Table 2 Definition and Description of the Six QoS Attributes

Service Response time

Performance

This is the measure of the time between when a request is made and a response is constructed for the user [13].

Quantitative

Ms

(2, 3, 0.5 etc.)

Availability

Assurance

This is a measure of the likelihood of the duration of time when the service will be in operation without downtime [13].

Quantitative

%

(99.5, 99.9, 999.9 etc.)

Cost

Financial

This is the cost of acquisition or usage cost of a service by a user [13].

Quantitative

$

(20, 30, 40, 5)

Usability

Usability

This is the ease with which a service can be used, operated, learned, understood, and installed by the user [13, 42].

Qualitative

Categorical range

{High, Medium, Low}

Security Management

Security and Privacy

This is a rating of the extent to which a service can satisfy user security requirements in terms of access control, privacy, data, infrastructure etc. [13]

Qualitative

Categorical range

{High, Medium, Low}

Flexibility

Agility

This is the rating of the ability to add or remove predefined features from a service in order to accommodate users’ preferences [13].

Qualitative

Categorical range

{High, Medium, Low}