The limited attentional resource of users is a bottleneck to delivery of push notifications in today's mobile and ubiquitous computing environments. Adaptive mobile notification scheduling, which detects opportune timings based on mobile sensing and machine learning, has been proposed as a way of alleviating this problem. However, it is still not clear if such adaptive notifications are effective in a large-scale product deployment with real-world situations and configurations, such as users' context changes, personalized content in notifications, and sudden external factors that users commonly experience (such as breaking news). In this paper, we construct a new interruptibility estimation and adaptive notification scheduling with redesigned technical components. From the deploy study of the system to the real product stack of Yahoo! JAPAN Android application and evaluation with 382,518 users for 28 days, we confirmed several significant results, including the maximum 60.7% increase in the users' click rate, 10 times more gain compared to the previous system, significantly better gain in the personalized notification content, and unexpectedly better performance in a situation with exceptional breaking news notifications. With these results, the proposed system has officially been deployed and enabled to all the users of Yahoo! JAPAN product environment where more than 10 million Android app users are enjoying its benefit.

Analyzing and feeding back the results on real-world services are important missions in the Big Data era to realize smart city. However, analyzing real-world data is still challenging because of dirtiness of data and large variety of analytic requirements. To cope with the challenges, this paper proposes and develops an analytical toolbox for smart city applications. The analytical toolbox consists of three phases: preparation, analysis, and visualization. The preparation phase deals with the dirtiness of the data by including fundamental data cleansing techniques and data integration techniques. The analysis phase is responsible for ETL (extract, transform and load) process and analytical query processing from the next phase. The visualization phase deals with analytical requirements from users and visualization of analytical results. This paper showcases a real-world use case of the proposed analytical toolbox. The use case is now open in public with help of Fujisawa city, Japan, and this fact indicates that the proposed analytical toolbox is feasible for real-world data analysis and feeding back to citizens.

In today's advancing ubiquitous computing age, with its ever-increasing amount of information from various applications and services available for consumption, the management of people's attention has become very important. In particular, the high volume of notifications on mobile devices has become a major cause of interruption of users. There has been much research aimed at detecting the opportune moment to present such information to users with in a way that lowers the cognitive load or frustration. However, evaluation of such systems in the real-world production environment with real users and notifications, and evaluation on user's engagement to the presented notification beyond simple responsiveness have not been adequately studied. To the best of our knowledge, this study is the first to investigate user interruptibility and engagement using a real-world large-scale mobile application and real-world notifications consisting of actual news content. We equipped the Yahoo! JAPAN Android app, one of the most popular applications on the national market, with our mobile-sensing and machine-learning-based interruptibility estimation logic. We conducted a large-scale in-the-wild user study with more than 680,000 users for three weeks. The results show that in most cases delaying the notification delivery until an interruptible moment is detected is beneficial to users and results in significant reduction of user response time (49.7%) compared to delivering the notifications immediately. We also observed a higher number of notifications opened in our system as well as constant improvement in user engagement levels throughout the entire study period.

In current society, there are numerous robots made for various purposes, including manufacturing, cleaning, therapy, and customer service. Other robots are used for enhancing H2H communication. In this research, we proposed a robotic system which detects the user's emotions and enacts them on a humanoid robot. By using this robotic avatar, users with motor disabilities are able to extend their methods of communication, as a physical form of expression will be added to the conversation.

Our research focuses on creating a robotic system that aids human-to-human communication. The robot acts as a personal companion that understands the user's emotions and helps express them alongside the user. First, the user's facial expression is detected through a connected camera device and relays the retrieved information to a humanoid robot. The humanoid robot then performs physical gestures that match the detected emotion. By using this system, those who are unable to freely move their own bodies can add a physical component to their communication method. In this paper, we have determined the efficacy of translating detected facial expressions into robot movements. Through experiments and surveys, we determined whether our proposed 'Ex-Amp Robot' helped enhance the communication of a hypothetically tetraplegic user.

Collecting urban data in a citywide scale plays a fundamental role in the research, development and implementation of smart cities. This demo introduces Cruisers, an automotive sensing platform for smart cities, which is developed based on the following ideas. a) Garbage collecting trucks are used as host automobiles to accommodate sensors, b) 3G cellular communication network is used to wirelessly deliver sensed data directly to servers, and c) Proxy server(s) are adopted to convert the format of sensed data to required ones. This platform has been deployed to 24 garbage collecting trucks at Fujisawa city, i.e., nearly 1/4 of the total number of such trucks in the city. An iOS application is also developed to demonstrate the sensing process and the covered area.

This paper proposes ''SmileWave", a system for revealing smile-based emotional contagion, propagation effect of the similar emotion through smiley facial expression, on the social network where users interact each other through web-based user interface rather than in-person interaction. SmileWave is a picture-based networking service and detects the change of smile degree when the user looks at posted smile images of others. Our extensive user study with 50 participants for 30 days confirmed the emotional contagion effect on SmileWave. Users' smile degree improved by 27% when the user looked at posted smile images. The result also proved that there is a stronger effect on smile-based emotional contagion when the examinee and the person in the image are in close relationship.

Despite extensive efforts on exploring the asymptotic capacity bounds for mobile ad hoc networks (MANETs), the general exact capacity study of such networks remains a challenge. As one step to go further in this direction, this paper considers two classes of Aloha MANETs (A-MANETs) NAand NCthat adopt an aggressive traffic-independent Aloha and the conventional traffic-dependent Aloha, respectively. We first define a notation of successful transmission probability (STP) in NA, and apply queuing theory analysis to derive a general formula for the capacity evaluation of NA. We also prove that NCactually leads to the same throughput capacity as NA, indicating that the throughput capacity of NCcan be evaluated based on the STP of NA as well. With the help of the capacity formula and stochastic geometry analysis on STP, we then derive closed-form expressions for the throughput capacity of an infinite A-MANET under the nearest neighbor/receiver transmission policies. Our further analysis reveals that although it is highly cumbersome to determine the exact throughput capacity expression for a finite A-MANET, it is possible to have an efficient and closed-form approximation to its throughput capacity. Finally, we explore the capacity maximization and provide extensive simulation/numerical results.

Recent technological trends in mobile/wearable devices and sensors have been enabling an increasing number of people to collect and store their "lifelog" easily in their daily lives. Beyond exercise behavior change of individual users, our research focus is on the behavior change of teams, based on lifelogging technologies and lifelog sharing. In this paper, we propose and evaluate six different types of lifelog sharing models among team members for their exercise promotion, leveraging the concepts of "competition" and "collaboration." According to our experimental mobile web application for exercise promotion and an extensive user study conducted with a total of 64 participants over a period of three weeks, the model with a "competition" technique resulted in the most effective performance for competitive teams, such as sports teams.

In today's ubiquitous computing environment where users carry, manipulate, and interact with an increasing number of networked devices, applications and web services, human attention is the new bottleneck in computing. It is therefore important to minimize a user's mental effort due to notifications, especially in situations where users are mobile and using multiple wearable and mobile devices. To this end, we propose Attelia II, a novel middleware that identifies breakpoints in users' lives while using those devices, and delivers notifications at these moments. Attelia II works in real-time and uses only the mobile and wearable devices that users naturally use and wear, without any modifications to applications, and without any dedicated psycho-physiological sensors. Our in-the-wild evaluation in users' multi-device environment (smart phones and smart watches) with 41 participants for 1 month validated the effectiveness of Attelia. Our new physical activity-based breakpoint detection, in addition to the UI Event-based breakpoint detection, resulted in a 71.8% greater reduction of users' perception of workload, compared with our previous system that used UI events only. Adding this functionality to a smart watch reduced workload perception by 19.4% compared to random timing of notification deliveries. Our multi-device breakpoint detection across smart phones and watches resulted in about 3 times greater reduction in workload perception than our previous system.

In today's ubiquitous computing environment where the number of devices, applications and web services are ever increasing, human attention is the new bottleneck in computing. To minimize user cognitive load, we propose Attelia, a novel middleware that identifies breakpoints in user interaction and delivers notifications at these moments. Attelia works in realtime and uses only the mobile devices that users naturally use and wear, without any modifications to applications, and without any dedicated psycho-physiological sensors. Our evaluation proved the effectiveness of Attelia. A controlled user study showed that notifications at detected breakpoint timing resulted in 46% lower cognitive load compared to randomly-timed notifications. Furthermore, our “in-the-wild” user study with 30 participants for 16 days further validated Attelia's value, with a 33% decrease in cognitive load compared to randomly-timed notifications.

Operating Systems (OS) in wireless sensor nodes can be classified into event-driven systems or multithreaded systems. Most event-driven systems, such as TinyOS, drive down power consumption although context switching for real-time processing is not available. Among multithreaded systems, non-preemptive systems, such as Protothreads in Contiki, often have lack of real-time processing capability. In Protothreads, if a higher-priority task was posted while a lower-priority task has been running, the lower-priority task cannot be preempted. Thus, one challenge is that without changing the semantics of Protothreads, how the system can be preemptive as well as lowering the power consumption for real-time tasks such as target tracking. In this paper, we propose a dynamically switchable scheduling system for operating systems using Protothreads where events with time constraint have occurred. This system enables to trigger interruption, to process real-time tasks preferentially when real-time events occurred, and to save energy by executing tasks except real-time tasks as a standard event-driven system. Exeprimental results show that latency in Contiki is reduced by about 75% in the best case and is kept constant with power efficiency.

Recent technological trends on mobile/wearable devices and sensors have been enabling increasing number of people to collect and store their “life-logs” easily in their daily lives. Beyond exercise behavior change of individual user, our research focus is on the behavior change of teams, based on life-logging technologies and information sharing. In this paper, we propose and evaluate six different types of information sharing model among team members for their exercise promotion, leveraging concepts of “competition” and “collaboration”. According to our experimental mobile web application for exercise promotion and extensive user study among 64 total users for three weeks, the model with “external competition” technique resulted the most effective performance for competitive teams such as sport teams.

We propose a novel technique that aggregates multiple sensor streams generated by totally different types of sensors into a visually enhanced video stream. This paper shows major features of SENSeTREAM and demonstrates enhancement of user experience in an online live music event. Since SENSeTREAM is a video stream with sensor values encoded in a two-dimensional graphical code, it can transmit multiple sensor data streams while maintaining their synchronization. A SENSeTREAM can be transmitted via existing live streaming services, and can be saved into existing video archive services. We have implemented a prototype SENSeTREAM generator and deployed it to an online live music event. Through the pilot study, we confirmed that SENSeTREAM works with popular streaming services, and provide a new media experience for live performances. We also indicate future direction for establishing visual stream aggregation and its applications.

The global spread of mobile phones creates a new vision in the world. It is called mobile sensing, in which human beings are regarded as sensors to produce aggregated models and knowledge. In this setting, it is likely that user privacy is violated. Therefore, we investigate privacy-preserving metho

Throughput-sensitive multimedia applications, such as on-demand video streaming and non-interactive live streaming require a high sending rate and a certain-level of smoothness. On the other hand, interactive streaming such as on-line conferencing requires a smooth sending rate. TFRC and TFWC support smoothness-sensitive multimedia applications, however, they cannot provide enough sending rate to throughput-sensitive multimedia applications. In this paper, we propose Tunable TFWC (TTFWC), an extension to TFWC to achieve various throughput behavior with regard to trade-off between smoothness and the sending rate based on application requirements. TTFWC supports throughput-sensitive multimedia applications in addition to smoothness-sensitive applications. Simulation results show that TTFWC with the value of tuning parameter 0.9 achieves approximately 10% higher throughput than the original TFWC without compromising TCP-Friendliness.

Deploying Wireless Sensor Networks (WSN) securely still requires users to have certain skills and exert effort. In the near "sensor everywhere" future, a much simpler method for deploying WSN will be necessary for end-users. We propose LiDSN(Light Communication for Deploying Secure Wireless Sensor Networks) which enables users to achieve deployment tasks via simple interaction. LiDSN leverages light-based communication between an LED and a light sensor in order to add a new sensor node securely into existing WSN. Through touching interaction, a new sensor node ID and secret key can be transmitted to the WSN, and then the WSN is able to identify which node should be added while maintaining the security of the WSN.

This paper proposes and evaluates a method to detect and classify tweets that are triggered by places where users locate. Recently, many related works address to detect real world events from social media such as Twitter. However, geotagged tweets often contain noise, which means tweets which are not content-wise related to users' location. This noise is problem for detecting real world events. To address and solve the problem, we define the Place-Triggered Geotagged Tweet, meaning tweets which have both geotag and content-based relation to users' location. We designed and implemented a keyword-based matching technique to detect and classify place-triggered geotagged tweets. We evaluated the performance of our method against a ground truth provided by 18 human classifiers, and achieved 82% accuracy. Additionally, we also present two example applications for visualizing place-triggered geotagged tweets.

Nowadays, since each sensor network is managed within a single organization, sensor data cannot be obtained externally. When these sensor networks are virtualized that means everyone is able to obtain data anywhere without minding which sensor network the data belongs, two features will be required. One of these is geographical range query. This research realizes it using Z-order in the same way with related works [1][2][3][4]. The other requirement is distributed sensor data management. Current systems adapt the way that stores the data in a (or some) centralized server(s), or that stores the data in many servers, having one centralized server to store indexes of the address of the data. This research proposes a method not relating real space geographical information and relative position of peer in ID space. By using this method, in the place where density of people and smart phones with many sensors increase suddenly such as Super Bowl and new year countdown in NY, by using DHT, sensor data don't concentrate on a specified peer on managing the data. This research simulates and evaluates this method.

Recent progress in information technology enables people to easily broadcast events live on the Internet. Although the advantage of the Internet is live communication between a performer and listeners, the current mode of communication is writing comments using Twitter or Facebook, or some similar messaging network. In one type of live broadcast, musical performances, it is difficult for a musician, when playing an instrument, to communicate with listeners by writing comments. We propose a new communication mode between performers who play musical instruments, and their listeners by enabling listeners to control the performer's camera or illumination remotely. The results of four weeks of experiment confirm the emergence of nonverbal communication between a performer and listeners, and among listeners, which increases camaraderie amongst listeners and performers. Additionally, the dramatic impact of a performance is increased by enabling listeners to control various camera actions such as zoom-in or pan in real time. The results also provide implications for design of future interactive live broadcasting services.

Compressive Sensing (CS) is a novel approach for data representation, which can represent signals at a rate below the Nyquist rate with low computation costs on encoder. For these characteristics, CS is very suitable for low power sensor nodes to save power consumption that is a primary problem in Wireless Sensor Networks (WSN). But there are many problems when using CS in a real environment. One of these is that pattern of sensor values change dynamically. It decreases the efficiency of power consumption and accuracy of recovery. To solve the problem, we propose Pattern-based Matrix-size Optimization Algorithm (PMOA), which aims to improve the accuracy of exact recovery and power consumption.

In sensing systems, data compression is a promised way to save energy because it reduces the rate of data transmission, but less attention has been paid to the underlying task scheduling algorithms. We present a Double Rate Bundle Scheduling algorithm (DRBS) that maximizes the sleep state period of the CPU to reduce energy consumption. Our prototype implementation in a Mote device improves energy efficiency up to 8% compared to existing algorithms.

Analyzing groups of people having a conversation enable to provide context-aware services, such as life log, group-wares, and the virtualization of social networks. We propose a novel method for extract chatting groups by leveraging Bluetooth RSSI and voice data acquired from smart phones. Neighboring people are detected from Bluetooth RSSI, and conversation groups are extract by talking states. The purpose of this paper is to define algorithm that works on efficiently on smart phones that are general and widespread mobile devices.

This paper proposes the information access method that is based on the distance between users and objects. In Addition, demonstrate Lupe system, which visualizes WSN status information utilizing our method. The evaluative experiment shows that our method is useful in where a number of sensors are setup. As a result our method and Lupe system enable to easily brows WSN status information for end-user.

We propose a simple interaction to transfer information on smart phone to laptop/tablet PCs. We often encounter the situation that we need to send URL, which is preliminary accessed in mobile devices, from mobile devices to personal computers (PCs) to see the web page with wider screen. To support this information transfer, we utilize combination between vibrator in smart phones and accelerometer in laptop/tablet PCs. URL information is encoded to vibration patterns, and the patterns are detected and decoded by accelerometer in PCs. We demonstrate the interaction's efficiency and reasonability with actual products.

We've known for a while that the Internet has ossified as a result of the race to optimize existing applications or enhance security. NATs, performance-enhancing-proxies,firewalls and traffic normalizers are only a few of the middleboxes that are deployed in the network and look beyond the IP header to do their job. IP itself can't be extended because "IP options are not an option". Is the same true for TCP?

A demonstration experiment called “Timely & Timely” was a evaluation of a system in which ubiquitous sensor's data and reporter's reports are displayed on digital signage and smart phones. This experiment was taken place at a shopping mall called “Lalaport Kashiwanoha” in Chiba, Japan. We have designed and implemented an information distribution system in which we can specify which information should reach which customers. Specifying the certain information is called “Channel” and the information receiving software running on Android smart phones is called “Ubiroid.” Each channel is defined by a USDL (Universal Service Description Language) based on XML. The developers and users can easily search and use channels thanks to this markup language. We rent 20 Android smart phones to the guests and received questionnaire results from those who participated in this experiment. This paper presents design, implementation, and evaluation of “Timely & Timely” and also shows the results from the experiment questionnaires.

Mobile nodes have limited computing resources, among which battery is one of the most important resources, since the lifetime of a node depends on the amount of battery and energy usage in the node. Application processes on mobile nodes include those are important for the users for certain duration of time, and those not. Therefore, exhausting whole battery for running non-important ones such as games, would be waste of energy. To maximize the user satisfactions with limited amount of energy, a sophisticated pacing mechanism is required for energy usage. We propose a process lifetime reservation system, called “pSurvive.” It enables users to reserve energy for running specific processes for a certain duration of time. Users are allowed to run any applications until the total energy consumption reaches the “deadline” to run the reserved processes. pSurvive enables this with the following three novel mechanisms. First, P-Monitor monitors running processes and devices (e.g. NIC, LCD, etc.) in a node for their energy consumption. Second, P-Analyzer estimates future energy consumption based on the energy usage information given by P-Monitor. Third, P-Reserver accepts energy reservation requests from users, and pace the energy consumption by shedding unnecessary tasks. This paper first discusses requirements for energy reservation on mobile nodes. It then reports the design and the implementation of pSurvive for Android mobile nodes, and shows that pSurvive achieves process lifetime reservation based on the fine-grained energy monitoring.

A Trusted Computing Base (TCB) such as a Trusted Platform Module (TPM) or a Mobile Trusted Module plays anessential role for security and privacy applications in embedded systems such as cell phones, smart sensors, and actuators. However, existing hardware-based TCBs lack flexibility for function updates, bug fixes, and feature updates. In this paper, we present a dependable TCB on a Cell Broadband Engine TM processor by providing a hardware and software hybrid TPM. Unlike prior approaches, we provide three new features: (1) TPM functions are implemented in software running in memory isolated by hardware, (2) our software TPM is launched and establishes a chain of trust from the hardware using a secure boot method, and (3) anew TPM command provides dynamic patching to the running software TPM and secure code overlays for the efficient use of the limited resources. We show the feasibility of this hybrid implementation of the TPM by assessing its performance and security properties.

The paper proposes an intuitive device selecting interface called ``Vib-connect'' for device collaboration. Recent progress in Information Technology allowed various devices to join wireless network. As a result, various ways of device collaborations and services became possible. However, interfaces for selecting devices are still complicated for end-users and far from being intuitive. To solve this problem, we propose ``vib-connect'', an interface which enables users to select device intuitively by pasting a vib-connector, a small vibration-based device. Vib-connect solves these problem by implementing these device information as a unique vibration pattern. By keeping smart-phones or any kind of vibration generating device, end-users can easily select devices to collaborate. We implement a prototype, and through the evaluation, we confirmed high accuracy in vibration pattern detection and high usability satisfaction by non-expert users. By using "Vib-connect", users without any technical expertize can easily select devices to collaborate with.

This paper presents u-Photo Mobile a clickable digital still image to visualize and operate ubiquitous services. U-Photo Mobile is designed and implemented to be executed on smart phones e.g. Apple's iPhone. Users shoot the ubiquitous services attached with a two-dimensional bar-code. The u-Photo Mobile system decodes the ID and finds functions of the service. The touch screen of u-Photo Mobile lets users check and control the service. The operation of ubiquitous services are realized by making a network connection between u-Photo Mobile and the services. With this intuitive method, the users can interact with ubiquitous service through the metaphor of “taking and tapping a photograph.” The u-Photo provides users with an instinctive technique, which realizes a seamless interaction between user's mobile phones and intelligent environments.

This paper introduces a new dependable operating system project, called DEOS, started in 2006, and scheduled to continue for six years. In this project, a safety extension mechanism called P-Bus is to be designed, and implemented in the Linux kernel so that a future dependability attribute is implemented with P-Bus. A hardware abstraction layer, called SPUMONE, is introduced so that a light-weight operating system, called ArcOS, and a monitoring service on top of ArcOS monitors the Linux kernel to provide a safety-net for the Linux kernel. New dependability metrics are being designed to enable developers and users to decide which hardware or software solution meets their dependability requirements, and thus can be used.

The number of elders who encounter falling accidents has been increasing in the past few decades. Falling accidents could cause major injuries, such as having bruise, breaking bone, and in the worst case, losing life. Therefore, preventing elders from falling accidents is important in order to ensu

Migration between different wireless access networks often involves disconnected period, which is caused by passing an area of bad wireless coverage and potential overhead to switch the network on the network interface to connect to. The disconnected period can cause extra transmission delay due to the timer-driven retransmission behavior in the transport protocols, such as TCP and SCTP. We propose a new retransmission scheme to achieve better migration performance in SCTP, which is a newer connection-oriented and reliable transport protocol that is becoming popular. Our scheme minimizes the extra transmission delay by leveraging address reconfiguration operation in SCTP without involving other layers. It decreases the delay more than 5 seconds compared to the original SCTP when migration involves approximately ten-second disconnected period. The implementation of our scheme is already imported in FreeBSD.

PR-SCTP provides a timeliness transport service. When the lifetime of the data specified by the application expires, the sender PR-SCTP gives up retransmitting the data, and transmits a Forward TSN chunk to make the receiver advance the Cumulative ACK point. However, on the mobile communication, connectivity of the nodes is intermittent. PRSCTP does not work properly in this case, thereby the timeliness transmission is impaired. In order to address this issue, we propose a new algorithm that transmits a Forward TSN triggered by readdressing events in SCTP associations. Our scheme allows PR-SCTP to restart transmission of data with lifetime smoothly regardless of duration of the connectivity disruption.

This paper proposes Spinning Sensors middleware that realizes a robotic sensor node mechanism comprised of a sensor node and a robotic actuator node such as a motor or a mobile robot. We can increase sensing space, time, and accuracy of a sensor node by attaching them onto robotic actuators. To realize a robotic sensor node, we need to achieve collaborative utilization of arbitrary sensors and actuators, and automated calculation of sensing area and time. We stated these problems as spontaneous coordination problem and sensing area calculation problem. The Spinning Sensors middleware provides the mechanism of device coordination, data processing, and management of spatiotemporal model of robotic sensor nodes. In this paper, we discuss a robotic sensor node model, and design and implementation of the middleware. We introduce three kinds of applications using the middleware such as environment monitoring, sensor controlled robot, and context-aware service. The experiments using the robotic sensor node and the middleware are conducted to evaluate and measure the possibility, performance, and practicality of a robotic sensor node mechanism.

Many handover techniques in the Internet have been introduced with the development of mobile computing technologies. Although many proposed handover schemes utilize multiple interfaces, having multiple interfaces can increase power consumption, device installation space and hardware costs of mobile devices. Therefore, we have been studying handover schemes for mobile nodes with a single wireless network interface. To achieve seamless and efficient handover, we focus on stream control transmission protocol (SCTP) which offers message-oriented, reliable and connection-oriented delivery transport service. Unlike other transport protocols such as TCP, SCTP can provide an end-to-end handover mechanism with a multi-homing feature. However, the handover mechanism in the current SCTP causes large handover delay especially when a mobile node has only one single wireless network interface. In this paper, we have investigated the current issues in the SCTP handover mechanism and propose a new handover scheme based on SCTP, which identifies a communication path as a pair of source and destination address. We also propose new data retransmission feature for smooth handover.

We explore the design patterns and architectural tradeoffs for achieving interoperability across communication middleware platforms, and describe uMiddle, a bridging framework for universal interoperability that enables seamless device interaction over diverse platforms. The proliferation of middleware platforms that cater to specific devices has created isolated islands of devices with no uniform protocol for interoperability across these islands. This void makes it difficult to rapidly prototype pervasive computing applications spanning a wide variety of devices. We discuss the design space of architectural solutions that can address this void, and detail the trade-offs that must be faced when trying to achieve cross-platform interoperability. uMiddle is a framework for achieving such interoperability, and serves as a powerful platform for creating applications that are independent of specific underlying communication platforms.

During day-to-day activities, a user refers to various data items on a PC, such as documents, images, and audio clips. However, when the number of items in the history increases, locating the data becomes more complicated. We propose a novel system called "OreDesk" to retrieve particular data items from the history. OreDesk calculates the "active index" and "relation index" values for each data item based on the user operations. Active index indicates the interest of a user in the data. Relation index indicates how closely one data item is related to another. By using these indices, data can be retrieved on the basis of the association of user experiences. OreDesk also provides users with facilities such as "searching tool for related data" and "timeline viewer"

We propose a novel tool, called objSampler, with which users can record and recall "encounters" with objects in ubiquitous computing environments. We encounter various things, individuals, and places in the real world either consciously, meaning encounters that we are aware of, or unconsciously, meaning those we are unaware of but physically close to them. While some of those encounters are particularly important or treasurable to us, the physical memory in our brain is often too volatile to remember them. In objSampler, we address this issue by providing a state-of-art hardware called objPipette that embeds a sensor node, an RF-ID reader, and a battery cell. Users can record conscious encounters with it by scanning RF-ID tags pasted on real world objects. In addition, the objPipette detects and records the places where the user is. Users can recall the recorded encounters by using a software support in objSampler, called objScope. This paper describes the design and implementation of objSampler. User study, which is also provided in this paper, shows that objSampler provides a unique and intuitive means to achieve the above goal

This paper presents an interactive analysis and visualization framework for behavior histories, called mPATH framework. In ubiquitous computing environment, it is possible to infer human activities through various sensors and accumulation of their data. Visualization of such human activities is one of the key issues in terms of memory and sharing our experiences, since it acts as a memory assist when we recall, talk about, and report what we did in the past. However, current approaches for analysis and visualization are designed for a specific use, and therefore can not be applied to diverse use. Our approach provides users with programmability by a visual language interface for analyzing and visualizing the behavior histories. The framework includes icons representing data sources of behavior histories, analysis filters, and viewers. By composing them, users can create their own analysis method of behavior histories. We also demonstrate several visualizations on the framework. The visualizations show the flexibility of creating behavior history viewers on the mPATH framework.

This paper proposes a service model based on the service hierarchical structure called Galaxy service model, and a service discovery framework called Galaxy service directory system. In a ubiquitous computing environment, software services are embedded into various devices. The application construction requires service discovery mechanism and a recursive definition of services. The service discovery mechanism should, therefore, provide applications with common interface to look up the hierarchically represented composite services. In existing service framework, applications cannot be combined into other applications, since they do not provide the recursive service representation facility. In contrast, a service in Galaxy has a hierarchical description by deploying nested services. This model makes other services and applications to deal with an application that is composed by services. Galaxy service directory system facilitates structure-bounded service registration and service discovery. The system enables applications to find different composition-levels of service through a common interface.

Components on embedded devices, such as networked appliances and sensors, are rapidly spreading. However, it is getting more difficult for users to keep track of all of the distributed components. Wireless connections among embedded introduces further confusion. To enable users to develop and manage distributed applications in such an environment, we have developed a middleware named uBlocks. uBlocks helps construction of data-centric applications on distributed components through multiple kinds of mobile devices from multiple users. uBlocks is based on a concurrent scheme named Independent Modeling Scheme. This technique models the component relationship to be monitor and modified it simultaneously through multi-modal/multiple user interfaces. In this paper, we describe the design and implementation of uBlocks and evaluate the system's performance.

This paper describes a snapshot-based interface for networked appliances operations that allows users to store and reproduce the conditions of media contents in those appliances by means of photographed image data of the networked appliances. The conditions of the appliances are stored as metadata in photographed image data and displayed over a display of each appliance. A user can reproduce the state of the appliances with those image data. Furthermore, such a reproduction can be made on other appliances with the same function. Storing the information as image data makes it easy for a user to refer to an exact data out of an enormous amount of data. One of advantages of this system is that, by photographing many appliances at the same time, one image data can hold various appliances conditions. We have developed a prototype system to realize the proposed interface and some applications to confirm its effective usage. We have also confirmed its possibility for practical use through an evaluation of the system's performance.

A ubiquitous computing environment entails numerous embedded devices with enough computational power. Such distributed computing resources can cooperate to create applications which support users' everyday lives. Such an environment requires robust middleware that can handle a large quantity of messages, such as event data or sensor data are occurred between devices. However, the lack of middleware technologies with such functionalities has been making it difficult to create ubiquitous computing applications that we can depend on in their everyday life. In this paper, we propose a novel middleware, named RT-Dragon, which can handle numerous messages with robustness. RT-Dragon can work effectively on systems both realtime and non-realtime runtime because of the mechanism of two level priority-based task processing. In this paper additionally, we evaluate the effectiveness of RT-Dragon on non-RT runtime.

This paper presents a novel effective scheme of configuring wireless personal area networks (WPANs), called master-driven connection control (MaCC). WPANs are based on a new wireless technology, which enables portable and mobile computing devices, and consumer electronic appliances to communicate with each other. Assuming that WPANs operate in a master-slave style, we exploit the information about master-slave relationships for identifying a network topology in an ad hoc fashion. Specifically, MaCC supports routing, providing the minimum-hop paths that cannot be obtained by flooding algorithms. In addition, it constructs the optimal topology on demand along the minimum-hop paths dynamically, because the performance of routing is dependent on network topologies. These functions need only a few control messages to achieve, and so can avoid excessive message propagation by flooding causing frame collisions in the WPANs. MaCC has several prominent features: self-direction of every node, adaptive formation of networks, and minimization of hop counts for routing control. In this paper, we describe the details of MaCC and analyze its overhead about initialization, routing discovery, and reconfiguration. The results show control messages propagated in a MaCC network at route discovery are reduced to less than one half of those in a network utilizing pure flooding.

A key challenge in ubiquitous computing is how to manage ambient information about the real-world environment where a variety of devices appear and disappear. Traditional capability description systems are inadequate in capturing dynamic changes in the environment. We propose the Toibox DVMS system, a multi-embedded database system that provides an integrated database view of computing devices. The integrated views are materialized; updates over the view provoke relevant operations for the specified devices. The materialized views are decentralized and incrementally maintained by data dissemination. This work presents the design of the Toibox system, based on our initial prototype implementations.

In ubiquitous computing environment, many embedded computers, sensors, devices, and networks are connected for creating context-aware embedded ubiquitous applications. We often build a smart house or a room to demonstrate such context-aware ubiquitous applications. However, the cost and time for building such a house is a barrier to the deployment of various embedded ubiquitous applications.We have developed Smart Furniture which instantaneously converts the legacy non-smart space into a smart space where location-based context-aware services, service roaming, personalized services and the connectivity to the Internet are provided. Since the Smart Furniture is equipped with embedded networked computers, sensors and various I/O devices, it can provide various services in open public and/or private space.In this talk, we will discuss the issues and future challenges in creating context-aware embedded ubiquitous applications with Smart Furniture. We first introduce four types of Smart Furniture; a pole type, a lamp type, a mirror type, and a message board type. Then, the Smart Furniture middleware and the various types of context-aware ubiquitous applications such as a Personalized Message Board System, a Secure Library System, an Environmental Monitor System, and a Mobile TV-phone System are described. Finally, we summarize the issues and challenges in providing context-awareness, adaptability, time-space coordination, and privacy negotiation in embedded ubiquitous applications.

This paper describes the design, implementation, and evaluation of a proximity-based dynamic path shortening scheme, called DPS. In DPS, active route paths adapt dynamically to node mobility based on the "local" link quality estimation at each own node, without exchanging periodic control packets such as Hello packets. Each node monitors its own local link quality only when receiving packets and estimates whether to enter the "proximity "of the neighbor node to shorten active paths in a distributed manner. Simulation results of DPS in several scenarios of various node mobility and traffic flows reveal that adding DPS to DSR and AODV (conventional prominent on-demand ad hoc routing protocols) significantly reduces the end-to-end packet latency up to 50-percent and also the number of routing packets up to 70-percent over DSR, particularly in heavy traffic cases. We also demonstrate the more simulation results obtained by using our two novel mobility models which generate realistic node mobility: random orientation mobility and random escape mobility models. Finally, simple performance experiments using DPS implementation on FreeBSD OS demonstrate that DPS shortens active routes in the order of milliseconds (about 5 ms).

Mobile ad hoc networks (MANETs) are temporarily constructed by mobile hosts in the absence of established infrastructures. Such networks can constitute a base for human cooperative works as well as for communications between information systems. However, there has not been sufficient work of name resolution scheme suitable for MANETs after assignment of IP addresses. In this paper, we propose a name resolution system called Autonomous Name Resolution Scheme (ANARCH). ANARCH provides a node with a unique user-oriented name and relieves users and their applications from the necessity of identifying the network addresses (i.e., IP addresses) of destination nodes. ANARCH exchanges control messages merely between nodes in the one-hop reach area. However, it resolves names beyond the one-hop reach area, namely, it adapts to a multi-hop function of MANETs. We have designed and implemented ANARCH on FreeBSD, and evaluated the performance in a MANET system built with PCs running the Dynamic Source Routing (DSR) protocol. In our experimental results, ANARCH exhibited effective name resolution in a practical time while resolving conflicting names.

This paper presents a new routing scheme called estimated-TCP-throughput maximization based routing (ETR) scheme for mobile ad hoc networks (MANET). Many routing protocols have been proposed to build multi-hop networks in MANET. Most of these protocols select a path based simply on hop metrics, although the shortest path is not always the best path under the influence of radio link quality. We propose that the path should be selected with the maximum end-to-end TCP throughput because most of applications use TCP. In ETR, as a new metric for routing, we introduce an estimated TCP-throughput. A source node measures loss and delay for a path with probing packets periodically. The node estimates maximum TCP throughput from the expression of first approximation with those measured values, and exchanges a path dynamically so that the performance of the using path will be the best of all paths. This paper shows the, design and implementation of ETR. We add ETR to dynamic source routing (DSR) protocol in our MANET testbed, and evaluate ETR. In the case of 50% packet loss at DSR layer. ETR improves TCP throughput by 93% than unmodified DSR. ETR can select the path whose TCP throughput is maximum from the multiple paths to a destination.

This paper proposes a middleware for home networks, called Virtual Networked Appliance (VNA) architecture, in which the service description method and the Service to Service (S2S) communication mechanism are separated in an orthogonal way. Through the separation, VNA architecture solved the following two problems of existing middleware technologies: aspect violation and middleware fragmentation. In this paper, we first clarify the two problems and their relationship. Then, we describe the proposed middleware architecture as a solution from the viewpoint of the overall configuration and the S2S communication mechanism.

We propose an efficient route discovery scheme for mobile ad hoc networks called Hop-Wise Limited broadcast (HOWL). HOWL executes an efficient route discovery by predicting current location of destination using hop counts of previously used routes. Furthermore, we introduce characterized environmental indicators (CEI), namely node density, average hop count of route, and frequency of link failure, which characterizes real world environments with the constraint that parameters such as speed or transmission range are similar for every node in the network. CEI is also applicable to simulation environments. We have implemented a preliminary phase of HOWL as an extension to dynamic source routing (DSR), which uses network-wide broadcasts as a means of sending route request messages, on ns-2 network simulator. Simulations show that HOWL is especially effective when the node density is low, average hop count of route is short, or frequency of link failure is high where up to 10 % reduction in overhead and approximately 5 % reduction in latency were demonstrated.

This paper proposes a pluggable service-to-service (S2S) communication mechanism in a middleware for home networks, called Virtual Networked Appliance (VNA) architecture. In the architecture, service description method and the plug-gable S2S communication mechanism are separated in an orthogonal way. Through the separation, VNA architecture solved problems of home networks on which users have to operate multiple heterogeneous middleware technologies simultaneously: middleware fragmentation problem, due to complexity of realizing heterogeneous services on one middle-ware technology: aspect realization violation problem. The pluggable S2S communication mechanism provides service programmers with a simple aspect representation method to define a service-specific protocol concern apart from the service's implementation. It also provides off-the-shelf protocol modules of such well-known communication protocols as RTP, RTSP, HTTP, and SMTP for an inter-service communication, and dynamically loads them based on the aspects defined by the programmer. This reduces the complexity of implementing heterogeneous services on the VNA architecture, thereby addressing the problems. In this paper, we first clarify the two problems. Then, we describe the proposed mechanism with an overview of the middleware architecture referring to a composite service: "Follow-You-and-Me Video."

In this paper, we present a new mobility-support model for applications, Application Module Request Broker (AMRB). We focus on two types of mobility: host mobility and application code mobility. These two types of mobility dynamically change the binding between applications name and location in the network. AMRB conceals these changes of banding to reduce a complexity in development of applications. In AMRB, we deal with mobile application codes that communicate with each other as Application Modules (AMs). AMRB provides AM's service transparent communication for applications by using a specifier which does not need to include any network location information. Furthermore, applications can use AM's service transparently of migration by exploiting location management mechanism. In this paper, we describe the design and implementation of AMRB and some evaluations. Also, we demonstrate a sample application that AMRB is effective for developing mobile sensor type applications.

This paper presents "OR2", an adaptive path tuning scheme for mobile ad hoc networks. In OR2, the active path adapts dynamically to node mobility without any link failures based on the local link quality. Most conventional routing protocols accommodate the change of network topology only when the link fails. Unless the movement of intermediate nodes leads to any link failures, they cannot adapt to the network topology even if other routes with less hop count become available. In contrast to these protocols, OR2 reduces the hop count of an active route while data packets are sent without link disconnection. Specifically, by introducing the notion of proximity that indicates the nearness of two communicating nodes, OR2 skips the upstream node in a proximity area and continues to shorten an active route as possible. For delay sensitive TCP flows, reducing the number of hops and path delay significantly improves the performance of TCP. We have implemented OR2 as an extension to DSR on FreeBSD. The experimental results have shown that OR2 is effective in enhancing TCP throughput and reducing end-to-end delay for all relevant flows.

A key challenge in packet scheduling over a wireless channel is to achieve effective throughput against bursty errors. Although there have been several proposals on packet scheduling for a wireless channel, they are only based on bi-modal channel states: good or bad. In this paper we propose a new packet scheduling scheme for wireless links based on the receiver's signal to noise ratio (SNR). The scheme is referred to as SNR-based packet scheduling (SPS). In SPS, outgoing packet flows are scheduled such that the flows with higher SNR values have larger weights in scheduling. SPS can achieve effectiveness by adopting a flexible mapping between weight and SNR. We present measured results of the relationship between throughput and SNR as well as the design and implementation of SPS. In our experiments, SPS has shown its effectiveness in enhancing total throughput for hosts with good and bad wireless connectivity over a wireless LAN.

We propose a scheme of rate control for continuous UDP flow with moderate fairness. First, per-packet relative one-way trip time (ROTT) of a UDP stream at a receiver on the Internet is investigated extensively, and it is found that spikes with successive plots, which we call spike-trains, often appear on a time-ROTT graph. Also, congestion-related losses are found to be strongly correlated only to the spike-trains and the path status is effectively identified by such spike-trains. Based on these observations, a rate control with moderate fairness using the path-status, PAth-STatus-based RAte control (PASTRA), is presented. The effectiveness of PASTRA in achieving moderate fairness for UDP streams on the Internet is demonstrated.

This paper proposes "MobileSocket" which realizes session layer communication continuity support for Java Applications towards the continuous operations for mobile applications. In the mobile computing environment where mobile hosts move around the network even during communications with the remote, maintenance of the communication continuity between the applications is significant. Not only mobility support but virtual circuit continuity support is required for communication continuity. Existing approaches have not provided the complete communication continuity for applications. "MobileSocket" is a user-level enhanced socket library written in Java, and provides library-based session layer mobility and virtual circuit continuity support for applications. Two mechanisms, dynamic socket switching (DSS) and the application layer window (ALW) were developed for MobileSocket and enable a simple implementation. The MobileSocket applications can be used in Java mobile applications and the agents, as well as for ordinary network applications. In this paper, after we clarify the communication continuity and existing approaches, we present the MobileSocket design, mechanism, and results of evaluation.

Describes the design and implementation of a middleware system named the Possession System. The system is designed based on the "possession model", which provides users with a consistent view of application components, networked sensors and distributed devices by introducing two separate abstractions: "body" and "soul". The Possession System realizes a simple framework to deal with the adaptation of distributed multi-user applications by changing the relations among "bodies" and "souls". Furthermore, it enables users to interact with system components with a simple operation named "possession". Distributed multi-user applications built on top of our middleware realize adaptive behavior, which is achieved by a mechanism combining system events with various behavioral changes of application components, including the migration of components. The middleware is applicable to adaptive systems in mobile and ubiquitous computing environments where unpredictable changes in the available computing resources, device configuration and geographic location frequently occur. We describe how multi-user applications using our middleware behave adaptively.

We propose the neighbor-state based queuing (NBQ) for improving the performance of flows sharing link bandwidth under various transfer protocols. Each router with NBQ informs the next upstream router of its link status. According to the received status, the NBQ dynamically sets the packet discard ratio of the non-adaptive flows. The NBQ reduces the wasted non-adaptive flows and provides available bandwidth for the adaptive flows. We have demonstrated dramatic improvements of the adaptive flow's throughput using our scheme through simulations.

Adaptive QoS systems are attractive for multimedia services that are accessed via the Internet or mobile computers. An important feature of an adaptive QoS system is that it allows application programs to specify the QoS level desired, and at the system to set the level according to the resources available. With an adaptive QoS system, the user should specify not only the target QoS, but also a QoS range to minimize the quality degradation resulting from resource shortages. The paper introduces QoSPath as an extensible object model for specifying, translating, and arbitrating QoS in adaptive QoS systems. The QoSPath model herein lets users and application programs specify their QoS preference by setting QoSPoints in a QoSPath, each of which specifies an objective QoS level against a subjective utility value. With the QoSPath model, a simple QoS preference can be specified by a few parameters, while more detailed specifications can be given by providing more information, thus the model offers both the simple and descriptive QoS specifications. It is designed to be flexible in that new QoS formats and translation modules can be easily defined with only a minimum knowledge of other parts of a system. It therefore separates the functions of QoS specification, translation/inverse-translation and arbitration.

We propose a new, efficient fast retransmission (EFR) scheme for wireless LANs. Wireless LANs are becoming popular and providing an efficient protocol over a wireless link is important. In our experiments with the 2.4 GHz WaveLAN, the poor TCP performance observed was attributed to frequent expiration of the retransmission timer. To avoid unnecessary expiration of the retransmission timer, we propose a scheme in which fast retransmission is performed efficiently. The proposed modification only affects a TCP sender, and our version of TCP where the change is interoperable with existing TCP implementations. The change is especially effective in wireless LAN environments, where we have demonstrated significant improvements in throughput, 10-15%, via experiments.

The TCP-R (TCP Redirection) is an extension of TCP, which maintains active TCP connections when the disconnection occurs due to the change of the IP address or the change of the network device. In mobile computing environments, the IP address may be changed frequently as the host moves across subnets or changes a network device. However, it is difficult for most network applications to work continuously in such a situation. There is much research to support such dynamics in the network layer, but these attempts in the IP layer tend to incur some complexity. This paper is intended as an investigation of the end-to-end mobility support in transport layer. We developed the simple and secure redirection mechanism in TCP, which enables us to keep our working activities without any intermediate agents. We also show that TCP-R can serve as a solution to the retransmission timeout problem which frequently occurs in mobile environments. We implemented and evaluated a prototype of TCP-R by modifying FreeBSD. The measured performance indicates that TCP-R can maintain operation continuously with minimal overhead and complexity.

Java has many benefits such as security in distributed environments, reusability of code, and portability because it is architecture neutral. From those characteristics, Java is beginning to be used in many new environments. Even though Java provides various advantages, it still has problems which must be solved. One issue is that there are often real-time constraints that should be met in those applications. Current Java execution environment and language specification cannot satisfy those requirements. Our research focuses on the current limits of the Java language and its execution environment, and to seek the possibility for real-time using Java and the technologies we have available today. To investigate issues in real-time Java, we have implemented a prototype real-time Java environment which provides real-time Java threads and a real-time synchronization mechanism. Then we evaluated its performance. The results indicate that timing requirements are better met and unbounded priority inversion is avoided in our system.

Synchronization and communication are two common sources of priority inversion which may make the behavior of systems unpredictable and unanalyzable. In microkernel-based systems, they are heavily used for building operating system servers and decomposing applications into several tasks. The management of priorities in IPC and synchronization should be integrated using a uniform mechanism since priority inversion occurs if such integration is not supported. Also, a highly preemptable server structure should be provided because the execution in a server may take up too much time. We propose an integrated real-time resource management model, and a real-time server model which solve the above problems. We implemented and evaluated the models in Real-Time Mach using a uniform mechanism. Our approach enables us to build operating system servers and to decompose applications into several tasks without incurring priority inversion.>

Real-time scheduling theory is designed to provide a priori verification that all real-time tasks meet their timing requirements. However, this body of theory generally assumes that resources are instantaneously pre-emptable and ignores the costs of systems services. In previous work [1, 2] we provided a theoretical foundation for including the costs of the operating system scheduler in the real-time scheduling framework. In this paper, we apply that theory to the Real-Time (RT) Mach scheduler. We describe a methodology for measuring the components of the RT Mach scheduler in user space. We analyze the predicted performance of different real-time task sets on the target system using the scheduling model and the measured characteristics. We then verify the model experimentally by measuring the performance of the real-time task sets, consisting of RT Mach threads, on the target system, The experimental measurements verify the analytical model to within a small percentage of error. Thus, using the model we have successfully predicted the performance of real-time task sets using system services, and developed consistent methodologies to accomplish that prediction.

Real-time operating systems generally depend on some form of priority information for making scheduling decisions. Priorities may take the form of small integers or deadline times, for example, and the priorities indicate the preferred order for execution of the jobs. Unfortunately, most systems suffer from some degree of priority inversion where a high priority job must wait for a lower priority job to execute. The authors consider the nature of the nonpreemptible code sections, called critical sections or critical regions, which give rise to this priority inversion in the context of a soft real-time operating system where average response time for different priority classes is the primary performance metric. An analytical model is described which is used to illustrate how critical regions may affect the time-constrained jobs in a multimedia (soft real-time) task set.>

Continuous media communication requires timely delivery of data such as digital video and audio packets. Quality of Service (QOS) parameters specify the temporal and spatial characteristic of such continuous media data. To insure timely delivery of continuous media data, the system needs to minimize the communication delay by securing required processor and network resources. We have extended the Capacity-Based Session Reservation Protocol(CBSRP), which was proposed to realizing predictable real-time communications, to support dynamic control of QOS. We have implemented a QOS control scheme by which the network dynamically adjusts the allocations of network bandwidth on a Fiber Distributed Data Interface(FDDI) network.

Workstations for digital audio and video applications must support predictable processing, presentation, and transmission of continuous media data while making efficient use of limited hardware resources. The authors present techniques for managing network resources and processing messages in a predictable fashion. Their solutions use a novel structure for the protocol processing software, and they examine several alternatives and discuss the engineering tradeoffs associated with each. Using simulation, they evaluate their protocol processing structures and show that the more sophisticated structures can improve the response time and predictability of time-constrained messages. The ideas presented in this paper can be applied to resource management in the operating system and to the structuring of application-level servers. The designers of gateway machines (for internetwork routing) which handle both time-constrained traffic and non-time-constrained traffic may also benefit from this study.>

An extension of the uniprocessor Hartstone benchmark for the distributed real-time environment, called the Distributed Hartstone benchmark, is described. The Distributed Hartstone measures system performance in the critical areas of communication latency and bandwidth, protocol preemptability, and priority queueing at the protocol and media access levels. Areas of the system which are particularly important for distributed, real-time computing are described. On the basis of the requirements that specify various areas of the system that a distributed real-time benchmark must stress, a series of task sets in the style of the Hartstone benchmarks are given. The benchmark results from a distributed real-time operating system (ARTS testbed) are given.>

The authors present the motivation for using an object model for real-time operating systems, and describe the object model used in the ARTS kernel. A discussion is presented of the novel object classification and the priority inheritance properties which arise from this taxonomy. Various methods for implementing critical regions are described, and some guidelines as to the use of each are given.>

The results of implementation studies utilizing commercially available IEEE 802.5 chip sets and boards are reported. Serious implementation flaws were discovered that prevent the full potential of the IEEE 802.5 token ring standard from being realized for real-time applications. Specifically, unbounded delays can be introduced which not only destroy the desired response time determinism offered by algorithmic scheduling, but which also negate asynchronous alert class guarantees and unnecessarily increase other asynchronous response times. An analysis is made of the scheduling properties of current implementations, and modifications to the current implementations are proposed to allow them to realize the full potential offered by the IEEE 802.5 standard for real-time applications.>

The priority-inversion problems in real-time communication are addressed, and solutions developed for the ARTS distributed real-time operating system are presented. The performance results of the multi-thread-based protocol implementation are compared with those of other implementation schemes, and the schedulability is analyzed. Experimental results indicate that the multi-thread-based protocol implementation could eliminate potential priority-inversion problems and also demonstrate the same schedulability as the softint implementation scheme in spite of about 10% additional implementation overhead.>

Scheduler 1-2-3 is an interactive analysis tool that can perform schedulability analysis for the development of real-time computing systems. The schedulability analysis can verify whether all hard real-time tasks in a target system will be completed by their deadlines at the system design phase. Scheduler 1-2-3 is a window-based stand-alone tool that can also be used as a synthetic workload generator in an integrated tool set that consists of a timing tool, a schedulability analyzer, and a real-time monitor/debugger.>

An integrated real-time tool set is described that consists of a schedulability analyzer and a real-time monitor/debugger for the ARTS kernel, which is being built for a distributed real-time testbed. The schedulability analyzer, called Scheduler 1-2-3, is an X11 window-based interactive tool and can verify whether the given real-time tasks can meet their deadlines under a specific scheduling policy. An advanced real-time monitor, ARM, also runs on the X11 window and visualizes the target system's runtime behavior in real time. ARM can be used with Scheduler 1-2-3 to analyze simulated runs and its monitorability.>

This paper describes design and implementation of an IPC model for a distributed software testbed Shoshin. The IPC model was designed to provide a reliable message communication among distributed processes and to support implementations of user level protocols for various applications. A multiprocess structure, which separates a link level and a transport level, has been used to provide a flexible protocol management. The basic performance of the current implementation and the extensibility of the model are also discussed.