什么是服务? A well-defined invokable unit of business function Accesses business data or facilitates a change of business data from one valid and consistent state to another Defined using explicit interfaces Independent of service implementations Provides contract between service requestors and service providers Invokable through common communication protocols Provides interoperability and location transparency7 什么是服务? ▪ A well-defined, invokable unit of business function ▪ Accesses business data or facilitates a change of business data from one valid and consistent state to another. ▪ Defined using explicit interfaces Independent of service implementations Provides contract between service requestors and service providers ▪ Invokable through common communication protocols Provides interoperability and location transparency