Design of a Model-Based SLA Management Service and Its Applications over Distributed SOA Environments - Grid Computing: Infrastructure, Service, and Applications - page 267

because the operations in those stages involve data transmission and
retrieving a data entity from remote SAP repositories.

10.6
In this chapter, we proposed a CIM model-based design of an SLA man-
ager which allows the service provider and its customers to specify require-
ments regarding SLAs and customize SLA management. We presented an
SLA model where SLA template class and SLA class are derived from a
common data structure. A model-based SLA manager and its core, called
SLA-based services, were introduced to facilitate the communication
between the service provider and the client and to manage the SLA copies
in a distributed environment. The proposed model-based design of SLA
Manager is highly l exible, customizable, and extensible to provide SLA
management services over the distributed service-oriented environments.
Our present work can be extended in the following ways. First, the cur-
rent SLA model can be extended to describe the association information
of different SLAs. In a cooperative infrastructure, the SLAs may not stand
alone but are associated with other SLAs. For example, the SLA estab-
lished between an application service provider and its client may be asso-
ciated with another SLA established between the application service
provider and a resource service provider. The failure of fuli lling one SLA
may result in the violation of other SLAs or the suspension of the other
services. Therefore, the status of one SLA may affect the execution of other
SLAs. Efi cient mechanisms to specify and handle the associations of the
SLAs help the service provider to fuli ll the SLAs and eventually reduce
the loss.
Second, the existing SLAs may be violated due to the difi culties of
accurately predicting the performance in advance. Especially in the case
where one single SLA consists of multiple jobs, the failure of executing
one job may affect the execution of the others. Therefore, the mechanisms
for adaptive SLA management are important. Some may consider the pos-
sibility of renegotiating the services and changing the established SLA to
cope with the dynamic situations. The mechanisms of adapting existing
SLAs may help the service provider to avoid the failures caused by inac-
curate predictions and overcome the uncertainties of the decompositions
and resource availabilities in distributed environments.
In addition, SLA agreement may involve multiple parties and each party
will share the responsibilities of fuli lling the SLA. These scenarios may be
common in computer services (e.g., service orchestration/compositions)
where multiple parties are involved in completing a business process. As
there might be multiple parties involved in the service negotiations, the

Conclusions