Class ServerModel

java.lang.Object

ServerModel

public final class ServerModel
extends Object

Represents the model for a chat server, storing information about users and channels on the server.

The ServerBackend interacts with this class via the registerUser(int), deregisterUser(int), and handle(int, Command) methods. Each of these methods generates a Broadcast representing the set of commands that should be sent to other clients connected to the server as a result of the interaction. See the protocol specification for an overview of the ServerModel's role in the program.

You may add private fields and helper methods to this file if you wish, but you may not modify any public method names or signatures.

Constructor Summary

Constructors

Constructor and Description
ServerModel() Constructs a ServerModel with any collections needed for modeling the server state initialized.

Method Summary

Methods

Modifier and Type	Method and Description
Broadcast	deregisterUser(int userId) Informs the model that the client with the given user ID has disconnected from the server.
Collection<String>	getChannels() Returns a collection of the names of all channels that are present on the server.
String	getOwner(String channelName) Returns the nickname of the owner of the given channel.
Collection<String>	getRegisteredUsers() Returns a collection of the nicknames of all users that are registered with the server.
Collection<String>	getUsers(String channelName) Returns a collection of the nicknames of all users in a given channel.
Broadcast	handle(int userId, Command command) Passes a command along to the model for processing.
Broadcast	registerUser(int userId) Informs the model that a client has connected to the server with the given user ID.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ServerModel

public ServerModel()

Constructs a ServerModel with any collections needed for modeling the server state initialized.

Method Detail

registerUser

public Broadcast registerUser(int userId)

Informs the model that a client has connected to the server with the given user ID. The model should update its state so that it can identify this user during later interactions with the model. Any user that is registered with the server (without being later deregistered) should appear in the output of getRegisteredUsers().

Parameters:

userId - the unique user ID created by the backend to represent the user.

Returns:

broadcast representing messages that should be sent as a a result of registering the user

deregisterUser

public Broadcast deregisterUser(int userId)

Informs the model that the client with the given user ID has disconnected from the server. After a user ID is deregisted, the server backend is free to re-assign this user ID to an entirely different client. As such, the model should take care to expunge any state pertaining to a user who is deregistered. Any user that is deregistered (without later being registered) should not appear in the output of getRegisteredUsers().

The behavior of this method if the given user ID is not registered with the model is undefined.

Parameters:

userId - the unique user ID created by the backend to represent the user.

Returns:

broadcast representing messages that should be sent as a a result of deregistering the user

handle

public Broadcast handle(int userId,
               Command command)

Passes a command along to the model for processing. In response, the model should process the command, updating its internal state and generating a Broadcast representing any messages that should be sent to clients in response to the message. The exact behavior is dependent on the internal state of the model and the exact nature of the input command; these behaviors are specified in the protocol specification.

The behavior of this method if the given user ID is not registered with the model is undefined.

Parameters:

userId - the unique user ID created by the backend to represent the user.

command - the command to be processed by the model

Returns:

broadcast representing messages that should be sent as as a result of command

getRegisteredUsers

public Collection<String> getRegisteredUsers()

Returns a collection of the nicknames of all users that are registered with the server. Provided for testing.

Returns:

the collection of registered user nicknames

getChannels

public Collection<String> getChannels()

Returns a collection of the names of all channels that are present on the server. Provided for testing.

Returns:

the collection of channel names

getUsers

public Collection<String> getUsers(String channelName)

Returns a collection of the nicknames of all users in a given channel. The returned collection is empty if no channel with the given channel name exists. Provided for testing.

Parameters:

channelName - the channel whose member nicknames should be returned

Returns:

the collection of user names on the specified channel

getOwner

public String getOwner(String channelName)

Returns the nickname of the owner of the given channel. The result is null if no channel with the given channel name exists. Provided for testing.

Parameters:

channelName - the channel whose owner nickname should be returned

Returns:

the nickname of the channel owner