feat(https_server): Added Server Sent Events demo

This commit adds the demo of Server Sent Events
functionality in the https_server/simple example
Closes https://github.com/espressif/esp-idf/issues/13603

Co-authored-by: default avatarAditya Patwardhan <aditya.patwardhan@espressif.com>

examples/protocols/http_server/simple/README.md

@@ -6,6 +6,15 @@
 The Example consists of HTTPD server demo with demonstration of URI handling :
     1. URI \hello for GET command returns "Hello World!" message
     2. URI \echo for POST command echoes back the POSTed message
+    3. URI \sse for GET command sends a message to client every second
+
+## User Callback
+
+The example includes a simple user callback that can be used to get the SSL context (connection information) when the server is being initialized. To enable the user callback, set `CONFIG_EXAMPLE_ENABLE_HTTPS_USER_CALLBACK` to `y` in the project configuration menu.
+
+## Server-Sent Events (SSE)
+
+The example also includes a simple SSE handler (having endpoint \sse), which sends a message to the client every second. To enable SSE, set `CONFIG_EXAMPLE_ENABLE_SSE_HANDLER` to `y` in the project configuration menu.
 
 ## How to use example
 

examples/protocols/http_server/simple/main/Kconfig.projbuild

@@ -26,4 +26,11 @@ menu "Example Configuration"
         help
             The client's password which used for basic authenticate.
 
+    config EXAMPLE_ENABLE_SSE_HANDLER
+        bool "Enable Server-Sent Events (SSE) handler"
+        default n
+        help
+            Enable this option to use Server-Sent Events (SSE) functionality.
+            This will allow the server to push real-time updates to the client over an HTTP connection.
+
 endmenu

examples/protocols/http_server/simple/main/main.c

@@ -22,7 +22,8 @@
 #include "esp_netif.h"
 #include "esp_tls.h"
 #include "esp_check.h"
-
+#include <time.h>
+#include <sys/time.h>
 #if !CONFIG_IDF_TARGET_LINUX
 #include <esp_wifi.h>
 #include <esp_system.h>
@@ -392,6 +393,40 @@ static const httpd_uri_t ctrl = {
     .user_ctx  = NULL
 };
 
+#if CONFIG_EXAMPLE_ENABLE_SSE_HANDLER
+/* An HTTP GET handler for SSE */
+static esp_err_t sse_handler(httpd_req_t *req)
+{
+    httpd_resp_set_type(req, "text/event-stream");
+    httpd_resp_set_hdr(req, "Cache-Control", "no-cache");
+    httpd_resp_set_hdr(req, "Connection", "keep-alive");
+
+    char sse_data[64];
+    while (1) {
+        struct timeval tv;
+        gettimeofday(&tv, NULL); // Get the current time
+        int64_t time_since_boot = tv.tv_sec; // Time since boot in seconds
+        esp_err_t err;
+        int len = snprintf(sse_data, sizeof(sse_data), "data: Time since boot: %lld seconds\n\n", time_since_boot);
+        if ((err = httpd_resp_send_chunk(req, sse_data, len)) != ESP_OK) {
+            ESP_LOGE(TAG, "Failed to send sse data (returned %02X)", err);
+            break;
+        }
+        vTaskDelay(pdMS_TO_TICKS(1000)); // Send data every second
+    }
+
+    httpd_resp_send_chunk(req, NULL, 0); // End response
+    return ESP_OK;
+}
+
+static const httpd_uri_t sse = {
+    .uri       = "/sse",
+    .method    = HTTP_GET,
+    .handler   = sse_handler,
+    .user_ctx  = NULL
+};
+#endif // CONFIG_EXAMPLE_ENABLE_SSE_HANDLER
+
 static httpd_handle_t start_webserver(void)
 {
     httpd_handle_t server = NULL;
@@ -414,9 +449,12 @@ static httpd_handle_t start_webserver(void)
         httpd_register_uri_handler(server, &echo);
         httpd_register_uri_handler(server, &ctrl);
         httpd_register_uri_handler(server, &any);
-        #if CONFIG_EXAMPLE_BASIC_AUTH
+#if CONFIG_EXAMPLE_ENABLE_SSE_HANDLER
+        httpd_register_uri_handler(server, &sse); // Register SSE handler
+#endif
+#if CONFIG_EXAMPLE_BASIC_AUTH
         httpd_register_basic_auth(server);
-        #endif
+#endif
         return server;
     }
 

examples/protocols/http_server/simple/pytest_http_server_simple.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 #
-# SPDX-FileCopyrightText: 2018-2022 Espressif Systems (Shanghai) CO LTD
+# SPDX-FileCopyrightText: 2018-2024 Espressif Systems (Shanghai) CO LTD
 # SPDX-License-Identifier: Apache-2.0
 import logging
 import os
@@ -14,6 +14,7 @@ import time
 import pytest
 
 try:
+    import http.client
     from idf_http_server_test import client
 except ModuleNotFoundError:
     sys.path.append(os.path.join(os.path.dirname(__file__), '..', '..', '..', '..', 'tools', 'ci', 'python_packages'))
@@ -171,3 +172,58 @@ def test_examples_protocol_http_server_lru_purge_enable(dut: Dut) -> None:
 
     for t in threads:
         t.join()
+
+
+@pytest.mark.esp32
+@pytest.mark.wifi_router
+@pytest.mark.parametrize('config', ['sse',], indirect=True)
+def test_examples_protocol_http_server_sse(dut: Dut) -> None:
+    # Get binary file
+    binary_file = os.path.join(dut.app.binary_path, 'simple.bin')
+    bin_size = os.path.getsize(binary_file)
+    logging.info('http_server_bin_size : {}KB'.format(bin_size // 1024))
+
+    # Upload binary and start testing
+    logging.info('Starting http_server simple test app')
+
+    # Parse IP address of STA
+    logging.info('Waiting to connect with AP')
+    if dut.app.sdkconfig.get('EXAMPLE_WIFI_SSID_PWD_FROM_STDIN') is True:
+        dut.expect('Please input ssid password:')
+        env_name = 'wifi_router'
+        ap_ssid = get_env_config_variable(env_name, 'ap_ssid')
+        ap_password = get_env_config_variable(env_name, 'ap_password')
+        dut.write(f'{ap_ssid} {ap_password}')
+    got_ip = dut.expect(r'IPv4 address: (\d+\.\d+\.\d+\.\d+)[^\d]', timeout=30)[1].decode()
+    got_port = int(dut.expect(r"(?:[\s\S]*)Starting server on port: '(\d+)'", timeout=30)[1].decode())
+
+    logging.info('Got IP   : {}'.format(got_ip))
+    logging.info('Got Port : {}'.format(got_port))
+
+    # Expected Logs
+    dut.expect('Registering URI handlers', timeout=30)
+
+    logging.info('Test /sse GET handler')
+    try:
+        logging.info(f'Connecting to {got_ip}:{got_port}')
+        conn = http.client.HTTPConnection(got_ip, got_port, timeout=15)
+        conn.request('GET', url='/sse')  # Ensure the URL path is correct
+        response = conn.getresponse()
+
+        # Process and verify only the first 5 lines of the response as the response is continuous
+        response_data = ''
+        for i, line in enumerate(response):
+            if i >= 5:
+                break
+            decoded_line = line.decode('utf-8').strip()
+            response_data += decoded_line
+
+        conn.close()
+
+        # Verify the format of the line
+        if 'data: Time since boot:' not in response_data:
+            raise RuntimeError(f'Unexpected line format: {response_data}')
+
+    except Exception as e:
+        logging.error(f'Error during SSE GET request: {e}')
+        raise RuntimeError('SSE handler test failed due to connection error')

examples/protocols/http_server/simple/sdkconfig.ci.sse

@@ -0,0 +1 @@
+CONFIG_EXAMPLE_ENABLE_SSE_HANDLER=y