Added simple example of using ping & pong

examples/echo.rb

@@ -1,8 +1,8 @@
-require 'lib/em-websocket'
+require File.expand_path('../../lib/em-websocket', __FILE__)
 
 EventMachine::WebSocket.start(:host => "0.0.0.0", :port => 8080, :debug => true) do |ws|
   ws.onopen    { ws.send "Hello Client!"}
   ws.onmessage { |msg| ws.send "Pong: #{msg}" }
   ws.onclose   { puts "WebSocket closed" }
   ws.onerror   { |e| puts "Error: #{e.message}" }
-end
+end

examples/ping.rb

@@ -0,0 +1,24 @@
+require File.expand_path('../../lib/em-websocket', __FILE__)
+
+EventMachine::WebSocket.start(:host => "0.0.0.0", :port => 8080, :debug => false) do |ws|
+  timer = nil
+  ws.onopen {
+    puts "Ping supported: #{ws.pingable?}"
+    timer = EM.add_periodic_timer(1) {
+      p ["Sent ping", ws.ping('hello')]
+    }
+  }
+  ws.onpong { |value|
+    puts "Received pong: #{value}"
+  }
+  ws.onping { |value|
+    puts "Received ping: #{value}"
+  }
+  ws.onclose {
+    EM.cancel_timer(timer)
+    puts "WebSocket closed"
+  }
+  ws.onerror { |e|
+    puts "Error: #{e.message}"
+  }
+end