Description
In the assignments and project, you are going to implement a simple Distributed Player
Status System (DPSS): a distributed system to manage player status across multiple game
servers used by players and administrators.
Consider three geo-locations: North-America (NA), Europe (EU) and Asia (AS) for your
implementation. The server for each geo-location (called GameServer) must maintain a
number of player accounts. An Account contains specific information (first name, last
name, age, password of at least 6 characters and IP-address) about a Player and is
identified by a unique username.
A Username has a minimum length of 6 characters and
a maximum length of 15 characters. The accounts are placed in several lists that are
stored in a hash table according to the first character of the username indicated in the
account.
For example, all the accounts with the username starting with an “A” will
belong to the same list and will be stored in a hash table (acting as the database) using the
key “A”. Each server also maintains a log containing the history of all the operations that
have been performed on that server.
This should be an external text file (one per server)
and shall provide as much information as possible about what operations are performed,
at what time and who performed the operation.
The system has two distinct types of users: Players and Administrators. Players can be
identified by their username, password and IP-address. Whenever a player performs an
operation, the system must identify the geo-location that the player belongs to based on
his/her IP-address and perform the operation on that server.
The players maintain a log
(text file) of the actions they performed on the system and the response from the system
when available. For example, if you have 10 players using your system, you should have
a folder containing 10 logs. Administrators can be identified by their username, passwordand IP-address.
For the sake of this assignment all the administrators have the same
username which is Admin and the password is also Admin. The administrators also
maintain a log.
IP-Addresses
For this assignment, there are only three possible ranges of IP-addresses:
1. 132.xxx.xxx.xxx : IP-addresses starting with 132 indicate a North-American geolocation.
2. 93.xxx.xxx.xxx : IP-addresses starting with 93 indicate an European geo-location.
3. 182.xxx.xxx.xxx : IP-addresses starting with 182 indicate an Asian geo-location.
The operations that can be performed are the following:
Operations performed by Players
• createPlayerAccount (FirstName, LastName, Age, Username, Password,
IPAddress)
When a player invokes this method from his/her geo-location through a client
program called PlayerClient, the server associated with this player (determined by
the IPAddress) attempts to create an account with the information passed if the
username does not exist and that the passed information is valid according to the
problem description, and inserts the account at the appropriate location in the hash
table. The server returns information to the player whether the operation was
successful or not and both the server and the player store this information in their
logs.
• playerSignIn (Username, Password, IPAddress)
When a player invokes this method from his/her geo-location through a client
program called PlayerClient, the server associated with this player (determined by
the IPAddress) attempts to verify if the account exists, that the password matches
the account password and that the account is not currently signed-in. If these
conditions are met, the server sets the account status to online and returns a
confirmation to the player.
Otherwise a descriptive error is returned. Both the
server and the player store this information in their logs. (There are many ways
this can be done. You are encouraged to design your system in such a way that it
is simple to distinguish between online and offline accounts without impacting the
performance of the system.)
• playerSignOut (Username, IPAddress)
When a player invokes this method from his/her geo-location through a client
program called PlayerClient, the server associated with this player (determined by
the IPAddress) attempts to verify if the account exists and that the account is
currently signed-in.
If these conditions are met, the server sets the account status
to offline and returns a confirmation to the player. Otherwise a descriptive error is
returned. Both the server and the player store this information in their logs.
Operation performed by Administrators
• getPlayerStatus (AdminUsername, AdminPassword, IPAddress)
When an administrator invokes this method from his/her geo-location through a
client program called AdministratorClient, the server associated with this
administrator (determined by the IPAddress) attempts to, if the credentials are
valid, concurrently find out the number of online players and offline players in the
other geo-locations using UDP/IP sockets and returns the result to the
administrator.
Please note that it only returns the player counts (a number) and not
the player information. For example, if NA has 6 players online, EU has 7 players
online and AS has 8 players online and they each have 1 player offline it should
return the following (which should also be stored in the server and administrator
log): NA: 6 online, 1 offline. EU: 7 online, 1 offline, AS: 8 online, 1 offline.
Thus, this application has a number of GameServers (one per geo-location) each
implementing the above operations for that geo-location, PlayersClient (one per
player) invoking the player’s operations at the associated GameServer as
necessary and AdministratorsClient (one per administrator) invoking the
administrator’s operations at the associated GameServer. When a GameServer is
started, it registers its address and related/necessary information with a central
repository.
For each operation, the PlayersClient/AdministratorClient finds the
required information about the associated GameServer from the central repository
and invokes the corresponding operation.
In this assignment, you are going to develop this application using Java RMI.
Specifically, do the following:
• Write the Java RMI interface definition for the GameServer with the specified
operations.
• Implement the GameServer
• Design and implement a PlayerClient which invokes the geo-location’s server
system to test the correct operation of the DPSS invoking multiple GameServer
(each of the servers initially has a few accounts) and multiple players.
• Design and implement an AdministratorClient which invokes the geo-location’s
server system to test the correct operation of the DPSS invoking multiple
GameServer (each of the servers initially has a few accounts) and multiple
administrators.
You should design the GameServer maximizing concurrency. In other words, use proper
synchronization that allows multiple users to perform operations for the same or different
accounts at the same time.
