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1 VISIT: Course Code : MCS-032 Course Titlle : Object Oriented Analysis and Design Assignment Number : MCA(3)/032/Assign/ Assignment Marks : 100 Weightage : 25% Last Dates for Submission : 15 7 th October, 2014 (For July 2014 Session) 15 th April, 2015 (For January 2015 Session) There are eight questions in this assignment, which carry 80 marks. Rest 20 marks are for viva-voce. Answer all the questions. Make necessary assumptions where ever required. Please go through the guidelines regarding assignments given in the Programme Guide for the format of presentation. Question 1: What is Object Orientated Modeling (OOM)? Explain advantages of OOM over structured modeling. (10 Marks) Object-Oriented Modeling (OOM) mean? Object-oriented modeling (OOM) is the construction of objects using a collection of objects 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 and database development and transforms it into a unified data model and language iswar se do minute aakhe bandh karke dua karnaki wo unki manzil paa le thanx Page 1

2 VISIT: environment. Object-oriented modeling allows for object identification and communication while supporting data abstraction, inheritance and encapsulation. Object-Oriented Modeling (OOM) Object-oriented modeling is the process of preparing and designing what the model s code will actually look like. During the construction or programming phase, the modeling techniques are implemented by using a language that supports the objectoriented programming model. OOM consists of progressively developing object representation through three phases: analysis, design, and implementation. During the initial stages of development, the model developed is abstract because the external details of the system are the central focus. The model becomes more and more detailed as it evolves, while the central focus shifts toward understanding how the system will be constructed and how it should function. Benefits of Object-Oriented Approach Object-oriented databases make the promise of reduced maintenance, code reusability, real world modeling, and improved reliability and flexibility. However, these are just promises and in the real world some users find that the object-oriented benefits are not as compelling as they originally believed. For example, what is code reusability? Some will say that they can reuse much of the object-oriented code that is created for a system, but many say there is no more code reusability in object-oriented systems than in traditional systems. Code reusability is a subjective thing, and depends heavily on how the system is defined. The object-oriented approach does give the ability to reduce some of the major expenses associated with systems, such as maintenance and development of programming code. Here are some of the benefits of the object-oriented approach: iswar se do minute aakhe bandh karke dua karnaki wo unki manzil paa le thanx Page 2

3 VISIT: Reduced Maintenance: The primary goal of object-oriented development is the assurance that the system will enjoy a longer life while having far smaller maintenance costs. Because most of the processes within the system are encapsulated, the behaviors may be reused and incorporated into new behaviors. Real-World Modeling: Object-oriented system tend to model the real world in a more complete fashion than do traditional methods. Objects are organized into classes of objects, and objects are associated with behaviors. The model is based on objects, rather than on data and processing. Improved Reliability and Flexibility: Object-oriented system promise to be far more reliable than 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 any time. The new objects may inherit data attributes from one, or many other objects. Behaviors may be inherited from super-classes, and novel behaviors may be added without effecting existing systems functions. High Code Reusability: When a new object is created, it will automatically inherit the data attributes and characteristics of the class from which it was spawned. The new object will also inherit the data and behaviors from all superclasses in which it participates. When a user creates a new type of a widget, the new object behaves "wigitty", while having new behaviors which are defined to the system. Question 2: What is UML? Briefly explain use of Use Case Diagram and Sequence Diagram with the help of an example of each. he Unified Modeling Language (UML) is a general-purpose modeling language in the field of software engineering, 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. iswar se do minute aakhe bandh karke dua karnaki wo unki manzil paa le thanx Page 3

4 VISIT: 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 between use cases, actors, and systems. In particular, the diagram does not show the order in which steps are performed to achieve the goals of each use case. You can describe those details in other diagrams and documents, which you can link 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 you can 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 of service requirements, and implementation constraints must be represented separately. Architecture and internal details must also be described separately. For more information about how to define user requirements, seemodeling User 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 for drawing 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 sequence diagrams 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. iswar se do minute aakhe bandh karke dua karnaki wo unki manzil paa le thanx Page 4

5 VISIT: If you have identified messages arriving at an interface of a component, you can draw sequence diagrams to describe how the internal parts of the component interact to achieve the result required for each incoming message. 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) iswar se do minute aakhe bandh karke dua karnaki wo unki manzil paa le thanx Page 5

6 VISIT: Question 4: What is an instance diagram? Draw an instance diagram for the arithmetic expression: A= (B+C*D)/(B-C+D). iswar se do minute aakhe bandh karke dua karnaki wo unki manzil paa le thanx Page 6

7 VISIT: An InstanceDiagram is a part of the UnifiedModelingLanguage that one does not see mentioned too often. The basic idea is to make a static snap shot of instances (not classes) 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 these models. iswar se do minute aakhe bandh karke dua karnaki wo unki manzil paa le thanx Page 7

8 VISIT: Question 6: What is state diagram? Explain its advantages. Draw state diagram for Railway Ticket Booking on IRCTC website. A state diagram is a type of diagram used in computer science and related fields to describe the behavior of systems. 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 state diagrams exist, which differ slightly and have different semantics. A state diagram, also called a state machine diagram or statechart diagram, is an illustration of the states an object can attain as well as the transitions between those states in the Unified Modeling Language (UML). In this context, a state defines a stage in the evolution or behavior of an object, which is a specific entity in a program iswar se do minute aakhe bandh karke dua karnaki wo unki manzil paa le thanx Page 8

9 VISIT: or the unit of code representing that entity. State diagrams are useful in all forms of object-oriented programming (OOP). The concept is more than a decade old but has been refined as OOP modeling paradigms have evolved. A state diagram resembles aflowchart in which the initial state is represented by a large 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 stacked sections. In that case, the upper section contains the name of the state, the middle section (if any) contains the state variables and the lower section contains the actions performed in that state. If there are no horizontal lines through a box, only the name of the state is written inside it. External straight lines, each with an arrow at one end, connect various pairs of boxes. These lines define the transitions between states. The final state is portrayed as a large black dot with a circle around it. Historical states are denoted as circles iswar se do minute aakhe bandh karke dua karnaki wo unki manzil paa le thanx Page 9

10 VISIT: as VIJAY..now in facebook.join ON FB VIJAY writing we are not responsible for anything. State diagrams are used to give an abstract description of the behavior of a system. This behavior is analyzed and represented in series of events, thatt could occur in one or more possible states. Hereby "each diagram usually represents objects of a single class and track the different states of its objects through the system" MSG: All you know that Vijay sir is CS.and because of his busy schedule,we (Anikesh, Neeraj) will when sir will become free from his work, they will surely continue to maintain this blog.. you can iswar se do minute aakhe bandh karke dua karnaki wo unki manzil paa le thanx Page 10

11 VISIT: Question 7: What is need of concurrency management in Object Oriented Systems? Explain the important issues related to concurrency management with the help of an example. Concurrent programming encompasses programming languages and algorithms used to implement concurrent systems. Concurrent programming is usually considered to be more general than parallel iswar se do minute aakhe bandh karke dua karnaki wo unki manzil paa le thanx Page 11

12 VISIT: programming because it can involve arbitrary and dynamic patterns of communication and interaction, whereas parallel systems generally have a predefined and well-structured communications pattern. The base goals of concurrent programming include correctness, performance and robustness. Concurrent systems such asoperating systems and Database management systems are generally designed to operate indefinitely, including automatic recovery from failure, and not terminate unexpectedly (see Concurrency control). Some concurrent systems implement a form of transparent concurrency, in which concurrent computational entities may compete for and share a single resource, but the complexities of this competition and sharing are shielded from the programmer. Because they use shared resources, concurrent systems in general require the inclusion of some kind of arbiter somewhere in their implementation (often in the underlying hardware), to control access to those resources. The use of arbiters introduces the possibility of indeterminacy in concurrent computation which has major implications for practice including correctness and performance. For example arbitration introduces unbounded nondeterminism which raises issues with model checking because it causes explosion in 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 which several computations are executing simultaneously, and potentially interacting with each other. The computations may be executing on multiple cores in the same chip, preemptively timeshared threads on the same processor, or executed on physically separated processors. A number of mathematical models have been developed for general concurrent computation including Petri nets, 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, the number of possible execution paths in the system can be extremely large, and the resulting outcome can be indeterminate. Concurrent use of shared resources can be a source of indeterminacy leading to issues such as deadlock, and starvation. [1] The design of concurrent systems often entails finding reliable techniques for coordinating their execution, data exchange, memory allocation, and execution scheduling to minimize response time and maximize throughput. [2] Question 8: What is association in UML Diagram? Briefly explain different types of associations available in UML. Also iswar se do minute aakhe bandh karke dua karnaki wo unki manzil paa le thanx Page 12

13 VISIT: explain the process of mapping a ternary association into UML Association Association is a relationship between classifiers which is used to show that instances of classifiers could be either linked to each other or combined logically or physically into some aggregation. UML specification categorizes association as semantic relationship. Some other UML sources also categorize association as a structural relationship. Wikipedia states that association is instance level relationship and that associations can only be shown on class diagrams. Not sure where they got that information from but it is not based on UML specification. Association could be used on different types of UML 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 are orthogonal concepts,..." which is clearly an overstatement. Orthogonal usually means completely independent. While notation for aggregation type, navigability, and association end ownershipcould be applied independently, the concepts themselves are not orthogonal. For example, in UML 2.4 end property of association owned by an end class is navigable, which clearly makes navigability dependent on ownership. iswar se do minute aakhe bandh karke dua karnaki wo unki manzil paa le thanx Page 13

14 VISIT: as VIJAY..now in facebook.join ON FB VIJAY writing we are not responsible for anything. Association relationship overview diagram An association is usually drawn as a solid line connecting two classifiers or a single classifier to itself. Name of the association can be shown somewhere near the middle of the association line but not too close to any of the ends of the line. Each end of the line could be decorated with the name of the association end. Association End Association end is a connection between the line depicting an association and the icon depicting the connected classifier. Name of the association end may be placed near the end of the line. The association end name is commonly referred to as role name (but it is not defined as such in the UML 2.4 standard). The role name is optional and suppressible. Professor "playing the role" of author is associated with textbook end typed as Book. MSG: All you know that Vijay sir is CS.and because of his busy schedule,we (Anikesh, Neeraj) will when sir will become free from his work, they will surely continue to maintain this blog.. you can iswar se do minute aakhe bandh karke dua karnaki wo unki manzil paa le thanx Page 14

15 VISIT: as VIJAY..now in facebook.join ON FB VIJAY writing we are not responsible for anything. The idea of the role is that the same classifier can play the same or different roles in other associations. For example, 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 filled circle (aka dot). The dot is drawn at the point where line meets the classifier. It could be interpreted as showing that the model includes a property of the type represented by the classifier touched by the dot. This property is owned by the classifier at the other end. Association end query is owned by classifier QueryBuilder and association end qbuilder is owned by association Builds itself The "ownership" dot may be used in combination with the other graphic line-path notations for properties of associations 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 shall apply in models where such use is elected. The dot notation must be applied at the level of complete associations or higher, so that the absence of the dot signifies ownership by the association. In other words, 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 by a class is also an attribute. This notation may be used in conjunction with the line arrow notation to make it perfectly clear that the attribute is also an association end. Association end qb is an attribute of SearchService class and is owned by the class. Navigability End property of association is navigable from the opposite end(s) of association if instancess of the classifier at this end of the link can be accessed efficiently at runtime from instances at the other ends of the link. MSG: All you know that Vijay sir is CS.and because of his busy schedule,we (Anikesh, Neeraj) will when sir will become free from his work, they will surely continue to maintain this blog.. you can iswar se do minute aakhe bandh karke dua karnaki wo unki manzil paa le thanx Page 15

16 VISIT: as VIJAY..now in facebook.join ON FB VIJAY writing we are not responsible for anything. UML specification does not dictate how efficient this access should be or any specific mechanism to achieve the efficiency. It is implementation specific. When end property of association is marked as not navigable, in [UML 2.4] it means that "access from the other ends may or may not be possible, and if it is, it might not be efficient." The problem with this definition of 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 the association indicates that the association isnavigable from the opposite ends; otherwise, the association is not navigable from the opposite ends. This definition is odd because it makes navigability strongly dependent on ownership, while these are assumed to be orthogonal concepts; some examples in UML 2.4 specs show end properties owned by a class as 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. MSG: All you know that Vijay sir is CS.and because of his busy schedule,we (Anikesh, Neeraj) will when sir will become free from his work, they will surely continue to maintain this blog.. you can iswar se do minute aakhe bandh karke dua karnaki wo unki manzil paa le thanx Page 16

17 VISIT: as VIJAY..now in facebook.join ON FB VIJAY writing we are not responsible for anything. 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 an attribute of the featuring classifier. Arity Each association has specific arity as it could relate two or more items. Binary Association Binary association relates two typed instances. It is normally rendered as a solid line connecting two classifiers, or a solid line connecting a single classifier to itself (the two ends are distinct). The line may consist of one or more connected segments. Job and Year classifiers are associated A small solid triangle could be placed next to or in place of the name of binary association (drawn as a solid line) to show the order of the ends of the association. The arrow points along the line in the direction of the last end in the order of the association ends. This notation also indicates that the association is to be read from the first end to the last end. Order of the ends and reading: Car - was designed in - Year MSG: All you know that Vijay sir is CS.and because of his busy schedule,we (Anikesh, Neeraj) will when sir will become free from his work, they will surely continue to maintain this blog.. you can iswar se do minute aakhe bandh karke dua karnaki wo unki manzil paa le thanx Page 17

18 VISIT: as VIJAY..now in facebook.join ON FB VIJAY writing we are not responsible for anything. UML 2.4 specification states that this arrow is used for documentation purposes only and has no general semantic interpretation.. This is an odd clarification as UML diagrams are in fact used mostly for documentation purposes but even more important, this arrow according to the UML spec defines theorder of association ends - which does belong to semantics. N-ary Association Any association may be drawn as a diamond (larger than a terminator on a line) with a solid line for each association end connecting the diamond to the classifier that is the end s type. N-ary association with more than two ends can only be drawn this way. Ternary association Design relates three classifiers Shared and Composite Aggregation Aggregation is a binary association representing some whole/part relationship. Aggregation type could be either: shared aggregation (aka aggregation), or composite aggregation (aka composition). Aggregation Aggregation (shared aggregation) is a "weak" form of aggregation when part instance is independent of the composite: the same (shared) part could be included in several composites, and if composite is deleted, shared parts may still exist. MSG: All you know that Vijay sir is CS.and because of his busy schedule,we (Anikesh, Neeraj) will when sir will become free from his work, they will surely continue to maintain this blog.. you can iswar se do minute aakhe bandh karke dua karnaki wo unki manzil paa le thanx Page 18

19 VISIT: Shared aggregation is shown as binary association decorated with a hollow diamond as a terminal adornment at the aggregate end of the association line. The diamond should be noticeably smaller than the diamond notation for N-ary associations. Search Service has a Query Builder using shared aggregation Composition Composition (composite aggregation) is a "strong" form of aggregation. Composition requirements/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 necessarily deleted as part of the composite. Composite aggregation is depicted as a binary association decorated with a filled black diamond at the aggregate (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. UML specification needs to be updated to explicitly allow this interpretation. Hospital has 1 or more Departments, and each Department belongs to exactly one Hospital. If Hospital is closed, so are all of its Departments. iswar se do minute aakhe bandh karke dua karnaki wo unki manzil paa le thanx Page 19

20 VISIT: 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 be a member of one Department (or none). If Department is closed, its Staff is relieved (but excluding the "stand alone" Staff). Association Class An association may be refined to have its own set of features; that is, features that do not belong to any of the 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 be included in other associations. An association class can be seen as an association that also has class properties, or as a class that also has association properties. An association class is shown as a class symbol attached to the association path by a dashed line. The association path and the association class symbol represent the same underlying model element, which has a single name. The association name may be placed on the path, in the class symbol, or on both, but they must be the same name. Link Link is an instance of an association. It is a tuple with one value for the each end of the association, where each 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 than classifiers. Name of the link could be shown underlined though it is not required. End names (roles) and navigation arrows can be shown. iswar se do minute aakhe bandh karke dua karnaki wo unki manzil paa le thanx Page 20