Service level agreements can contain many service performance metrics with appropriate service level objectives. A common case in IT service management is a call center or services. Service level agreements are also defined at different levels: since the late 1980s, SSAs have been used by fixed telecommunications operators. Today, SLAs are so prevalent that large organizations have many different SLAs in the company itself. Two different units in an organization write an SLA, one being the customer and the other the service provider. This approach helps maintain the same quality of service across different units of the organization and across multiple locations in the organization. This internal SLA scripting also makes it possible to compare the quality of service between an internal department and an external service provider.  Many LTS comply with the information technology infrastructure library specifications when applied to IT services. Uptime is also a common metric, often used for data services such as shared hosting, virtual private servers, and dedicated servers. Usual agreements include the percentage of network availability, operating time, number of planned maintenance windows, etc. As applications are moved from dedicated hardware to the cloud, they must achieve the same or even more demanding service levels as traditional installations. SLAs for cloud services focus on data center characteristics and more recently include network features (see carrier cloud) to support end-to-end SLAs.  A Web Service Level Agreement (WSLA) is a standard for monitoring compliance with Web services service level agreements.
Authors can specify the performance assigned to a web service application, the desired performance goals, and the actions to take if performance is not achieved. The underlying advantage of cloud computing is that of shared resources that are supported by the underlying nature of a common infrastructure environment. Therefore, SLAs span the entire cloud and are offered by service providers as a service agreement and not a customer-based agreement. Measuring, monitoring, and reporting on cloud performance is based on the final UX or its ability to consume resources. The disadvantage of cloud computing compared to SLAs is the difficulty of determining the cause of service interruptions due to the complexity of the nature of the environment. Un secondo punto di vista meno ovvio è che le metriche scelte devono essere collegate direttamente ai processi del provider e all`attività delle sue persone, altrimenti lo SLA perde di significato. It is therefore not necessary to refer to measures that may be formally correct, but that are related to processes or events that are not entirely under the control of the supplier. .