According to the main interaction classes, the service consists of usage and management functionality. Both types of functionality must satisfy a set of QoS parameters. These parameters define the minimum required service quality in order to be useful for the customer side. The QoS parameters define qualitative as well as quantitative values.
The usage functionality covers the interactions needed by the user. These interactions represent the actual purpose of the service. Besides these, interactions beyond the service's purpose are needed to fulfill the customer's duties, to customize the service according to user's needs and to control the provider's service provisioning. The management functionality comprises these interactions.
the example the usage functionality of the virtual store service consists of searching the product database, retrieving information on a product and ordering a product. These interactions between user and provider are the purpose of the service. The management functionality for the dealer includes updating the product database, retrieving reports on the queries and orders of the users as well as receiving bills for the virtual store and paying them.The QoS parameters comprise a maximum number of queries per second, response time for user queries, time until database updates are in effect, payment interval, and so on.
The service agreement substantiates the service by describing the usage and management functionality as well as the QoS parameters.
The information presented up to this point describes the service bought by the customer side and provided by the provider side. To actually be usable, there must exist a service interface between these two sides. Service primitives, protocols and (where necessary) physical connectors are represented by the service interfaces.
The interface definitions must also be included in the service agreement to enable the customer side to access the service functionality. The interface is the point where the responsibility of the provider ends. It must be stressed, that the interfaces are not part of the service. This means, changing or adding interfaces for service access does not result in a different service, though the service agreement has to be changed.
In the same way the functionality was split up in usage functionality and management functionality, the interface is split up in a usage interface, called Service Access Point (SAP), and a management interface, called Customer Service Management Interface (CSM interface) [#!lane99a!#], where the corresponding management functionality is accessible.
SAP for the virtual store could be a web-server accessible through the Internet. The interface includes the service primitives represented by HTML forms, several protocols like HTTP and IP. A physical connector is not specified in this example.To sum up, the service agreement specifies the service by defining the functionality for usage and management from the customer's perspective, the service quality and logical as well as physical aspects of the usage and management interfaces between customer and provider side.The CSM interface needed by the dealer consists of a telephone number for a hotline and a leased line to modify the database and access reports. Payment is handled using a bank account.