Editing/Creating FDDEVS model Couplings using System Entity Structures

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1 Editing/Creating FDDEVS model Couplings using System Entity Structures This step by step guide will help you to understand - how to use an advanced feature of FDDEVS involving System Entity Structures to modify/create model coupling Note : Before you read this guide, you need to have followed and updated FDDEVS Software following the Guide to updating FDDEVS software to latest versions to enable the features discussed The topics we will visit in this Guide 1) A Brief Note on System Entity Structure (SES) 2) Step1: Creating Atomic and Coupled Models revisited 3) Step 2: Modify Couplings using System Entity Structures 4) Step 3: Modified model renaming with SES 1

2 1) A Brief note on System Entity Structure (SES) System Entity Structure o is a knowledge representation framework for supporting the compositions of hierarchical and modular structures o Please see pg 18 for reference material SESs allows o large/complex systems to be defined using smaller and simpler ones in a structured/organized manner. Since SES originated from the representation of simulation model structure o it is easily accommodated in modeling and simulation for automation o as you will see in future tutorials FDDEVS framework has the capability to use SES descriptions defined in a natural language to specify model couplings. Basic structural composition of a SES involve o Entity o Variable o Aspect : could be anything that exist in the real world or maybe in imagined world. Ex: Tennis Match, Book, Car, House, a Dragon! etc : are an attribute of an Entity Ex : Name of Player : represent ways of decomposing things into even smaller ones. Ex : Tennis Match can be decomposed into Player A, Player B, Umpire etc. o Specialization : represent categories or families of specific forms that a thing can assume. Ex : Tennis Match can be Singles match or Doubles. Tennisball can be Green or yellow color. o Multi Aspect : are aspects for which the components are all of the same kind. Ex : Tennisballs 2

3 Figure1 depicts the basic structural composition of an SES Figure 1: Basic structural composition of an SES 3

4 Using SES concepts, Figure 2 is the structural representation of a Tennis Game. Please refer to Appendix B for further information SES and PES structures. 4

5 Step 1 : Creating Atomic and Coupled Models revisited Recall the below diagram for Tennis PlayerA? 1. As a refresher, can you fill in the blanks for the FDDEVS natural language description below of PlayerA? in play for time 0.5! play ShotA! from play go to! hold in for time Infinity! when in ShotB go to! 2. As we will be experimenting with a new FDDEVS concepts in this tutorial let us create a new folder named TennisExp and set the work path to it if you forgot how to you can refer to Appendix A save the text as PlayerA.txt using the FDDEVS Builder GUI 3. Generate PlayerA DEVS java model 3.1. using the Builder GUI view the PlayerA.java using SimView Make sure your model is behaving correctly as it should. \ o If not, you can cheat a bit this time and refer the prior tutorials for correct natural language description. 5

6 4. Now can you fill in the blanks for PlayerB natural language description below? to start passivate in wait! when in and go to! for time 0.5! ShotB! from play go to! 5. Save the text as PlayerB.txt As before Generate DEVS java model and experiment through SimView for functionality. 6. Next make a Coupled Model named GameBetweenAandB with the 2 Tennis Players created above. To do so ( as recap), on FDDEVS Builder GUI Natural Language tab a) Click Open and type GameBetweenAandBSeS.txt b) Create Coupled Button c) In opened selection box choose PlayerA.xml and PlayerB.xml d) In Eclipse IDE view GamesBetweenAandBSeS.java and (repeat until code is full) e) View GamesBetweenAandBSeS.java in SimView. Observe the correct coupling and behavior of shot exchanges 6

7 Step 2 : Modify Couplings using System Entity Structures Before you proceed make sure you have Updated your FDDEVS software to the Latest Version with new features. i) Execute FDDEVS and notice that there are 2 new Tabs 1) SES 2) SES with Prune ii) Click on the SES Tab to start with 7

8 iii) ( In SES Tab) Open GameBetweenAandBSeS.txt Contents: From the struct perspective, GameBetweenAandB is made of PlayerA, and PlayerB! From the struct perspective, GameBetweenAandB sends ShotB to PlayerA! From the struct perspective, GameBetweenAandB sends ShotA to PlayerB! From the struct perspective, PlayerA sends ShotA to GameBetweenAandB! From the struct perspective, PlayerB sends ShotB to GameBetweenAandB! From the struct perspective, PlayerA sends ShotA to PlayerB! From the struct perspective, PlayerB sends ShotB to PlayerA! Note : The above natural language SES description was automatically created and used when the coupled model GameBetweenAandB was generated. 8

9 Though the descriptions are generally intuitive it is good to note in From the struct perspective, GameBetweenAandB is made of PlayerA, and PlayerB! o GameBetweenAandB, PlayerA and PlayerB are all Entities. o The Top Entity ( Parent) of the SES is GameBetweenAandB, and it is decomposed in to two parts namely PlayerA and PlayerB iv) Modify the SES description to experiment, For example o delete the sentence From the struct perspective, PlayerA sends ShotA to PlayerB! v) Click ShowParse button to 1) check for syntax errors ( there should be none in this case) 2) visualize the SES Tree as below 9

10 vi) Click Transform to generate a modified DEVS Java version of the Coupled Model. Make sure in Eclipse IDE, GamesBetweenAandB.java code is updated. vii) View the newly generated GameBetweenAandB.java o using Sim View Did you notice any difference related to overall model behavior and couplings? 10

11 Step 3: Modified model renaming with SES Since the model behavior is changed now o GameBetweenAandB will not be an appropriate descriptive name. 1) To give an appropriate name and save Click RenameTopEntity button 2) An Input Box will pop up where you can type a new name 11

12 The new name ModifiedGame will used as an example. Click OK note ModifiedGame is not a good descriptive name for the above model behavior but will be used only an example for discussion the relatively simple task of observing the modified model behavior and giving it an appropriate name is left as task to the student. 12

13 3) Notice that once you click OK a) the revised version will be saved as ModifiedGameSeS.txt b) the revised content will be updated on text area as below Modified Contents: From the struct perspective, ModifiedGame is made of PlayerA, and PlayerB! From the struct perspective, ModifiedGame sends ShotB to PlayerA! From the struct perspective, ModifiedGame sends ShotA to PlayerB! From the struct perspective, PlayerA sends ShotA to ModifiedGame! From the struct perspective, PlayerB sends ShotB to ModifiedGame! From the struct perspective, PlayerB sends ShotB to PlayerA! The old name GameBetweenAandB is revised with the new name ModifiedGame which is also now the Top Entity. 13

14 Question : Answer : Could we not have done a simple Save As to change the model name? Though it is possible to do a Save As, all instances of the old name appearing in the SES description ( ie GameBetweenAandB) needs to be replaced with the new name ( ie ModifiedGame) before you do the save. Also the name under which the model is saved needs to match the top entity name in the SES. Else the model generation will run into irregularities. RenameTopEntity process will handle these issues automatically. 4) With ModifiedGame is updated in SES tab text area Click Transform button to generate the new version with the new name. 14

15 EXERCISE Please follow the exercise titled An Exercise FDDEVS with SES on FDDEVS website. 15

16 APPENDIX Creating a new work folder Steps to follow i) On ECLIPSE IDE a. under FDDEVS project, b. Select src then New and Folder c. Give name TennisExp Images below show screen captures of the process.. 16

17 ii) On FDDEVS Builder Workspace a. Goto File, and next Create Folder b. Browse to TennisExp Folder and select it c. Type path for File Name ( recall we followed the same procedure in the guide Intro to FDDEVS Builder Working Environment ) d. Click Open 17

18 APPENDIX B Acknowledgment Material mentioned herewith is an excerpt from Prof B Zeigler DEVS Primer which would give the reader a short and effective introduction to SESs. If you need to learn in detail about SESs please refer to 1. Theory of Modeling and Simulation, B.P Zeigler, T.G Kim et al, Academic Press NY, Zeigler/dp/ /ref=sr_1_1?ie=UTF8&s=books&qid= &sr = Modeling and Simulation-Based Data Engineering: Introducing Pragmatics into Ontologies for Net-Centric Information Exchange,B.P Zeigler and Phillip Hammond, Academic Press, Introducing/dp/ /ref=sr_1_1?s=books&ie=UTF8&qid= &sr=1-1 18

System Entity Structures The System Entity Structure (SES) is a high level ontology framework targeted to modeling, simulation, systems design and engineering.

19 System Entity Structures The System Entity Structure (SES) is a high level ontology framework targeted to modeling, simulation, systems design and engineering. Its expressive power, both in strength and limitation, derive from that domain of discourse. An SES is a formal structure governed by a small number of axioms that provide clarity and rigor to its models. The structure supports hierarchical and modular compositions allowing large complex structures to be built in stepwise fashion from smaller, simpler ones. Tools have been developed to transform SESs back and forth to XML allowing many operations to be specified in either SES directly or in its XML guise. The axioms and functionally based semantics of the SES promote pragmatic design and are easily understandable by data modelers. Ontology is a knowledge representation concerned with describing things and their relationships. An ontology contains classes (elements), attributes of the classes, and relationships between classes with which to represent or model knowledge of a certain domain. The System Entity Structure (SES) is a formal ontology framework, axiomatically defined, to represent the elements of a system (or world) and their relationships in hierarchical manner. It provides a model to describe knowledge of a domain in a structural way. Since it is originated from the representation of simulation model structure, SES is easily accommodated in modeling and simulation for automation. While SES represents complex data in a rigorous way, it has flexibility and efficiency to change the structure according to a variety of choices. Figure 1 shows the basic representation elements of the SES. Figure 1.Basic SES representation SES consists of entities, (multi-)aspects, specialization, and variables. Entities represent things that have existence in a certain domain. Entities can have variables which can be assigned a value within given range and types Aspects represent ways of taking things apart into more detailed ones and labeled decomposition relation between the parent and the children. 19

20 Multi-aspects are aspects for which the components are all of the same kind. Specialization categorizes things in specific forms that it can assume. It is a labeled relation that expresses alternative choices that a system entity can take on. Entities can have variables, which can be assigned a value within given range. For example, a book can be represented in SES structure in Figure 2. Figure 2.Representation of a book in SES A book consists of front cover, back cover, and pages, which show the physical decomposition relation between book and covers. The front cover of a book can be made of either cardboard or paper. The cardboard is also manufactured in red or blue. Pages contain multiple entities of the same characteristics. Pages has a variable of numofpage whose values take on integer values. Decomposition of event sets provides an example of the use of SES in time segment XML descriptions. The SES operations causing structural change to extract specific information are: pruning, restructuring, and transforming. Pruning is an operation to cut off unnecessary structure in a SES based on the specification of a pragmatic frame. More specifically, it includes processes: a) to assign particular values to variables of entities, b) to trim the SES and get the minimal SES for end-users by picking specific elements from multiple choices. Restructuring is a mapping process within the same domain, and may result in the alternative structures. Transforming is also a mapping process, but from one domain to another domain. For example, a pruned SES is transformed into a simulatable DEVS model. An important computational representation of the System Entity Structure uses the extended markup language (XML). With the availability of appropriate tool support, this makes development of XML Schema transparent to the modeler. Finally, SES structures are compact relative to equivalent Schema and automatically generate associated executable simulation 20

21 models. Natural Language Representation The basic idea is as follows. The entity is considered as a collection of various message streams. It has been observed in complex systems that an entity node can act as receiver and sender simultaneously. It is logical to consider that a node may be processing more than one messages at a given instant. Consequently, developing a framework where the entity node model can operate with multiple message streams is the objective of this type of requirement specifications. The rules that provide a binding to this type of requirement specifications are provided in Table 1. The designer can specify each node s behavior as a sender and a receiver with respect to any specific message type. 21

22 Rules: 1 Copula "is" and "are" are treated the same. 2 Compounds x and y; x, y, and z; NOTE: the commas are mandatory for 3 or more constituents x, y, z, and w; x or y; x, y, or z; x, y, z, or w; 3 Determiners a, the, are removed from the input before processing 4 End of Sentence use! instead of. 5 Sentence Order 6 Forms 7 Specialization 8 Aspect 9 MultiAspect 10 Attached Variables 11 Range specifications of variables The entity mentioned first in the first sentence becomes the root of the SES. A variable must be attached to an entity before giving it a range specification (see below). Otherwise sentences can be in any order. In the following, CAPITALs indicate variables, lower case indicate mandatory key words in the order shown. THING can be VARIANT1, VARIANT2, or VARIANT3 in CLASSFAMILY! From VIEW perspective, THING is made of COMPONENT1, COMPONENT2, and COMPONENT3! From multiple perspective, THINGS are made of more than one THING! THING has VAR1, VAR2, and VAR3! The range of THING's VAR1 is RANGE! 22

23 Prepared by Lahiru Ariyananda ACIMS, University of Arizona. 23

INTRODUCTION TO FDDEVS BUILDER ENVIRONMENT WITH EXAMPLE ATOMIC MODEL GENERATION AND VISUALIZATION. Lahiru Ariyananda ACIMS UNIVERSITY OF ARIZONA

INTRODUCTION TO FDDEVS BUILDER ENVIRONMENT WITH EXAMPLE ATOMIC MODEL GENERATION AND VISUALIZATION Lahiru Ariyananda ACIMS UNIVERSITY OF ARIZONA Outline This presentation will help you to setup a working