Sprint2： backend chatroom

[rookiefromgis]

Basic server construction consists of main.go and server.go. The server contains server-type structure data and three methods: creating a server object, starting the server service, and processing the connection business.

[rookiefromgis]

version2: Realize the broadcast function of users going online and sending messages to each other

1. create a new file user.go to represents the client:

• contain user struct (Name, Addr, channel, conn customer link): use the online map to record the current online user (name: user), and each is bound to a channel.
• Create an API for a user object and start listening.
• Monitor the channel message corresponding to the user: The ListenMessage method monitors the current user channel, and once there is a message, it will be sent directly to the corresponding client.

2.Changes in the server.go:

• Add OnlineMap and Message properties (list of online users, Channel of message broadcast).
• Create and add users in the Handler method that processes the client online (add the online user to the OnlineMap、broadcast the current user online message、 blocked state of handler).
• Add broadcast message method BroadCast.
• Add a new method of monitoring broadcast message channel: the goroutine that listens to the Message broadcast message Channel, and once there is a message, it will be sent to all online users.
• Use a goroutine to monitor Message alone in the interface that starts the service.
• Improve the handler processing business method, create a goroutine for the current client: read the existing message business (when the client is closed, read as 0, and return to offline broadcast).

[rookiefromgis]

Version3: Add two new functions: Online users' query and Modify users' name

• Add API for sending messages to object clients.
• Add the processing of "who" and "rename: Michael" instructions and return online user information in the domessage() method: Add an else if statement to the DoMesage() method to determine whether the entered name is valid (null/existed).

[rookiefromgis]

Version4: Add function to force offline when timeout and private chat function

• Any message from the user indicates that the user is active. If no message is sent for a long time, it is considered to be timed out, and the user connection must be forcibly closed.
• In the user's Handler() goroutine, add the user's active channel, and once there is a message, send data to the channel (islive monitors whether the user is active)。
• In the user's handler(), add a timer function, and the timeout will force the user to go offline。
• user.go : In the DoMessage() method, add the processing of the message instruction, and return the online user information: Add three branches in 'else if' :① get the username of the other party; ② get the user object of the other party according to the username; ③ get the message content, and sends the message content through the user object of the other party.

[rookiefromgis]

Bug: when running the “go run main.go server.go” command, the terminal shows:

command-line-arguments

.\server.go:16:24: undefined: User .\server.go:28:31: undefined: User .\server.go:50:37: undefined: User .\server.go:60:10: undefined: NewUser

The reason for the error belongs to the multi-file loading problem in Golang. When executing the go run command, we need to include all the .go files to be loaded into the parameters.

Two Solutions:

1. Enter the command “go run *.go”
2. Configure Run_kind in the IDE, no error will be reported in package mode but reported in file mode because the function involved is undefined (user. go is not started in the project).

[rookiefromgis]

Bug: ”-net.Dial error: dial tcp 127.0.0.1:8888: connectex: No connection could be made because the target machine actively refused it.“

possible reasons：

1. The server is not started
2. The port is occupied(find the port and kill)
3. Firewall blocking(Authorize as administrator)