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Providing QoS strategies and cloud‐integration to web servers by means of aspects
Author(s) -
Giunta Rosario,
Messina Fabrizio,
Pappalardo Giuseppe,
Tramontana Emiliano
Publication year - 2013
Publication title -
concurrency and computation: practice and experience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.309
H-Index - 67
eISSN - 1532-0634
pISSN - 1532-0626
DOI - 10.1002/cpe.3031
Subject(s) - computer science , quality of service , cloud computing , scheduling (production processes) , web service , aspect oriented programming , web server , server , modularity (biology) , distributed computing , computer network , world wide web , the internet , operating system , software , operations management , economics , biology , genetics
Summary The main responsibilities of a web server are to listen from the communication channel and to prepare replies to requests. Additional responsibilities include adapting processing activities, for example, through scheduling or request filtering, so as to satisfy Quality of Service (QoS) requirements. Typical QoS‐related concerns address behavioural constraints (e.g. response time bounds, satisfiable by scheduling the most urgent requests first) and resource monitoring, for optimal use. Although such concerns are spread across several web server components, they should be handled separately from communication‐related ones, for the sake of modularity. For this purpose, we advocate recourse to aspect‐oriented programming and illustrate it by showing how a QoS‐related layer can be smoothly superimposed on top of a well‐known, unmodified, web server Jigsaw. As part of the provided support, requests are assessed and partitioned into those that can be appropriately handled by using local resources and those needing further resources. For the latter requests, cloud‐based resources are gathered. Aspect‐orientation enables new QoS‐related code to be separated from web server modules so as to keep existing code unaltered, while runtime behaviour is modified with the measures needed to handle QoS concerns. Copyright © 2013 John Wiley & Sons, Ltd.