岡本 秀輔

This paper describes a C++ library to build web applications. The idea is borrowed from Node.js and Express. js which are a rapid web development framework for JavaScript. Our library consists of a few header files so that it can be available by including them into a source code. The API uses some C++ 14 features, especially 'auto' type, and the program which uses this library becomes concise and clear. In this paper, the design policy, several sample programs and its implementation are presented.

In an university, students take an oral exam to check the understanding level. Especially, in a programming class, a student writes a program source code to solve a practice. Then, the student takes an oral exam. To support the ordering of the oral exam and the checking source code, this paper proposes a reservation system for oral exam. A student uploads source code files to the system. Then, the student is registered to a queue of the oral exam. The student can check the own turn because the own student ID is highlighted. A teacher checks the source code files and asks some questions to the student. Finally, the teacher grades the student and registers the grade to the system.

In this paper, we propose a location registration scheme using location-based Social Networking Services. Our system provides schedules of a teacher on a Web page. The schedule includes the classes, the meetings, and the official trips. However, the teacher might not have any time to register schedules or forget to register the schedule. Therefore, we need a scheme to register the schedule easily. One of approaches is the location registration. If a student knows a location of the teacher, the student knows whether the teacher is in the room or not. Our system register the location information by collaborating with location-based SNSs.

Educational programming languages are programming languages that have been designed for beginners, with the purpose of teaching them the skill of logical thinking or as an introduction to regular programming languages. Although these languages are relatively easier for beginners, difficult concepts of regular programming languages are still being introduced into some of them. As a new approach to this problem, an educational visual programming environment called Islay has been developed. Due to the adoption of the simple concept of state-transition diagram, Islay becomes even easier for beginners than some other educational programming languages. In this research, a new version of Islay is developed as an Android application, with more features being added and a new user interface that is suitable for tablet devices.

In our previous work, we proposed a dynamic data reallocation method for Web-based multiserver Multiplayer Online Role-Playing Game(MORPG) systems. This method handles the data allocation as a combinational optimization problem. It is solved by using a tabu search that is a well-known meta-heuristic algorithm. Our system has some Web servers and an additional computation server. The computation server solves algorithm and decides the data allocation. However, each load of server is not completely balanced. This means that some Web server might have free computing resources. We aim to use these resources effectively. Therefore, our system handles a Web server that has free resources as a computation server. In this paper, we propose a selection method of a computation server in the Web servers. The server loads might be predicted because the data allocation is decided according to the last server loads and the user requests. Therefore, our system predicts the load of each server and selects a Web server. This selected server acts the computation server and decides the data allocation for the next term. After that, the computation server predicts the server load and selects the next computation server. We evaluates the performance of our system by measuring the latency values for game users and the server loads.

This paper proposes a remote control system of Sphero using a web browser. Sphero is a robotics ball that is controlled by using a smartphone. A user can control Sphero using Android or iOS application. However, the user is supposed to be with the Sphero. We provides a remote control system as a web application. The user can control Sphero using a web browser. The Sphero connects to a smartphone and the smartphone connects to the web server. The smartphone is a relay station. The user sends operation commands to the web server using the web browser. The smartphone receives the commands from the web server and forwards it to the Sphero. The smartphone also sends camera images to the web server. The web browser receives the image from the web server and displays it. This means that the user can observe the state of the Sphero and control Sphero at a different place from a place that the Sphero exists. We confirm the behavior of our system and clarify some problems.

An interactive animation is a presentation of moving pictures that behave dynamically according to the input from users. It can be composed of animation characters modeled as finite-state machines. Based on the fact that the behavior of a finite-state machine can be defined by a state-transition diagram, an interactive animation authoring tool called Islay has been developed. Islay allows users to create interactive animation simply by drawing state-transition diagrams on a GUI-based editor. Up to now Islay mainly runs on the PCs. But we cannot use it on the portable devices that have become popular recently. In this research, a new version of Islay that runs on Android devices is developed with its user interface adapted to the touch screen interface.

In our previous work, we proposed a load distribution technique and a dynamic data reallocation method for web-based Multiplayer Online Role-Playing Game (MORPG) systems. Our proposed approach reduced the average server latency for game players. However, latency values varied widely resulting in some game players gaining an advantage over others. In this paper, we deal with data allocation and consider latency fairness in the form of a combinational optimisation problem. We develop an optimisation model in which the objective function minimises the differences in latency values and we solve instances from this model using an exact algorithm. Our model improved latency fairness and more stable server loads than the previous data reallocation method. Furthermore, it provides more stable gameplay using ten web servers instead of five. Copyright © 2014 Inderscience Enterprises Ltd.

This paper describes a near-optimal allocation method for web-based multi-player online role-playing games (MORPGs), which must be able to cope with a large number of users and high frequency of user requests. Our previous work introduced a dynamic data reallocation method. It uses multiple web servers and divides the entire game world into small blocks. Each ownership of block is allocated to a web server. Additionally, the ownership is reallocated to the other web server according to the user's requests. Furthermore, this block allocation was formulated as a combinational optimization problem. And a simulation based experiment with an exact algorithm showed that our system could achieve 31% better than an ad-hoc approach. However, the exact algorithm takes too much time to solve a problem when the problem size is large. This paper proposes a meta-heuristic approach based on a tabu search to solve a problem quickly. A simulation result shows that our tabu search algorithm can generate solutions, whose average correctness is only 1% different from that of the exact algorithm. In addition, the average calculation time for 50 users on a system with five web servers is about 25.67 msec while the exact algorithm takes about 162 msec. An evaluation for a web-based MORPG system with our tabu search shows that it could achieve 420 users capacity while 320 for our previous system.

This paper presents a tool for creating interactive 3D animations and video games in terms of state transition diagrams whose content can run on any HTML5 browser with WebGL enabled. © 2013 IEEE.

Our interactive animation software is written in JavaScript, and is serial execution. However, it has a problem, which is related to drawing intervals. In case the software has to process a number of animation objects, it takes a long time. The longer drawing intervals are, the slower speed of animation playing is. So, we parallelize interactive animation software with Web Workers that is one part of HTML5. We partition drawing animation with some approaches, and parallelize their process. This time, we report the parallelization approach that takes into consideration the property of Web Workers and the interactive animation software. © 2013 IEEE.

Our previous work proposed a clustering algorithm to cluster research documents automatically. It used Web hit counts of AND-search on two words as a document vector. Target documents are clustered with a result of k-means clustering method, in which cosine similarity is used to calculate a distance. This paper uses this algorithm to cluster twitter users. However, the twitter users have different characteristics from the research documents. Therefore, we investigate problems of the using our algorithm for twitter users and propose some ideas to resolve it. © 2013 IEEE.

This paper describes a method for rapidly authoring multiplayer online games. The game author specifies state machines that define the behavior of game characters. The results are translated into a JavaScript code. The entire application is supported by Node.js at the server side and by modern Web browsers at the client side. Utilization of the WebSocket feature allows the communication between the Web browsers and the web server to be processed efficiently, and the player's interaction with the game interface is smooth. © 2013 ACM.

This paper describes a web mining method for clustering research documents automatically. Web hit counts of AND-search for two words are used to form a document feature vector. Target documents are clustered using the k-means clustering method twice, in which cosine similarity is used to calculate the distance measure. © 2013 Inderscience Enterprises Ltd.

The web-based-application user base has witnessed rapid growth. It has become necessary to develop techniques that enable systems to manage simultaneous access by a large number of users. We focus on web-based MultiPlayer Online Role-Playing Games (MORPGs), which must be able to cope with a large number of users and a high frequency of user requests. In our previous work, we introduced a system using multiple web servers and a dynamic data allocation method, which is able to manage dynamic change in user requests. Using this method, we achieved a capacity of 320 users, as opposed to the user capacity of 200 for single-server MORPG system. However, we found some cases in which our method was not effective. In this paper, we propose three rules for dynamic data allocation to address different situations. Our evaluation shows that the cache works effectively if the most avatars gather in a certain place. Copyright © 2012 Inderscience Enterprises Ltd.

A tool for authoring interactive three-dimensional animations is presented of which features are intuitive comprehensiveness of the user interface by way of state-transition diagrams and output being Flash contents that run on almost all web browsers. © 2012 IEEE.

We present a tool for authoring interactive Flash games, which consists of its front-end graphical interface and a newly developed translator into Flash via Action Script3.0. The main feature is that the behaviors of characters are described in terms of state transition diagrams. Each state has a picture and activities. The picture represents appearance of the character in that state. The activities can be selected out of a set of performances such as relocation of the character and generation of other characters. A transition is conditioned in terms of events such as mouse click and collision with other characters. The graphical editor of state-transition diagrams built in this tool is so easy to manipulate that even children can compose interactive Flash games. © 2012 IEEE.

A tool for creating interactive animations and video games in terms of state-transition diagrams is presented. This tool runs on any web browsers capable of JavaScript and HTML5 and allows users to convert their program into a set of HTML, JavaScript and image files that runs on browsers even without this tool. © 2012 IEEE.

This paper describes a web mining method to classify research documents automatically. Web hit counts of AND-search on two words are used to form a document vector. Target documents are classified with a result of k-means clustering method, in which cosine similarity is used to calculate a distance. © 2012 ACM.

In our previous work, we proposed a load distri-bution technique and dynamic data reallocation method for web-based MORPG system. This approach could reduce the average server latency for game players. However, each latency widely varied, which leads unfair situation for game players. In this paper, we deal with data allocation with taking into account the fairness as a combinational optimization problem. We develop an optimization model whose objective function is to minimize the difference among latency value. We exactly solve this problem and compare the results with our previous data allocation method. © 2012 IEEE.

This paper describes a preliminary experiment and a discussion to introduce server consolidation to our web-based system. Unfortunately, naive virtualization of our system suffers from severe performance degradation. The experimental results obtained made clear the bottleneck of virtualized system. And a key to improve the performance is also presented. © 2011 ACM.

This paper describes a web system for supporting a school event using Twitter. This system collects messages related to a school event from Twitter and shows them in a various way. And it has a function for non-Twitter users to post a message with a specific tag to Twitter. Last year, we built a prototype system and provided it for our school festival. This paper shows the overview of our system, the experimental results and the discussion of result. Additionally, two new functions to increase the number of users and our future plans to evaluate our system are also presented. © 2011 IEEE.

In recent times, the web-based applications has grown rapidly and there has been an explosive increase in the number of users. Hence, it is necessary to develop technique to deal with several users. In this study, we particularly focus on web-based multiplayer online role-playing games (MORPGs), which have a large number of users and deal with high frequency of user requests. In our previous work, we introduced a method to deal with a large number of users using multiple web servers and a dynamic data allocation method to deal with dynamic change in the user request. Using our method, we achieved a user capacity of 320 for the web-based MORPG system as opposed to 200 user capacity of the single server MORPG system. However, we found some cases in which our dynamic data allocation role was not effective. In this paper, we propose three rules for our dynamic data allocation method to address various situations. We evaluate these rules using four web servers and investigate their properties and effectiveness.

Server virtualization helps us system and network administrators manage computer resources and reduce power consumption. However, to make efficient use of virtualization, its various loads, especially I/O operations, require careful consideration. Here we conducted three experiments to examine the effects of I/O load in a virtualization environment. First, We measured the performance of I/O operations executed on a virtual machine (VM) and the power consumption of the host machine, varying the I/O schedulers on both machines. The results varied according to the combinations of the I/O schedulers. Four of the 16 combinations in particular showed low I/O performance and high power consumption. We then investigated the effect of I/O priority to VM processes with a completely fair queuing scheduler on I/O performance. In this case, the I/O execution of high-priority required less than half the time of that of a lower priority process. Finally, we investigated the effects of I/O priority while jointly varying the block size of I/O requests issued by the VMs. I/O execution was effective when the block size was large but not when it was small. © 2011 IEEE.

Purpose: The purpose of this paper is to propose a load distribution technique for a web server. It utilizes Web Workers, which is a new feature of Javascript. Design/methodology/approach: The authors have been implementing a web-based MORPG as an interactive, real-time web application previously, the web server alone was responsible for manipulating the behavior of all the game characters. As more users logged in, the workload on the server was increased. Hence, the authors have implemented a technique whereby the CPU load of the server is distributed among the clients. Findings: The authors found that some caching mechanism is useful for utilizing client-side calculation. The caching suppresses the increase of communication load. A performance evaluation reveals that the technique plays a role in decreasing the CGI latency of both low-end server and high-end server. The average latency is reduced to 59.5 percent of the original system. Originality/value: Web Workers allows scripts to be executed with keeping the page response on a web browser. It is intended to be used for raising user experience. This technique utilizes Web Workers for a web server to distribute the load to its clients. © Emerald Group Publishing Limited.

We have investigated the bottleneck in web based MORPG system and proposed a load distribution method using multiple web servers This technique uses a dynamic data allocation method called the moving home This paper describes the evaluation of our method using 4 8 16 web servers We evaluated it on both the single server system and multi server system And we confirm that the effect of the moving home through the comparison between the multi server system without the moving home and that with the moving home Our experimental result shows that the upper bound of the number of avatars in the eight server system with the moving home becomes 380 by contrast that in the single server system is 200

In this paper, we describe a load distribution technique that employs web workers. We have been implementing a web-based MORPG as an interactive, real-time web application previously, the web server alone was responsible for manipulating the behavior of all the game characters. As more users logged in, the workload on the server was increased. Hence, we have implemented a technique whereby the CPU load of the server is distributed among the clients a performance evaluation reveals that our technique plays a role in decreasing the CGI latency of low-end servers and can decrease the CPU load of high-end servers when many users are logged in. Copyright 2010 ACM.

Recently, due to the spread of broadband access to the Internet, the speeding up JavaScript on Web browsers and the development of communication technology such as Ajax, a variety of Web applications are provided. However, the access congestion to the Web server and the lower usability in case of higher frequent communication are major problems on the Web application. We have investigated the bottleneck in Web-based MORPG system and proposed the load-distribution technique using multiple Web servers[8]. This technique uses a dynamic allocation of the data, called the moving home. We proposed some rules for the moving home[9]. In this paper, we applied these rules to our MORPG system and evaluated them. © 2010 IEEE.

The recent spread of broadband Internet access, speeding up of Java Script in Web browsers, and development of communications technology such as Ajax has led to the development of a variety of Web applications. The access congestion of Web servers and lower usability in the case of frequent requests are the major problems that affect the use of Web applications. In this study, we investigate the bottlenecks in single-server system. and propose a technique to improve the usability of Web-based MORPG servers.