messageProtocol node(D) 2..* network(D) reqOn Logical abstractProtocol node(C) Protocol messageProtocol Protocol element(D) 2..* network(D) *) Depends on the type of integrator that is used reqOn Service reqOn isArequirementOn element Fig. 2.55 Concepts in the D-dimension. Integration levels 2 and 3 The diagram reflects the principle substructuring by message discrimination, which causes the three levels of logical entities in the D-dimension. A protocol on the protocol element level is either abstract (event oriented) or message oriented. It depends on whether the integrator (see Fig. 2.49) on which the protocol element relies takes care of message handling or not. Protocols between logical nodes inte- grate protocols between protocol elements, and protocols between node network functions integrate protocols between logical nodes. These protocols are always message oriented. The concepts logical connection, association and physical media connection relate C-dimension and D-dimension concepts, see Fig. 2.56. Integrator 1.. V provides Association(D) 2. * AssociationEndpoint Logical connection(D) ConnectionEndpoint 1..* A Service element Physical 2.. V provides media Physical media Physical media connection connection (D) endpoint(C) network function(C) Fig. 2.56 Concepts in the DC-plane. Integration levels 2 and 4 The diagram in Fig. 2.57 shows relevant concepts and relations in the P-dimen- sion of functional space. 2 Foundations of Sysnet Modelling Node network reqOn Network Platform provides function(C) application service platform(P) interface Logical reqOn node(C) Service Application element Integrator(C) Fig. 2.57 Concepts in the P-dimension. Integration levels 2 and 3 The final diagram in Fig. 2.58 shows concepts that are viewed in all three dimensions simultaneously. isSubstrOf networkInterface Physical Physical node network Node network function platform Fig. 2.58 Concepts on integration level 4, physical network Implementation Independent Models In Sect. 1.3 we identified sysnets (standardized and applie