Refactor Mongoose documentation

PUBLISHED_FROM=e9a4e5c7b4a1d03b93a2a79e29de19e60e919929

docs/http/server_example.md

@@ -0,0 +1,53 @@
+---
+title: HTTP server example
+---
+
+To create an HTTP server, follow this pattern:
+
+1. Create a listening connection by calling `mg_bind()` or `mg_bind_opt()`
+2. Call `mg_set_protocol_http_websocket()` for that listening connection.
+  That attaches a built-in HTTP event handler which parses incoming
+  data and triggers HTTP-specific events. For example, when an HTTP request
+  is fully buffered, a built-in HTTP handler parses the request and
+  calls user-defined event handler with `MG_EV_HTTP_REQUEST` event and
+  parsed HTTP request as an event data.
+3. Create event handler function. Note that event handler receives all
+  events - low level TCP events like `MG_EV_RECV` and high-level HTTP
+  events like `MG_EV_HTTP_REQUEST`. Normally, an event handler function
+  should only handle `MG_EV_HTTP_REQUEST` event.
+
+Here's an example of the simplest HTTP server. Error checking is omitted for
+the sake of clarity:
+
+```c
+#include "mongoose.h"
+
+static const char *s_http_port = "8000";
+
+static void ev_handler(struct mg_connection *c, int ev, void *p) {
+  if (ev == MG_EV_HTTP_REQUEST) {
+    struct http_message *hm = (struct http_message *) p;
+
+    // We have received an HTTP request. Parsed request is contained in `hm`.
+    // Send HTTP reply to the client which shows full original request.
+    mg_send_head(c, 200, hm.message.len, "Content-Type: text/plain");
+    mg_printf(c, "%.*s", hm.message.len, hm.message.p);
+  }
+}
+
+int main(void) {
+  struct mg_mgr mgr;
+  struct mg_connection *c;
+
+  mg_mgr_init(&mgr, NULL);
+  c = mg_bind(&mgr, s_http_port, ev_handler);
+  mg_set_protocol_http_websocket(c);
+
+  for (;;) {
+    mg_mgr_poll(&mgr, 1000);
+  }
+  mg_mgr_free(&mgr);
+
+  return 0;
+}
+```