Design of a Model-Based SLA Management Service and Its Applications over Distributed SOA Environments - Grid Computing: Infrastructure, Service, and Applications - page 260

proposeSLA()

pending proposed rejected

proposeSLA() rejectSLA()

or timeout

SLA signed

SLA created

SLA
abandoned
and deleted

agreedTo

cancelSLA()

start time
arrives

active cancelled

cancelSLA()

end time arrives

SLA
deleted

expired

SLA deleted

FIGURE 10.6

The lifecycle of an SLA.

digital signatures, the SLA proposal enters the agreedTo state. Typically,
every SLA will have a designated start and end time when the SLA is
active. Once the start time recorded in the SLA arrives (which may or may
not be immediately), the status of the SLA becomes active .
If an agreement is never reached, the SLA proposals will eventually be
abandoned, and deleted. The active state is exited normally when the SLA
expiration time is reached (the expired state), or abnormally if the SLA is can-
celled by either side (the cancelled state). Eventually, the SLA will be deleted.
There may be additional substates of active . For example, the service pro-
vider may refuse to provide service until certain conditions are met—for
example, payment up front for its services, or if interim payments are late.
Such substates will need to be handled by the service provider on a case-
by-case basis.

10.4.2.5 Management of SLA Copies

During the SLA negotiation process, multiple versions of the SLA pro-
posals may be created before reaching an agreement. Efi cient means of
SLA copy management is required to ensure that different versions of
SLA proposals are preserved until i nal agreement is reached.