Page 90 - Cloud computing: From paradigm to operation

1 Framework and requirements for cloud computing

8.5.13 Service levels and service level agreements

Service level agreements are important components of cloud computing governance and represent
measurable elements needed to assure an agreed upon quality of service between a cloud service customer
and a cloud service provider.

The cloud computing service level agreement (cloud SLA) is a service level agreement between a cloud
service provider and a cloud service customer based on a taxonomy of cloud computing specific terms to
set the quality of the cloud services delivered. It characterizes the quality of the cloud services delivered in
terms of:
• a set of measurable properties specific to cloud computing (business and technical);
• a given set of cloud computing roles (cloud service customer and cloud service provider and related
sub-roles).
For instance, cloud service customers need a cloud SLA to specify the technical performance requirements
of one or more cloud services. A cloud SLA can cover terms regarding the quality of service, security,
performance and remedies for failures to meet the terms of the SLA. A cloud service provider can also list
within the cloud SLA a set of promises explicitly not made to cloud service customers, i.e., limitations and
obligations that cloud service customers need to accept. A cloud SLA should define the classification of data
objects (i.e., cloud service customer data, cloud service provider data, and cloud service derived data), who
has access and control of data objects in these data classifications and how they will be used.

The service level agreement should specify information relating to the availability of the services, the
confidentiality and integrity of the services and the access controls which apply to the services. The service
level agreement should specify how any personally identifiable information will be handled in relation to
the cloud services.
The service agreement – alternatively known as the master service agreement (MSA), terms of service (ToS),
terms and conditions (T&C), or simply "the contract" – is the higher order document in agreements between
parties and the service level agreement (SLA) is subservient. This is an important distinction because the SLA
acronym is frequently, and incorrectly, used to reference the contractual relationship as a whole – a role that
an SLA alone is incapable of performing. The service agreement addresses the whole of the contractual
relationship and therefore contains contractual elements not directly related to cloud computing.

9 Functional view

9.1 Functional architecture

The functional architecture for cloud computing describes cloud computing in terms of a high level set of
functional components. The functional components represent sets of functions that are required to perform
the cloud computing activities described in clause 8 for the various roles and sub-roles involved in cloud
computing.
The functional architecture describes functional components in terms of a layering framework where specific
types of functions are grouped into each layer and where there are interfaces between the functional
components in successive layers.
9.1.1 Layering framework

The layering framework used in the CCRA has four layers, plus a set of functions which spans across the layers.
The four layers are:
• user layer;
• access layer;
• service layer;
• resource layer.

The functions which span the layers are called the multi-layer functions.

82