors ● OSS and community driven aware – Github https://github.com/Microsoft/language-server-protocol ● Request-response and notifications based (over JSON-RPC) ● Transport not constrained: can be stdio, IPC, UDP… ● Deployment not constrained: local thread, local process, remote connection...
- 10. Clients interact with a Language Server ● Clients simply connect to the language server input and output (that may involve starting the language server, or not) ● Then clients orchestrate requests and read response/notifications on JSON-RPC over those streams, and define how user interact with those.
- 11. Protocol operations ● Map well the needs of a Text Editor
- 12. Example of communication ● Request for hover { "jsonrpc": "2.0", "id": "27", "method": "textDocument/hover", "params": { "textDocument": { "uri": "file:///home/mistria/runtime- demoLSP/mess/style.css" }, "uri": "file:///home/mistria/runtime- demoLSP/mess/style.css", "position": { "line": 1, "character": 2 } } } ● Response for hover { "jsonrpc": "2.0", "id": "27", "result": { "contents": [ "Sets the background color of an element." ], "range": { "start": { "line": 1, "character": 2 }, "end": { "line": 1, "character": 26 } } } }
- 13. Turning the matrix into a star Eclipse IDE VSCode EclipseCh e Emacs NeoVim Gnome- Builder ... N IDEs/Editors Total cost: O(M + N) integrations • Designed for separation, distributed work and reusability • Accessible one can decide to only work on the layer they’re skilled at • Enforce consistency of language supports in tools Java JS TS C# YAML JSON Ceylon Go ... 32 2 2 2 2 2 2 2 Language Server Protocol 2 2 2 2 2 2 2 2
- 14. Language Server “SDKs” ● Libs already exist in multiple languages to create language servers or clients. ● They typically map operations and entities of LSP to APIs and Data Types. ● Eclipse LSP4J is a Java API to produce Java-based LSP clients or servers.
- 15. Benefits for Eclipse technologies ● Ceylon, Xtend, Xtext, EMF... can implement the LSP in their SDK and enable code-assist in many tools at once ● Frameworks or tools that build on top of languages can also provide additional hints/static analysis/linters ● IDEs can implement support for LSP to easily support many languages
- 16. Demo Language Server Protocol Demoed and detailed at +3 others so far: Atom, Monaco, Gnome Builder +20 others so far: PowerShell, C++, JSON, CSS/LESS/SASS, PHP, Haxe, RAML, API Elements, groovy, SQL, Ocaml/Reason, Go, Rust, Scala, Polymer, Julia, Python, Isabelle. GraphQL, ember
- 17. Demo debrief (1/2) In ~20 minutes we: – Showed CSS/HTML/C# integration in Eclipse IDE is a matter for a few basic lines of Java and plugin.xml – Edition using language server is comfortable and can quickly be better than edition with unmaintained editors – Showed VSCode integration for language servers is simple too – Showed Java integration in VSCode is powered by Eclipse JDT Language Server – ….
- 18. Demo debrief (2/2) In ~20 minutes we: – ... – Showed how easy it is to create own language server with Java and Eclipse LSP4J (just implement a few interfaces!) – Showed how a home-made language server can very easily be integrated in Eclipse IDE and VSCode – Modified the language server and showed how tools can take advantage of iteration and new features without effort
- 19. Not convinced yet? With 10 more minutes... ● We could have shown a similar demo with any of Python, PHP, Kubernetes Yaml dialect, or any of the 20+ other supported languages ● We could have shown the same languages supported similarly in Eclipse Che, Eclipse Orion, NeoVim, Gnome-Builder or any of the other supported tools
- 20. Limitations of LSP ● Focused on EDITION only. Missing other steps of dev such as running, testing, debugging (a protocol-ish is ongoing for debug) ● Misses some important operations – Type hierarchy – Refactorings ● Syntax highlighting not part of the protocol (but well covered by TextMate grammars) ● Composition of LSP: how to chain them? Do multiple LS on the same file complete one and other or conflict?
- 21. (Desired) Future of LSP ● Support for more typical edition actions (such as refactorings or type hierarchy) ● Adoption of the Debug Server Protocol (including support for Run and Tests)
- 22. Join the LSP game! ● https://github.com/Microsoft/language-server-protocol – Contribute to specification – Contribute by listing your support for a language or a tool ● Eclipse LSP4J: Contribute to Java bindings for LSP ● Eclipse LSP4E: Contribute to Eclipse IDE support for LSP ● Eclipse Che supports LSP ● Eclipse Orion supports LSP ● Other edition time technologies: consider adopting the protocol for wider consumption