te machine of its provider interface with the state machines of all provider interfaces of the objects on which it depends. The behavior of AMs is con- structed in a similar way. The details of this specification technique are given in Chaps. 6 and 7 in Muth (2001). D3 Applying AMLs in AMLn Models The behavior of an AMLn model is completely confined to its layer structure. The only interface type in such a model that cannot be specified by AMLs are net- work interfaces and message protocols (see AMLp in the next section). Thus, AMLs can be used for describing operations, interfaces and behaviors of: All kinds of layer interfaces (i.e., service points and control points). Interfaces between the ESMs of an LSM (control layers only). These interfaces are abstract protocols, since they are mapped on a message protocol by the LSM-LPM separation. Since an ESM is an abstract machine and an LSM is an abstract machine system, the whole range of behavior description techniques of AMLs can be used to describe the behavior of ESMs and LSMs. SAGs and SACs (generic primitives for these interfaces are defined as parts of AMLn). Abstract objects and object structure specifications may be used wherever an LSM, a layer interface, a SAG or a SAC acts in an object-oriented fashion. Typical examples, that have been discussed in this book are management layers. The model below shows the LSM that we defined for TMN and relies on abstract objects called managed objects (MO). NW-MO Management method Management method Management method Compiled model D4 AMLp Message communication is very different to communication based on ASPs. ASPs are strictly functional-oriented, which implies that confirmation of an opera- tion request must be defined as a separate ASP, for example. The message protocol that realizes this communication does not necessarily define a separate response message type (could be just a piggy-back bit of another message). Messages are optimized for requiring minimum bandwidth, processing capacity, and response time, which im