Service systems are highly complex and often difficult to study, design and implement given their socio-technical-organisational nature. This complexity leads to a poor understanding as to how service systems can be innovative and competitive. Within the service sector, Knowledge-Intensive Service firms compete by the skills and knowledge of their employees to deliver online business services. However, current service systems for Knowledge-Intensive Service firms are either too static to describe the dynamic mechanism, or too visionary to use in real world applications, which makes activities such as designing, developing, and evolving adaptive service applications unpractical. In this paper, we present a generic service system architecture describing service characteristics with descriptors such as customer-centric, knowledge-driven, reusability, safeguards, interoperability, and Internet delivery channels. Finally, we propose an implementation framework to achieve secure and adaptive service delivery and a service life cycle describing the service production process.