LISA 2002 - Technical Program Abstract
Defining and Monitoring Service Level Agreements for Dynamic e-Business
Alexander Keller and Heiko Ludwig - IBM T. J. Watson
Pp. 189-204 of the Proceedings of LISA '02:
Sixteenth Systems Administration Conference,
USENIX Association, 2002).
Fueled by the growing acceptance of the Web Services Architecture,
an emerging trend in application service delivery is to move away from
tightly coupled systems towards structures of loosely coupled,
dynamically bound systems to support both long and short business
relationships. It appears highly likely that the next generation of e-Business systems will consist of an interconnection of services, each
provided by a possibly different service provider, that are put
together on an ``on demand'' basis to offer an end to end service to a
Such an environment, which we call Dynamic e-Business (DeB), will
be administered and managed according to dynamically negotiated
Service Level Agreements (SLA) between service providers and
customers. Consequently, system administration will increasingly
become SLA-driven and needs to address challenges such as dynamically
determining whether enough spare capacity is available to accommodate
additional SLAs, the negotiation of SLA terms and conditions, the
continuous monitoring of a multitude of agreed-upon SLA parameters and
the troubleshooting of systems, based on their importance for
achieving business objectives.
A key prerequisite for meeting these goals is to understand the
relationship between the cost of the systems an administrator is
responsible for and the revenue they are able to generate, i.e., a
model needs to be in place to express system resources in financial
terms. Today, this is usually not the case.
In order to address some of these problems, this paper presents
the Web Service Level Agreement (WSLA) framework for defining
and monitoring SLAs in inter-domain environments. The framework
consists of a flexible and extensible language based on the XML schema
and a runtime architecture based on several SLA monitoring services,
which may be outsourced to third parties to ensure a maximum of
WSLA enables service customers and providers to unambiguously
define a wide variety of SLAs, specify the SLA parameters and the way
how they are measured, and tie them to managed resource
instrumentations. A Java-based implementation of this framework,
termed SLA Compliance Monitor, is publicly available as part of
the IBM Web Services Toolkit.
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