Hex: Eiffel Style. 1 Keywords. 2 Introduction. 3 EiffelVision2. Rory Murphy 1 and Daniel Tyszka 2 University of Notre Dame, Notre Dame IN 46556

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1 Hex: Eiffel Style Rory Murphy 1 and Daniel Tyszka 2 University of Notre Dame, Notre Dame IN Abstract. The development of a modern version of the game of Hex was desired by the team creating Hex: Eiffel Style. The development team sought to use modern graphical, networking, and overall programming methodologies in their development of this game. The team also sought to develop a cross-platform code base which would allow for the rapid portability and deployment of the application for several types of systems including Windows, Solaris, and Linux. The development of the system was completed using Eiffel, a pure Object-Oriented language and the EiffelVision and EiffelNet libraries for graphics and for networking respectively. 1 Keywords -Turn-based game -EiffelVision2 -EiffelNet and Sockets -Microsoft.NET 2 Introduction The creators of Hex: Eiffel Style set out to create an implementation of the once popular board game. The Graphical User Interface (GUI) was to be based on mouse click events and to be cross-platform between Unix/Linux and Windows. In addition to creating the standalone implementation, the designers desired to develop network capabilities where the game could be played between to users over a Local Area Network (LAN) or the Internet. The network features were to be implemented via basic stream sockets. 3 EiffelVision2 In order to create a cross-platform system, including GUI, the designers chose to create their interface by taking advantage of EiffelVision2, the built-in graphics libraries that are part of Eiffel Studio. EiffelVision has the abilities to create robust menus widgets within the interface. Since the game needed to operate in three modes, Local, Client, and Server, it was necessary that the user be able to set the board size, game mode, and when necessary the IP address of the server that the client is connecting to. All of these configuration options needed to be set via the GUI. The graphics for the board itself rely heavily upon the abilities of EV_PIXMAP. The board is drawn on top of an EV_PIXMAP widget, with variable size (ranging from a 7x7 board to a 12x12 Hex board). The user s click events are also dependent on EV_PIXMAP, as this type of widget has the built-in functionality to locate click events. A user s click needs to be located precisely in order to determine if a move is valid or not. If a move is valid, then a game piece must be drawn.

2 This was accomplished by creating a polygon object to be drawn at the appropriate place on the board with the appropriate player color as well. A screen shot of Hex is shown in Figure 1 below.

2 2 This was accomplished by creating a polygon object to be drawn at the appropriate place on the board with the appropriate player color as well. A screen shot of Hex is shown in Figure 1 below. 4 EiffelNet Figure 1: Hex Screenshot, 2 nd Player Has Just Achieved Victory The network support for the game was implemented by using EiffelNet library, again supplied with EiffelStudio. This library allows the designers to develop cross-platform networking ability as the library handles architecture dependent details of sockets. Sockets are the fundamental element in computer networking. In order to send and receive information between two computers, a socket must be created first. With a socket created, information can be sent to the socket of one computer which then passes the information on to the second system. By using EiffelNet, the socket creation and information passing was rather simple. With EiffelNet, any object (in the Object-Oriented sense) can be sent to the socket as long as that class inherits from the Eiffel class, STORABLE. In the case of Hex, the HEX_MOVE class was the object that needed to be written to the socket. HEX_MOVE is the class which defines a user s move in the game. Additionally, the HEX_CLIENT and HEX_SERVER classes inherit directly from the NETWORK_CLIENT and NETWORK_SERVER classes. This was done in the spirit of using pre-built, trusty components. The networking was further simplified by the fact that Hex is a turn based game and once a player moves, his or her application is sent into a waiting mode until his or her opponent sends a new move. It would be much more difficult if this were not the case, such as synchronous moves being made.

3 3 5 Problems Encountered The developers experienced two major road blocks in the development of Hex. The first issue was regarding the cross-platform of the GUI. The methods used for drawing the board and pieces required specific abilities of the Windows Eiffel Library (WEL) and the GTK Eiffel Library (GEL). The graphics package works fine on the Windows systems used for development, however, the developers did not have access to a new enough version of GTK on the Solaris machines. The second issue was with the stability of the sockets. The developers were unable to reliably reproduce behavior when it came to network play on Windows machines. Across different versions of Windows and even the same versions of Windows, Hex would still crash unexpectedly while in either network mode. The developers would like to test the abilities of EiffelNet on the Unix machines, but are unable to due to the problems faced with EiffelVision s cross-platform issues. 6 Future Work The developers plan to rigorously maintain and further the development of Hex. The first steps in this will be to determine if running the game on Linux machines is more reliable. This will be accomplished as soon as a development machine can be setup with Eiffel Studio 5.2 and the necessary GTK installation. The next major revision to the game will include a port to the Microsoft.NET framework. This should improve Windows networking abilities significantly. This will lead to two branches of development however, a Unix tree and a significantly different tree for Windows, at least when it comes to the network side of the game. In addition to network reliability, the developers plan to improve the board graphics and the game pieces. Currently, the board and pieces are drawn in the manner they are as to make it easy to resize the board. Changing the graphics to use image files for the board and pieces will require some significant work in graphics development as each board size will need its own board image. Similar to other games on the Internet (for example Yahoo! Games), the developers might add chat abilities to the game. This would allow to players to communicate within the program rather than having to use an independent instant messaging program. Lastly, a single player mode is desired by the developers. This will allow a single user to play a game of Hex against the computer. The Artificial Intelligence engine will be a significant undertaking as well. In the game of Hex, the strategy can vary for the different board sizes, and this alone provides for a challenge. On a more basic level than that even, Hex requires the ability to plan several moves ahead.

4 4 7 Conclusion The developers set out to develop an implementation of Hex that would include an interactive GUI and network play. The developers did not have much previous knowledge regarding either of these aspects of the game. The team gained significant knowledge of the EiffelVision library and the components that make up EiffelVision2. The graphical aspect to the project was a complete success. The second significant part of the project, network play, was also successful. The game can be played over the network at this point. Even though the play is not as reliable as desired, the development will continue and the team has contacted Eiffel Software developers for insight into the current issues at hand. The team has learned a great deal about EiffelNet and has developed a good understanding of sockets. Though the stability of the final system was not at the level that the developers desired, with more work a version of the game that can be released to the public should be available soon. The team still hopes to have a version of Hex available within a month available to the Notre Dame community so all can join the fun and excitement of this strategy game.

5 8 Development Team Rory Murphy is a Junior Computer Engineering major at the University of Notre Dame. He resides permanently in Bentonville, Arkansas.

5 5 8 Development Team Rory Murphy is a Junior Computer Engineering major at the University of Notre Dame. He resides permanently in Bentonville, Arkansas. When Rory is not writing Eiffel code, he is usually found writing code in some other language. If this language is some derivative of C, he may also be found with a pint of Guinness. Daniel Tyszka is a Junior Mechanical Engineering major at the University of Notre Dame. His permanent residence is Oak Brook, Illinois, a small town west of Chicago by about 20 miles. He is superpower includes the ability to expel an intense laser beam from his mouth. His current interests include his research in the manufacturing of orthopaedic implants, ultimate Frisbee, traveling, and the occasional pint of Guinness.

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