esource, Supplier/Partner, Enterprise and Common Business which are aligned with the eTOM framework. Within each domain there is a high degree of cohesion between the business entities, and between the domains, there is a loose coupling. Thus, it allows a segmentation of a problem into smaller manageable pieces. Since SID is quite complex and large more guidelines are required. 8.3.4.3 TNA The Technology Neutral Architecture (TNA) defines principles to guide OSS developers to create OSS components that can operate in a distributed environment. The Contract Interface defines the "API" for interfacing those components to each other across the architecture. This architecture is called "Technology Neutral" since it does not define how to implement the architecture; but rather what principles must be applied for a particular technology specific architecture, to be NGOSS compliant. The TNA supports the service oriented architecture (SOA) that allows stateless message com- munication with application services. TNA is designed to be sustainable through technological changes. Core Networks and Operations Support Systems Market / Sales Market Strategy & Plan Marketing Campaign Contact/Lead/Prospect Market Segment Competitor Sales Statistic Sales Channel Product Strategic Product Product Portfolio Plan Product Performance Product Specification Product Offering Product Usage Statistic Customer Applied Customer Customer Customer Order Customer Problem Billing Rate Customer Bill Collection Customer Interaction Customer Statistic Customer SLA Customer Bill Customer Bill Inquiry Service Service Service Applications Service Performance Service Strategy & Plan Service Specification Service Configuration Service Usage Service Trouble Service Test Resource Resource Resource Topology Resource Performance Resource Strategy & Plan Resource Specification Resource Configuration Resource Usage Resource Trouble Resource Test Supplier / Partner S/P Performance S/P Bill Supplier/Partner S/P Interaction S/P Order S/P Problem S/P Bill Inquiry 