Editing Service-level objective (section)

==Examples==

Sturm and Morris argue <ref>Rick Sturm,  Wayne Morris "Foundations of Service Level Management", April 2000, Pearson.</ref> that SLOs must be:

* Attainable
* Repeatable
* Measurable
* Understandable
* Meaningful
* Controllable
* Affordable
* Mutually acceptable

While Andrieux et al. define the SLO as "the quality of service aspect of the agreement. Syntactically, it is an assertion over the terms of the agreement as well as such qualities as date and time".<ref name=":0" /> Keller and Ludwig more concisely define an SLO as "commitment to maintain a particular state of the service in a given period" with respect to the state of the SLA parameters.<ref>Alexander Keller, Heiko Ludwig "The WSLA Framework: Specifying and Monitoring Service Level Agreements for Web Services", Journal of Network and Systems Management, Vol 11, n. 1, March 2003.</ref>  Keller and Ludwig go on to state that while service providers will most often be the lead entity in taking on SLOs there is no firm definition as such and any entity can be responsible for an SLO.  Along with this an SLO can be broken down into a number of different components.

* Obliged - The entity that is required to deliver the SLO.
* Validity Period - The time in which the SLO will be delivered.
* Expression - This is the actual language that defines what the SLO will be.

Optionally an EvaluationEvent maybe assigned to the SLO, an EvaluationEvent is defined as the measure by which the SLO will be checked to see if it's meeting the Expression.

SLOs should generally be specified in terms of an achievement value or service level, a target measurement, a measurement period, and where and how they are measured.<ref name=":1" /> As an example, "90% of calls to the helpdesk should be answered in less than 20 seconds measured over a one-month period as reported by the [[Automatic call distributor|ACD system]]". Results can be reported as a percent of time that the target answer time was achieved and then compared to the desired service level (90%).

{| class="wikitable"
!Type of Measure
!Example SLO Requirement
!Measurement Period
|-
|Availability 
|The application will be available 99.95% of the time
|Over a year
|-
|Service Desk Response
|75% of help desk calls will be answered in less than a minute
85% of help desk calls will be answered within two minutes

100% of help desk calls will be answered within three minutes
|Over a month
|-
|Incident Response Time
|99% of severity 1 tickets will be resolved within three hours
98% of severity 2 tickets will be resolved within eight hours

98% of severity 3 tickets will be resolved within three business days

98% of severity 4 tickets will be resolved within five business days
|Over a quarter
|-
|Response Time
|85% of TCP replies within 1.5 seconds of receiving a request
99.5% of TCP replies within 4 seconds of receiving a request
|Over a month
|}