Figure shows the separation of the service life cycle into the phases design, negotiation, provisioning, usage and deinstallation, which is an extension of the life cycle proposed in [#!han99!#].
The service life cycle starts with the design of the service. This includes interactions like the specification of the needed functionality and of possible QoS parameters as well as performing a cost assessment to be able to rate the service in the following phase.
Afterwards, the provider is able to offer the service to the customer which starts the negotiation phase. Depending on the complexity of the service this can be a very difficult and time-consuming task. Usually the customer and provider side have to negotiate QoS parameters, tariffs, penalties, discounts, escalation mechanisms, terms of usage (e.g., thresholds for number of transactions per minute) and management of the service (e.g., problem solution time). In fact the agreement contains the description of future interactions in a more or less detailed way that take place between the customer and provider side. The negotiation phase ends with signing a service agreement.
[Service life cycle]Service life cycle [r]The provisioning phase, which follows the negotiation phase, contains interactions needed to properly install the agreed service. This means that the service provider has to implement, configure and test the service and its management. Additionally, the customer delivers needed data to the provider (e.g., user information, network connection points, etc.). Often the service agreement has to be adapted, as several parameters are not known until the implemented service is tested. Usually QoS parameters and accounting units of an individually designed service are not specified to concrete values until the end of a test run. The provisioning phase ends with a statement of acceptance of the service by the customer.
The actual service usage by the customer takes place in the usage phase. During this phase the service is operational. It includes two sub-phases: operation phase and change phase. The operation phase includes all tasks needed to keep the service operational, like support, (QoS) monitoring, fault identification, fault resolution, maintenance, reporting, charging, billing and reviews. However, modifications to the service or its implementation may be required during the usage phase. These interactions are summarized in the change phase. Such modifications may change the service functionality, the quality or just the implementation being transparent to the abstract service. In some cases this implies an adaption of the service agreement.
Finally, the service ends with the deinstallation. Usually, the complete implementation is removed and involved resources are released.