Feedback from an eclipse plugin developer to provide support to large set of ide based on language server protocol

1. Feedback from an Eclipse plugin developer
to provide support to a large set of IDE
based on Language Server Protocol
Aurélien Pupier
Principal Software Engineer
19th
November 2019
@apupier
Eclipse Tools Day Grenoble 2019

2. I’m an Eclipse Plugin developer.
I want to reach a larger audience for my Language.
Context
2

3. 3
Which complexity?
IDE skills Language skills
Eclipse
Desktop IDE
VS Code
Emacs
...
N implementations
with high skill required in language and IDE extension

4. Write Code Editing capabilities once, run in all IDEs!
The Promise of Language Server Protocol
4

5. Write Code Editing capabilities once, run in all IDEs!
(after a setup for each IDE and for most features)
The (real) Promise of Language Server Protocol
5

6. - Autocomplete
- Hover
- Code Lens
- Goto Definition/References
- Formatting / Coloring
- Renaming
- Code actions
- Highlighting
- Folding
- Diagnostic
Code editing capabilities
6

7. 7
Language Server
More coming...
N implementations with low skill for IDE
+ 1 implementations with high skill required in language only

8. 8
Language Server

9. How to write the server?
9
LSP4J

10. How to write the server?
10
● LSP4J
● Fat jar for easy launch
● Restrict to a single-file scope (if possible)
● TextDocumentSyncKind.Full
● sysin/sysout
○ ⇒ No log on sysout!!

11. Server Implementation examples
11
● Very simple
○ https://github.com/apupier/language-server-template-java
● Good examples
○ https://github.com/camel-tooling/camel-language-server
○ https://github.com/angelozerr/lsp4xml
● A full blown headless Eclipse desktop
○ https://github.com/eclipse/eclipse.jdt.ls
● Search in Official site listing
○ https://microsoft.github.io/language-server-protocol/implementors/servers/

12. I have a first server iteration:
Now test with IDEs!
12
● Configuration more or less easy
● Too complex for real users!!
⇒ Need to provide a client per IDE starting the server!
⇒ in different languages!
⇒ in different communities!

13. With which IDE to start?
13
● Eclipse Desktop IDE
○ we know it!
● VS Code
○ De facto “reference implementation”
○ Trendy
○ Can be reused in Eclipse Che
● Listen to your existing community

14. Technical advice - IDE integration
Eclipse Desktop (1/2)
14
● LSP4E
● (Process)StreamConnectionProvider
● Content-type association
● Generic text editor only!

15. Technical advice - IDE integration
Eclipse Desktop (2/2)
15
● To help development:
○ Configure remote debug possibilities
○ Communication log

16. Technical advice - IDE integration
VS Code (1/2)
16
● How to launch Java from TypeScript?
○ Java LSP client example, now also Camel Client
● Writing a test is not trivial
● Not friendly with bad request
○ log on stdout → crash!

17. Technical advice - IDE integration
VS Code (2/2)
17
● To help development:
○ Logging
○ LSP inspector

18. Technical advice - IDE integration
Eclipse Che 7
18
● Reuse VS Code extension
● Web-based demo!

19. Technical advice - IDE integration
CodeMirror
19
● Embeddable web editor
● /! WebSocket
● Limited functionalities

20. In a nutshell
20
● LSP known only in Eclipse/Tooling world
● Key points:
○ List of potential supported IDEs
○ Demo in one desktop and one web-based IDE
○ Marketplace entries
● Few work weeks to have several IDEs supported
● Plan a bit of time to bootstrap for all wanted IDEs

21. Start writing your Language Server!
Aurélien Pupier
Principal Software Engineer
@apupier
Eclipse Tools Day Grenoble 2019

22. 22

23. Technical advice - IDE integration
Atom
23
● Easy to publish to Marketplace
● Small codebase
● Hard to debug/setup dev env

24. Technical advice - IDE integration
Vim
24
● Lightweight
● Only readme provided
● Ecosystem is too complicated for newcomers

25. Time/resource management
25
● Half-day per week for 2 developers during 7
months
○ Regularly skipped…
○ But also several hours reading docs
● 1-2 days per week for 2 developers during 2
months
● Communities working on LSP are active

26. Architecture - multi-Language Server
26
● Several LS on same file?
● How to avoid redundancy?
○ Extension points in a LS?
○ Clients responsible to merge results?
○ Formatting?

27. What’s next?
27
● Cross-LS…
● Other protocols?
○ Debug Adapter Protocol
○ Graphical server protocol?
○ Creating new project?
● IDE client?
○ Docker
○ LS Marketplace?
○ Clients generator?