Page 170 - Cloud computing: From paradigm to operation

1 Framework and requirements for cloud computing

Table I.7 – A use case for cloud service cancellation

Derived – Cloud service deregistration (See clause 7.2)
requirements – Automation of service deregistration (See clause 7.2)
– Notification of service deregistration (See clause 7.2)
– Request for maintaining cloud service (See clause 7.2)

Table I.8 – A use case for SLA establishment in cloud service brokerage

Title A use case for SLA establishment in cloud service brokerage.

Description This use case describes SLA establishment among a CSN: cloud service broker, CSPs and CSCs.
SLA is a part of the cloud service agreement that includes cloud service level objectives (SLO)
and cloud service qualitative objectives for the covered cloud service(s) [b-ISO/IEC 19086-1].
Since a CSC communicates with a CSN: cloud service broker to consume a cloud service, the
CSN: cloud service broker is responsible for establishing a SLA with the CSC. Also, CSPs need to
provide service level information to the CSN: cloud service broker so that the CSN: cloud
service broker understands feasible service levels.
A CSP determines to sell cloud services though a CSN: cloud service broker and the CSP
registers cloud service information including service level in CSB workspace. For instance, the
CSP can provide "service availability" service level which can be expressed as a percentage of
uptime to total usage time of a cloud service. The CSP registers a lower limit for the availability
service level (ex: 99.99%) and remedies (e.g., discounting service price) for failure to meet the
SLA to the CSN: cloud service broker.
The CSN: cloud service broker verifies that all services with service level descriptions are
correctly registered by the CSP.
The CSN: cloud service broker repackages services, registered by the CSP, into brokerage
services according to business needs such as service customization or service integration. The
CSN: cloud service broker needs to provide service levels of a service which the CSC requests
to the CSN: cloud service broker. For instance, the CSN: cloud service broker repackages a
service and offers 99.98% of service availability where the service level of the original service
registered by the CSP is 99.99%.
The CSC, who needs an IaaS service satisfying at least 99.90% availability, connects to CSB
workspace and selects a cloud service according to the business requirements. After the CSC
selects a cloud service, the CSN: cloud service broker generates a SLA document and shares
the SLA document to CSC. Once the CSC accepts terms and conditions in the SLA document, a
SLA between the CSN: cloud service broker and the CSC is established.
After the SLA between the CSN: cloud service broker and the CSC is established, the CSN: cloud
service broker makes a request to the CSP to initiate the service. When the CSN: cloud service
broker makes the request, it is assumed that a SLA between the CSP and the CSN: cloud service
broker is established according to the service level descriptions registered by the CSP.
Roles/sub-roles CSP, CSN: cloud service broker, CSC

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