Kenji Kono

Efficient RMI: dynamic specialization of object serialization

This paper describes a novel approach to object serialization in remote method invocation (RMI). Object serialization transforms objects representations between heterogeneous platforms. Efficient serialization is primary concern in RMI because the conventional approaches incur large runtime overheads. The approach described specializes a serializing routine dynamically according to a receivers platform, and this routine converts the senders in-memory representations of objects directly into the receivers in-memory representations. This approach simplifies the process of RMI: the receiver can access the passed objects immediately without any data copies and data conversions. A new platform can join the existing community of senders and receivers because a specialized routine for the platform is generated as needed. Experimental results show that significant performance gains are obtained by this approach. The prototype implementation of this approach was 1.9-3.0 times faster than Sun XDR, and the time needed for generating a specialized routine was only 0.6 msec.

Using Attack Information to Reduce False Positives in Network IDS

Reducing the rate of false positives is of vital importance in enhancing the usefulness of signature-based network intrusion detection systems (NIDSs). To reduce false positives, a network administrator must throughly investigate a lengthy list of signatures and carefully disable the ones that detect attacks not harmful to the user’s environment. This is a daunting task; if some signatures are disabled by mistake, the NIDS fails to detect critical remote attacks. We designed a NIDS, TrueAlarm, to reduce the rate of false positives. Conventional NIDSs alert administrators to the detection of a malicious message, regardless of whether the message actually attempts to compromise the protected server. In contrast, TrueAlarm delays the alert until it confirms that an attempt has been made. In TrueAlarm, NIDS cooperates with a server-side monitor that observes the protected server’s behavior. TrueAlarm alerts administrators only when a server-side monitor detects deviant server behavior that must have been caused by a message detected by NIDS. Our experimental results show that TrueAlarm reduces the rate of false positives. Using real network traffic collected over 15 days, TrueAlarm produced no false positives, while a conventional NIDS produced 125.

An integrated laboratory for processor organization, compiler design, and computer networking

An integrated laboratory dealing with processor organization, compiler design, and computer networking has been developed. The goals of the laboratory are to make it possible for each student to work with modern and attractive materials and to learn about the interfaces between system modules, to provide students with opportunities to collaborate in the construction of a large system, and to give students a sense of accomplishment. The goals have been met based on the responses of students who have used it, verifying its effectiveness. This paper describes the design and development of the baseline components to be integrated, the laboratory organization and schedule, and the results and evaluation of the laboratory.

YabAI: The First Rescue Simulation League Champion

RoboCupRescue project aims to simulate large urban disasters. In order to minimize damage resulting from disasters, various rescue agents try to accomplish their missions in the disaster space in the simulation system. Ability of an individual agent, however, is utterly insufficient. Agents need to cooperate with other same and different types utilizing as little communication as possible under stringently limited visual sensory information. Our YabAI team, however, successfully implemented effective cooperations under this limitation.

An integrated laboratory for computer architecture and networking

Processors, compilers, and networks -- important materials covered by computer science curricula -- are often treated independently in laboratories associated with corresponding lecture courses. An integrated laboratory called CNP for juniors majoring in computer science at the University of Electro-Communications has been developed and is now under way, where a networking protocol stack implemented by students is translated into object codes by a compiler implemented by students, which in turn are executed on a processor implemented also by students. The goals of the integrated laboratory are to deal with modern and attractive materials, to provide students with opportunities of collaborating in constructing a large system, as well as to have students share a feeling of accomplishments among them. Responses from students approved our intention and verified the effectiveness. In this paper, we describe the design and development of baseline components to be integrated, laboratory organizations and schedules, and results and evaluations of the laboratory.

A practical approach to automatic parameter-tuning of web servers

This paper presents a practical approach to automatically tuning the parameters of the Apache Web server. In particular, two significant parameters, KeepAliveTimeout and MaxClients, are dealt with. The notable features of our approach are twofold. First, it is easy to deploy because no modifications to Apache or the underlying operating system are required. Second, our approach is based on the detailed analysis on how each parameter affects the servers behavior. Experimental results demonstrate that our prototype works well on different workloads; it can discover almost optimal values and quickly adapt to workload changes.

User-level disk-bandwidth control for resource-borrowing network applications

This paper presents the design and implementation of DiscNice, a mechanism for controlling disk bandwidth at the user-level. To throttle disk I/O at the user-level, DiscNice infers what the internal behavior of the underlying OS is and predicts the disk I/O size that is incurred by file I/O. To infer internal kernel behavior, we extensively used a concept called the graybox technology and elaborated it to predict the disk I/O behavior. In the graybox technology, the underlying OS is treated as a graybox, which means that we could exploit: 1) our knowledge of the OS, 2) the state information the OS exposes to us, and 3) how the OS reacts to various operations to predict the internal kernel behavior. By exploiting the graybox knowledge on Linux, we developed a graybox technique for predicting the disk I/O behavior. Our technique could also be applied to Windows XP with minor modifications because it does not rely on a detailed knowledge of Linux