Page 159 - Cloud computing: From paradigm to operation

Framework and requirements for cloud computing 1

– Remedies for failures to meet the terms of the SLA: It is recommended that a CSN: cloud service
broker provide agreed remedies for failures to meet the terms of the SLA.
NOTE 4 – Examples of a remedies are migration, scale up, performance extension and so on.

7.4 Functional requirements for cloud service access management
– Delivering cloud service provision request: It is recommended that a CSN: cloud service broker
deliver the provisioning request to CSPs as requested by the CSC.
– Delivering cloud resource request: When a CSC needs more cloud resources of a cloud service, it is
recommended that a CSN: cloud service broker deliver the CSC's request for resources to a CSP.
– Access information forwarding: It is required that a CSN: cloud service broker forward the access
information of a cloud service from a CSP to the authorized CSC.
– Prohibiting access information storing: It is recommended that a CSN: cloud service broker provide
prohibiting of the access information for a cloud service not to open or store.

7.5 Functional requirements for cloud service management
– Cloud service SLA management: It is recommended that a CSN: cloud service broker provide SLA
management of running cloud service across multiple CSPs.
– Cloud service monitoring: It is recommended that a CSN: cloud service broker monitor the status of
cloud services by using gathered monitoring information of the cloud service from multiple CSPs.
NOTE 1 – The monitoring information is gathered periodically or aperiodically at runtime to check conditions
or status of cloud services. The monitoring information includes measured data for metrics of service levels in
SLA or resource utilization of cloud services.
NOTE 2 – A CSN: cloud service broker monitors status of logical resources (e.g., virtual machine) of cloud
services.
– Delivering request of cloud service control: It is recommended that a CSN: cloud service broker
deliver requests of control actions for a cloud service from a CSC to a CSP for managing status of the
cloud service.
– Validation of result for request of cloud service control: It is recommended that a CSN: cloud service
broker validate the status of cloud service whether the status is changed correctly or not in
accordance with the delivered request for a control action of a cloud service by a CSC.
NOTE 3 – Since changing status of cloud service takes time according to the circumstance of the CSP, a CSN:
cloud service broker does not know the result of the control request instantly. Therefore, to validate the status
of cloud service, the CSN: cloud service broker needs to check periodically the current status of cloud service
by communicating with the CSP until the validation is finished.
– Initiation of validation: It is recommended that a CSN: cloud service broker initiate cloud service
control status validation only after the CSN: cloud service broker receives an acknowledgement for
a cloud service control request from a CSP.
NOTE 4 – The acknowledgement for a service control request is a message from a CSP to inform receipt of a
request for a service control from a CSN: cloud service broker.
– Status checking period for validation: It is recommended that a CSN: cloud service broker provide
checking periods in service control status validation by predicting the completion time of the cloud
service control to reduce communication overhead between the CSN: cloud service broker and a CSP.
NOTE 5 – Service control checking period is the duration of time of one cycle for checking status of the service.
The checking period is determined probabilistically by statistically predicting the completion time of the cloud
service control.
NOTE 6 – To predict the completion time of a cloud service control, statistical methods, such as moving
average and variance, are applied to accumulated history of completion time of previous control requests for
the same or similar services. Using the statistical methods, a CSN: cloud service broker generates a probability
distribution for completion of service control at a given time.
NOTE 7 – The service control checking periods are determined by a normal probability distribution. The CSN:
cloud service broker increases the frequency of checking status of service when the probability of service
control completion is high. The CSN: cloud service broker decreases the frequency when the probability of
service control completion is low.

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