8. Cloud Service Life cycle 
A cloud service life cycle consists of service requirements, service discovery, service negotiation, service composition, and service consumption. In the service requirements phase, consumers detail the functional requirements (functions and tasks that a service should provide), technical requirements (e.g., hardware and operating systems), and budgetary requirements (acceptable service cost). The service discovery phase consists of searching for cloud services that match consumers’ functional, technical, and budgetary requirements. The service negotiation phase consists of message exchanges between consumers and brokers, and between brokers and providers for establishments of service-level agreements. In the service composition phase, a broker combines a set of services from multiple providers, and delivers the combined service as a single virtualized service to a consumer. In the service consumption phase, the service is delivered to the consumer.
9. Cloud Computing Benefits
• No up-front investment: Cloud computing uses a pay-as you- go pricing model. A service provider does not need to invest in the infrastructure to start gaining benefit from cloud computing. It simply rents resources from the cloud according to its own needs and pay for the usage.
• Lowering operating cost: Resources in a cloud environment can be rapidly allocated and de-allocated on demand. Hence, a service provider no longer needs to provision capacities according to the peak load. This provides huge savings since resources can be released to save on operating costs when service demand is low.
• Highly scalable: Infrastructure providers pool large amount of resources from data centers and make them easily accessible. A service provider can easily expand its service to large scales in order to handle rapid increase in service demands (e.g., flash-crowd effect). This model is sometimes called surge computing .
• Easy access: Services hosted in the cloud are generally web-based. Therefore, they are easily accessible through a variety of devices with Internet connections. These devices not only include desktop and laptop computers, but also cell phones and PDAs.
• Reducing business risks and maintenance expenses: By outsourcing the service infrastructure to the clouds, a service provider shifts its business risks (such as hardware failures) to infrastructure providers, who often have better expertise and are better equipped for managing these risks. In addition, a service provider can cut down the hardware maintenance and the staff training costs.
• Improved time-to-market by reducing development and infrastructure deployment times.
• Increased service availability and reliability resulting from the replication of service components and rapid deployment of new service instances.
• Cloud interoperability, which lets users deploy a service on multiple clouds, thus providing unlimited scalability and optimized service performance.
 K. M. Sim, “Agent-Based Cloud Computing,” IEEE TRANSACTIONS ON SERVICES COMPUTING,, vol. 5, no. 4, pp. 564-577, OCTOBER-DECEMBER 2012.