B.P.Douglass,Real-Time UML : Developing Efficient Objects for Embedded Systems,98.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....be made smaller and tighter. Otherwise, it will become too cumbersome and multifaceted to be really useful. I think it will gradually shrink, leaving only three or four types of diagrams that are really needed and are useful. The rest will probably become obsolete and will eventually disappear [3]. What we have here is essentially a statement of the need for conceptual integrity. Use a small number of powerful descriptions that work together to help describe the software product; provide one good way to describe every construct of interest. This will prevent the documentation from ....

Douglass, B.P. Real-time UML: developing efficient objects for embedded systems (2nd edition), Addison-Wesley, Reading, MA, 1999.

....of those classes. This is the main reason that methodologies usually impose (or suggest) class diagrams to be elaborated first than object diagrams. There is an additional task in which it must be assured that there is consistency between the information that is described by both diagrams [5]. This fact can be interpreted as a symptom that some information is being unnecessarily replicated. For instance, the existence of the singleton stereotype in UML, which indicates that a given class can only have one single instance corroborates the perspective that sees the class diagram as a ....

B. Douglass. Real-Time UML: Developing Efficient Objects for Embedded Systems. Addison-Wesley, 1998.

....As the development progresses these requirements are transferred into sequence diagrams and finally on to the relevant objects. The total time required for each object to complete its tasks is checked to be less than or equal to the time associated to the use case sequence. 2 Douglass [5] has built substantially on Jacobson s approach, providing a detailed description of the issues involved in embedded system development as well as considerable discussion on how to pictorially represent the intentions of the developer with the UML notation. The crucial rigorous proof is still ....

....the collaborating objects is preserved. That is, textual analysis, domain knowledge, preliminary study or business modeling resulting in classes and relationships as usual. Interaction diagrams In most texts on the UML, the use cases are expanded upon using sequence diagrams. Douglass [5] has shown how simple temporal parameters can be expressed on sequence diagrams. Typically these are maximum allowable response times and periods for iterative messages. By extending the syntax to support interval based parameters it is possible to temporally describe every message. Those ....

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Douglass, B.P. Real time UML -- Developing Efficient Objects for Embedded Systems. Addison Wesley, 1998.

....UML adopted David Harel s statecharts [6] for the intra object behavior modeling. Statecharts is a behavioral language for the specification of real time, event driven, and reactive systems . States in a statechart are conditions of existence that persist for a significant period of time [7]. Events trigger transitions from one state to another. They may be guarded by conditions, which must evaluate to true before transitioning to the next state. Actions can occur as the result of a state transition. The statechart model can be used to support AOSD by extracting the hardwiring of ....

. Bruce Powel Douglass, "Real-Time UML: Developing efficient Objects For Embedded Systems", Addison-Wesley, 1998.

....the system while a dynamic one describes the behavioural ones. Larman s main contribution relies on proposing to define the system behaviour as a black box before proceeding to a logical design of how a software application will work. The main idea behind this solution has also been sketched in [Boo96, FS97, Mu197, Dou98, RV00]. This has a clear impact, during analysis, on the sequence diagrams definition and on the assignment of operations to classes. Sequence diagrams are considered as system sequence diagrams that show the events that external actors generate; their order and the system response to those events. On ....

B.Douglass. "Real-time UML: Developing Efficient Objects for Embedded Systems", Addison-Wesley, 1998.

....systems that enables the construction of models that could be used to make quantitative predictions regarding these characteristics . It tries to unify the various different approaches that have evolved for modeling real time application in UML. These are namely the approaches from Douglass [Dou98] that uses mainly the existing predefined UML diagrams, and the work from Selic that uses extensively the option of UML to define stereotypes (a kind of visual macros in diagrams) to impose a notation similar to ROOM (Real Time Object Oriented Modeling) Sel94] his prior modeling environment onto ....

Douglass, Bruce Powel, Real-Time UML: Developing Efficient Objects for Embedded Systems, Addison-Wesley, Reading, MA, 1998.

....a state transition. Orthogonal regions, which are shown as dashed lines in statecharts, combine multiple simultaneous descriptions of the same object. Interactions between regions occur typically through shared variables, awareness of state changes in other regions and message passing mechanisms [Dou98] such as broadcasting, and propagating events. We choose statecharts to model the behavior of objects and aspects because: 1) They provide rich set of semantics that are suitable for concurrency. 2) When using statecharts we assume a finite set of states [Paz97] which will reduce the ....

....[Har00] Modeling Orthogonal Concerns using Orthogonal Regions Statecharts support decomposition of states in an AND OR fashion, combined with the communication mechanisms to allow communications between states. Broadcast, Propagated, and the IN( operator are the main communication mechanisms [Dou98]. Broadcast events are events communicated to more than one orthogonal component. And State is when an object is in its sub states concurrently. Each of the concurrent sub state is called an orthogonal component. Statechart models govern orthogonal states whereby an object must be in exactly one ....

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Bruce Powel Douglass, "Real-Time UML: Developing efficient Objects For Embedded Systems", AddisonWesley, 1998.

....wayinto objects is a critical task, since usually there is no direct one to one mapping from use cases to objects. Several use cases can give rise to one object and one use case can originate a couple of objects. Douglass presents 11 useful strategies to find identify the objects of a system [9], but they can not be directly applied to this purpose, because none of them is based on the use cases that were previously identified. A strategy, composed of some guidelines, is needed to guide the developers on how to transform use cases into objects. There are some approaches for that ....

....of those classes. This is the main reason that methodologies usually impose (or suggest) class diagrams to be first elaborated than object diagrams. This implies an additional task in whichitmust be assured that there is consistency between the information that is described by both diagrams [9]. This fact can be interpreted as a symptom that some information is being unnecessarily replicated. For instance, the existence of the singletonAE stereotype in UML, which indicates that a given class can only have one instance, corroborates the perspective that sees the class diagram as a ....

B.P.Douglass. Real-Time UML: Developing Efficient Objects for Embedded Systems. Addison-Wesley, 1998.

....TCP IP stack packages developed for the ISO network communication standard, when a project asks for a communication port, writing a new stack does not seem worth the effort. The proponent of software reuse foresees a future where software component are built and traded like brick and mortar parts [4]. For the time being, we have to settle on more primitive forms of reuse, let al..one in the embedded world. Hardware and software firmware together completes a product. The trend is that more and more load is put on the software side whereas hardware is built of standard parts. This again makes it ....

....in Process Control System Based on our observation that processor speed and memory size may not be a constraint anymore, we suggest that it is beneficial to bring object component oriented (OO) ideas into real time system development. People have already been preaching this idea for a while [4, 8]. We shall give in this section some practical reasons. First of all OO design methodology has been used in process control system development for years. The advantage of it for non real time system development equally applies to the real time system development. Consider a simple state machine ....

B. P. Douglass, Real-Time UML - Developing Efficient Objects for Embedded Systems, Addison-Wesley Publishing Company, 1998

....is particularly important for the emerging research field software performance engineering (see e.g. 22] 23] as well as for system engineering at large. As a first step in this direction, Douglass specified language extensions of the UML for specifying real time constraints such as deadlines [6]. Furthermore, there are activities of the OMG to extend the current version of the UML for modeling real time applications. Therefore, the OMG sent out a Request for Proposal (RFP) that addresses the issue of schedulability, performance, and time [16] An initial response to the RFP that was ....

....the designer to choose the types of UML diagrams best suited for the intended representation of a system. In this paper, we choose state diagrams and activity diagrams as UML building blocks for enabling quantitative system analysis with the UML. The diagrams are presented using the notation from [6]. State diagrams of the UML provide a simple but formal means of modeling the complex event driven system behavior. All semantics necessary to express behavior (i.e. states, historical properties, transitions, and compound transitional connectors) are available on the state diagram palette. The ....

B.P. Douglass, Real-time UML: Developing Efficient Objects for Embedded Systems, 2 Edition, Addison Wesley 1999.

....User defined currentState #next Transitions Figure 3. Class diagram of Statechart pattern statechart diagram is that of Harel s statecharts [9] with extensions to make that object oriented. Table 1 compares several design patterns for implementing a FSM; Conditional Statements pattern [10], State pattern [6, 7, 11] and StateTable pattern [10] which have been proposed for implementing the state transition specification. These patterns have critical problems with support of substates, mapping from diagram to code, and readability of code. In order to solve these problems, the system ....

....Figure 3. Class diagram of Statechart pattern statechart diagram is that of Harel s statecharts [9] with extensions to make that object oriented. Table 1 compares several design patterns for implementing a FSM; Conditional Statements pattern [10] State pattern [6, 7, 11] and StateTable pattern [10], which have been proposed for implementing the state transition specification. These patterns have critical problems with support of substates, mapping from diagram to code, and readability of code. In order to solve these problems, the system designer needs a new design pattern which meets the ....

B.P. Douglass, Real-Time UML - Developing Efficient Objects for Embedded Systems, Addison-Wesley, 1998.

.... However, it still requires more formalism for the Requirements Specification [7] and, if compared to Formal Techniques, presents gaps, which result in problems [3] UML (The Unified Modeling Language) 8, 9, 10] is an important step forward the standardisation of the OO models representation [11], but it doesn t provide mapping procedures between the development phases. The use of formal techniques [7, 12] allows consistence analysis and system behaviour simulation, through wellSilvino Jos Silva Bastos is MSc in Automation Applied Computing and works in Brazilian Navy. E mail: ....

....concept of packages, which are containers used to group the model elements inside a same container. 2.1 UML System Modelling Different authors [15, 16] suggest different methods to employ UML in system modelling. The method adopted in this work is based on procedures proposed by Bruce Douglass [11, 16]. It also includes some author s contributions, presented as recommendations and heuristics to guide the modelling process, which are essential in the preparation of the UML model to be transformed in a Formal SDL Specification. The following steps shall be sequentially performed during model ....

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DOUGLASS, B.P. Real Time UML: Developing Efficient Objects for Embedded Systems. Addison Wesley, 1998.

....Level Framing and Integrated Layer Processing, CT90] for more info. 8 There are serially linked if all possible protocols traverse a common path, which is usually true for link and physical layers. arrived at this structure from the merger of a Interface Pattern found in the Java context [Doug98] and OSI s 9 service access points (SAP) The interface pattern provided a structure for reuse of an implementation by multiple clients, and the SAP s provided a successful framework. In our protocol structure the SAP s have become the interface objects but they no longer reside on the ....

Douglass, B. Real-Time UML: Developing Efficient Objects For Embedded Systems. Berkeley, California: Addison Wesley Longman, 1998

....with time annotation to evaluate performance. widely acceptance between the software engineering community. UML will be enriched with performance annotations, we will use the proposal stated in [10] Another proposals to annotate time aspects in UML have been stated for the real time field [3], therefore with different objectives. Using patterns, with the corresponding performance annotations, in conjunction with the guides given by PROP, the engineer will be assisted in the construction of the complete performance annotated UML diagrams for the system. In order to obtain numerical ....

B. Douglass. Real-Time Uml: Developing Efficient Objects for Embedded Systems. Object Technology Series. Addison-Wesley, 1999.

....adequate alternative for embedded systems. Several researchers have also selected UML as the notation for specifying embedded systems, which confirms the usefulness of UML for this engineering field and indicates that this notation is gaining widespread acceptance and usage within this community [4, 5, 6, 7, 8, 9]. For specifying the systems, the authors are using the main views captured by the following UML diagrams: 1) use case diagrams are utilized to catch the functional aspects of the system as viewed by its users; 2) object diagrams show the static configuration of the system, and the relations ....

B. P. Douglass, Real-Time UML: Developing Efficient Objects for Embedded Systems, Addison-Wesley, 1998.

....be used universally for the modelling of systems, including automatic control applications with both hardware and software components, so the authors believe that it is an appropriate choice for embedded systems. To confirm the usefulness of UML for this engineering field, several research teams (Douglass, 1998; Lyons, 1998; Lanusse et al. 1998; McLaughin et al. 1998; Kabous et al. 1999; Jigorea et al. 2000) have also adopted UML as the notation for specifying embedded systems, which means that this notation is gaining widespread acceptance and usage within this community. The main views used by ....

Douglass, B. P. (1998). Real-Time UML: Developing Efficient Objects for Embedded Systems, Addison-Wesley.

....in aims and scope. They offer solutions ranging from high level strategies for organising software to low level implementation mechanisms. Recently, there has been a growing number of patterns which express known concurrent behaviour of interacting entities over a possibly distributed platform [1, 5, 9, 16]. The proposed design pattern is based on the well known Observer pattern where a server process is in charge of monitoring a real time environment and informing a set of clients processes (called the observers) when changes in the monitored values (e.g. sensor values) occur. In this context, we ....

B. Douglass. Real-Time UML: Developing Efficient Objects for Embedded Systems. Addison-Wesley, 1998.

....definition and acquired data; # manually control all the controllable elements; # export data acquired by the system to other data analysis tools; and # perform basic trouble shooting operations in case of a hardware malfunction. Each of these tasks is represented by one or more UC scenarios [19, 20]. Their combination constitutes a preliminary list of the capabilities available to the TSG system s users, and is thus, the abstract, top most view of the TSG s requirements. 6.4.2. Step 2 The second step is to identify the application domains with which the TSG host shares attributes. The ....

Douglass, BP. Real-time UML: developing efficient objects for embedded systems. Addison-Wesley, Reading, MA, 1998

....the UML metamodel: the Core, DataTypes, and Common Behavior packages [14] This paper extends our work to the State Machine package. The State Machine package consists of the modeling concepts used to specify the behavior of various dynamic model elements, which are viewed as statechart diagrams [2, 18]. The state machine in UML is a variation of classical (Harel) statecharts [7] designed to be compatible with concepts in object orientation. However, there are some semantic differences between the two notations. One major difference is that the synchrony hypothesis in the classical statecharts ....

....Formalizing the abstract syntax and static semantics: Syntactically, Pseudostate inherits from StateVertex and has an attribute for determining its kind. The static semantics given for pseudo states are: 1] An initial vertex can have at most one outgoing transition and no incoming transitions. [2] History vertices can have at most one outgoing transition. 3] A join vertex must have at least two incoming transitions and exactly one outgoing transition. 4] A fork vertex must have at least two outgoing transitions and exactly one incoming transition. 5] A junction or choice vertex must ....

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B. P. Douglass, Real-Time UML: Developing Efficient Objects for embedded systems, Addison-Wesley, 1998.

....states can be orthogonal) and . Real time conditions. Especially in the context of embedded systems, statecharts are often used for system (and software) specification. In this way statecharts are frequently used for the generation of executable code (e.g. C or C ) for embedded systems (see [5], 11] 13] In contrast to this, in our approach statecharts serve exclusively for the abstract description of (software) behavior as a starting point for selecting existing software modules and appropriately combining them. The aim is not to generate code (see above) The same state based ....

Douglass, B. P. Real-Time UML -- Developing Efficient Objects for Embedded Systems, Addison Wesley, Reading, Massachusetts, 1998

....reads the level and then does not pass the value quick enough (because other more important tasks are taking place on the processor) then after some large D , say two minutes, there is no point in the computation proceeding. 3. M in N must meet D. This is what is sometimes called firm deadlines [Dou98] Where some number M out of some larger number N, must be met by the deadline D. An example taken from [Dou98] is a patient ventilator machine in a hospital. An occasional breath could come a few seconds late with no effect to the patient. However the result of too few breaths or none at all for ....

....on the processor) then after some large D , say two minutes, there is no point in the computation proceeding. 3. M in N must meet D. This is what is sometimes called firm deadlines [Dou98] Where some number M out of some larger number N, must be met by the deadline D. An example taken from [Dou98] is a patient ventilator machine in a hospital. An occasional breath could come a few seconds late with no effect to the patient. However the result of too few breaths or none at all for a few minutes could be disastrous. It is envisaged that one or more of the above interpretations will be ....

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B. P. Douglass. Real-Time UML Developing efficient objects for embedded systems. Addison-Wesley, 1998.

.... 1997b; Rational, 1997c; Rational, 1997d; Rational, 1997e) UML, which aims to unify significant object oriented research (Rumbaugh, 1996) adapts and extends the works of Rumbaugh et al. 1991) Booch (1994) and Jacobson et al. 1992) UML is also being extended into the real time domain (Douglass, 1998). 13 Advantages and disadvantages of HOORA are discussed at the end of the present chapter (section 2.4) and also at the beginning of chapter 3. CHAPTER 2. FIELD SURVEY AND REVIEW 57 UML is a diagrammatic language that provides a rich set of notations for OO development. The main categories of ....

Douglass, B. P. (1998). Real-time UML: Developing efficient objects for embedded systems, Object Technology, Addison Wesley Longman, Inc. ISBN: 0-201-32579-9.

....the first mapping phase. The mapping of statecharts into code is not trivial, due to the numerous modelling mechanisms that exist in the statechart formalism. The most common software implementation of a statechart is with an enumerated variable that is used as a selector of a switch command [1,4]. Each case clause implements a given state of the diagram. This approach is conceptually simple, but becomes problematic when applied to relatively complex state machines, especially models that are hierarchically described. In this case, the flat state machine must be considered, which ....

....technique is not efficient, since hierarchical and complex systems must be considered. Several authors presented proposals that suggest the way code must be generated from state machines that model the internal behaviour of objects. Among those proposals, the State [6] and the State Table [4] design patterns and the solution presented in [7] have to be taken into account. Those solutions were mainly idealized for software systems where principles such as reuse, extensibility, and simplicity are usually more important than performance and memory usage. However, for real time embedded ....

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B. P. Douglass. Real-Time UML: Developing Efficient Objects for Embedded Systems. Object Technology. Addison-Wesley, 1998.

....a design notation. The currently available design tools, such as the Rational Rose s UML (Unified Modeling Language) tool, do not provide a way to do this. This shortcoming is the main reason that motivates our research. The work involves the investigation of the design method to be used (UML [1, 2]) a simulation environment (C SIM [3, 4] a syntax that can capture the simulation requirements (SimML [5] and a parser to transform the design into simulation program (in the perl [6] scripting language) What is SimML We have developed a syntax called SimML (Simulation Modelling Language) ....

....= 200291 avgTime = 7.63624 Different scenarios can be investigated easily by altering the simulation parameters or if needed, the structure of the system. For example, if two servers are to be used instead of one, only the following line needs to be changed: OBJECT s of Server OBJECT s[2] of Server. The new structure gave these results for the same simulation length: totalTime = 688537 totalJobs = 200292 totalDone = 200291 avgTime = 3.43768 Future Work We are now investigating the feasibility of performing an automatic transformation from the UML s class and sequence ....

B.P. Douglass, Real Time UML: Developing Efficient Objects for Embedded Systems, Addison-Wesley, 1998.

....one cannot decrease the complexity of a problem at hand, but we may increase the awareness of where the problems arise. We claim that the challenge of embedded system design is not concerned with the static architecture of an application, for which real time variants of the UML (e.g. RT UML, Dou98] are an interesting method. The challenge rather is how to obtain real time aware, understandable, verifiable, flexible and reusable designs, defining precisely, intuitively and mathematically sound the dynamics of an application. Of course there are partial answers. Examples are Petri nets ....

Bruce Powel Douglass. Real-time UML: Developing Efficient Objects for Embedded Systems. Addison-Wesley, 1998.

....including real time embedded systems. However, UML is not a software process. UML does not specify the different stages of the development of a software project. The UML standard specifies a notation for several different diagrams, but it does not describe how to create and apply each diagram. [Dou98] presents a methodology for building embedded systems using the UML notation and object oriented analysis and design techniques. This document describes the object oriented design and implementation of a digital sound recorder, or Dictaphone, using the UML notation and the method described by ....

B. P. Douglass, Real-time UML: developing efficient objects for embedded system, Addison Wesley 1998.

....Types of relationships include association, aggregation, composition aggregation, generalization and specialization. These must be adequately specified before describing the dynamic behavior of entities. Types of object interaction include sequential composition, and concurrency. We use UML icons [1] shown in Figure 3 to indicate different kinds of message flow between interacting objects. The icons are classified in two categories, arrival pattern and synchronization pattern. An arrival pattern icon can be combined with a synchronization pattern icon to capture two orthogonal dimensions. For ....

B. P. Douglass. Real-Time UML - Developing Efficient Objects for Embedded Systems. Addison-Wesley, Reading, MA, 1998.

....modified in these interactions. From the point of view of the press, the interaction is done when some of its sensors will inform it so. So far, we have identified some basic services or functions the press will provide. Next we seek for the data it will operate on. Following informal strategies [8] we draw the class diagram in Fig. 4, i.e. the classes, their relationships with each other, and the attributes. The relationship between the classes (UnLoad) is called an association and it models references from one class to the other. In the eventual implementation it can only be ....

B. P. Douglass. Real-Time UML: Developing Efficient Objects for Embedded Systems. Addison-Wesley, 1998.

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B.P.Douglass,Real-Time UML : Developing Efficient Objects for Embedded Systems,98.

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Bruce Powel Douglass, Real-Time UML: Developing Efficient Objects for Embedded Systems, Addison Wesley, Reading, MA, 1998.

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Bruce Powel Douglass, Real-Time UML: Developing Efficient Objects for Embedded Systems, Addison Wesley, Reading, MA, 1998.

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Bruce Powel Douglass. Real-Time UML: Developing Efficient Objects for Embedded Systems. The Addison-Wesley Object Technology Series. Addison-Wesley, October 1999. Second Edition.

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B. Douglass. Real-Time UML: Developing Efficient Objects for Embedded Systems. Addison-Wesley, second edition, 1998.

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Bruce Powel Douglass. Real-Time UML: Developing Efficient Objects for Embedded Systems. The Addison-Wesley Object Technology Series. Addison-Wesley, October 1999. Second Edition.

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Bruce Powel Douglass. Real-Time UML: Developing Efficient Objects for Embedded Systems. The Addison-Wesley Object Technology Series. Addison-Wesley, October 1999. Second Edition.

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B. P. Douglass, Real-Time UML: Developing Efficient Objects for Embedded Systems. Addison-Wesley, 2000.

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Douglass, B.P. (1998), Real-Time UML: developing efficient objects for embedded systems, Addison Wesley Longman.

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B.P. Douglass, Real Time UML -- Developing efficient objects for embedded systems (Massachusetts: AddisonWesley, 1998).

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B.P. Douglass, Real Time UML -- Developing efficient objects for embedded systems (Massachusetts: AddisonWesley, 1998).

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). Douglass, B. P., 2000, Real-Time UML: Developing Efficient Objects for Embedded Systems, Addison-Wesley, pp. 2-12.

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