The Access Control And Consistency Management Of VinaGame's Distributed Shared Server Cluster

The rapid growth of the Internet has made network access server which face an upsurge in the number and the future growth rate is even more unpredictable. Nowadays, the server must have an ability to provide large number of concurrent accesses services, if the customer increases and leads to volume of treatment beyond the scope of the server's bearing, then the results are bound to cause server deny to provide service or collapse, seriously affecting the quality of service, resulting in enormous economic losses. Clearly, a single server's limited performance can not solve this problem but to form a multi-server system, and through software technology handle all business requests and I/O through put average distribution to all servers, then the system will fully have sufficient management capacity, this is the initial basic design idea of cluster system.First, this paper introduces the game server status, through studying two server architecture games, MMORPG games and leisure games, and the analysis of the system architecture, system design of the five servers: Login server: Verify the client version and the user's name and password. Center server: maintain a list of online users. Load balancing strategy and communication between servers. User Logins successful, the center server records the user information. And load distribution for the user's to the smallest lobby server. At the beginning and the end game, it is responsible for forwarding the data in the games. Lobby server: maintain a list of rooms to provide city services and provide users to create a game room. Database server: the completion of data update. Game Server: the maintenance of the ongoing game. In this article the server architecture used this way, each server has its own calculation mission. Cluster servers in each lobby are independent to bear the calculation mission, when the player was assigned to a lobby server, the database server send player's information data to the lobby server, the lobby server takes charge players'online data storage, each match, players acquire the new data, the lobby server is not only preserve the data and send the data to the database server to be saved. When the audience lobby where the server crashes because of one reason or another, and continue to provide services from a center server in accordance with the principle of load balancing for the client continuing to lobby the new distribution server, and client server based on the new lobby landing IP address, you can continue to run games. And this process is transparent to the players.After construct system and cluster, there is an important question in clusters, that is the consistency of data, in order to improve reliability and performance of data access, data often have multiple copies stored separately in the system on different physical nodes, in this system, the user's data not only stored in the central database and a local database. When the data need to update, not only to update the local database and update the central database. Whenever user requests data to query other users, he hoped that the data are the players'last time update data. So read the updated strategy is that if the searched user and search user in a lobby server. Then the lobby server processes the request. If the searched user in another lobby server, then the request should be sent to the designated server to handle the request, this will ensure that the query data is the user last time updated data. Another important issue in cluster is access control problem, the early computer systems do not limit users access the system resources to operate restrictions on permissions. However, with the computer resources continuously enriched, the user doesn't need and should not access any resources, which required the use of access control to be managed. The basic tasks of access control are on the basis of identifying the principal and certification to determine whether allow the main body to visit object, and limit access the main body to the object. Access control can be divided into autonomous access control and mandatory access control and role-based access control. This system is an autonomy access control system, use access control list to control the access resources, each row of the access control list represents a user, and each column represents a system resource, each element in the list express resource access permissions to the users.After the establishment of the cluster system and each module of a system, the writer introduce data flow of the system, including the user's login process, users'data query process, as well as the update process of the user's data. System environment is the operating system Windows XP, software development environments are: Microsoft Visual Studio. NET 2003, Database: SQL Server 2000.Author introduces a system data flow testing and test results of the analysis, for each server, the log server: the lightest load. The lobby server: the main stress of the lobby server is from room list, according to experimental data, which cost about a physical CPU core of 3-5% of the computing power. In addition to consumption of computing power, there are memory problems, the lobby server mainly store the information of the player's role. Center server: center server maintains many online users, using a larger memory. Database server: database server is responsible for the completion of other servers to read and write database operations. Database server is beyond the calculation stress, the main bottleneck is the database access performance. Game Server: deal with game's logic, need higher device and CPU. Center database: use SQL Server 2000, running separately on hardware and need higher device. For consistency update, the update in the LAN and WAN has a 0.1 seconds discrepancy by orders of magnitude. For consistency management mechanism, the user wishes to visit the last updated data, this difference is acceptable. Access control for example, the user in line with the permissions can permit access to specific resources. In short, the game server cluster is a more complex system, to build the system, not only the system itself, but also with the system environment. The use of server clustering technology, through careful planning and network maintenance, the server can provide users with faster and better service. Clustering technology as the server hardware systems and network operating system will be the development of availability, high reliability, and system redundancy and so on gradually be increased. Future cluster file system can rely on the system to achieve all of the documents, equipment and the overall access network resources, and generate a complete system image. In this way, regardless of the application of which in the cluster servers, the cluster file system allows any user can access this software. Any application can access any document in this cluster. Therefore, the stability of enterprise must to use technology of server cluster. Same will have more and more people to join the study the server cluster direction.