anchor.diff:  
   ### Send message to users [/chat/public]
   
  -The **Server** will send message to the users through this api.
  -
   ### Receive message from server [GET]
   
   + Attributes
  
positive.code: 
  ### Mechanism
  
  When a **User** connects to **Server**. He will input his `username` and pushes his `sessionId` and `username` to the **Server**.
  After that, the **Server** save the **User** information and response `userId` to **User**.
  When he pushes a message. The **Server** will receive it and broadcasts to the others.
  When a user *joins* or *leave* the room. Other people will be *notified* by **Server**.
  
  ### Register a new user [/chat/register]
  
  
negative.code: ### Send message to server [/chat/public/server]
  
  Due to the structure of **Faye**, we have to use **another** channel to transfer message from Client to Server.
  
  > **Note:** a channel must have a **single responsibility** to maintain the **stability** of the application.
  >
  > A channel will be a **publisher** or **subscriber**.
  