Modeling the Architecture of Distributed Real-Time Systems Dominikus Herzberg André Marburger Ericsson Eurolab Deutschland GmbH Aachen University of Technology 52134 Herzogenrath, Germany 52074 Aachen, Germany OMER-2, Herrsching am Ammersee, Germany, May 10-12, 2001 Modeling the Architecture of Distributed RT Systems Dominikus Herzberg, Slide 1 OMER-2, Herrsching, Germany, May 10-12, 2001 Ericsson Eurolab Deutschland GmbH, Germany
System Architecture Modeling of Telecom Systems � ROOM/UML-RT � OSI Reference Model (1) Layers are a key concept for abstracting distributed peer ◆ SAP communication relations � CEP ◆ CEP (2) SAPs subsume layers (3) SAPs are more powerful than strict layering is (4) SAPs ≠ Ports � ISDN/GSM Reference Model (5) Planes are a key concept for separating concerns ◆ Typed SAP (6) Typed SAPs subsume planes (7) Typed SAPs are more expressive than planes are (8) Typed SAPs “>” SAPs � Conclusions Modeling the Architecture of Distributed RT Systems Dominikus Herzberg, Slide 2 OMER-2, Herrsching, Germany, May 10-12, 2001 Ericsson Eurolab Deutschland GmbH, Germany
A Quick Primer on ROOM / UML-RT Port Connector Capsule Protocol Note: Note: Protocol ≠ Protocol Protocol ≠ Protocol Modeling the Architecture of Distributed RT Systems Dominikus Herzberg, Slide 3 OMER-2, Herrsching, Germany, May 10-12, 2001 Ericsson Eurolab Deutschland GmbH, Germany
TISO2920-94/d10 Modeling the Architecture of Distributed RT Systems Dominikus Herzberg, Slide 4 OMER-2, Herrsching, Germany, May 10-12, 2001 Ericsson Eurolab Deutschland GmbH, Germany
Service Access Modeling according to OSI RM Service User PDU Service User [Identifier] [Identifier] exchange uses SAP services [SAPI, QoS] CEP [CEPI] SDU SDU exchange exchange Connection provides services Service Provider PDU Service Provider exchange CEP Connection Endpoint SDU Service Data Unit CEPI CEP Identifier PDU Protocol Data Unit SAP Service Access Point QoS Quality of Service SAPI SAP Identifier Modeling the Architecture of Distributed RT Systems Dominikus Herzberg, Slide 5 OMER-2, Herrsching, Germany, May 10-12, 2001 Ericsson Eurolab Deutschland GmbH, Germany
Interfaces of a Communication Layer Entity inter-layer service provider intra-node peer-to-peer inter-node peer-to-peer SAP n reliable, indestructible n unreliable, breakable n QoS is not an issue n virtual connection Port CEP n partner’s location is known n partner’s address is known (not location) n direct communication SAP -1 print() send(from,to, print() ) inter-layer service user CEP Connection Endpoint SAP Service Access Point Modeling the Architecture of Distributed RT Systems Dominikus Herzberg, Slide 6 OMER-2, Herrsching, Germany, May 10-12, 2001 Ericsson Eurolab Deutschland GmbH, Germany
OSI RM revisited [1/2] Layer (N+1) SDU N QoS N , ToS N SAPI PDU N (SDU N ) Layer (N) QoS’ N-1 ToS’ N-1 CEPI SDU N-1 (PDU N ) QoS N-1 , ToS N-1 service provisioning infrastructure Layer (N-1) = SAP -1 = SAP = CEP Modeling the Architecture of Distributed RT Systems Dominikus Herzberg, Slide 7 OMER-2, Herrsching, Germany, May 10-12, 2001 Ericsson Eurolab Deutschland GmbH, Germany
OSI RM revisited [2/2] Layer (N+1) SDU N SDU N SAPI PDU N (SDU N ) Layer (N) CEPI SDU N-1 (PDU N ) SDU N-1 (PDU N ) PDU N-1 (PDU N ) Layer (N-1) = SAP -1 = SAP = CEP Modeling the Architecture of Distributed RT Systems Dominikus Herzberg, Slide 8 OMER-2, Herrsching, Germany, May 10-12, 2001 Ericsson Eurolab Deutschland GmbH, Germany
Pattern: Integrating CEPs as Concrete Elements Modeling the Architecture of Distributed RT Systems Dominikus Herzberg, Slide 9 OMER-2, Herrsching, Germany, May 10-12, 2001 Ericsson Eurolab Deutschland GmbH, Germany
Service Access Modeling according to ROOM (Selic et al.) upper layers n SAP/SPP concept is confusing n Insufficient semantic preciseness ◆ How do ports differ from SAPs? peers Capsule/ (layer bridges) Actor n Lack of proper notation n ROOM is strict on layering lower layers n SAPI, QoS, ToS? SAP (protocol P) Layer3 Layer (N) Co- Layer2 ordinator Layer (N-1) Layer1 SPP (protocol P*) Modeling the Architecture of Distributed RT Systems Dominikus Herzberg, Slide 10 OMER-2, Herrsching, Germany, May 10-12, 2001 Ericsson Eurolab Deutschland GmbH, Germany
The ISDN/GSM Reference Model: Layers and Planes Planes decompose services n User Plane and separate concerns transparent transfer of information among user applications; additionally, any information which controls the exchange of data within a connection [I.320] n Control Plane transfer of information for the control of user plane connections, e.g. establishment of a connection, controlling an already established connection, providing supplementary services, resource allocation/deallocation [I.320] Typical informal description of the architecture n Management Plane Modeling the Architecture of Distributed RT Systems Dominikus Herzberg, Slide 11 OMER-2, Herrsching, Germany, May 10-12, 2001 Ericsson Eurolab Deutschland GmbH, Germany
Service Access Modeling according to ISDN Protocol RM n SCF (Synchronization and Coordination Function) performs (N+1) Layer the C- and U-plane synchronization N-Primitives N-Service ISDN Network Service user according to X.213 n SCF does not handle PDUs N-Service provider n SCF is a component of the plane management function Synchronization and coordination function N(c)-Primitives N(u)-Primitives N(c)-Service C-plane U-plane N(u)-Service user sub-N- sub-N- user n The general principle of N(c)-Service N(u)-Service provider provider accessing services according to OSI remains valid C-plane U-plane sub-N-layer sub-N-layer T1302850-94/d05 n The general concept of SAPs according to OSI remains valid FIGURE 5/.320 n but planes have to be Relationship of the Network Service to the service provided represented by different kinds of by C-plane sub-N-layer and U-plane sub-N-layer SAPs Modeling the Architecture of Distributed RT Systems Dominikus Herzberg, Slide 12 OMER-2, Herrsching, Germany, May 10-12, 2001 Ericsson Eurolab Deutschland GmbH, Germany
Architecture Model based on ISDN M M M M M C U C U M M C U C U M M C U Modeling the Architecture of Distributed RT Systems Dominikus Herzberg, Slide 13 OMER-2, Herrsching, Germany, May 10-12, 2001 Ericsson Eurolab Deutschland GmbH, Germany
Architecture Model based on the MCS Framework MCS Modular Communication Systems (S. Boecking) M M C U M C U M C U M C U M C U Modeling the Architecture of Distributed RT Systems Dominikus Herzberg, Slide 14 OMER-2, Herrsching, Germany, May 10-12, 2001 Ericsson Eurolab Deutschland GmbH, Germany
Architecture Model: CEPs, SAPs, and Ports M C M U M C U P C P U M C U Modeling the Architecture of Distributed RT Systems Dominikus Herzberg, Slide 15 OMER-2, Herrsching, Germany, May 10-12, 2001 Ericsson Eurolab Deutschland GmbH, Germany
Summary & Conclusions Formalization � The SAP concept is a standard concept in telecommunications ◆ CEP & SAP � Layers (abstraction) ◆ Typed SAP � Planes (separation of concerns) Introduction � ROOM is an excellent candidate for modeling architectures ◆ SAP ≈ Port, but SAP ≠ Port ◆ minor language extensions required (semantics, notation) Use � Precise and expressive architecture descriptions ◆ replaces informal diagrams ◆ basis for architectural patterns Modeling the Architecture of Distributed RT Systems Dominikus Herzberg, Slide 16 OMER-2, Herrsching, Germany, May 10-12, 2001 Ericsson Eurolab Deutschland GmbH, Germany
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