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Course Code : MCS-032Course Titlle : Object Oriented Analysis and DesignAssignment Number : MCA(3)/032/Assign/2014-15Assignment Marks : 100Weightage : 25%Last Dates for Submission : 157

th

October,

2014 (For July 2014 Session)15th

April, 2015 (For January 2015 Session)

There are eight questions in this assignment, which carry 80 marks. Rest 20 marks arefor viva-voce. Answer all the questions. Make necessary assumptions where everrequired. Please go through the guidelines regarding assignments given in the ProgrammeGuide for the format of presentation.

Question 1:What is Object Orientated Modeling (OOM)? Explainadvantages of OOM over structured modeling.(10 Marks)

Object-Oriented Modeling (OOM) mean?

Object-oriented modeling (OOM) is the construction of objects using a collection ofobjects that contain stored values of the instance variables found within an object.Unlike models that are record-oriented, object-oriented values are solely objects.

The object-oriented modeling approach creates the union of the application anddatabase development and transforms it into a unified data model and language

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environment. Object-oriented modeling allows for object identification andcommunication while supporting data abstraction, inheritance and encapsulation.

Object-Oriented Modeling (OOM)

Object-oriented modeling is the process of preparing and designing what the model’scode will actually look like. During the construction or programming phase, themodeling techniques are implemented by using a language that supports the object-oriented programming model.

OOM consists of progressively developing object representation through three phases:analysis, design, and implementation. During the initial stages of development, themodel developed is abstract because the external details of the system are the centralfocus. The model becomes more and more detailed as it evolves, while the centralfocus shifts toward understanding how the system will be constructed and how itshould function.

Benefits of Object-Oriented Approach

Object-oriented databases make the promise of reduced maintenance, code reusability, real worldmodeling, and improved reliability and flexibility. However, these are just promises and in thereal world some users find that the object-oriented benefits are not as compelling as theyoriginally believed. For example, what is code reusability? Some will say that they can reusemuch of the object-oriented code that is created for a system, but many say there is no more codereusability in object-oriented systems than in traditional systems. Code reusability is a subjectivething, and depends heavily on how the system is defined. The object-oriented approach doesgive the ability to reduce some of the major expenses associated with systems, such asmaintenance and development of programming code. Here are some of the benefits of theobject-oriented approach:









Reduced Maintenance: The primary goal of object-oriented development is the assurance thatthe system will enjoy a longer life while having far smaller maintenance costs. Because most ofthe processes within the system are encapsulated, the behaviors may be reused and incorporatedinto new behaviors.

Real-World Modeling: Object-oriented system tend to model the real world in a morecomplete fashion than do traditional methods. Objects are organized into classes of objects, andobjects are associated with behaviors. The model is based on objects, rather than on data andprocessing.

Improved Reliability and Flexibility: Object-oriented system promise to be far more reliablethan traditional systems, primarily because new behaviors can be "built" from existing objects.Because objects can be dynamically called and accessed, new objects may be created at anytime. The new objects may inherit data attributes from one, or many other objects. Behaviorsmay be inherited from super-classes, and novel behaviors may be added without effectingexisting systems functions.

High Code Reusability: When a new object is created, it will automatically inherit the dataattributes and characteristics of the class from which it was spawned. The new object will alsoinherit the data and behaviors from all superclasses in which it participates. When a user createsa new type of a widget, the new object behaves "wigitty", while having new behaviors which aredefined to the system.

Question 2:What is UML? Briefly explain use of Use Case Diagramand Sequence Diagram with the help of an example ofeach.

he Unified Modeling Language (UML) is a general-purpose modeling language in the field of softwareengineering, which is designed to provide a standard way to visualize the design of a system

With the help of a use case diagram, you can discuss and communicate: The scenarios in which your system or application interacts with people, organizations, or external systems.









The goals that it helps those actors achieve. The scope of your system.

A use case diagram does not show the detail of the use cases: it only summarizes some of the relationships betweenuse cases, actors, and systems. In particular, the diagram does not show the order in which steps are performed toachieve the goals of each use case. You can describe those details in other diagrams and documents, which you canlink to each use case. For more information, see Describing Use Cases in Detail in this topic.The descriptions you provide for use cases will use several terms related to the domain in which the system works,such as Sale, Menu, Customer, and so on. It is important to define these terms and their relationships clearly, and youcan do that with the help of a UML Class Diagram. For more information, see UML Class Diagrams: Guidelines.Use cases deal only in the functional requirements for a system. Other requirements such as business rules, quality ofservice requirements, and implementation constraints must be represented separately. Architecture and internaldetails must also be described separately. For more information about how to define user requirements, seeModelingUser Requirements.The examples used in this topic relate to a Web site on which customers can order meals from local restaurants.

UML Sequence Diagrams

You can use sequence diagrams for a variety of purposes at different levels of program detail. Typical occasions fordrawing a sequence diagram are as follows:

If you have a use case diagram that summarizes your system's users and their goals, you can draw sequencediagrams to describe how the main components of the system interact to fulfill the goal of each use case.For more information, see UML Use Case Diagrams: Guidelines.









If you have identified messages arriving at an interface of a component, you can draw sequence diagrams todescribe how the internal parts of the component interact to achieve the result required for each incomingmessage. For more information, see UML Component Diagrams: Guidelines.

Drawing sequence diagrams has several benefits: You can easily see how tasks are distributed between components. You can identify patterns of interaction that make it difficult to update the software.

Question 3:Draw a DFD for Library Management System. (10 Marks)









Question 4: What is an instance diagram? Draw an instance diagramfor the arithmetic expression:A= (B+C*D)/(B-C+D).









An InstanceDiagram is a part of the UnifiedModelingLanguage that one does not seementioned too often. The basic idea is to make a static snap shot of instances (notclasses) in your system or subsystem. Make it show exactly who points to whom.

Question 5:What are different types of Object Oriented models?Explain the types of characteristics represented by thesemodels.









Question 6:What is state diagram? Explain its advantages. Drawstate diagram for Railway Ticket Booking on IRCTCwebsite.A state diagram is a type of diagram used in computer science and related fields to describe the behavior ofsystems. State diagrams require that the system described is composed of a finite number of states;sometimes, this is indeed the case, while at other times this is a reasonable abstraction. Many forms of statediagrams exist, which differ slightly and have different semantics.

A state diagram, also called a state machine diagram or statechart diagram, is anillustration of the states an object can attain as well as the transitions between thosestates in the Unified Modeling Language (UML). In this context, a state defines astage in the evolution or behavior of an object, which is a specific entity in a program









or the unit of code representing that entity. State diagrams are useful in all forms ofobject-oriented programming (OOP). The concept is more than a decade old but hasbeen refined as OOP modeling paradigms have evolved.

A state diagram resembles aflowchart in which the initial state is represented by alarge black dot and subsequent states are portrayed as boxes with rounded corners.There may be one or two horizontal lines through a box, dividing it into stackedsections. In that case, the upper section contains the name of the state, the middlesection (if any) contains the state variables and the lower section contains theactions performed in that state. If there are no horizontal lines through a box, onlythe name of the state is written inside it. External straight lines, each with an arrowat one end, connect various pairs of boxes. These lines define the transitionsbetween states. The final state is portrayed as a large black dot with a circle aroundit. Historical states are denoted as circles









State diagrams are used to give an abstract description ofthe behavior of a system. This behavior is analyzed and represented in series of events, that could occur in oneor more possible states. Hereby "each diagram usually represents objects of a single class and track thedifferent states of its objects through the system"


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Question 7:What is need of concurrency management in ObjectOriented Systems? Explain the important issues relatedto concurrency management with the help of an example.

Concurrent programming encompasses programming languages and algorithms used to implement concurrentsystems. Concurrent programming is usually considered to be more general than parallel









programming because it can involve arbitrary and dynamic patterns of communication and interaction, whereasparallel systems generally have a predefined and well-structured communications pattern. The base goals ofconcurrent programming include correctness, performance and robustness. Concurrent systems suchasOperating systems and Database management systems are generally designed to operate indefinitely,including automatic recovery from failure, and not terminate unexpectedly (see Concurrency control). Someconcurrent systems implement a form of transparent concurrency, in which concurrent computational entitiesmay compete for and share a single resource, but the complexities of this competition and sharing are shieldedfrom the programmer.

Because they use shared resources, concurrent systems in general require the inclusion of some kindof arbiter somewhere in their implementation (often in the underlying hardware), to control access to thoseresources. The use of arbiters introduces the possibility of indeterminacy in concurrent computation which hasmajor implications for practice including correctness and performance. For example arbitrationintroduces unbounded nondeterminism which raises issues with model checking because it causes explosionin the state space and can even cause models to have an infinite number of states.

In computer science, concurrency is a property of systems in whichseveral computations are executing simultaneously, and potentially interacting with each other. Thecomputations may be executing on multiple cores in the same chip, preemptively time-shared threads on the same processor, or executed on physically separated processors. A number ofmathematical models have been developed for general concurrent computation including Petrinets, process calculi, the Parallel Random Access Machine model, the Actor model and the Reo

Issues[edit]

Because computations in a concurrent system can interact with each other while they are executing, thenumber of possible execution paths in the system can be extremely large, and the resulting outcome canbe indeterminate. Concurrent use of shared resources can be a source of indeterminacy leading to issues suchas deadlock, and starvation.[1]

The design of concurrent systems often entails finding reliable techniques for coordinating their execution, dataexchange, memory allocation, and execution scheduling to minimize response time and maximize throughput. [2]

Question 8:What is association in UML Diagram? Briefly explaindifferent types of associations available in UML. Also









explain the process of mapping a ternary association into

UML AssociationAssociation is a relationship between classifiers which is used to show that instances of classifiers couldbe either linked to each other or combined logically or physically into some aggregation.UML specification categorizes association as semantic relationship. Some other UML sources alsocategorize association as a structural relationship. Wikipedia states that association is instancelevel relationship and that associations can only be shown on class diagrams. Not sure where they got thatinformation from but it is not based on UML specification. Association could be used on different types ofUML structure diagrams:

class diagram associations, use case diagram associations, deployment diagram artifact associations, deployment diagram communication path.

There are several concepts related to association: association end ownership, navigability, association arity, aggregation type.

UML 2.4 specification states that for the association: "Aggregation type, navigability, and end ownership areorthogonal concepts, ..." which is clearly an overstatement. Orthogonal usually means completely independent.While notation for aggregation type, navigability, and association end ownershipcould be appliedindependently, the concepts themselves are not orthogonal. For example, in UML 2.4 end property ofassociation owned by an end class is navigable, which clearly makes navigability dependent on ownership.









Association relationship overview diagramAn association is usually drawn as a solid line connecting two classifiers or a single classifier to itself. Name ofthe association can be shown somewhere near the middle of the association line but not too close to any of theends of the line. Each end of the line could be decorated with the name of the association end.

Association EndAssociation end is a connection between the line depicting an association and the icon depicting theconnected classifier. Name of the association end may be placed near the end of the line. The association endname is commonly referred to as role name (but it is not defined as such in the UML 2.4 standard). The rolename is optional and suppressible.

Professor "playing the role" of author is associatedwith textbook end typed as Book.



















The idea of the role is that the same classifier can play the same or different roles in other associations. Forexample, Professor could be an author of some Books or an editor.Association end could be owned either by

end classifier, or association itself

Association ends of associations with more than two ends must be owned by the association.Ownership of association ends by an associated classifier may be indicated graphically by a small filledcircle (aka dot). The dot is drawn at the point where line meets the classifier. It could be interpreted asshowing that the model includes a property of the type represented by the classifier touched by the dot. Thisproperty is owned by the classifier at the other end.

Association end query is owned by classifier QueryBuilderand association end qbuilder is owned by association Builds itselfThe "ownership" dot may be used in combination with the other graphic line-path notations for properties ofassociations and association ends. These include aggregation type and navigability.UML standard does not mandate the use of explicit end-ownership notation, but defines a notation which shallapply in models where such use is elected. The dot notation must be applied at the level of completeassociations or higher, so that the absence of the dot signifies ownership by the association. In otherwords, in binary associations the dot will be omitted only for the ends which are not owned by a classifier.Attribute notation can be used for an association end owned by a class, because an association end owned bya class is also an attribute. This notation may be used in conjunction with the line arrow notation to make itperfectly clear that the attribute is also an association end.

Association end qb is an attribute of SearchService classand is owned by the class.

NavigabilityEnd property of association is navigable from the opposite end(s) of association if instances of the classifier atthis end of the link can be accessed efficiently at runtime from instances at the other ends of the link.

























UML specification does not dictate how efficient this access should be or any specific mechanism to achieve theefficiency. It is implementation specific.When end property of association is marked as not navigable, in [UML 2.4] it means that "access from theother ends may or may not be possible, and if it is, it might not be efficient." The problem with this definitionof not navigable is that it actually means "whatever" or "who cares?" navigability.UML 2.4 also provides another definition of navigability:An end property of association that is owned by an end class, or that is a navigable owned end of theassociation indicates that the association isnavigable from the opposite ends; otherwise, the associationis not navigable from the opposite ends.This definition is odd because it makes navigability strongly dependent on ownership, while these areassumed to be orthogonal concepts; some examples in UML 2.4 specs show end properties owned by a classas not navigable, which contradicts to the definition above; and navigability is defined using"navigableowned end of the association".Deprecated navigability convention:

non-navigable ends were assumed to be owned by the association navigable ends were assumed to be owned by the classifier at the opposite end.

Notation: navigable end is indicated by an open arrowhead on the end of an association not navigable end is indicated with a small x on the end of an association no adornment on the end of an association means unspecified navigability

Both ends of association have unspecified navigability.

A2 has unspecified navigability while B2 is navigable from A2.

A3 is not navigable from B3 while B3 has unspecified navigability.

























A4 is not navigable from B4 while B4 is navigable from A4.

A5 is navigable from B5 and B5 is navigable from A5.

A6 is not navigable from B6 and B6 is not navigable from A6.A visibility symbol can be added as an adornment on a navigable end to show the end’s visibility as anattribute of the featuring classifier.

ArityEach association has specific arity as it could relate two or more items.

Binary AssociationBinary association relates two typed instances. It is normally rendered as a solid line connecting twoclassifiers, or a solid line connecting a single classifier to itself (the two ends are distinct). The line may consistof one or more connected segments.

Job and Year classifiers are associatedA small solid triangle could be placed next to or in place of the name of binary association (drawn as a solidline) to show the order of the ends of the association. The arrow points along the line in the direction of thelast end in the order of the association ends. This notation also indicates that the association is tobe read from the first end to the last end.

Order of the ends and reading: Car - was designed in - Year









Order of the ends and reading: Car - was designed in - Year









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UML 2.4 specification states that this arrow is used for documentation purposes only and has nogeneral semantic interpretation. This is an odd clarification as UML diagrams are in fact used mostly fordocumentation purposes but even more important, this arrow according to the UML spec defines theorder ofassociation ends - which does belong to semantics.

N-ary AssociationAny association may be drawn as a diamond (larger than a terminator on a line) with a solid line for eachassociation end connecting the diamond to the classifier that is the end’s type. N-ary association with morethan two ends can only be drawn this way.

Ternary association Design relates three classifiers

Shared and CompositeAggregationAggregation is a binary association representing some whole/part relationship. Aggregation typecould be either:

shared aggregation (aka aggregation), or composite aggregation (aka composition).

AggregationAggregation (shared aggregation) is a "weak" form of aggregation when part instance is independent ofthe composite:

the same (shared) part could be included in several composites, and if composite is deleted, shared parts may still exist.



























Shared aggregation is shown as binary association decorated with a hollow diamond as a terminaladornment at the aggregate end of the association line. The diamond should be noticeably smaller than thediamond notation for N-ary associations.

Search Service has a Query Builder using shared aggregation

CompositionComposition (composite aggregation) is a "strong" form of aggregation. Compositionrequirements/features listed in UML specification are:

it is a whole/part relationship, it is binary association, part could be included in at most one composite (whole) at a time, and if a composite (whole) is deleted, all of its composite parts are "normally" deleted with it.

Note, that UML does not define how, when and specific order in which parts of the composite are created. Also,in some cases a part can be removed from a composite before the composite is deleted, and so is not necessarilydeleted as part of the composite.Composite aggregation is depicted as a binary association decorated with a filled black diamond at theaggregate (whole) end.

Folder could contain many files, while each File has exactly one Folder parent.If Folder is deleted, all contained Files are deleted as well.When composition is used in domain models, both whole/part relationship as well as event of composite"deletion" should be interpreted figuratively, not necessarily as physical containment and/or termination. UMLspecification needs to be updated to explicitly allow this interpretation.

Hospital has 1 or more Departments, andeach Department belongs to exactly one Hospital.If Hospital is closed, so are all of its Departments.









Note, that though it seems odd, multiplicity of the composite (whole) could be specified as 0..1 ("at most one")which means that part is allowed to be a "stand alone", not owned by any specific composite.

Each Department has some Staff, and each Staff could bea member of one Department (or none). If Department is closed,its Staff is relieved (but excluding the "stand alone" Staff).

Association ClassAn association may be refined to have its own set of features; that is, features that do not belong to any ofthe connected classifiers but rather to the association itself. Such an association is called an association class.It is both an association, connecting a set of classifiers and a class, and as such could have features and might beincluded in other associations.An association class can be seen as an association that also has class properties, or as a class that also hasassociation properties.An association class is shown as a class symbol attached to the association path by a dashed line. Theassociation path and the association class symbol represent the same underlying model element, which has asingle name. The association name may be placed on the path, in the class symbol, or on both, but they must bethe same name.

LinkLink is an instance of an association. It is a tuple with one value for the each end of the association, whereeach value is an instance of the type of the end. Association has at least two ends, represented by properties(end properties).Link is rendered using the same notation as for an association. Solid line connects instances rather thanclassifiers. Name of the link could be shown underlined though it is not required. End names (roles) andnavigation arrows can be shown.







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