HTML block code with instant effect

I need a html code block with a chat effect, as informed the example at: [login to view URL] -> Only contained in the attached image. This code should be a good design and only two people will talk. Reading all conversation should be read from a json file, being told by my system. Once a new conversation is posted, whether the person is seeing or the other end, the chate should have the effect and make the refresh in reading. The json file will contain only the conversation id, date, photo, name and message text. The conversation ID will serve so that the same code can be used several times in vairas conversations, but always only two people will talk.