many cases, components require a complete shut-down and restart before
configuration changes take effect, thus causing an interruption of service. Dynamic
reconfiguration support is necessary for components to fit into an autonomic
environment. As part of our research we are modifying open source Web based
components, such as the Apache HTTP server, to enable dynamic configuration.
Second, autonomic systems will require extensive monitoring, analysis and diagnosis.
Most Web components currently provide sophisticated support to accomplish these
tasks, however, ensuring that these processes do not burden the system with excessive
overhead costs will be a challenge. Third, an architecture like the one proposed here
relies on the specification of SLAs, goals and policies to determine acceptable
performance. Users require a specification language in which these high level SLAs
and policies can be expressed and SLAs must be translated into observable measures
to be used as goals for each component. We plan to use the WSLA language [5] as the
starting point and investigate how goals for individual components can be specified
and derived from Web service SLAs.
References
1. Apache Server Monitor,
http://demo.freshwater.com/SiteScope/docs/ApacheServerMon.htm.
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Spreitzer, M. and Youssef, A.: Web Services on Demand: WSLA-driven automated
management. IBM Systems Journal, 43(1), (2004) 136 – 158.
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(2003), 41-50.
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13. SOAP Version 1.2 Part 1: Messaging Framework, June 2004,
http://www.w3.org/TR/soap12-part1/.
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