title: Models, methods, and tools for developing MMOG backends on commodity clouds
Creators: name: Kasenides, Nicos
Publisher: name: University of Central Lancashire
Year: 2023

description: Online multiplayer games have grown to unprecedented scales, attracting millions of players worldwide. The revenue from this industry has already eclipsed well-established entertainment industries like music and films and is expected to continue its rapid growth in the future. Massively Multiplayer Online Games (MMOGs) have also been extensively used in research studies and education, further motivating the need to improve their development process. The development of resource-intensive, distributed, real-time applications like MMOG backends involves a variety of challenges. Past research has primarily focused on the development and deployment of MMOG backends on dedicated infrastructures such as on-premise data centers and private clouds, which provide more flexibility but are expensive and hard to set up and maintain. A limited set of works has also focused on utilizing the Infrastructure-as-a-Service (IaaS) layer of public clouds to deploy MMOG backends. These clouds can offer various advantages like a lower barrier to entry, a larger set of resources, etc. but lack resource elasticity, standardization, and focus on development effort, from which MMOG backends can greatly benefit. Meanwhile, other research has also focused on solving various problems related to consistency, performance, and scalability. Despite major advancements in these areas, there is no standardized development methodology to facilitate these features and assimilate the development of MMOG backends on commodity clouds. This thesis is motivated by the results of a systematic mapping study that identifies a gap in research, evident from the fact that only a handful of studies have explored the possibility of utilizing serverless environments within commodity clouds to host these types of backends. These studies are mostly vision papers and do not provide any novel contributions in terms of methods of development or detailed analyses of how such systems could be developed. Using the knowledge gathered from this mapping study, several hypotheses are proposed and a set of technical challenges is identified, guiding the development of a new methodology. The peculiarities of MMOG backends have so far constrained their development and deployment on commodity clouds despite rapid advancements in technology. To explore whether such environments are viable options, a feasibility study is conducted with a minimalistic MMOG prototype to evaluate a limited set of public clouds in terms of hosting MMOG backends. Foli lowing encouraging results from this study, this thesis first motivates toward and then presents a set of models, methods, and tools with which scalable MMOG backends can be developed for and deployed on commodity clouds. These are encapsulated into a software development framework called Athlos which allows software engineers to leverage the proposed development methodology to rapidly create MMOG backend prototypes that utilize the resources of these clouds to attain scalable states and runtimes. The proposed approach is based on a dynamic model which aims to abstract the data requirements and relationships of many types of MMOGs. Based on this model, several methods are outlined that aim to solve various problems and challenges related to the development of MMOG backends, mainly in terms of performance and scalability. Using a modular software architecture, and standardization in common development areas, the proposed framework aims to improve and expedite the development process leading to higher-quality MMOG backends and a lower time to market. The models and methods proposed in this approach can be utilized through various tools during the development lifecycle. The proposed development framework is evaluated qualitatively and quantitatively. The thesis presents three case study MMOG backend prototypes that validate the suitability of the proposed approach. These case studies also provide a proof of concept and are subsequently used to further evaluate the framework. The propositions in this thesis are assessed with respect to the performance, scalability, development effort, and code maintainability of MMOG backends developed using the Athlos framework, using a variety of methods such as small and large-scale simulations and more targeted experimental setups. The results of these experiments uncover useful information about the behavior of MMOG backends. In addition, they provide evidence that MMOG backends developed using the proposed methodology and hosted on serverless environments can: (a) support a very high number of simultaneous players under a given latency threshold, (b) elastically scale both in terms of processing power and memory capacity and (c) significantly reduce the amount of development effort. The results also show that this methodology can accelerate the development of high-performance, distributed, real-time applications like MMOG backends, while also exposing the limitations of Athlos in terms of code maintainability. Finally, the thesis provides a reflection on the research objectives, considerations on the hypotheses and technical challenges, and outlines plans for future work in this domain.