1 Introduction
1.1 SLA actors and elements
1.2 Literature classification
1.3 Paper contribution
1.4 Paper organisation and reading-map
2 SLA Characteristics and Objectives
2.1 SLA Characteristics
2.2 Service Level Objectives (SLO)
3 Service Quality Categories & QSD
4 SLA Methodologies
4.1 Dynamic & Static Methodologies
4.2 Decision-Making
5 Modelling and Architecture
5.1 SLA Modelling
5.2 SLA Architecture
5.3 SLA Monitoring
6 Open Problems and Future Research Direction
6.1 The SLA Negotiation Procedures
6.2 Methodology & Modelling
6.3 Implementation and Deployment
6.4 SLA Monitoring
6.5 Security
7 Conclusions