Apache服务器集群中套接字迁移的研究与实现

利用进程迁移实现Apache服务器集群的负载均衡,可有效提升系统的整体性能,套接字迁移是其中的一个关键问题。阐述了Apache服务器的体系结构及其在集群系统内的进程迁移实现技术。分析了Apache服务器集群系统内套接字迁移中可能存在的问题,进行了相应的理论研究。最后给出了Apache服务器进程迁移过程中套接字迁移的解决方案和具体实现,并进行了测试和分析。     

Apache服务器中WWW虚拟主机技术

介绍了WWW服务器虚拟主机的工作原理,并对Apache服务器上设置虚拟主机的各种方法及其优缺点作了全面的讨论。其中对大规模虚拟主机设计方法的研究具有现实意义,为具体应用提供了有效的指导和选取的准则。     

用Apache架设Web服务器

随着Linux的逐渐普及,想必不少Linux爱好者希望创建自己的Web服务器。本文将一步一步教你如何在Linux下用Apache架设Web服务器。     

Apache服务器的几种优化方法

目前网络上大部分的网站服务器都采用Apahce服务器来进行搭建,本文通过对Apahce服务器中的配置文件的设置,有针对性的提出了几点关于Apache的优化方法,提高Apache服务器在网站搭建中的性能。     

集群系统中进程迁移的研究

进程迁移对集群系统的动态负载均衡、容错和系统管理具有重要意义.说明分布式系统中进程迁移的目的和一般步骤,对比了两个典型的集群操作系统Kerrighed和openMosix中的进程迁移机制,分析其对系统性能的影响.     

Apache Web服务器安全最大化

提出在各种安全层次安全化Apache2.0,即使在Apache2.0中发现了新的安全漏洞的情况下,如何安装和配置Apache2.0WebServer以最小化未授权访问或被成功入侵的风险.因此用户可以享受Apache2.0的新的特征并且不必担心其安全漏洞,而不管这些漏洞只是想象还是事实上就存在这些严重威胁.     

Server Cluster中服务器状态的监测

在集群服务器系统中，通过分配器实时接收所有机器发来的信息，汇集在一起，供网页来读取，可以实现基于Web的图形界面方式的，对各台服务器状态的监测。在网页中使用Applet或AxtiveX控件，既实现了数据的实时变化，同时又避免了整个页面的刷新和闪烁。基于以上原理，提出一种简单可行的且基于Web的，对集群服务器进行管理监测的解决方案。     

Apache Web服务器服务原理源代码探究

Apache服务器是一款源代码开放、应用排名世界第一的Web服务器软件,它接收处理数据非常快并且性能稳定卓越,能够跨越众多操作系统平台。主要论述了其原理与相对应的源代码。     

MOSIX进程迁移机制研究

MOSIX是一个优秀的集群系统软件，它对Linux内核进行了扩充，采用自适应资源管理方法，通过抢占式进程迁移实现动态负载平衡。该文简要介绍了进程迁移及MOSIX系统，主要分析了MOSIX进程迁移的实现机制。     

Tomcat与IIS或Apache服务器集成的应用研究

为解决中小型远程监测JSP网站开发中,Tomcat服务器单独运行时不能获取和显示实时MPEG-2视频数据流的问题,提出Tomcat与IIS或Apache服务器集成的解决方案.详细分析了方案的技术选择、配置和工作原理,阐述了具体实现Tomcat与IIS或Apache服务器集成的方法,实验结果表明了该方案在远程监测中的可行性与有效性.结果表明,Tomcat与IIS或Apa-che服务器集成可有效解决服务器难以处理大量视频数据流的问题,还可提升网站访问速度和稳定性.     

Apache最新高级实用技巧

Apache是Internet上最流行的Web服务器，它稳定、高效、安全、跨平台，足以胜任绝大部分商业、政府机关、教育界搭建网络平台的需要。本文从实际应用出发，对于Apache中虚拟主机的高级设置，Linux环境下Apache对Asp(active server page)技术的支持进行了详细地介绍。同时鉴于Apache新版的新特性，对以Apache为平台的站点的性能优化详加阐述。     

Video server scheduling using random early request migration

Video request migration among servers to achieve effective video-on-demand (VoD) services is investigated in this work. Our study is focused on the design and analysis of a random early migration (REM) scheme for user requests. When a new request is dispatched to a video server, the REM-based scheduler decides whether request migration is needed with a certain probability, which is a function of the service load. To analyze the request migration process, we introduce a state matrix representation that stores the service load information of each video server and plays an important role in the determination of migration paths. Based on this representation, we develop two methods to calculate performance metrics: the service failure rate and the system delay in service migration. Simulation results show that the REM scheme outperforms both the DASD dancing algorithm [1] and the traditional migration scheme adopted in [2,3] with shorter service delay and lower failure rates. It is also confirmed that our theoretical results match well with experimental results. Revised: 24 October 2004, Published online: 8 April 2005     

Heterogeneous process migration: the Tui system

Heterogeneous process migration is a technique whereby an active process is moved from one machine to another. It must then continue normal execution and communication. The source and destination processors can have a different architecture, that is, different instruction sets and data formats. Because of this heterogeneity, the entire process memory image must be translated during the migration. Tui is a migration system that is able to translate the memory image of a program (written in ANSI-C) between four common architectures (m68000, SPARC, i486 and PowerPC). This requires detailed knowledge of all data types and variables used with the program. This is not always possible in non-type-safe (but popular) languages such as ANSI-C, Pascal and Fortran. The important features of the Tui algorithm are discussed in great detail. This includes the method by which a program's entire set of data values can be located, and eventually reconstructed on the target processor. Performance figures demonstrating the viability of using Tui to migrate real applications are given. © 1998 John Wiley & Sons, Ltd.     

An adaptive plan-oriented and continuous software migration to cloud in dynamic enterprises

Replacing existing software/hardware components with their equivalent cloud services is an important decision faced by IT managers in today's enterprises. A variety of possible migration targets and cloud services with too many configurations and cost models, disparate and changing strategic objectives of the enterprise management that triggers the migration process, and the complex structure of the legacy applications make software migration to the cloud a challenging issue. In contrast to the existing approaches that model the migration process as an optimization problem to find the optimal deployment of software components on cloud services without presenting a practical migration plan, in this paper, a plan-oriented migration approach is proposed by which the enterprise management is able to follow migration steps of a valid plan. All valid plans are modeled using a labeled transition system, and a recommender engine directs the management through the possible migration paths using predefined fitness functions. It was observed that, particularly in dynamic and changing conditions that a flexible migration plan is essential, the proposed plan-oriented method is very much effective in satisfying the enterprise strategic objectives. Evaluations have been performed using two quality indicators: total cost of ownership and scalability index.     

Task assignment in multiple server farms using preemptive migration and flow control

Existing task assignment policies proposed for assigning tasks in stand-alone server farms are not efficient in multiple server farm environments because they have not been designed to exploit the properties of such environments. With the emergence of high speed networks and operating systems that have features such as preemptive migration, the importance of designing task assignment policies for assigning tasks in multiple server farms has increased. Such policies can result in better overall performance compared to those that optimise performance in stand-alone server farms.This paper proposes a task assignment policy suitable for assigning tasks in multiple server farms. The proposed policy, called Multi-Cluster Task Assignment based on Preemptive Migration (MCTPM) is based on a multi-tier host architecture that reduces the variance of task sizes in host queues by processing tasks with similar sizes using a set of hosts that have a distinct task size range. MCTPM controls the traffic flow into server farms via a global dispatching device so as to optimise the performance. MCTPM supports preemptive task migration between servers in the same farm and between servers in different farms.Performance analysis of the proposed policy indicates that significant performance improvements are possible under a wide range of workload scenarios. For example, MCTPM outperforms existing policies such as MC-Random, MC-TAGSPM and MC-MTTPM by factors of 190, 5 and 10.5 respectively under certain scenarios.     

Data collection and restoration for heterogeneous process migration

This study presents a practical solution for data collection and restoration to migrate a process written in high‐level stack‐based languages such as C and Fortran over a network of heterogeneous computers. We first introduce a logical data model, namely the Memory Space Representation (MSR) model, to recognize complex data structures in process address space. Then, novel methods are developed to incorporate the MSR model into a process, and to collect and restore data efficiently. We have implemented prototype software and performed experiments on different programs. Experimental and analytical results show that: (1) a user‐level process can be migrated across different computing platforms; (2) semantic information of data structures in the process's memory space can be correctly collected and restored; (3) costs of data collection and restoration depend on the complexity of the MSR graph in the memory space and the amount of data involved; and (4) the implantation of the MSR model into the process is not a decisive factor of incurring execution overheads. With appropriate program analysis, we can practically achieve low overhead. Copyright © 2002 John Wiley & Sons, Ltd.     

Apache反向代理在Web应用中的研究与实现

针对目前多数高校公网IP地址有限,但需要对外提供各种不同的Web应用服务,同时,某些Web应用服务由于访问流量大,出现超负载影响网络运行稳定的现象。本文提出利用Apache反向代理的关键技术,来实现单一地址和端口映射到多个内网服务器的不同Web应用,并解决Web应用服务器集群负载均衡问题。     

Modeling vulnerability discovery process in Apache and IIS HTTP servers

Vulnerability discovery models allow prediction of the number of vulnerabilities that are likely to be discovered in the future. Hence, they allow the vendors and the end users to manage risk by optimizing resource allocation. Most vulnerability discovery models proposed use the time as an independent variable. Effort-based modeling has also been proposed, which requires the use of market share data. Here, the feasibility of characterizing the vulnerability discovery process in the two major HTTP servers, Apache and IIS, is quantitatively examined using both time and effort-based vulnerability discovery models, using data spanning more than a decade. The data used incorporates the effect of software evolution for both servers. In addition to aggregate vulnerabilities, different groups of vulnerabilities classified using both the error types and severity levels are also examined. Results show that the selected vulnerability discovery models of both types can fit the data of the two HTTP servers very well. Results also suggest that separate modeling for an individual class of vulnerabilities can be done. In addition to the model fitting, predictive capabilities of the two models are also examined. The results demonstrate the applicability of quantitative methods to widely-used products, which have undergone evolution.     

基于内容识别的Web集群负载均衡算法的研究

可扩展Web服务器集群是目前高性能网络服务器的主要架构方法,负载均衡技术是集群系统中任务分配的核心环节.提出了一种基于内容识别的负载均衡算法,引入了访问量阈值的概念,并通过动态的修正访问量阈值以适应网络负载的变化;利用动态反馈机制来获取服务器的负载状态,同时通过保证负载的局部性,减少相同内容在多个服务器中的重复缓存,提高服务器Cache的命中率.