If the command has a http .... starting you must use a http protocol, otherwise the device will not understand it or better it will reject the application-layer connection and the "handshaking".

Look at the http library from philips. The part that zedmtrappe provided is a way to do it, but it's not a really right way, because the http header is missing some key strings, like the Connection: close:

HTTP/1.1 applications that do not support persistent connections MUST include the "close" connection option in every message.

As you don't know if the embedded http server supports a persistent connection, you should always close it. Anyway if you do use such things, you should do it the right way, so you don't regret it in the future:

[Link: en.wikipedia.org]