SummerSim 2009 PowerPoint

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Towards an automatic transformation from a DEVS to a SDL specification
Pau Fonseca i Casas SCSC 2009
Index
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   
SDL
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XML representation XML representation
DEVS
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Algorithm Example Concluding remarks
SDL – DEVS – Algorithm – Example – Concluding remarks
SDL

Specification and Description Language (SDL) is an object-oriented, formal language defined by the International Telecommunication Union – Telecommunication Standardization Sector (ITU–T) (formerly Comité Consultatif International Télégraphique et Téléphonique [CCITT]) as Recommendation Z.100.
SDL – DEVS – Algorithm – Example – Concluding remarks
SDL XML Schema
SDL – DEVS – Algorithm – Example – Concluding remarks
XML Schema process view
SDL – DEVS – Algorithm – Example – Concluding remarks
Textual SDL
        
process P; start; nextstate idle; state idle; input s; output t; nextstate idle; endstate idle; endprocess P;
process
P idle 1(1) s
idle
t idle
SDL – DEVS – Algorithm – Example – Concluding remarks
DEVS model


M=<X, S,Y, δint, δext, λ, ta> where:
      

   
X, set of input values S, set of state values Y, set of output values δint, internal transition function δint: S  S δext, external transition function δext Q x X  S, where Q={(s,e)|sS, 0≤e≤ta(s)}, set of states e, time from the last transition λ: S Y, output function ta, time advance function ta: S R+0
SDL – DEVS – Algorithm – Example – Concluding remarks
Coupled models
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C ={X Y D EIC EOC IC select} where
    

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Xself is the set of external input events, Yself is the set of output events, D is a set of DEVS component models, EIC is the external input coupling relation, EOC is the external output coupling relation, IC is the internal coupling relation, select is a function, the tie-breaking selector.
SDL – DEVS – Algorithm – Example – Concluding remarks
Coupled models
SDL – DEVS – Algorithm – Example – Concluding remarks
XML Schema for atomic DEVS model
SDL – DEVS – Algorithm – Example – Concluding remarks
Algorithm

   
    
Draw the state diagram (based on the number of states in the finite case and the states defined by the transitions in the infinite case). Draw the external transitions in the SDL diagram. If needed, add a parameter to represent the inputs. Represent the variables modified in a procedure block. If the final state for the external transition is a state with an internal transition defined, an output event with the internal event must be represented. Draw the internal transitions. Represent the ta in a procedure block Represent the output function in a procedure block. Represent the variables modified in a procedure block. Send the internal event with the calculated ta like a parameter (simplify if ta=∞).
SDL – DEVS – Algorithm – Example – Concluding remarks
SDL – DEVS – Algorithm – Example – Concluding remarks
Generator example

DEVSperiod=(X,Y,S,δext,δint,λ,ta)
     
X={} Y={1} S={“passive”, ”active}xR+ δint=(phase, σ)=(“active”, period) λ=(“active”, σ)=1 ta=(phase, σ)= σ
SDL – DEVS – Algorithm – Example – Concluding remarks
Generator example states
INT passive active
INT
SDL – DEVS – Algorithm – Example – Concluding remarks
SDL representation of the example
SDL – DEVS – Algorithm – Example – Concluding remarks
Concluding remarks


A representation for SDL language in XML is shown, a XSD to validate the XML representing the SDL model is implemented. An algorithm that allows the transformation of DEVS formalisms to SDL is shown.
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We had shown the transformation of two well known DEVS examples to an SDL language, showing how this methodology can be applied. We had shown an example of a first approximation of an implementation of this algorithm, with the help of a XML commercial tool.

The concept of legitimacy has been described in SDL.
SDL – DEVS – Algorithm – Example – Concluding remarks
Concluding remarks

Since we can transform a DEVS model to an SDL model, we can use SDL as a graphical representation for the DEVS models,

We can construct simulation models with the combination of the best features of these two formalisms allowing the definition of a simulation models using the DEVS rules and the graphical power of SDL.
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The future work is focused in the development of a plugin that allows the complete loading of a DEVS model in SDLPS simulator without the need of any external tool
SDL – DEVS – Algorithm – Example – Concluding remarks
Tanks
Pau Fonseca i Casas pau@fib.upc.edu http://www-eio.upc.es/~pau
Technical University of Catalonia Barcelona School of Informatics Computing laboratory Barcelona Jordi Girona 1-3 (+34)93401773