Service Level Agreement Driven Adaptive Resource Management For Web Applications on Heterogeneous Compute Clouds

Cloud computing is an emerging topic in the field of parallel and distributed computing. Many IT giants such as IBM, Sun, Amazon, Google, and Microsoft are promoting and offering various storage and compute clouds. Clouds provide services such as high performance computing, storage, and application hosting. Cloud providers are expected to ensure Quality of Service (QoS) through a Service Level Agreement (SLA) between the provider and the consumer. In this research, I develop a heterogeneous testbed compute cloud and investigate adaptive management of resources for Web applications to satisfy a SLA that enforces specific response time requirements. I develop a system on top of EUCALYTPUS framework that actively monitors the response time of the compute resources assign to a Web application and dynamically allocates the resources required by the application to satisfy the specific response time requirements

Managing Cache Consistency to Scale Dynamic Web Systems

Data caching is a technique that can be used by web servers to speed up the response time of client requests. Dynamic websites are becoming more popular, but they pose a problem –- it is difficult to cache dynamic content, as each user may receive a different version of a webpage. Caching fragments of content in a distributed way solves this problem, but poses a maintainability challenge: cached fragments may depend on other cached fragments, or on underlying information in a database. When the underlying information is updated, care must be taken to ensure cached information is also invalidated. If new code is added that updates the database, the cache can very easily become inconsistent with the underlying data. The deploy-time dependency analysis method solves this maintainability problem by analyzing web application source code at deploy-time, and statically writing cache dependency information into the deployed application. This allows for the significant performance gains distributed object caching can allow, without any of the maintainability problems that such caching creates

Web page performance analysis

Computer systems play an increasingly crucial and ubiquitous role in human endeavour by carrying out or facilitating tasks and providing information and services. How much work these systems can accomplish, within a certain amount of time, using a certain amount of resources, characterises the systems’ performance, which is a major concern when the systems are planned, designed, implemented, deployed, and evolve. As one of the most popular computer systems, the Web is inevitably scrutinised in terms of performance analysis that deals with its speed, capacity, resource utilisation, and availability. Performance analyses for the Web are normally done from the perspective of the Web servers and the underlying network (the Internet). This research, on the other hand, approaches Web performance analysis from the perspective of Web pages. The performance metric of interest here is response time. Response time is studied as an attribute of Web pages, instead of being considered purely a result of network and server conditions. A framework that consists of measurement, modelling, and monitoring (3Ms) of Web pages that revolves around response time is adopted to support the performance analysis activity. The measurement module enables Web page response time to be measured and is used to support the modelling module, which in turn provides references for the monitoring module. The monitoring module estimates response time. The three modules are used in the software development lifecycle to ensure that developed Web pages deliver at worst satisfactory response time (within a maximum acceptable time), or preferably much better response time, thereby maximising the efficiency of the pages. The framework proposes a systematic way to understand response time as it is related to specific characteristics of Web pages and explains how individual Web page response time can be examined and improved

Webアクセスにおける動的コンテンツ検索の応答性向上のための先読み機能を持ったネットワーク内キャッシュシステムの研究

近年，Google mapやJorudanでの乗換検索，食べログの店舗検索をはじめとする動的コンテンツが多くの人に利用されている．これら動的コンテンツは，ユーザの入力や現在時刻などをもとにして，サービス提供者側のサーバで動的に生成され，ユーザに送り返される．すなわち，ユーザが要求するコンテンツを入手するために，ユーザとサービス提供者サーバは直接通信をやりとりする必要がある．このため，動的コンテンツはユーザから見た応答性を向上させることが難しい．本論文では，これら動的コンテンツの応答性を向上させるため，「動的コンテンツ検索先読み機能を持つネットワーク内キャッシュシステム」を提案した．本システムでは，動的コンテンツ要求をユーザに代行して先読みサーバが行い，先読みサーバ内にキャッシュとして保持し，よりユーザに近い位置でコンテンツを返送できる．提案システムを代表的な動的コンテンツの一つである乗換検索に対して実装し，その有効性を評価した．その結果，先読みサーバを用いることにより，両コンテンツの応答性を最短10ms，先読みサーバの負荷が高い場合でも100ms以内にユーザに送信することができ，コンテンツのユーザから見た応答性を向上させた．また，最大で85%のユーザに対してコンテンツの応答性を向上させることができた．加えて先読みサーバを複数のユーザが利用することにより，先読みサーバを用いない場合より先読み回数を削減できることができた．システム評価から得られたデータによって，動的コンテンツはメモリ上にキャッシュとして保持する必要があるなど，コンテンツ応答性をより向上させるための知見を得た，先読みを行う入力として，ユーザからの要求だけでなくソーシャル情報を用いる場合は，どのような状況であればソーシャル情報は有効な入力となるかを検討した．最後に，乗換検索だけでなくより一般的な動的コンテンツに対して本システムを適用する場合には，語の共起を利用して検索語の先読みを行う必要があるなど，考慮しなければならないことについての知見を得た．電気通信大学201

Towards Efficient Delivery of Dynamic Web Content

Advantages of cache cooperation on edge cache networks serving dynamic web content were studied. Design of cooperative edge cache grid a large-scale cooperative edge cache network for delivering highly dynamic web content with varying server update frequencies was presented. A cache clouds-based architecture was proposed to promote low-cost cache cooperation in cooperative edge cache grid. An Internet landmarks-based scheme, called selective landmarks-based server-distance sensitive clustering scheme, for grouping edge caches into cooperative clouds was presented. Dynamic hashing technique for efficient, load-balanced, and reliable documents lookups and updates was presented. Utility-based scheme for cooperative document placement in cache clouds was proposed. The proposed architecture and techniques were evaluated through trace-based simulations using both real-world and synthetic traces. Results showed that the proposed techniques provide significant performance benefits. A framework for automatically detecting cache-effective fragments in dynamic web pages was presented. Two types of fragments in web pages, namely, shared fragments and lifetime-personalization fragments were identified and formally defined. A hierarchical fragment-aware web page model called the augmented-fragment tree model was proposed. An efficient algorithm to detect maximal fragments that are shared among multiple documents was proposed. A practical algorithm for detecting fragments based on their lifetime and personalization characteristics was designed. The proposed framework and algorithms were evaluated through experiments on real web sites. The effect of adopting the detected fragments on web-caches and origin-servers is experimentally studied.Ph.D.Committee Chair: Dr. Ling Liu; Committee Member: Dr. Arun Iyengar; Committee Member: Dr. Calton Pu; Committee Member: Dr. H. Venkateswaran; Committee Member: Dr. Mustaque Ahama