Duke University - CURIOUS '01

author: D. Bernstein, A. English, B. Koh
 
 

Table of Contents

Introduction
Design and Basic Operation(brief)
Usage Suggestions
Supported Games
Supported Protocols

INTRODUCTION
 
 

NOOGA, which stands for Network Object Oriented Game Architecture, provides users with the basic network infrastructure for creating simple turn-based board games. Written entirely in Java 1.3, NOOGA is portable across multiple platforms and uses RMI to support network activity. It is designed such that users with minimal or no network knowledge can add new games and create clients for the NOOGA server. Recognizing that RMI is mainly a Java-supported technology, NOOGA also provides connectivity via TCP/IP socket connections, thereby enabling the server to communicate with clients written in other languages. It is our hope that NOOGA will be a useful teaching tool which can provide examples of good and bad OO design as well as ideas for future assignments.
 
 
 
 
 
 

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DESIGN AND BASIC OPERATION ........... in a nutshell
 
 

Server
The server side of NOOGA is comprised of essentially two types of components: the NOOGAServer and the NOOGAGameHandler.
The NOOGAServer waits in a loop until a sufficient number of clients have added themselves before starting a game. The server maintains separate waiting lists for each game it is equipped to launch. Once the threshold number of players has been met for a particular game list, the server spawns a NOOGAGameHandler in a thread to run the game and resumes waiting. The server is flexible in that it is relatively easy to add new game handling capability since all game handlers must implement the NOOGAGameHandler interface.

Client
The main components of the client side are: the NOOGAClient, NOOGAFE, NOOGAConnector

The NOOGAFE, or NOOGA Front End, is the client side component which displays the game to the player and allows player interaction (game-type specific). This is the component a user would create if asked to program a "client" for NOOGA. Since all RMI interaction is contained within the NOOGAClient, NOOGAServer, and NOOGAGameHandler, no knowledge of RMI is needed to construct a NOOGAFE. This is the design feature which allows users to write clients for NOOGA without network knowledge.

The NOOGAClient forms the gateway between server and client. It represents the server side's handle on the client side; all requests/instructions performed on the client side by the server or game handler are invoked on the NOOGAClient which forwards the invocation to the NOOGAFE (NOOGA Front End). Conversely, the NOOGAClient is also the client side's handle on the server side, as all method invocations from client to server must be performed on the NOOGAClient, which forwards the invocation to the server side. All RMI communication is contained within the NOOGAClient, NOOGAServer, and NOOGAGameHandler.
Clients initiate a connection to a NOOGAServer via the NOOGAConnector. NOOGAConnector basically sets up the connection between the NOOGAClient and NOOGAServer.

MiddleWare : the SSNOOGAFE/XMLNOOGAFE and NOOGASocketListener
As mentioned in the introduction, NOOGA provides a TCP/IP socket access layer which allows non-Java clients to interface with the NOOGAServer. This is done by "tricking" the server side into communicating with a fake NOOGAClient - the SSNOOGAFE and XMLNOOGAFE - which, using either a simple string or xml protocol, forwards requests and instructions to the remote client over a TCP/IP socket behind the scenes. Using the appropriate protocol, socket clients communicate with the XML or SS NOOGAFE which forwards requests and instructions to the server/game handler via RMI. The SSNOOGAFE communicates with clients using a simple-string protocol, while the XMLNOOGAFE accomplishes the same task with an xml protocol.
The NOOGASocketListener is the socket equivalent of the NOOGAConnector. Clients wishing to connect via socket cannot open a direct connection to the NOOGAServer. They must initiate a connection with the NOOGASocketListener on a predefined port, which sets up the middleware RMI/socket connection between server and client.

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USAGE SUGGESTIONS
 
 

It is our hope that NOOGA can be useful as a teaching tool both in and out of the classroom. Since it was almost entirely written by students, NOOGA is plagued by many common design mistakes. For example, bad variable names, redundant code, and hard coding, among other flaws, can be found in certain parts of code. However, there also exist features which are examples of good design. NOOGA's extensive class hierarchy allows new game handler and socket protocol modules to be added with relative ease. Additionally, the isolation of RMI within the NOOGAServer, NOOGAGameHandler, and NOOGAClient classes is a good design feature because client code never has to implement RMI in order to interface with the server. These can be pointed out in lecture followed by good/bad design reasoning. Outside of the classroom, NOOGA can be given to students as part of an assignment. In the same way that Nachos is used to teach OS design and concepts by having students modify its code and add new features, NOOGA can be used to teach OOP by allowing students to add new modules which provide additional functionality. Adding support for new game types, for instance, would give students practice in familiarizing themselves with the NOOGA API and in realizing how it's structure makes it flexible in some ways and inflexible in others. Their OO reasoning can also be put to the test if asked how they would re-design NOOGA from scratch, learning from mistakes that have already been committed in the original version.
 

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SUPPORTED GAMES

Currently, NOOGA supports:

Joggle - like the classic word game "Boggle"

Joggle Racer - similar to Joggle, but more competitive in that players "race" to submit words before other players. each word can only be submitted once, after which other players will not receive points for submitting the same word.

Dots - connect the dots on a grid to form squares. the player with the most squares wins

BattleShip - like the classic board game

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SUPPORTED PROTOCOLS

NOOGA supports RMI, XML, and Simple String connectivity.