UML DIAGRAMS
There are three classifications of UML diagrams:
- Behavior diagrams. A type of diagram that depicts behavioral features of a system or business process. This includes activity, state machine, and use case diagrams as well as the four interaction diagrams.
- Interaction diagrams. A subset of behavior diagrams which emphasize object interactions. This includes communication, interaction overview, sequence, and timing diagrams.
- Structure diagrams. A type of diagram that depicts the elements of a specification that are irrespective of time. This includes class, composite structure, component, deployment, object, and package diagrams.
Diagram
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Description
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Learning Priority
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Activity Diagram
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Depicts high-level business processes, including data flow, or to model the logic of complex logic within a system.
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High
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Class Diagram
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Shows a collection of static model elements such as classes and types, their contents, and their relationships.
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High
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Communication Diagram
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Shows instances of classes, their interrelationships, and the message flow between them. Communication diagrams typically focus on the structural organization of objects that send and receive messages. Formerly called a Collaboration Diagram.
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Low
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Component Diagram
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Depicts the components that compose and application, system, or enterprise. The components, their interrelationships, interactions, and their public interfaces are depicted.
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Medium
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Composite Structure Diagram
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Depicts the internal structure of a classifier(such as a class, component, or use case), including the interaction points of the classifier to other parts of the system.
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Low
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Deployment Diagram
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Shows the execution architecture of systems. This includes nodes, either hardware or software execution environments, as well as the middleware connecting them.
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Medium
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Interaction Overview Diagram
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A variant of an activity diagram which overviews the control flow within a system or business process. Each node/activity within the diagram can represent another interaction diagram.
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Low
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Object Diagram
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Depicts objects and their relationships at a point in time, typically a special case of either a class diagram or a communication diagram.
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Low
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Package Diagram
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Show how model elements are organized into packages as well as the dependencies between packages.
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Low
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Sequence Diagram
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Models the sequential logic, in effect the time ordering of messages between classifiers.
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High
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State Machine Diagram
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Describes the states an object or interaction may be in, as well as the transitions between states. Formerly referred to as a state diagram, state chart diagram, or a state-transition diagram.
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Medium
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Timing Diagram
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Depicts the change in state or condition of a classifier instance or role over time. Typically used to show the change in state of an object over time in response to external events.
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Low
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Use Case Diagram
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Shows use cases, actors, and their interrelationships.
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Medium
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USE CASE DIAGRAM:
A use case diagram is a type of behavioral diagram defined by the Unified Modeling Language (UML). Its purpose is to present a graphical overview of the functionality provided by a system in terms of actors, their goals- represented as use cases- and any dependencies between those use cases.
Use case diagram depict:
- Use cases. A use case describes a sequence of actions that provide something of measurable value to an actor and is drawn as a horizontal ellipse.
- Actors. An actor is a person, organization, or external system that plays a role in one or more interactions with your system. Actors are drawn as stick figures.
- Associations. Associations between actors and use cases are indicated in use case diagrams by solid lines. An association exists whenever an actor is involved with an interaction described by a use case. Associations are modeled as lines connecting use cases and actors to one another, with an optional arrowhead on one end of the line. The arrowhead is often used to indicating the direction of the initial invocation of the relationship or to indicate the primary actor within the use case. The arrowheads are typically confused with data flow and as a result I avoid their use.
- System boundary boxes (optional). You can draw a rectangle around the use cases, called the system boundary box, to indicate the scope of your system. Anything within the box represents functionality that is in scope and anything outside the box is not. System boundary boxes are rarely used, although on occasion I have used them to identify which use cases will be delivered in each major release of a system.
- Packages (optional). Packages are UML constructs that enable you to organize model elements (such as use cases) into groups. Packages are depicted as file folders and can be used on any of the UML diagrams, including both use case diagrams and class diagrams. I use packages only when my diagrams become unwieldy, which generally implies they cannot be printed on a single page, to organize a large diagram into smaller ones.
RELATIONSHIPS IN USE CASE DIAGRAM:
Three relationships among use cases are supported by the UML standard, which describes graphical notation for these relationships.
Include
In one form of interaction, a given use case may
include another. The first use case often depends on the outcome of the included use case. This is useful for extracting truly common behaviors from multiple use cases into a single description. The notation is a dashed arrow from the including to the included use case, with the label “<<include>>”. This usage resembles a macro expansion where the included use case behavior is placed inline in the base use case behavior. There are no parameters or return values.
Extend
In another form of interaction, a given use case, (the extension) may extend another. This relationship indicates that the behavior of the extension use case may be inserted in the extended use case under some conditions. The notation is a dashed arrow from the extension to the extended use case, with the label <<extend>>. This can be useful for dealing with special cases, or in accommodating new requirements during system maintenance and extension.
To make the points at which extension may occur explicit extension points may be defined in use cases which are listed in a compartment below the use case name.
Generalization
In the third form of relationship among use cases, a generalization/ specialization relationship exists. A given use case may be specialized form of an existing use case. The notation is a solid line ending in a hollow triangle drawn from the specialized to the more general use case. This resembles the object-oriented concept of sub-classing, in practice it can be both useful and effective to factor common behaviors, constraints and assumptions to the general use case, describe them once, and deal same as except details in the specialized cases.
SEQUENCE DIAGRAM:
The well-known Message Sequence Chart technique has been incorporated into the Unified Modeling Language (UML) diagram under the name of Sequence Diagram. A sequence diagram shows, as parallel vertical lines, different processes or objects that live simultaneously, and, as horizontal arrows, the messages exchanged between them, in the order in which they occur. This allows the specification of simple runtime scenarios in a graphical manner.
Sequence diagrams are typically used to model:
1. Usage scenarios. A usage scenario is a description of a potential way your system is used. The logic of a usage scenario may be part of a use case, perhaps an alternate course. It may also be one entire pass through use case, such as the logic described by the basic course of action or a portion of the basic course of action, plus one or more alternate scenarios. The logic of a usage scenario may also be a pass through the logic contained in several use cases. For example, a student enrolls in the university, and then immediately enrolls in three seminars.
2. The logic of methods. Sequence diagrams can be used to explore the logic of a complex operation, function, or procedure. One way to think of sequence diagrams, particularly highly detailed diagrams, is a visual object code.
3. The logic of services. A service is effectively a high-level method, often one that can be invoked by a wide variety of clients. This includes web-services as well as business transactions implemented by a variety of technologies such as CICS/COBOL or CORBA-compliant object request brokers (ORBs).
ACTIVITY DIAGRAM:
In the Unified Modeling Language, an activity diagram represents the business and operational step-by-step workflows of components in a system. An activity diagram shows the overall flow of control.
Describing the basic notations:
- Initial node. The filled in circle is the starting point of the diagram. An initial node isn’t required although it does make it significantly easier to read the diagram.
- Activity final node. The filled circle with a border is the ending point. An activity diagram can have zero or more activity final nodes.
- Activity. The rounded rectangles represent activities that occur. An activity may be physical, such as Inspect Forms, or electronic, such as Display Create Student Screen.
- Flow/edge. The arrows on the diagram. Although there is a subtle difference between flows and edges I have never seen a practical purpose for the difference although I have no doubt one exists. I’ll use the term flow.
- Fork. A black bar with one flow going into it and several leaving it. This denotes the beginning of parallel activity.
- Join. A black bar with several flows entering it and one leaving it. All flows going into the join must reach it before processing may continue. This denotes the end of parallel processing.
- Condition. Text such as [Incorrect Form] on a flow, defining a guard which must evaluate to true in traverse the node.
- Decision. A diamond with one flow entering and several leaving. The flows leaving include conditions although some modelers will not indicate the conditions if it is obvious.
- Merge. A diamond with several flows entering and one leaving. The implication is that one or more incoming flows much reach this point until processing continues, based on any guards on the outgoing flow.
- Partition. Activity Diagram is organized into many partitions, also called swim lanes, indicating who/what is performing the activities (the Applicant, Registrar, or System).
- Sub-activity indicator. The rake in the bottom corner of an activity, such as in the Apply to University activity, indicates that the activity is described by a more finely detailed activity diagram.
- Flow final. The circle with the X through it. This indicates that the process stops at this point.
CLASS DIAGRAM:
In the Unified Modeling Language (UML), a class diagram is a type of static structure diagram that describes the structure of a system by showing the system’s classes, their attributes, and the relationships between the classes.
Relationships
A relationship is general term covering the specific types of logical connections found on class and object diagrams. UML shows the following relationships:
- Instance-Level Relationships
A Link is the basic relationship among objects. It is represented as a line connecting two or more object boxes. It can be shown on an object diagram or class diagram. A link is an instance or an association.
o Association
An Association represents a family of links. Binary associations (with two ends) are normally represented as a line, with each end connected to a class box. Higher order associations can be drawn with more than two ends. In such cases, the ends are connected to a central diamond.
An association can be named, and the ends of an association can be adorned with role names, ownership indicators, multiplicity, visibility, and other properties. There are five different types of association. Bi-directional and uni-directional associations are the most common ones. For instance, a flight class is associated with a plane class bi-directionally. Associations can only be shown on class diagrams.
o Aggregation
Class diagram showing Aggregation between two classes
Aggregation is a variant of the “has a” or association relationship; composition is more specific than aggregation. As a type of association, an aggregation can be named and have the same adornments that an association can. However, an aggregation may not involve more than two classes.
Aggregation can occur when a class is a collection or container of other classes, but where the contained classes do not have a strong life cycle dependency on the container—essentially, if the container is destroyed, its contents are not.
In UML, it is graphically represented as a clear diamond shape on the containing class end of the tree of lines that connect contained class(es) to the containing class.
o Composition
Composition is a stronger variant of the “has a” or association relationship; composition is more specific than aggregation.
Composition has a strong life cycle dependency between instances of the container class and instances of the contained class(es): If the container is destroyed, every instance that it contains is destroyed as well.
The UML graphical representation of a composition relationship is a filled diamond shape on the containing class end of the tree of lines that connect contained class(es) to the containing class.
- Differences between Composition and Aggregation
The whole of a composition must have a multiplicity of 0..1 or 1, indicating that a part must be for only one whole. The whole of an aggregation may have any multiplicity.
When attempting to represent real-world whole-part relationships, e.g., an engine is part of a car, the composition relationship is most appropriate. However, when representing a software or database relationship, e.g., car model engine ENG01 is part of a car model CM01, an aggregation relationship is best, as the engine, ENG01 may be also part of a different car model, CM02. This is often called a “catalog” relationship.
- Class Level Relationships
o Generalization
Class diagram showing generalization between one super class and two subclasses
The generalization relationship indicates that one of the two related classes (the subtype) is considered to be a specialized form of the other (the supertype) and supertype is considered as GENERALIZATION of subtype. In practice, this means that any instance of the subtype is also an instance of the supertype. The relationship is most easily understood by the phrase ‘A is a B’.
The UML graphical representation of a Generalization is a hollow triangle shape on the supertype end of the line (or tree of lines) that connects it to one or more subtypes.
The generalized relationship is also known as the inheritance or “is a“ relationship.
The supertype in the generalization relationship is also known as the “parent”, super class, base class, or base type.
The subtype in the generalization relationship is also known as the “child’, subclass, derived class, derived type, inheriting class, or inheriting type.
- Generalization-Specialization relationship
A is a type of B
E.g.”an oak is a type of tree”, “a sedan is a type of vehicle”
In UML modeling, a realization relationship is relationship between model elements, in which one model element (the client) realizes the behavior that the other model element (the supplier) specifies. A realization is displayed in the diagram editor as a dashed line with an unfilled arrowhead towards the supplier.
o Dependency(UML)
A dependency exists between two defined elements if a change to the definition of one would result in a change to the other. This is indicated by a dashed pointing from the dependent to the independent element. Several named varieties exist. A dependency can be between instances, class, or both.
The association relationship indicates that (at least) one of the two related classes makes reference to the other. In contrast with the generalization relationship, this is most easily understood through the phrase ‘A has a B’{a mother cat has kittens, kittens have a mother cat}.
The UML representation of an association is a line with an optional arrowhead indicating the role of the object(s) in the relationship, and an optional notation at each end indicating the multiplicity of instances of that entity ( the number of objects that participate in the association). Common multiplicities are:
Indicator Meaning
0..1 No instances, or one instance(optional, may)
1 Exactly one instance
0..* or * Zero or more instances
1..* One or more instances(at least one)
n Exactly n instances(n>1)
0..n Zero or n instances(n>1)
1..n One or n instances(n>1)
COMPONENT DIAGRAM:
In the Unified Modeling Language, a component diagram depicts how a software system is split up into physical components and shows the dependencies among these components. Physical components could be, for example, files, header, link libraries, modules, executables, or packages. Component diagrams can be used to model and document any system’s architecture.
Component diagrams are particularly useful with larger teams. Your initial architectural modeling efforts during cycle 0 should focus on identifying the initial architectural landscape for your system. UML component diagrams are great for doing this as they enable you to model the high-level software components, and more importantly the interfaces to those components. Once the interfaces are defined, and agreed to by your team, it makes it much easier to organize the development effort between sub teams. You will discover the need to evolve the interfaces to reflect new requirements or changes to your design as your project progresses, changes that need to be negotiated between the sub teams and then implemented appropriately.
INTRODUCTION TO RATIONAL ROSE
Rational rose
Rational Rose is an object-oriented Unified Modeling Language(UML) software design tool intended for visual modeling and component construction of enterprise-level software applications. In much the same way a theatrical director blocks out a play, a software designer uses Rational rose to visually create(model) the framework for an application by blocking out classes with actors(stick figures), use case elements(ovals), objects(rectangles) and messages/relationships(arrows) in a sequence diagram using drag-and-drop symbols. Rational Rose documents the diagram as it is being constructed and then generates code in the designer’s choice of C++, Visual Basic, Java, Oracle8,CORBA or Data Definition Language.
Two popular features of Rational Rose are its ability to provide iterative development and round-trip engineering. Rational Rose allows designers to take advantage of iterative development(sometimes called evolutionary development) because the new application can be created in stages with the output of one iteration becoming the input to the next.(This is in contrast to waterfall development where the whole project is completed from start to finish before a user gets to try it out.) Then, as the developer begins to understand how the components interact and makes modifications in the design, Rational Rose can perform what is called “round-trip engineering” by going back and updating the rest of the model to ensure the code remains consistent.
Rational rose is extensible, with downloadable add-ins and third-party applications. It supports COM/DCOM(ActiveX), JavaBeans, and Corba component standards.
Views in UML/Rational Rose
There are four views for a model created in Rational Rose, each representing the system from a different point of view.
The Use Case View
The use case view contains the diagrams used in analysis(use case, sequence, and collaboration), and all the elements that compromise these diagrams(e.g., actors).More recent versions of Rational Rose also allow for additional documentation in the form of word-processed documents and/or URLs to Web-based materials. The purpose of the use case view is to envisage what the system must do, without dealing with the specifics of how it will be implemented.
Logical View
The logical view contains the diagrams used in object design(class diagrams and state transition diagrams). It offers a detailed view of how the system envisaged in the use case view will be implemented. The basic element in this view is the class, which includes an outline of its attributes and operations. This directly corresponds to a class created in your chosen implementation language. From the logical view, skeletal code can be generated for implementation into a computer language. More recent versions of Rational Rose not only can generate skeletal code for Visual C++, Visual Java, or Visual BASIC, but also reverse engineer programs created in these languages into Rational Rose models. This allows existing components to be included in documented models, if there is access to the source code. In addition, changes that need to be made during implementation can be reflected in the documentation of the design model.
Component View
The component view is a step up from the logical view and contains diagrams used in system design(component diagrams). This includes information about the code libraries, executable programs, runtime libraries, and other software components that comprise the completed systems. Components can be pre-existing; for example, a Windows program in Visual C++ will utilize Microsoft Foundation Class to provide the framework for the Windows interface. Components that do not exist and need to be created by the developers will have to be designed in the logical view.
Deployment View
The deployment view illustrates how the completed system will be physically deployed. This view is necessary for complex applications in which a system will have different components located on different machines. For example, interface components may be located on a user machine while other components may be located on a network server.
INTRODUCTION TO VISUAL BASIC
Visual Basic (VB) is an event driven programming language and associated development environment from Microsoft for its COM programming model. Visual Basic was derived from BASIC and enables the rapid application development(RAD) of graphical user interface(GUI) applications, access to databases using DAO, RDO, or ADO, and creation of ActiveX controls and objects. Scripting languages such as VBA and VBScript are syntactically similar to Visual Basic, but perform differently.
A programmer can put together an application using the components provided with Visual Basic itself. Programs written in Visual Basic can also use the Windows API, but doing so requires external function declarations.
LANGUAGE BASICS:
Visual Basic was designed to be easy to learn and use. The language not only allows programmers to create simple GUI applications, but can also develop fairly complex applications as well. Programming in VB is a combination of visually arranging components or controls on a form, specifying attributes and actions of those components, and writing additional lines of code for more functionality. Since default attributes and actions are defined for the components, a simple program can be created without the programmer having to write many lines of code. Performance problems were experienced by earlier versions, but with faster computers and native code compilation this has become less of an issue.
Forms are created using drag and drop techniques. A tool is used to place controls (e.g., text boxes, buttons, etc.) on the form (window). Controls have attributes and event handlers associated with them. Default values are provided when the control is created, but may be changed by the programmer. Many attribute values can be modified during run time based on user actions or changes in the environment, providing a dynamic application. For example, code can be inserted into the form resize event handler to reposition a control so that it remains centered on the form, expands to fill up the form, etc. By inserting code into the event handler for a keypress in a text box, the program can automatically translate the case of the text being entered, or even prevent certain characters from being inserted.
Unlike many other programming languages, Visual Basic is generally not case sensitive, although it will transform keywords into a standard case configuration and force the case of variable names to conform to the case of the entry within the symbol table entry. String comparisons are case sensitive by the default, but can be made case insensitive if so desired.
The Visual Basic compiler is shared with other Visual Studio languages(C, C++), but restrictions in the IDE do not allow the creation of some targets (Windows model DLL’s) and threading models.
Result: Thus the UML diagrams and introduction to Visual Basic was studied.
