Information Technology Reference
In-Depth Information
In this chapter, we will discuss the following
topics for QoS-oriented Service Computing, which
includes Service Level Agreement (SLA), green
service, service metering, service monitoring,
QoS assured service, and on-demand resource
provisioning. In a case study, we discuss how
we employ QoS-oriented service computing in a
multi-server, multi-user on-line game to facilitate
the on-demand resource provisioning to guarantee
the QoS-assured services.
provision infrastructures interoperable with a
broad set of technologies and business process.
Other advantages of using SOAs include their abil-
ity to build composite applications by integrating
Web services via workflow, which can automate
the whole process without direct human interac-
tion or control. SOA can also facilitate enabling
a scalable infrastructure to meet the requirements
of on-demand resource provisioning.
Standards and Specification
Languages for SLA Representation
BACKGROUND OF
SERVICE COMPUTING AND
CLOUD COMPUTING
Web service has now been widely used in e-Sci-
ence, service-oriented infrastructure, and various
computing paradigms (e.g. Cloud computing, Grid
computing, service computing), hence ensuring
Quality of Service (QoS) is becoming increasingly
important. Service Level Agreement (SLA) can
be employed to serve as a bilateral contract that
exists between a customer and a service provider
to specify the user requirements, quality of ser-
vice, responsibilities and obligations (http://www.
gridipedia.eu). SLA can contain numerous service
performance metrics with corresponding Service
Level Objectives (SLO). It describes quality of ser-
vice and other commitments by a service provider
in exchange for financial commitments based on
an agreed schedule of prices and payments (http://
www.gria.org/about-gria/a-business-perspective).
It is critical that the electronic SLA can be
presented in a certain specification language and
this language should be extensible and standard-
based, so that the SLA provisioning and man-
agement system can deal with SLA in a flexible
manner. Although there were some articles (e.g.
Dobson, 2004; Seidel et al., 2007) that reviewed
the associated specification languages for QoS
and SLA, the discussed specification languages
are either out of data, or not complete.
The SLA life cycle typically includes asso-
ciated service provider discovery, negotiation,
conformance monitoring, enforcement, and
end-of-life invoicing, etc. The SLA life cycle
This section reviews literatures related to service
computing and Cloud computing. Especially,
we provide a survey on relevant standards and
specification languages which can be employed
in presenting the SLA. We identified appropriate
standards for SLA representation. The survey
has also resulted in the formulation of reference
architecture for SLA life cycle management.
Service-Oriented Architecture
A Service-Oriented Architecture (SOA) contains
a collection of services which can communi-
cate with each other. The communication can
involve either data exchange or it could involve
more services managing a specific activity. In
this context, a service is a function that is well
defined, self-contained, and does not depend on
the context or state of other services. SOAs offer
a variety of advantages over traditional distributed
computing systems and for this reason they tend
to replace the platforms upon which the business
services are offered to the clients. They provide
location independence for services, which means
that services can run anywhere. The searching and
connection to other service can be dynamic and
follow a loosely coupled approach, which can thus
enable the formulation of general purpose service
Search WWH ::
Custom Search