Add documentation to client examples

Author: clue

examples/11-http.php

@@ -1,5 +1,10 @@
 <?php
 
+// Simple plaintext HTTP client example (for illustration purposes only).
+// This shows how a plaintext TCP/IP connection is established to then send an
+// application level protocol message (HTTP).
+// Real applications should use react/http-client instead
+
 use React\EventLoop\Factory;
 use React\Socket\Connector;
 use React\Socket\ConnectionInterface;

examples/12-https.php

@@ -1,5 +1,10 @@
 <?php
 
+// Simple secure HTTPS client example (for illustration purposes only).
+// This shows how a secure TLS connection is established to then send an
+// application level protocol message (HTTP).
+// Real applications should use react/http-client instead
+
 use React\EventLoop\Factory;
 use React\Socket\Connector;
 use React\Socket\ConnectionInterface;

examples/13-netcat.php

@@ -1,5 +1,10 @@
 <?php
 
+// Simple plaintext TCP/IP and secure TLS client example that pipes console I/O.
+// This shows how a plaintext TCP/IP or secure TLS connection is established and
+// then everything you type on STDIN will be sent and everything the server
+// sends will be piped to your STDOUT.
+
 use React\EventLoop\Factory;
 use React\Socket\Connector;
 use React\Socket\ConnectionInterface;
@@ -8,6 +13,16 @@
 
 require __DIR__ . '/../vendor/autoload.php';
 
+if (!defined('STDIN')) {
+    echo 'STDIO streams require CLI SAPI' . PHP_EOL;
+    exit(1);
+}
+
+if (DIRECTORY_SEPARATOR === '\\') {
+    fwrite(STDERR, 'Non-blocking console I/O not supported on Microsoft Windows' . PHP_EOL);
+    exit(1);
+}
+
 if (!isset($argv[1])) {
     fwrite(STDERR, 'Usage error: required argument <host:port>' . PHP_EOL);
     exit(1);

examples/14-web.php

@@ -1,5 +1,11 @@
 <?php
 
+// Simple plaintext HTTP and secure HTTPS client example (for illustration purposes only).
+// This shows how an URI parameter can parsed to decide whether to establish
+// a plaintext TCP/IP or secure TLS connection and then send an
+// application level protocol message (HTTP).
+// Real applications should use react/http-client instead
+
 use React\EventLoop\Factory;
 use React\Socket\ConnectionInterface;
 use React\Socket\Connector;