1.1 Preface
Massively Multiplayer Online Game (MMOG) is the recently popular game genre that is capable of supporting more than thousands of players in a persistence game world concurrently. With the growing of mobile game market size and improvement of wireless technology, a MMOG on mobile device is possible and being concerned. There are many issues that may be encountered when developing a MMOG. Since the mobile game must be created to run on hundreds of device, to deploy and distribute MMOG on mobile device makes the game development more challenged. Therefore, a middleware solution for MMOG on mobile device gains more and more respect.
1.2 Motivation
With the capability growth of mobile device and the innovation of the wireless communication technique, wireless entertainment is respected recently. By the investigation in IGDA (International Game Developers Association) [1] , 2005 Mobile Game White Paper [2] , the recent market trend shows that: the availability and
quality of games are enhanced, network capability is improved and more traditional game publishers jump in. The game-play habits of consumers also change and reveal that they play for more than just killing down time.
Furthermore, the evolution of wireless technique leads the high speed, high quality and low latency network connectivity on mobile handsets. The connectivity
will support new distribution models and realize new game play types. It provides not only the online game service but enable the true real-time games between handsets and even as part of existing large network with PC and consoles.
All of the above inspires the design of mobile online games and game development platforms. Even though there are many existing MMOG and mobile game middleware solutions, most of them are closed and commercial products and focus only on MMO (Massively Multiple Online) or Mobile topic. As a MMO platform, it confronts more challenges in server-side management and system architecture, such as scalability, flexibility, load-balancing and performance. When the game world grows up, the system should support the increasing players and contents and then provide a load-balancing and high-performance service. Furthermore, the whole system should offer a flexible game protocol and content design to satisfy many different game types.
On the other hand, to design a mobile game platform, there are usually more client-side handset issues to be considered. The mobile client application is easy to be interrupted by surrounding environment. For example, when user is out of service range or receiving a coming call, the client application may suspend and even lose application resource. Therefore, we propose a client framework for MMOG on mobile device that consider both MMOG and mobile games issues. We hope to provide a flexible and easy-to-deploy platform and also make the combination of traditional MMOG and mobile MMOG possible.
1.3 Research Objectives
The objectives of our framework can be summarized as the following four parts:
y Easy to Adapt and Extend
The game contents and types of a MMOG can be various. An inflexible MMOG middleware will restrain the originality of game design. The communication protocol of middleware online service must be straightforward and easy to adapt and extend.
The Game objects that present in the game world should also be as flexible as possible. We can provide some typical game object models but should not assume the forms of them. An ideal game middleware must provide the maximum resilience for game design.
y Easy to Develop and Deploy
Time to market is very important for the game provider. The development of game contents need to be easy and fast. The platform should provide simple and flexible API for game developer. Moreover, most MMOG vendors update the contents frequently to provide attractive game. The game deployment mechanism should be simple to reduce the cost of content extension.
y Dealing with the Mobile-specific issue
The situation of a mobile game client is more complex than typical PC or console games. Although the quality and speed of wireless communication has been improved, the surrounding environment and many telecom issues will still make the network connectivity being poor. The application state on mobile handset is also hard to control. The limited hardware resource and high-priority telecom service will let the client application be interrupted easily. Thus, the framework of MMO mobile game client should take above problems into account and provide easy-to-use interface to handle those status.
y Combination of mobile and traditional MMOG
The spirit and game-play on PC MMOG and mobile MMOG can be the same.
Although the PC or console provides more resource and capability to present such kind of game, the innovation of mobile device makes the combination possible. Even if the presentation may be different, by using the same communication protocol, the mobile device should be able to function the same game logic and play in the same virtual game world.
1.4 Outline of the thesis
In Chapter 2, we discuss the background of MMOG and mobile application development and introduce some existing platforms. In Chapter 3, we propose the architecture of our system, and discuss the purpose and responsibility of each component. For deep understanding, we describe the implementation details and the design method in Chapter 4. To demonstrate the usefulness of the platform we propose, the contents of Chapter 5 presents a hybrid MMO game built on our system.
Finally, in Chapter 6, we give the conclusion and future works for our system.