Websockets support

[thekid]

This pull request adds websockets to the web server.

In a nutshell

use web\Application;
use web\handler\WebSocket;

class Ws extends Application {

  public function routes() {
    return [
      '/ws' => new WebSocket(function($conn, $payload) {
        $conn->send('You said: '.$payload);
      }),
      '/'   => function($request, $response) {
        $html= ... // Shortened for brevity
        $res->send($html, 'text/html; charset=utf-8');
      }
    ];
  }
}

Complete implemenation at https://gist.github.com/thekid/f933e8ffbc59b35af5e639bdd6f538c2

Backwards compatibility

This pull request breaks BC and thus institutes a 5.0-RELEASE, with the necessity to create compatibility releases for these libraries:

frontend:  "xp-forge/web": "^4.2",
lambda-ws: "xp-forge/web": "^4.0 | ^3.0",
rest-api:  "xp-forge/web": "^4.0 | ^3.0 | ^2.0 | ^1.0",
sessions:   "xp-forge/web": "^4.0 | ^3.0 | ^2.0 | ^1.0",
web-auth:   "xp-forge/web": "^4.0 | ^3.0 | ^2.0 | ^1.0",

All libraries except lambda-ws continue to work as intended. For the AWS Lambda web adapter, see xp-forge/lambda-ws#13

TODO

• Multiplex protocol handling both http and websocket
• Integration tests for WebSocket protocol
• Extend logging API to handle both websocket messages and HTTP requests
• System testing with various server implementations
• Solution for development webserver (reverse proxy w/ websocket <-> SSE translation)

See also

• https://developer.mozilla.org/en-US/docs/Web/API/WebSocket
• https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events

[thekid]

Integration tests for WebSocket protocol

Here's the test:

diff --git a/src/it/php/web/unittest/IntegrationTest.class.php b/src/it/php/web/unittest/IntegrationTest.class.php
index a546932..678dca0 100755
--- a/src/it/php/web/unittest/IntegrationTest.class.php
+++ b/src/it/php/web/unittest/IntegrationTest.class.php
@@ -1,6 +1,7 @@
 <?php namespace web\unittest;
 
 use test\{Assert, After, Test, Values};
+use websocket\WebSocket;
 
 #[StartServer(TestingServer::class)]
 class IntegrationTest {
@@ -161,4 +162,17 @@ class IntegrationTest {
     $r= $this->send('GET', '/cookie', '1.0', ['Cookie' => $header]);
     Assert::equals((string)strlen($header), $r['body']);
   }
+
+  #[Test]
+  public function websocket_message() {
+    try {
+      $ws= new WebSocket($this->server->connection, '/ws');
+      $ws->connect();
+      $ws->send('Test');
+      $echo= $ws->receive();
+    } finally {
+      $ws->close();
+    }
+    Assert::equals('Echo: Test', $echo);
+  }
 }

This institutes a dependency on the websocket client implementation - xp-forge/websockets#6 - and the ability to pass paths - xp-forge/websockets#7 - and would thus bump the minimum version requirement for the respective library to ^4.0, which in turn would cause this library to become PHP 7.4+, resulting in a BC break. Alternatives would be to hardwire websocket handshake and protocol into the integration test, greatly reducint its readability, or to backport the PR to the websocket library's 3.0-SERIES.

[thekid]

System testing with various server implementations

Developed on async server. Verified this works with prefork API, see the PID change for the requests:

[thekid]

Solution for development webserver

This could be done by starting the development webserver as a backend and then:

• Proxying all HTTP requests
• Translating websocket messages to server-sent events

A POC shows this is viable.

[thekid]

This is commented to guarantee synchronous execution of this method due to the backend server only being able to handle one request at a time. We could consider using a worker pool in order to speed things up in a future pull request, or handling requests to static resources inside the proxy itself.

[thekid]

A couple smaller things to be addressed