Design of a Model-Based SLA Management Service and Its Applications over Distributed SOA Environments - Grid Computing: Infrastructure, Service, and Applications - page 250

allocating the various resources for delivering the services over a dis-
tributed environment. In SNAP [23], a multiphase SLA-driven resource
management protocol is presented to manage distributed resources
for a task SLA, resource SLA, and bounding service level agreement to
fulfill complex tasks. The Globus Architecture for Reservation and
Allocation (GARA) has been proposed in [22] to reserve resources to
ensure the end-to-end QoS in grids. The Virtual Application Service
(VAS) [24] is an extension of GARA, which supports the QoS negotia-
tion and the submission of jobs with deadline constraints. Adaptive
resource management has been proposed (e.g., G-QoSm [25]) to cope
with the dynamic feature of resource availability in cooperative
environments.
As mentioned above, realizing SLA management has various aspects
covering SLA negotiation, SLA decomposition, resource allocation, adap-
tation, and optimization. In real-life situations, not all services require the
full functionality mentioned above. Hence, a generic SLA management
service is required to facilitate SLA-related operations. In this chapter, we
propose a model-based design for an SLA manager, which provides a
generic SLA management service in distributed environments. It facili-
tates the SLA negotiation between the service provider and the client and
manages the SLA copies for SLA-relevant process in distributed net-
worked environments.

10.3 Architecture of an SLA Manager

10.3.1 SLA Manager and Its Environment

SLA Manager is a software module that provides APIs to manage the SLA
copies and facilitate the communication between a service provider and
its service clients for establishing the SLAs. It supports SLA-relevant oper-
ations such as retrieving the SLA templates, negotiating the services, set-
tling the agreement, monitoring the SLA status during the service delivery,
and so on.
Figure 10.1 shows the relationships between SLA Manager and its work-
ing environment. SLA Manager provides interfaces through which service
clients can retrieve service templates, specify their requirements, and
negotiates an SLA with the service provider regarding the service terms
and conditions. In addition to this, SLA Manager closely interacts with the
service manager to provide offers and counter-offers to the service clients.
Overall, SLA Manager dei nes a standardized protocol and a set of meth-
ods that help in the SLA-relevant operations.