In digital library, the specification and management of QoS is necessary to enhance user experiences. QoS
represents the parameters that can be used to characterise and assess the functional and non-functional aspects of
digital services. Some of these parameters are objective in nature and can be automatically measured, whereas
others are subjective in nature and can only be measured through user evaluations (e.g., focus groups). The
proposed SLA-based approach is designed to move away from subjective measures based on opinions. Harris &
Rockliff (2003) discussing the scope and contents as well as the role of service agreements in Australian health
libraries. Comuzzi et. al (2009) focused on establishing and monitoring SLAs for complex service based systems.
The authors use business, software and infrastructures services as a SLAs hierarchies spanning through multiple
domain and layers of a service economy. The authors applying the framework to industrial use cases. However, the
proposed SLAs framework specifically on the service provider side only. Therefore, the approach is not suitable
for digital library QoS measuring where QoS in the library is also expressed by parameters that focus on the