Add WebSocket server (#129)

* server: Add WebSocket server option

* CONTRIBUTORS: Add myself to contributors

* docs: Update standalone docs with websocket server

CHANGELOG.md

@@ -10,11 +10,15 @@ and this project adheres to [Semantic Versioning][semver].
 ### Added
 
 - Testing against Python 3.9 ([#186])
+- Websocket server implementation `start_websocket` for LSP ([#129])
 
 ### Changed
 
 ### Fixed
 
+[#186]: https://github.com/openlawlibrary/pygls/pull/186
+[#129]: https://github.com/openlawlibrary/pygls/pull/129
+
 ## [0.10.3] - 05/05/2021
 
 ### Added

CONTRIBUTORS.md

@@ -7,6 +7,7 @@
 - [DeathAxe](https://github.com/deathaxe)
 - [Denis Loginov](https://github.com/dinvlad)
 - [Jérome Perrin](https://github.com/perrinjerome)
+- [Matej Kašťák](https://github.com/MatejKastak)
 - [Max O'Cull](https://github.com/Maxattax97)
 - [Samuel Roeca](https://github.com/pappasam)
 - [Tomoya Tanjo](https://github.com/tom-tan)

docs/source/pages/advanced_usage.rst

@@ -50,6 +50,22 @@ The code snippet below shows how to start the server in *STDIO* mode.
 
     server.start_io()
 
+WEBSOCKET
+^^^^^^^^^
+
+WEBSOCKET connections are used when you want to expose language server to
+browser based editors.
+
+The code snippet below shows how to start the server in *WEBSOCKET* mode.
+
+.. code:: python
+
+    from pygls.server import LanguageServer
+
+    server = LanguageServer()
+
+    server.start_websocket('0.0.0.0', 1234)
+
 Logging
 ~~~~~~~
 

examples/json-extension/.vscode/launch.json

@@ -29,6 +29,19 @@
             "env": {
                 "PYTHONPATH": "${workspaceFolder}"
             }
+        },
+        {
+            "name": "Launch Server [WebSockets]",
+            "type": "python",
+            "request": "launch",
+            "module": "server",
+            "args": ["--ws"],
+            "justMyCode": false,
+            "python": "${command:python.interpreterPath}",
+            "cwd": "${workspaceFolder}",
+            "env": {
+                "PYTHONPATH": "${workspaceFolder}"
+            }
         }
     ],
     "compounds": [

examples/json-extension/server/__main__.py

@@ -27,7 +27,11 @@ def add_arguments(parser):
 
     parser.add_argument(
         "--tcp", action="store_true",
-        help="Use TCP server instead of stdio"
+        help="Use TCP server"
+    )
+    parser.add_argument(
+        "--ws", action="store_true",
+        help="Use WebSocket server"
     )
     parser.add_argument(
         "--host", default="127.0.0.1",
@@ -46,6 +50,8 @@ def main():
 
     if args.tcp:
         json_server.start_tcp(args.host, args.port)
+    elif args.ws:
+        json_server.start_ws(args.host, args.port)
     else:
         json_server.start_io()
 

pygls/protocol.py

@@ -188,6 +188,8 @@ def __init__(self, server):
         self.transport = None
         self._message_buf = []
 
+        self._send_only_body = False
+
     def __call__(self):
         return self
 
@@ -370,16 +372,18 @@ def _send_data(self, data):
 
         try:
             body = data.json(by_alias=True, exclude_unset=True)
-
             logger.info('Sending data: %s', body)
 
             body = body.encode(self.CHARSET)
-            header = (
-                f'Content-Length: {len(body)}\r\n'
-                f'Content-Type: {self.CONTENT_TYPE}; charset={self.CHARSET}\r\n\r\n'
-            ).encode(self.CHARSET)
+            if not self._send_only_body:
+                header = (
+                    f'Content-Length: {len(body)}\r\n'
+                    f'Content-Type: {self.CONTENT_TYPE}; charset={self.CHARSET}\r\n\r\n'
+                ).encode(self.CHARSET)
 
-            self.transport.write(header + body)
+                self.transport.write(header + body)
+            else:
+                self.transport.write(body.decode('utf-8'))
         except Exception:
             logger.error(traceback.format_exc())
 

pygls/server.py

@@ -15,6 +15,7 @@
 # limitations under the License.                                           #
 ############################################################################
 import asyncio
+import json
 import logging
 import re
 import sys
@@ -30,7 +31,7 @@
                              WorkspaceEdit)
 from pygls.lsp.types.window import ShowDocumentCallbackType, ShowDocumentParams
 from pygls.progress import Progress
-from pygls.protocol import LanguageServerProtocol
+from pygls.protocol import LanguageServerProtocol, deserialize_message
 from pygls.workspace import Workspace
 
 logger = logging.getLogger(__name__)
@@ -97,6 +98,25 @@ def write(self, data):
         self.wfile.flush()
 
 
+class WebSocketTransportAdapter:
+    """Protocol adapter which calls write method.
+
+    Write method sends data via the WebSocket interface.
+    """
+
+    def __init__(self, ws, loop):
+        self._ws = ws
+        self._loop = loop
+
+    def close(self) -> None:
+        """Stop the WebSocket server."""
+        self._ws.close()
+
+    def write(self, data: Any) -> None:
+        """Create a task to write specified data into a WebSocket."""
+        asyncio.ensure_future(self._ws.send(data))
+
+
 class Server:
     """Class that represents async server. It can be started using TCP or IO.
 
@@ -196,7 +216,7 @@ def start_io(self, stdin=None, stdout=None):
 
     def start_tcp(self, host, port):
         """Starts TCP server."""
-        logger.info('Starting server on %s:%s', host, port)
+        logger.info('Starting TCP server on %s:%s', host, port)
 
         self._stop_event = Event()
         self._server = self.loop.run_until_complete(
@@ -209,6 +229,39 @@ def start_tcp(self, host, port):
         finally:
             self.shutdown()
 
+    def start_ws(self, host, port):
+        """Starts WebSocket server."""
+        try:
+            import websockets
+        except ImportError:
+            logger.error('Run `pip install pygls[ws]` to install `websockets`.')
+            sys.exit(1)
+
+        logger.info('Starting WebSocket server on {}:{}'.format(host, port))
+
+        self._stop_event = Event()
+        self.lsp._send_only_body = True  # Don't send headers within the payload
+
+        async def connection_made(websocket, _):
+            """Handle new connection wrapped in the WebSocket."""
+            self.lsp.transport = WebSocketTransportAdapter(websocket, self.loop)
+            async for message in websocket:
+                self.lsp._procedure_handler(
+                    json.loads(message, object_hook=deserialize_message)
+                )
+
+        start_server = websockets.serve(connection_made, host, port)
+        self._server = start_server.ws_server
+        self.loop.run_until_complete(start_server)
+
+        try:
+            self.loop.run_forever()
+        except (KeyboardInterrupt, SystemExit):
+            pass
+        finally:
+            self._stop_event.set()
+            self.shutdown()
+
     @property
     def thread_pool(self) -> ThreadPool:
         """Returns thread pool instance (lazy initialization)."""

setup.cfg

@@ -38,6 +38,8 @@ exclude =
     tests.*
 
 [options.extras_require]
+ws =
+    websockets==9.*
 dev =
     bandit==1.6.0
     flake8==3.7.7

tox.ini

@@ -3,6 +3,7 @@ envlist = py{36,37,38,39}
 
 [testenv]
 extras =
+    ws
     test
     dev
 commands =