Okay... Sorry for the triple post but while waiting for an answer to this topic, I continued my investigation. I wondered why I had a SSL connection while I was trying to connect though normal HTTP. Then I foudn over the Internet that I could do something like that:
config.setSecurityMode(ConnectionConfiguration.SecurityMode.disabled);
To force the connection though HTTP instead of HTTPS... And it worked 
Well... At least, I'm connected... Now let's see how I can developp what I want.
Thanks