SOFTWARE DESIGN AND IMPLEMENTATION OF COMMUNICATION SERVER IN MORPG BASED ON CLIENT-SERVER ARCHITECTURE

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1 SOFTWARE DESIGN AND IMPLEMENTATION OF COMMUNICATION SERVER IN MORPG BASED ON CLIENT-SERVER ARCHITECTURE Ridho Rahman Hariadi 1, Riyanarto Sarno 1, Royyana Muslim Ijtihadie 1 1 Informatics Department, Faculty of Information Technology, Sepuluh Nopember Institute of Technology (ITS), Surabaya, 60111, Indonesia ridho@if.its.ac.id, riyanarto@its-sby.edu, roy@its.ac.id ABSTRACT The rapid development of Indonesia s internet infrastructure has triggering a new trend in internet user behavior. Playing an online game is not considered as a rare behavior, a lot of game servers are built to satisfy gamers who need interaction and competition in game. A server with efficient bandwidth management is required to serve a huge number of player in MORPG. The function of this server is to serve the communication and state update process between a huge number of client which is connected to this server. State changes on one client will be transmited to the other client which is concern. This research has successfully designs and implements a bandwidth-efficient online game communication server. From testing, this communication server can handles up to 300 players which concurrently connected. Keywords: communication server, multiplayer online game, client-server architecture, real-time application 1 INTRODUCTION In multiplayer online game, players can interact with one another. This kind of games have a lot of players because compete with another feel more interesting and challenging than playing alone against the computer [3]. The reasons for this is because people have more intelligent than computer, humans have more intuition and can learn from the experience. The first multiplayer game already introduced in 1980, using a split window mode, the screen is divided into 2 or 4 players for each part [4]. At that time the system was only use 1 computer and did not use network. The networked game s biggest problem is the complexity level of bandwidth management and state consistency [5]. Bandwidth needs to have a direct relationship level scalability game. Bandwidth requirement will drastically increase proportionate to the number of players so the bandwidth of the server will become the bottleneck in the game [6]. Problem is the other important issues in the state of the game, will be a strange thing when a player saw that a NPC (Non playable character) is still living in the player but the other view is in a state of death. Besides the network, game development process itself is very long and complex [1]. There are a lot of things should be done in making the game, from the story flow, graphics, AI, up to a virtual world that is filled by thousands of different objects and possibility. It is a very serious challenge for game developers to create games quickly and with quality in the network bandwidth is small and high latency [5]. This research presents a bandwidthefficient MORPG communication server. The challenge in making online game is the design of communication protocol that can support hundreds and even thousands of players. MORPG in this research is implemented by using client-server architecture. Client-server architecture used by many companies online game, because the clientserver architecture provides centralized control of each state in the [7]. Previous research on the Multiplayer Online Role Playing Games have been conducted by Arie Affianto [10]. A system called Online RPG Battle was built using Flash and Flash Communication Server MX. There was also a RPG created with XNA released by Microsoft in June 2008 [11]. That game had not apply the ability of networking and interaction between players. 163

2 164 The 5 th International Conference on Information & Communication Technology and Systems 2 MODEL, ANALYSIS, DESIGN, AND IMPLEMENTATION 2.1 Client-Server Architecture Client-server architecture is a paradigm in information technology that refers to a way to distribute applications to the two parties, namely: the client and the server. In client-server model, an application is divided into two separate parts, but still is a component unit of the client and server components. Client components are also often referred to as the front-end, while the server component is called the back-end. Components of the client application is run in a workstation and receive input data from users. The client component will prepare the data entered by the user using a particular technology for processing and sending it to the server components that run on the server machine, usually in the form of a request for some services that are owned by the server. The server component will receive a request from the client, and processing and return processing results to the client. Client also received information of the data processing server and display it to users, using applications that interact with the user. The communication process begins when a client application to send queries in the form of a packet - UDP packet to the server, application server and parsing the data input form of a query message from the client, the process that is requested on the query, and send the results to the client. Servers store and manage all-state each state to its client, the change of state occurs in one of the client will be sent to the server and the server will send the update to the state of another client. 2.2 Multiplayer Online Role Playing Game (MORPG) Multiplayer online role playing game is a game where a player takes over the role of characters that exist in the imagination of the environment created by pencerita in the game, and experience the adventure of their own imagination of the characters. This game is also designed to be played online via the internet and played by many people. The core of this system is the interaction, collaboration or competition between players. Thus, the game is not interesting when played alone. In this game, players can do things that can be done by the characters as in the real world. Each character in the MORPG have the ability and health status that is usually called a health point (HP) and the point (MP). This status represented in the form of a number that has a maximum value and can change over the increased level of players. Example game that implements this system is Ragnarok Online, Rising Force Online, and World of Warcraft. 2.3 Area of Interest Management Area of interest management is a technique used to improve system scalability and to reduce data communication between server and client. Area of interest in working with management to pemilahan data which must be sent to a client. Basic idea of this technique is not every client needs to obtain information that is useful for him because this will only be a waste of resources available. Changes state and the information will only be sent to the client concerned. When the number of clients that connect to the server to increase the number of objects was increasing and the state must be updated by the server, it also means that it was increasing and the use of bandwidth utilization on the network. Therefore, techniques such as area of interest management is acting as pemfilter the data to be sent is very useful to improve the system scalability. Illustrated in Figure 2 the area of interest management based on the distance, only the enemy that is within a certain distance (indicated by yellow color) can be seen by the player. Figure 1 Communication Server System Architecture

A24 - Software Design And Implementation Of Communication Server 165 In MORPG Based On Client-Server Architecture - Ridho Rahman Hariadi StatusGet is used to get player s status.

3 A24 - Software Design And Implementation Of Communication Server 165 In MORPG Based On Client-Server Architecture - Ridho Rahman Hariadi StatusGet is used to get player s status. Table 3 StatusGet ID Packet Type(CStatGet) Figure 2. Area of Interest Management 2.4 Data format is needed in the communication protocol for this client-server system. Data format is designed specific to individual needs for data communications between the game client and server communication. Data format is designed to use data types with the smallest allocation of bytes that are required in order to minimize the number of bytes to be transferred. Data format used is divided into two, the format for sending data from client to server and data format for sending from the server to the client from Client to Server Move is used in player s movement. Table 1 Move StatusUpdate is used to update player s status. Table 4 StatusUpdate ID HP MP type. Packet Type(CStatUpdate) Player s Health Point Player s Mana Point TypeGet is used to get player s ID Table 5 TypeGet Packet Type(CTypeGet) PositionX PositionY PositionZ StateDirection (byte) Packet type (CMove) Coordinat X player position Coordinat Y player position Coordinat Z player position Player s condition and direction TypeUpdate is used to update player s type. Table 6 TypeUpdate ID Type (byte) Weapon (byte) Packet Type(CTypeUpdate) Player s Type Player s Weapon GetNear is used to get the location of other players which is near. Table 2 GetNear Packet Type(CGetNear)

4 166 The 5 th International Conference on Information & Communication Technology and Systems from Server to Client GetNear is used to send the location of other players which location is near. ChangedCount ChangedList (List) UnchangedCount UnchangedList (List) Table 7 GetNear Packet Type (S GetNear) ChangedList count List berisi : ID PositionX PositionY PositionZ StateDirection (byte) UnchangedList count List of : ID PositionUpdate is used to send player s position Table 8 PositionUpdate ID PositionX PositionY PositionZ StateDirection (byte) Packet Type(S PosUpdate) Coordinat X player position Coordinat Y player position Coordinat Z player position Player s condition and direction StatusUpdate is used to send player s status. Table 9 StatusGet ID HP MP Packet Type(S StatGet) Player s Health Point Player s Mana Point TypeGet is used to send player s type. Table 10 TypeGet Packet Type(S TypeGet) ID Name (string) Player s Name Type (byte) Player s Type Weapon (byte) Player s Weapon 3 RESULT Performance testing is conducted to test the reliability of communications protocols and are designed to measure how much ability the number of connections that can be handled by this server communication. Performance testing is done by measuring the difference between the number of players, delay, and bandwidth usage on the server. Testing is done is done by running the client 1 gradually every 5 seconds. Player-player on-spawn (appear) at the same condition with all the player continues to move in areas adjacent to each player with the other player. This condition is the condition with the largest level of bandwidth usage. Figure 3 describes the delay on the client and Figure 4 illustrates the bandwidth usage on the server. Delay (dalam ms) Bandwith (dalam KB/s) Delay Jumlah Player Figure 3 Delay on the Client Penggunaan Bandwith Jumlah Player Figure 4 Bandwith Usage on the Server Download Upload

5 A24 - Software Design And Implementation Of Communication Server 167 In MORPG Based On Client-Server Architecture - Ridho Rahman Hariadi Bandwith (dalam KB/s) Penggunaan Bandwith Tanpa Menggunakan AoIM Jumlah Player Figure 5 Bandwidth Usage on the Server without AoIM From the test we can prove that the communication server is able to handle up to 300 connections player. Figure 3 shows that the delay keep stable until a certain number of players connected and then will be increased over the increasing number of players connected. The increases in the delay occurred because of the increased time used to perform a one-time loop process on the server which is caused by the increasing number of players who must be iterated. Bandwidth usage on the server depicted in Figure 4 and Figure 5.The Figure 4 shows the download and upload bandwidth used by the server. There is shown that the upload bandwidth tends to increase the number of linier player, but the download bandwidth tends to change. This is because large download bandwidth is influenced by the state updates by each client. The more the number of connected client, there will be more state update by the client. Large upload bandwidth is influenced by the number of update that the server send to the client to announce all the changes that occur in the client s view. Update on the state changes made by using this area of interest management technique keeps the bandwidth usage minimum, and tend to change depending on the distribution condition of the characters in the game. In Figure 5 it is shown that without the use of the area of interest management, the upload bandwidth will be increased dramatically and exponentially graph form to make the CPU utilization level on the big game client, so that when the 80 player connections, CPU utilization level has reached 100%. 4 CONCLUSION Dow nload Upload From the observation from the testing process, the author took the following conclusions: 1. Communication server software that has been made to handle the synchronization with the client, and have some work to serve a number of communications between a client that is connected with this server communication. Synchronization is done by sending update to state that is sent by a client to another client concerned. 2. Communications protocol that has been made can handle data transfer between client and server with the good. So that efficient data format is designed to use data types with the smallest allocation of bytes that are required in order to minimize the number of bytes to be transferred. 3. Game client software is created with the Microsoft XNA technology has been able to connect to the server and the communication has been able to run the functions of the well. 4. Performance measurement system that has been made with the comparison made between the number of players, delay, and bandwidth usage on the server. 5. Delay time that is used to do a loop on the server affect the process of delay received by the client. 6. The use of technical area of interest management in the update state of each client to reduce the upload bandwidth used by the server significantly. REFERENCES [1] Abdennour El Rhalibi, Madjid Merabti, Yuanyuan Shen AoIM in Peer-to-Peer Multiplayer Online Games. [2] Blizzard Entertainment The World of Warcraft homepage. <URL: [3] Jose Pablo Zagal, Miguel Nussbaum, Ricardo Rosas A Model to Support the Design of Multiplayer Games. [4] Lothar Pantel, Lars C. Wolf On the Impact of Delay on Real-Time Multiplayer Games [5] J. Smed, T. Kaukoranta, H. Hakonen Aspects of Networking in Multiplayer Computer Games [6] Joseph D. Pallegrino, Constantinos Dovrolis Bandwidth Requirement and State Consistency in Three Multiplayer Game Architectures [7] Daniel Bauer, Ilias Iliadis, Sean Rooney, Paolo Scotton Communication Architecture for Massive Multi-Player Games

6 168 The 5 th International Conference on Information & Communication Technology and Systems [8] Mark J. P. Wolf Chapter 6:Genre and the Video Game. The Medium of the Video Game [9] Thomas H. Apperley Genre and Game Studies: Toward a Critical Approach to Video Game Genres. [10] Arie Affianto Game Online Multiplayer RPG-Battle Berbasis Web dengan Teknologi Macromedia Flash MX, Flash Remoting, dan Flash Communication Server MX [11] Microsoft Corporation XNA Creators Club Online: Role Playing Game Starter Kit. URL: [12] Soon Tee Teoh Computer Game Design and Programming: Network Games in XNA [13] Shawn Hargreaves Making Networked Games with the XNA Framework

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