[[abstract]]This paper presents a CASE tool for the specification, design, implementation, testing and maintenance of multimedia presentations. The proposed system is based on a Petri net machine to control event-based resource synchronization. Data flow diagrams and control flow diagrams are used as the specification of a multimedia presentation. The system then allows the specification to be stepwise refined toward the final multimedia presentation[[conferencetype]]國際[[conferencedate]]19980628~19980701[[booktype]]紙

施國琛

This paper presents a CASE tool for the specification, design, implementation, testing and maintenance of multimedia presentations. The proposed system is based on a Petri net machine to control event-based resource synchronization. Data flow diagrams and control flow diagrams are used as the specification of a multimedia presentation. The system then allows the specification to be stepwise refined toward the final multimedia presentation國際19980628~19980701紙

Tamkang University Institutional Repository

A CASE Tool Supports the Software Life Cycle ofParticipator Dependent Multimedia PresentationsTimothy K. Shih, Yih-Jia Tsai, Jason C. Hung, and Ding-Rong JiangDepartment of Computer Science and Information EngineeringTamkang University, Tamsui, Taiwan, R.O.C.email: TSHIH@CS.TKU.EDU.TWfax: Intl. (02) 620 9749AbstractThis paper presents a CASE tool for the specification,design, implementation, testing, and maintenance of mul-timedia presentations. The proposed system is based on aPetri net machine to control event-based resource synchro-nization. Data flow diagrams and control flow diagrams areused as the specification of a multimedia presentation. Thesystem then allows the specification to be stepwise refinedtoward the final multimedia presentation.1. IntroductionStructured analysis and design have been used in softwaredevelopment. The methodology can be used in multimediapresentation designs. The development of a multimedia pre-sentation involves the analysis of a presentation script, thecollection of multimedia resources, and the realization ofa presentation layout and navigation control flow. In linewith the growing needs of multimedia presentations, manyauthoring systems were developed. However, in the com-munity of multimedia computing, there is no discussion ofthe need of a good presentation development methodology.We have surveyed a number of presentation design tools.We found that, not many authoring system focus on theconcept of stepwise refinement. Moreover, multimedia pre-sentation development life cycle and paradigm were hardlyfind in the literature of multimedia computing. We believethat, the development of a multimedia presentation is sim-ilar to software development. Using Water Fall paradigm,the presentation developer will benefit from experiences andtechniques of the structured analysis research of SoftwareEngineering. However, designing a presentation is similarto but different from writing a software. We give a summaryof presentation development life cycle, which is assisted byour paradigm and tool: Analysis: Presentation Requirements Analysis Specification: Presentation DFD/CFD Design: Interactive Multimedia Petri Net Implementation: Presentation Generation Testing: Presentation Testing Maintenance: Presentation DocumentationThis paper is organized as the following. We present thelife cycle of multimedia presentations in section 2. The anal-ysis of presentation requirements is discussed in section 2.1.Presentation specification and the proposed multimedia dataflow/control flow diagram is discussed in section 2.2. Aninteractive Petri net program serves as the presentation de-sign assistant tool is proposed in section 2.3. Section 2.4,as an extension to the interactive Petri net, proposes a newdirection of multimedia presentation designs. Multimediapresentation implementation, testing, and maintenance arediscussed in section 2.5 and section 2.6. A short conclusionsummarizes our contributions is also presented in section 3.2. Presentation Life CycleAs mentioned in the introduction section, the develop-ment life cycle of multimedia presentations consists of sev-eral phases. In this section, we discuss these phases indetail.2.1. Analysis of Presentation RequirementsIn a typical software development cycle, the first step is toconduct an analysis of the problem and the requirement. Ifthe problem is suitable and worth it to be solved by softwareprograms, the system analyzer starts to prepare for a sys-tem specification of the software. In the development of amultimedia presentation, the main theme of the presentationhas to be decided first. The analysis of presentation require-ments is the most important factor achieving the successof a multimedia presentation. How to attract the audienceand demonstrate the main theme of a presentation throughtext, sound, and graphic illustrations are the purposes ofpresentation analysis.Authorized licensed use limited to: Tamkang University. Downloaded on March 24,2010 at 02:44:48 EDT from IEEE Xplore.  Restrictions apply. 2.2. Presentation SpecicationWe propose a revised DFD/CFD mechanism for produc-ing multimedia presentation specifications. The design ofa multimedia presentation, utilizing message passing fornavigation, has a similar concept to writing a software spec-ification. The proposed multimedia data flow/control flowdiagram is based on DFD and CFD, with the extension ofsome new objects: Multimedia Resource: similar to the data store in a DFD,a multimedia resource is denoted by a pair of thick parallellines. State Variable: besides resources, an interactive presen-tation may contain state variables store presentation data,such as the audience’s name. A state variable is representedby a pair of thin parallel lines. State variables not only keepinformation, but also control dynamic presentations (to bediscussed in section 2.4). Resource Data: similar to the data link in a DFD, resourcesare passed to a presentation program by a link with a regulararrow. Navigation Message (NM): similar to the control link ina CFD, a navigation message is passed by a link with alight-weighted arrow. Dynamic Mutation: to support dynamic multimedia pre-sentations, the dynamic mutation link is introduced, whichis represented by a curved arrow. There are four types ofmutations in a multimedia DFD/CFD: state variable change,layout change, resource change, and navigation change. External Entity (EE): similar to one in DFD/CFD, an ex-ternal entity could represent a user, a hardware device, oranother system which pass data/controls to the multimediapresentation. An EE is denoted by a box surrounded bythick lines. Presentation Window (PWin): similar to a process in aDFD, a presentation window is denoted by a circle.2.3. Presentation DesignA presentation window must be refined. Stepwise refine-ment of a presentation allows the presentation to be specifiedin different levels of details. A multimedia DFD/CFD ofmultiple levels is to help a presentation designer to organizethe script structure of a presentation. However, it is not pow-erful enough to define the precise schedule or layout of thatpresentation. Incorporated with an interactive multimediaPetri net diagramming mechanism, the last level of a pre-sentation window is refined to a Petri net, which describesthe temporal behavior of a presentation window.The spatial organization of the presentation is specifiedby using the graphical user interface of our system. Ourinteractive multimedia Petri net is a variation of timed Petrinet, with the addition of User Transitions and Sync Arc.Since a multimedia presentation is interactive, it is necessaryfor us to introduce the above two objects for participantdependent synchronization.A timed Petri net is a bipartite graph with two types ofnodes: the transition nodes and the place nodes. A transi-tion controls synchronization and a place holds a token anda time duration. A transition is fired only after each placeadjacent to the transition releases the token. A place holdsa multimedia resource to be played for the time duration.Transitions and places are connected by sync arcs in ourrevised Petri net. We add user transitions and user arcs tothe timed Petri net. A user transition receives a navigationmessage from the user before it is fired. A user transition isdirectly connected to some transitions. The activation of theuser transition interrupts the demonstration of the presen-tation window and causes the activations of the connectedtransitions simultaneously.The followings are components of the Petri nets: Transition: is for synchronization control. Transitions areshown as vertical dark bars. User Transition: accepts a message and causes the activa-tion of connected transitions. User transitions are shown asvertical light bars. Place: is for playing a multimedia resource. Places areshown as ellipses. User Arc: connects from a user transition to a transition.User arcs are shown as curved arrowheaded arcs. Sync Arc: connects from a place to a transition, or froma transition to a place. Sync arcs are shown as straightarrowheaded lines.In the specification of a presentation, the designer doesnot need to have all multimedia resources ready at the be-ginning. The presentation system allows dummy resources.For example, dummy text or picture resources are repre-sented as labeled boxes. Video or animation resources notonly have labeled boxes but also have animation ICONsshowing the duration of those resources. Sound or MIDIresources also have animation ICONs. The presentation de-signer can test the presentation prototype before resourcesare ready for the final version of presentation.We have discussed the global view of our diagrammingmechanism. However, a multimedia presentation in oursystem is dynamic and mutable. In the following subsection,we propose other diagramming techniques to achieve ourgoal – allowing dynamic multimedia presentation.2.4. Dynamic PresentationsUsually, when a multimedia presentation is designed,the usage of resources, the layout, and the navigation se-quences are all fixed until the presentation is re-designed2Authorized licensed use limited to: Tamkang University. Downloaded on March 24,2010 at 02:44:48 EDT from IEEE Xplore.  Restrictions apply. again. We want to improve this approach by allowing dy-namic replacement of resources, layouts, and controls. Thismakes the presentation generator have the ability of comput-ing the presentation representation at the run-time. Possi-ble dynamic events are: asserting/retracting of information,changing resources, changing layouts, and changing navi-gation controls.On the top of the revised timed Petri net, we further addthe following components: Selection: selects one of the outgoing navigation messages.A selection could be a push button, a menu item, or a keystroke of the presentation window. A selection holds aninternal representation of which outgoing navigation mes-sages will be sent upon the activation of the selection. Aselection is represented as a circle labeled with an “S” (or aname) in the Petri net diagram. Assignment: assigns a value to a state variable. An assign-ment uses a state variable. When an assignment receiveda navigation message (with a parameter holding a value),the assignment set the state variable to the value. An as-signment is denoted by a box labeled with the “Var <= Val”sign. Condition: decides whether to proceed with a change. Acondition has pairs of state variables and values. The valueis checked against the state variable. If they match eachother, the associated outgoing change is fired. A conditionis represented by a box with the “Var ?= Val” sign.The Petri nets of a presentation may contain a numberof selections. Usually, a selection is associated with only anavigation message. However, if the selection is tight to acondition, the selection may have more than one outgoingmessages. Which message to send out is decided by thecondition’s value. We allow an assignment statement tochange the value of a state variable. State variables are usedin a presentation to hold internal states. These variableswill be saved on the disk when the presentation terminates(upon the user’s decision), and will be loaded when thepresentation starts again. All state variables are global.That is, they are accessible from all Petri nets. Therefore,information sharing is feasible. A condition decides whetherto proceed with a change to the propagation of a navigationmessage. A condition may change the execution flow of aPetri net.2.5. Presentation Implementation and Test-ingAfter the user designs the schedule and layout of the pre-sentation via our Petri net tool and graphical user interface,our presentation system generates the presentation automat-ically. Unlike a typical software development, no programis written. This generation strategy is also used by mostmultimedia presentation systems available on the market.The advantage is that if the specification and design of apresentation is correct, our system guarantees the correctimplementation.It is possible to obtain the software metrics of a pre-sentation. Our system is able to calculate the metrics of apresentation based on the following criteria: number of presentation windows number and size of multimedia resources number of navigation messages number of state variables number of dynamic mutations number of selections number of assignments number of conditionsSoftware metrics of a presentation indicates the com-plexity and the amount of efforts to test the presentation.Complexity of the presentation also indicate the effort tocollect presentation resources and the size of potential diskstorage used. Presentation testing is essentially important toensure a smooth demonstration without missing resourcesand non-existing navigation sequences. It is hard to per-form a complete testing by the user due to the amount ofnavigation sequences. Fortunately, our system facilitatesautomatic testing by means of an tool. The tool traversesthe presentation based on the following testing criteria: every presentation window should be tested every multimedia resource should be tested every navigation message should be tested every selection should be tested every assignment should be tested every condition should be testedThe testing includes all Petri nets, which may acceptnavigation messages sent to transitions or user transitions.Synchronization of multimedia resources used by places aretested as well. Moreover, selections, assignments, and con-ditions are tested. Since there is no particular order that theuser navigates the presentation, the path topology of testingis arbitrary. Our testing tool traverses a graph consists ofnodes (i.e., selections, assignments, conditions, and startingtransitions/user transitions) and links (i.e., navigation mes-sages) based on a modified breadth first search (BFS) algo-rithm. Upon the activation of a presentation window, eachselection, assignments, or conditions are kept in a queue forfurther traverse. When the internal state of the presenta-tion is changed due to the change of state variables (whichmay cause navigation change, layout change, or resourcechange), some modified nodes are added to the queue usedin the BFS algorithm for re-testing. The testing tool keepsa testing log file which indicates the testing order.3Authorized licensed use limited to: Tamkang University. Downloaded on March 24,2010 at 02:44:48 EDT from IEEE Xplore.  Restrictions apply. Another feature of our system is an evaluation tool of thepresentation design status. It is very likely that a user designan incomplete or inconsistent presentation. The followingis a list of potential mistakes that a user may create in apresentation: non-used state variables non-used multimedia resources non-used assignments non-used conditions incomplete navigation messages incomplete selections incomplete assignments incomplete conditions incomplete presentation windows (i.e., if any component ofthe window is incomplete) inconsistent presentation windows (i.e., unbalanced links) undocumented presentation windowsNon-used items, such as state variables not used in anycondition, multimedia resources not linked to places, or as-signments and conditions not triggered by navigation mes-sages, are marked by the tool. Incomplete items, with oneof their properties missing, are also marked. A presenta-tion window is inconsistent if the window and its refinementhave different links (i.e., the unbalanced link problem). Aninconsistent or undocumented presentation window is alsomarked. The user is able to check the list of problematicitems before releasing the presentation.2.6. Presentation MaintenanceIt is possible that the user will release different versionsof a presentation. Therefore, presentation maintenance is animportant issue. A presentation specification in our systemcontains a number of presentation windows. Each presen-tation window has a documentation box. It is important todocument the presentation script in the box for further refer-ences. Moreover, how to keep track of different versions ofa presentation window is important. In a multimedia presen-tation database we developed [3, 2], presentation windowsas well as presentation resources are reusable objects. Eachof these objects has several versions. A presentation is acomposed object from these reusable objects. The databasesystem serves as an underlying supporting tool for severalmultimedia presentation systems that we have developed[4, 2], including the one we propose in this paper.3. ConclusionsThe preliminary experiences of using the system showthat, the proposed multimedia DFD/CFD is easy to learnsince data flow diagrams have been used by many engineersand managers for decades. The concept is adapted easily.Comments from many undergraduate students taking a mul-timedia course show that it is quite easy to use our system.Contributions in this paper are: firstly, we apply the WaterFall paradigm to presentation development and revise dataflow/control flow diagrams for the use of multimedia pre-sentations. Next, we proposed a multimedia Petri net fordynamic multimedia presentations. Finally, a system wasdeveloped on MS Windows 95/NT to justify our approach.References[1] T. K. Shih. “Multimedia Abstract Machine”. In Proceedingsof the Third Joint Conference on Information Science, 1997.[2] T. K. Shih and R. E. Davis. “IMMPS: A Multimedia Presen-tation Design System”. IEEE Multimedia, Summer, 1997.[3] T. K. Shih, C.-H. Kuo, and K.-S. An. “An Object-OrientedDatabase for Intelligent Multimedia Presentations”. In Pro-ceedings of the IEEE International Conference on System,Man, and Cybernetics Information, Intelligence and SystemsConference, 1996.[4] T. K. Shih, C.-H. Kuo, and H.-J. Lin. “Visual MultimediaPresentation Designs”. In Proceedings of the 1996 PacificWorkshop on Distributed Multimedia Systems, pages 306 –315, 1996.4Authorized licensed use limited to: Tamkang University. Downloaded on March 24,2010 at 02:44:48 EDT from IEEE Xplore.  Restrictions apply. 

A CASE tool supports the software life cycle of participator dependent multimedia presentations

Timothy K. Shih

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A CASE Tool Supports the Software Life Cycle of Participator Dependent Multimedia Presentations

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A CASE tool supports the software life cycle of participator dependent multimedia presentations

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