Client-server Applications Research Articles

Library Support in an Actor-Based Parallel Programming Platform

Actor model-based design is actively researched for parallel embedded SW design since the model exposes the potential parallelism explicitly in an architecture-neutral form. In most actor-oriented models, actors are self-contained and data channels are the only sharable object between actors, and they compose a system in a flat layer. In contrast, it is common to use shared library functions and construct vertically layered software for efficiency and modularity. To fill this gap between modeling and implementation, we propose a special actor, library task, with new types of ports: library master port and library slave port. It is a sharable and mappable object that defines a set of function interfaces inside. N:1 master-slave connection allows sharing a library task and the master-slave connection can specify vertically layered software and client-server applications naturally. To support the library task in our embedded software design environment, we develop an automatic mapping algorithm as well as an automatic code generator. The design environment with the library task is applied for two target platforms: IBM CELL Broad band Engine and an ARM-based multicore simulator. Preliminary experiments show that the special actor, or library task, extends the expression power of the previous actor model with efficiently generated codes.

PsychVACS: A System for Asynchronous Telepsychiatry

To describe the technical development of an asynchronous telepsychiatry application, the Psychiatric Video Archiving and Communication System. A client-server application was developed in Visual Basic.Net with Microsoft(®) SQL database as the backend. It includes the capability of storing video-recorded psychiatric interviews and manages the workflow of the system with automated messaging. Psychiatric Video Archiving and Communication System has been used to conduct the first ever series of asynchronous telepsychiatry consultations worldwide. A review of the software application and the process as part of this project has led to a number of improvements that are being implemented in the next version, which is being written in Java. This is the first description of the use of video recorded data in an asynchronous telemedicine application. Primary care providers and consulting psychiatrists have found it easy to work with and a valuable resource to increase the availability of psychiatric consultation in remote rural locations.

Head-Tail Video Streaming Over Peer To Peer Systems

P2P systems similar to file sharing applications are being used vastly due to unrestricted nature of these systems. Their unrestricting comes from their ability to cooperate and aggregate peer’s resources and their scalability. On the other side, today technologies are traditional client-server applications. These applications can perform strongly but they are not scalable due to limitations on server resources. This limitation of the client/server technology leads designers to use alternative technologies mainly P2P. As a streaming system, P2P streaming network can be formed into two types, Tree-based and Mesh-based. In this paper a new mesh-based P2P system named Head-Tail streaming is proposed. Head-Tail simplifies packet scheduling and node failure recovery by using paired-peer sending and node failure prediction. Our system outperforms ordinary systems comparing as delay and receive time. Our system performs better than ordinary systems based on two reasons : Overlapping sequence of chunks and node replacement policy.

Remote Laboratory Java Server Based on JACOB Project

Remote laboratories play an important role in the educational process of engineers. This paper deals with the structure of remote laboratories. The principle of the proposed remote laboratory structure is based on the Java server application that communicates with Matlab through the COM technology for the data exchange under the Windows operating system. Java does not support COM directly so the results of the JACOB project are used and modified to cope with this problem. In laboratories for control engineering education a control algorithm usually runs on a PC with Matlab that really controls the real plant. This is the server side described in the paper in details. To demonstrate the possibilities of a remote control a Java client server application is also introduced. It covers communication and offers a user friendly interface for the control of a remote plant and visualization of measured data.

On the Design and Implementation of Interactive XML Applications

This paper describes issues and challenges in the design and implementation of interactive client-server applications where program logic is expressed in terms of an extensible markup language (XML) document. Although the technique was originally developed for creating interactive short message service (SMS) applications, it has expanded and is used for developing interactive web applications. XML-Interactive (or XML-I) defines the program states and corresponding actions. Because many interactive applications require sustained communication between the client and the underlying information service, XML-I has support for session management. This allows state information to be managed in a dynamic way. The paper describes several applications that are implemented using XML-I and discusses design issues. The software framework has been implemented in a Java environment.

MSSL: A framework for trusted and incentivized peer-to-peer data sharing between distrusted and selfish clients

Conventional client-server applications can be enhanced by enabling peer-to-peer data sharing between the clients, greatly reducing the scalability concern when a large number of clients access a single server. However, for these “hybrid peer-to-peer applications,” obtaining data from peer clients may not be secure, and clients may lack incentives in providing or receiving data from their peers. In this paper, we describe our mSSL framework that encompasses key security and incentive functions that hybrid peer-to-peer applications can selectively invoke based on their need. In contrast to the conventional SSL protocol that only protects client-server connections, mSSL not only supports client authentication and data confidentiality, but also ensures data integrity through a novel exploit of Merkle hash trees, all under the assumption that data sharing can be between untrustworthy clients. Moreover, with mSSL’s incentive functions, any client that provides data to its peers can also obtain accurate proofs or digital money for its service securely and reliably. Our evaluation further shows that mSSL is not only fast and effective, but also has a reasonable overhead.

Flexible delivery of visualization software and services

An important issue in the design of visualization systems is to allow flexibility in providing a range of interfaces to a single body of algorithmic software. In this paper we describe how the ADVISE architecture provides exactly this flexibility. The architecture is cleanly separated into three layers: user interface, web service middleware and visualization components. This gives us the flexibility to provide a range of different delivery options, but all making use of the same basic set of visualization components. These delivery options comprise a range of user interfaces (visual pipeline editor, tailored application, web page), coupled with installation choice between a stand-alone desktop application, or a distributed client-server application.

Engineering rich internet applications with a model-driven approach

Rich Internet Applications (RIAs) have introduced powerful novel functionalities into the Web architecture, borrowed from client-server and desktop applications. The resulting platforms allow designers to improve the user's experience, by exploiting client-side data and computation, bidirectional client-server communication, synchronous and asynchronous events, and rich interface widgets. However, the rapid evolution of RIA technologies challenges the Model-Driven Development methodologies that have been successfully applied in the past decade to traditional Web solutions. This paper illustrates an evolutionary approach for incorporating a wealth of RIA features into an existing Web engineering methodology and notation. The experience demonstrates that it is possible to model RIA application requirements at a high-level using a platform-independent notation, and generate the client-side and server-side code automatically. The resulting approach is evaluated in terms of expressive power, ease of use, and implementability.

공개용 리소스를 활용한 Haplotype 재조합 시스템 개발

Haplotype은 연관성을 띠면서 함께 유전하는 SNP (Single Nucleotide Polymorphism) 집단을 반영하고 있기 때문에 맞춤의학 분야에서 haplotype기반의 연구 중요성이 지속적으로 급증하고 있다. in silico 방법을 바탕으로 Haplotype 재조합을 위해 현재 가장 널리 사용되는 공개용 리소스 응용소프트웨어로는 PL-EM, Haplotyper, PHASE 및 HAP 등이 있다. PL-EM, Haplotyper 및 PHASE 등은 리눅스와 유닉스 시스템에서 구동되는 명령라인 응용 소프트웨어이고, HAP는 클라이언트-서버 환경에서 웹기반으로 구동되는 소프트웨어이다. 본 논문에서는 실험적으로 검증된 데이터들을 이용하여 공개용 리소스 소프트웨어들의 정확성을 검증하고, 그러한 검증결과를 토대로 선별된 Haplotyper와 PL-EM 등으로 개발한 통합 haplotye 재조합 시스템에 대해 소개하고자 한다. 개발된 통합 시스템은 사용자 친화적 웹 인터페이스를 갖는 클라이언트-서버 시스템으로 최종 사용자들에게 양질의 haplotype 분석 결과를 제공할 수 있다. Haplotyper의 경우 5명의 개체로부터 얻은 길이가 5인 SNP 유전자형 데이터를 가지고 결과를 분석하였고, PL-EM의 경우 15명의 개체로부터 얻은 길이가 13인 SNP 유전자형 데이터를 가지고 결과를 분석하였다. 그 결과 본 시스템은 두 부분으로 나누어 개개인의 haplotype 정보와 haplotype 집단 정보를 이해하기 쉽게 체계적으로 제공하는 것을 확인하였다. 이러한 측면에서 본 시스템은 haplotype 지도 작성을 통한 질병 유전자 발굴 및 맞춤의약 개발 연구에 매우 유용한 도구로 사용될 수 있으리라 여겨진다. Haplotype-based research has become increasingly important in the field of personalized medicine since the haplotype reflects a set of SNPs (Single Nucleotide Polymorphisms) that are genetically associated and inherited together. Currently, the most widely used application softwares available for haplotype reconstruction, based on in silico method, include PL-EM, Haplotyper, PHASE and HAP. PL-EM, Haplotyper and PHASE are command-line application running on LINUX or Unix system and HAP is a web-based client-server application. This paper deals with an integrated haplotype reconstruction system that have been developed with PL-EM and Haplotyper selected from the accuracy test with experimentally verified data on public application softwares. This integrated system is a kind of client-sever one with user friendly web interface and can provide end-users with a high quality of haplotype analysis. SNPs genotype data with a length of 5 derived from 5 people and SNPs genotype data with a length of 13 derived from 15 people were used to test the analysis results of Haplotyper and PL-EM respectively. As a result, this system has been confirmed to provide the systematic and easy-to-understand analysis results that consist of two main parts, i.e. individual haplotype information and haplotype pool information. In this respect, the integration system will be utilized as a useful tool for the discovery of disease related genes and the development of personalized drugs through facilitating the reconstruction of haplotype maps.

Developing A One Stop Shop Model For Integrated Land Information Management

In Ghana much attention has not been given to the development of land information system which will integrate the data on land ownership, land use and land value for all the land agencies under the land administration system to facilitate the processing of applications within the land delivery systems. This situation presents a lot of delays and inefficiencies in delivering land services to the investor and other potential clients of land sector agencies involved in the land administration practised in Ghana. This paper describes the development of a one stop shop model for integrating information on the attributes of a parcel and their accessibility. A cross sectional survey was conducted in six land sector agencies in Kumasi on data formats, standards and accessibility in provision of land delivery services to their clients. The results of the survey were then used to design a client server application based on a one stop shop concept to integrate the parcel attribute information. The client server application was designed with Microsoft SQL Server 2000, VB.Net 2005 and Microsoft Visio. A Land Management Key (LANMANK) program was finally developed with geodatabase capabilities for storing and displaying spatial data as well as other non-spatial data. LANMANK has a unique parcel identifier for land transactions such as land transfers, title registration, property rating, building and development permits processing. Also, it allows the user to create back ups for the database and also restore the database at a later date.

Autoadaptivity and Optimization in Distributed ECG Interpretation

This paper addresses principal issues of the ECG interpretation adaptivity in a distributed surveillance network. In the age of pervasive access to wireless digital communication, distributed biosignal interpretation networks may not only optimally solve difficult medical cases, but also adapt the data acquisition, interpretation, and transmission to the variable patient's status and availability of technical resources. The background of such adaptivity is the innovative use of results from the automatic ECG analysis to the seamless remote modification of the interpreting software. Since the medical relevance of issued diagnostic data depends on the patient's status, the interpretation adaptivity implies the flexibility of report content and frequency. Proposed solutions are based on the research on human experts behavior, procedures reliability, and usage statistics. Despite the limited scale of our prototype client-server application, the tests yielded very promising results: the transmission channel occupation was reduced by 2.6 to 5.6 times comparing to the rigid reporting mode and the improvement of the remotely computed diagnostic outcome was achieved in case of over 80% of software adaptation attempts.

SoftRDMA: Implementing iWARP over TCP kernel sockets

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Remote direct memory access (RDMA) allows for the minimization of CPU and memory bus loads associated with network I/O. The Transmission Control Protocol/Internet Protocol (TCP/IP)-based Internet Wide Area RDMA Protocol (iWARP) stack now makes RDMA available for Ethernet local area networks and wide area networks. As 10-Gb/s Ethernet becomes deployed in data centers and Ethernet link speeds continue to increase faster than the memory bus bandwidth, the capability of RDMA to eliminate all intrahost data copy operations related to network I/O makes it attractive for accelerating TCP/IP. Whereas RDMA network adapters offload iWARP/TCP functionality to dedicated hardware, we have designed an onloaded iWARP software implementation, called SoftRDMA, which runs on the host CPU, closely integrated with Linux® TCP kernel sockets. SoftRDMA offers asynchronous nonblocking user-space I/O. It enables iWARP with conventional Ethernet adapters, as well as in mixed iWARP hardware and software environments, facilitating RDMA system integration. Furthermore, SoftRDMA benefits client–server applications with asymmetric loads and high aggregate throughput on the server. With iWARP checksumming turned off, SoftRDMA delivers a throughput exceeding 5 Gb/s using a single CPU core. We suggest zero-copy transmission in software and hardware acceleration for the iWARP framing layer for even higher performance. </para>

MODELING AND OPTIMIZATION OF COMPLEX SERVICES IN SERVICE-BASED SYSTEMS

Service-based approaches have significantly extended client server applications and allow to assemble a variety of components, services, and systems into multi-tier applications, flexibly supporting increasing business needs and requirements. Deployment of applications, composed of application components and services available in a distributed, heterogeneous environment, highly increased the complexity of systems offering complete, collaborative, continuous, and constraint-free solutions. The aim of this article is to present a model of complex services composed of atomic services available in different versions and offered in a heterogeneous environment. The purpose of the introduced model is to provide a framework to analyze access limitations, services costs, security, and resource constraints, i.e., tasks that must be proactively monitored and resolved in distributed, networked systems. The introduced model is applied to formulate a complex services selection and optimization tasks taking into account different strategies assuring quality of services.

Matlab Based Remote Control of Thermo-Optical Plant

The paper is focused on a thermo-optical plant that is used for experimental work at the Faculty of Electrical Engineering and Information Technology STU in Bratislava. Our attention was dedicated to one approach of its remote control. A Java client-server application was created that enables to connect the graphical user interface with the Matlab engine running on the server.

Design of a client server application using the Bluetooth protocol

In 1998, five major companies (Ericsson, Nokia, IBM, Toshiba and Intel) formed a group to create a license-free technology for universal wireless connectivity in the handheld market. The result is Bluetooth. The Bluetooth specifications (currently in version 1.1) define a radio frequency (RF) wireless communication interface and the associated set of communication protocols and usage profiles. The link speed, communication range and transmission power level for Bluetooth were chosen to support low-cost, power-efficient, single-chip implementations of the current technology. In fact, Bluetooth is the first attempt at making a single-chip radio that can operate in the 2.4-GHz ISM (industrial, scientific and medical) RF band. While most early Bluetooth solutions are dual-chip, vendors have recently announced a singlechip versions as well. The current study of the Bluetooth technology describes structure, protocol stack, architecture, connectivity, security issues, and finally design a client server application using Java programming language.

Can “Patient Keeper” Help In-Patients?

The aim of this paper is to present our "Patient Keeper" application, which is a client-server medical application. "Patient Keeper" is designed to run on a mobile phone for the client application and on a PC for the server application using J2ME and JAVA2, respectively. This application can help doctors during visits to their patients in hospitals. The client application allows doctors to store on their mobile phones the results of their diagnoses and findings such as temperature, blood pressure, medications, analysis, etc., and send this information to the server via short message service (SMS) for storage in a database. The server can also respond to any request from the client and send the result via Bluetooth, infrared, or over the air. Experimental results showed a significant improvement of the healthcare delivery and reduction for in-patient stay.

A proxy-based integrated cache consistency and mobility management scheme for client–server applications in Mobile IP systems

In this paper, we investigate a proxy-based integrated cache consistency and mobility management scheme for supporting client–server applications in Mobile IP systems with the objective to minimize the overall network traffic generated. Our cache consistency management scheme is based on a stateful strategy by which cache invalidation messages are asynchronously sent by the server to a mobile host (MH) whenever data objects cached at the MH have been updated. We use a per-user proxy to buffer invalidation messages to allow the MH to disconnect arbitrarily and to reduce the number of uplink requests when the MH is reconnected. Moreover, the user proxy takes the responsibility of mobility management to further reduce the network traffic. We investigate a design by which the MH’s proxy serves as a gateway foreign agent (GFA) as in the MIP Regional Registration protocol to keep track of the address of the MH in a region, with the proxy migrating with the MH when the MH crosses a regional area. We identify the optimal regional area size under which the overall network traffic cost, due to cache consistency management, mobility management, and query requests/replies, is minimized. The integrated cache consistency and mobility management scheme is demonstrated to outperform MIPv6, no-proxy and/or no-cache schemes, as well as a decoupled scheme that optimally but separately manages mobility and service activities in Mobile IPv6 environments.

Analysis of TTL-Based Consistency in Unstructured Peer-to-Peer Networks

Consistency maintenance is important to the sharing of dynamic contents in peer-to-peer (P2P) networks. The TTL-based mechanism is a natural choice for maintaining freshness in P2P content sharing. This paper investigates TTL-based consistency maintenance in unstructured P2P networks. In this approach, each replica is assigned an expiration time beyond which the replica stops serving new requests unless it is validated. While TTL-based consistency is widely explored in many client-server applications, there has been no study on TTL-based consistency in P2P networks. Our main contribution is an analytical model that studies the search performance and the freshness of P2P content sharing under TTL-based consistency. Due to the random nature of request routing, P2P networks are fundamentally different from most existing TTL-based systems in that every node with a valid replica has the potential to serve any other node. We identify and discuss the factors that affect the performance of P2P content sharing under TTL-based consistency. Our results indicate a tradeoff between search performance and freshness: the search cost decreases sublinearly with decreasing freshness of P2P content sharing. We also compare two types of unstructured P2P networks and find that clustered P2P networks improve the freshness of content sharing over flat P2P networks under TTL-based consistency.

Prediction-based real-time resource provisioning for massively multiplayer online games

Massively Multiplayer Online Games (MMOGs) are a class of computationally intensive client–server applications with severe real-time Quality of Service (QoS) requirements, such as the number of updates per second each client needs to receive from the servers for a fluent and realistic experience. To guarantee the QoS requirements, game providers currently over-provision a large amount of their resources, which makes the overall efficiency of provisioning and utilization of resources rather low and prohibits any but the largest providers from joining the market. To address this deficiency, we propose a new prediction-based method for dynamic resource provisioning and scaling of MMOGs in distributed Grid environments. Firstly, a load prediction service anticipates the future game world entity distribution from historical trace data using a fast and flexible neural network-based method. On top of it, we developed generic analytical game load models used to foresee future hot-spots that congest the game servers and make the overall environment fragmented and unplayable. Finally, a resource allocation service performs dynamic load distribution, balancing, and migration of entities that keep the game servers reasonably loaded such that the real-time QoS requirements are maintained. Experimental results based on a realistic simulation environment demonstrate the advantages of our prediction service compared to other conventional methods, especially due to its ability to adapt to different user load patterns, and a reduction of the average over-allocation from 250% (in the case of static over-provisioning) to around 25% using our dynamic provisioning method.

User Interface Oriented Application Development (UIOAD)

A fast and efficient model of application development called user interface oriented application development (UIOAD) is proposed. This approach introduces a convenient way for users to develop a platform independent client-server application. Keywords—Software Development, XML, XForms, XUL, eForm, User Interface.