gh level view (see Figure 21.4): Framework services: These services support distribution and transparency. Mandatory services: These services support decision, sequencing, and security. Business services: These are general services provided by the NGOSS solution. The high level view is supported by a number of artifacts that make up technology- neutral architecture. TNA artifacts are either core artifacts or container artifacts. Core artifacts are the basic units of composition in the architecture and container artifacts are the artifacts that encapsulate or package core artifacts. The TNA is built on a set of concepts. Some of them are: NGOSS component: An NGOSS component is defined as a software entity that has the following characteristics: - It is independently deployable. It is built conforming to the specifications of component software model. - It uses contracts to expose its functionality. NGOSS contract: The interoperability of the NGOSS architecture is defined using NGOSS contracts. TNA provides the specification of NGOSS contract operations and behavior. It exposes functionality contained in an NGOSS component. NGOSS framework services Common communications vehicle Business services Other mandatory NGOSS services Figure 21.4 High level view of TNA. NGOSS NGOSS contract implementation: This is a technology-specific realization of the NGOSS contract. The implementation is based on requirements and specifications provided by the NGOSS business and system view. NGOSS contract instance: This is a runtime manifestation of a contract implementation that is manageable. It provides one or more functions to other runtime entities and represents the unit of binding. NGOSS announcement: This is an invocation initiated by a client compo- nent instance. The innovation will result in the conveyance of information from the client component instance to the server component instance. It can be a request to the server component instance to perform a function on its instance. NGOSS announcement signature: This defines the