Update web socket examples

examples/C/src/browser-ui/README.md

@@ -18,6 +18,6 @@ The UI runs in the browser and connects to the program via either HTTP or via a
 </tr>
 <tr>
 <td> <img src="img/Uptime.png" alt="Uptime" width="400">
-<td> <a href="Uptime.lf"> Uptime.lf</a>: This version combines ServerUI with WebSocketServer to serve a web page and then feed it data continuously through a web socket. The application displays the total time that application has been running and updates this time once per second.</td>
+<td> <a href="Uptime.lf"> Uptime.lf</a>: This version uses WebSocketServer to serve a web page and then feed it data continuously through a web socket. The application displays the total time that application has been running and updates this time once per second.</td>
 </tr>
 </table>

examples/C/src/browser-ui/Uptime.lf

@@ -1,18 +1,20 @@
 /**
- * This example combines `ServerUI` with `WebSocketServer`. The former starts a web server that
- * listens for HTTP requests on port 8080 and serves the web page defined in `uptime.html`. That web
- * page includes JavaScript that connects to a web socket on port 8080 that is provided by the
- * `WebSocketServer` reactor. The resulting web page simply reports the total time that this program
- * has been running. That time is updated on the web page once per second.
+ * This example uses `WebSocketServer` to start a web server that listens for HTTP requests on port
+ * 8080 and serves the web page defined in `uptime.html`. That web page includes JavaScript that
+ * connects to a web socket on port 8080 that is provided by the `WebSocketServer` reactor. The
+ * resulting web page simply reports the total time that this program has been running. That time is
+ * updated on the web page once per second.
  *
  * This uses the <a href="https://libwebsockets.org">libwebsockets</a> (see <a
  * href="https://libwebsockets.org/lws-api-doc-main/html/index.html">API documentation</a> and <a
  * href="https://libwebsockets.org/lws-api-doc-main/html/md_READMEs_README_build.html">installation
  * instructions</a>). To install on MacOS, we recommending using brew:
- * <pre> brew install libwebsockets
- * </pre> This puts the compiled libraries in {@code /usr/local/lib}, and these libraries can be
- * linked to using the {@code -lwebsockets} compile option or the {@code WebSocketCmake.txt} Cmake
- * include file.
+ * ```
+ * brew install libwebsockets
+ * ```
+ * This puts the compiled libraries in {@code /usr/local/lib}, and these libraries can be linked to
+ * using the {@code -lwebsockets} compile option or the {@code WebSocketCmake.txt} Cmake include
+ * file.
  *
  * @author Edward A. Lee
  */
@@ -30,10 +32,6 @@ main reactor {
       hostport=8080,
       initial_file = {= LF_SOURCE_DIRECTORY LF_FILE_SEPARATOR "Uptime.html" =})
 
-  reaction(startup) {=
-    lf_print("Point your browser to http://localhost:8080");
-  =}
-
   reaction(seconds) -> w.send {=
     instant_t uptime = lf_time_logical_elapsed();
     // Truncate to the nearest second.

examples/C/src/lib/WebSocketServer.lf

@@ -315,12 +315,6 @@ reactor WebSocketServer(
               if (to_send->binary) {
                 result = lws_write(to_send->wsi, &buffer[LWS_PRE], length, LWS_WRITE_BINARY);
               } else {
-                // Check for null terminator.
-                if (buffer[LWS_PRE + length - 1] != '\0') {
-                  // Null terminator is missing.
-                  buffer[LWS_PRE + length] = '\0';
-                  length += 1;
-                }
                 result = lws_write(to_send->wsi, &buffer[LWS_PRE], length, LWS_WRITE_TEXT);
               }
               if (result < length) {
@@ -495,6 +489,10 @@ reactor WebSocketServer(
 
     lf_thread_t listener;
     lf_thread_create(&listener, &websocket_thread, &self->status);
+
+    if (self->initial_file != NULL) {
+      lf_print("**** Point your browser to http://localhost:%d", self->hostport);
+    }
   =}
 
   reaction(received_action) -> received {=

examples/C/src/lib/WebSocketServerString.lf

@@ -13,7 +13,7 @@
  * the running LF program. To specify a file located in the same directory as your source LF file,
  * you can use a syntax like this:
  * ```
- * s = new WebSocketServer(
+ * s = new WebSocketServerString(
  *    initial_file = {= LF_SOURCE_DIRECTORY LF_FILE_SEPARATOR "filename.html" =}
  * )  
  * ```
@@ -40,15 +40,15 @@
  *
  * A key limitation is that this should use the secure sockets API in libwebsockets to get SSL.
  *
- * @param hostport The host port number, which defaults to 8000.
+ * @param hostport The host port number, which defaults to 8080.
  *
  * @author Edward A. Lee
  */
 target C
 
 import WebSocketServer from "WebSocketServer.lf"
 
-reactor WebSocketServerString(hostport: int = 8000, initial_file: string = {= NULL =}) {
+reactor WebSocketServerString(hostport: int = 8080, initial_file: string = {= NULL =}) {
   input in_dynamic: char*
   input in_static: string
 
@@ -62,6 +62,9 @@ reactor WebSocketServerString(hostport: int = 8000, initial_file: string = {= NU
 
   reaction(startup) {=
     self->ws.connected = false;
+    if (self->initial_file != NULL) {
+      lf_print("**** Point your browser to http://localhost:%d", self->hostport);
+    }
   =}
 
   reaction(in_dynamic, in_static) -> server.send {=
@@ -76,7 +79,7 @@ reactor WebSocketServerString(hostport: int = 8000, initial_file: string = {= NU
         strcpy(message_copy, in_static->value);
       }
       to_send->message = message_copy;
-      to_send->length = strlen(in_dynamic->value) + 1;
+      to_send->length = strlen(in_dynamic->value);
       to_send->wsi = self->ws.wsi;
 
       lf_set(server.send, to_send);

examples/C/src/sdv/ParkingAssist.html

@@ -59,7 +59,7 @@ <h1>Controls</h1>
     window.onload = function() {
 
         // Create the web socket connection for the dashboard display.
-        const socket = new WebSocket('ws://localhost:241', 'ws');
+        const socket = new WebSocket('ws://localhost:8080', 'ws');
 
         socket.addEventListener('open', (event) => {
             console.log('WebSocket connection established for dashboard display');
@@ -97,7 +97,7 @@ <h1>Controls</h1>
         });
 
         // Create the web socket connection for the controls.
-        const socket2 = new WebSocket('ws://localhost:240', 'ws');
+        const socket2 = new WebSocket('ws://localhost:8081', 'ws');
 
         socket2.addEventListener('open', (event) => {
             console.log('WebSocket connection established for the controls.');

examples/C/src/sdv/ParkingAssist.lf

@@ -24,8 +24,6 @@
  * should be displayed.
  * <li> There is only one distance sensor and no mechanism for setting up a test environment where
  * obstacles are placed.
- * <li> The web server works by being polled. It should instead accept a web socket connection so
- * that the program can push data to the display.
  * <li> The web server has no security.
  * </ul>
  *
@@ -36,9 +34,8 @@ target C {
   keepalive: true
 }
 
-import WebSocketServer from "../lib/WebSocketServer.lf"
+import WebSocketServerString from "../lib/WebSocketServerString.lf"
 import PlayWaveform from "../rhythm/PlayWaveform.lf"
-import ServerUI from "../lib/ServerUI.lf"
 
 /**
  * Emulator for automotive sensors. It outputs sensor data periodically with the specified sample
@@ -64,7 +61,7 @@ reactor Sensors(
 
   timer t(0, sample_interval)
 
-  s = new WebSocketServer(hostport=240, max_clients=1)  // Allow only one client
+  s = new WebSocketServerString(hostport=8081)
 
   /**
    * Given JSON of the form {..., "key":"value", ... }, if the value is an int, put that int value
@@ -88,7 +85,7 @@ reactor Sensors(
   =}
 
   reaction(s.received) {=
-    char* json = s.received->value->message;
+    char* json = s.received->value;
     lf_print("Received control: %s", json);
     int accelerator;
     if (json_to_int(json, "accelerator", &accelerator) == 0) {
@@ -126,24 +123,19 @@ reactor Dashboard {
   input speed: int
   input front_distance: int
 
-  state connection: web_socket_instance_t = {= {0} =}
+  state connection: bool = false
 
-  s = new WebSocketServer(hostport=241, max_clients=1)  // Allow only one client
+  s = new WebSocketServerString(
+      hostport=8080,
+      initial_file = {= LF_SOURCE_DIRECTORY LF_FILE_SEPARATOR "ParkingAssist.html" =})
 
-  reaction(speed, front_distance) -> s.send {=
+  reaction(speed, front_distance) -> s.in_dynamic {=
     // Ignore the inputs if we are not connected.
-    if (self->connection.connected) {
+    if (self->connection) {
       // Construct payload.
       char* message;
       asprintf(&message, "{\"front_distance\": %d, \"speed\": %d}", front_distance->value, speed->value);
-
-      // Construct struct to send.
-      web_socket_message_t* response = (web_socket_message_t*)malloc(sizeof(web_socket_message_t));
-      response->length = strlen(message);  // Do not include the null terminator.
-      response->wsi = self->connection.wsi;
-      response->message = message;
-
-      lf_set(s.send, response);
+      lf_set(s.in_dynamic, message);
     }
   =}
 
@@ -200,7 +192,6 @@ main reactor {
   s = new Sensors()
   d = new Dashboard()
   a = new SoundAlert()
-  p = new ServerUI(initial_file="ParkingAssist.html")
   s.speed -> d.speed
   s.front_distance -> d.front_distance
   s.front_distance -> a.front_distance