As I guess, Lawrence, the service specification is an internal document. While I fine with deriving Service Description from the service spec, it would be interesting to know how you have resolved the ownership issue of this specification; does it belong to IT or to Business? Example: consumer provides the instructions and funds and the service invests them accordingly; who is the custodian of the service spec?
Actually, it is an open question: how to formally manage SLA between Service Description and Service Contracts? There may be regular cases where SLA in the Contracts may somehow differ from the SLA in the Service Description. For example, 1) not all SLA attributes may be included into some Service Contracts; 2) Service Contract's SLA may include additional attributes (upon agreement); 3) some SLA attributes may appear with different constraints. In your example, the response time may be set as 'not more than 4 seconds' for some consumers served in special geographical region where number of consumers is not high and computational resources are available (while it is the same service and the same version of the Service Description). - Michael ________________________________ From: LAWRENCE <[email protected]> To: [email protected] Sent: Mon, December 21, 2009 11:08:40 AM Subject: [service-orientated-architecture] Re: Descriptions vs Contracts We use - Service Specification (a service description is part of a specification) to describe the functional behavior 'contract' between the provider and all consumers. e.g. if the consumer provides a valid customer number, the provider will return the customer's name and address. and - Service Level Agreement, to describe usage 'contract' between specific provider and consumer (though the same contract may be made between the provider and all consumers) e.g. if the consumer makes no more than 1000 requests per hour, the provider will respond in no more than 5 seconds. See http://cbdi. wikispaces. com/Service+ Specification
