CIS 380 Study Guide Test 1
CIS 380 Study Guide Test 1 CIS 380
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This 9 page Study Guide was uploaded by miranda Notetaker on Monday September 26, 2016. The Study Guide belongs to CIS 380 at Eastern Kentucky University taught by Dr. Randles in Fall 2016. Since its upload, it has received 52 views.
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Date Created: 09/26/16
Miranda Sheaffer- CIS 380 CHAPTER 4 1. a logical model shows what the system does, not how it does it. the distinction is important bc focusing on implementations issues at this point would restrict your research for the most effective system design. four basic symbols that represent processes, data flows, data stores, external entities. process name identifies a specific function and consists of a verb followed by a singular noun.a process appears as a black box. at least one data flow must enter and one data flow must exit each process symbol as they do in the create invoice. a process can connect to any other symbol. 2. a DFD does not show the detailed contents of a data store, the specific structure and data elements are defined in the data dictionary. key issue with data store and time is the matter of seconds while a transition is processed or a period of months while data is accumulated for year end processing.data store is a flat rectangle that is open on the right side and closed on the left side, the name of the data store appears between the lines and identifies the data it contains- name is plural consisting of a noun and adjectives if needed.a data store must be connected to a process with data flow. data store has at least one incoming and one outgoing data flow and is connected to a process symbol with data flow. 3. external entities show the boundaries of the information system and how the information system interacts with the outside world. external entity is named by the singular form of a department, outside organization and other information system or person. external entity must be connected to a process by a data flow.first step in constructing a DFD is to draw a context diagram. to draw a context diagram you place a single process symbol in the center of the page, symbol represents the entire info system and you identify it as process 0. then you place the external entities around the perimeter of the page and use data flows to connect the entities to the central process.you do not show any data stores in a context diagram bc data stores are internal to the system. 4. context diagram for the order system appears more complex than the grading system bc it has two more external entities and three more data flows, number of components, number of levels, and the degree of interaction among its processes, external entities, data stores and data flows make a system more complex than another. 5 conventions page 4.9-4.10 5. process numbers do not suggest that the processes are accomplished in a sequential order each process is always considered to be available, active, and awaiting data to be processed. a specific sequence is documented in the process descriptions not in the DFD. diverging data flow is where same data travels to two or more different locations. diverging data flow is the best way to show the flow rather than showing two identical data flows which could be misleading. if same data flows in both directions, you can use the double headed arrow to connect symbols. to identify specific data flows into and out of a symbol you use separate data flow symbols with single arrowheads. 6. under the leveling concept the context diagram represents the highest level view of an information system followed by diagram 0, the grading system is simple, completely represented by a context diagram and a diagram 0. the more complex and includes an additional level of DFDs larder info systems such as the manufacturing system might require an analyst to work though many DFD levels to reach the systems functional primitive processes. 7. you show a data store only when two or more processes use that data store. daily payments data store was internal to process 3 so the analyst did not show it in diagram 0. main objective is to ensure that your model is accurate and easy to understand. reviewing data and process models with users allows you to obtain their feedback and approval for the logical design system. 8. a data dictionary is a central storehouse of info about the systems data. it collects, documents, and organizes specific facts about the system including the contents of data flows data stores external entities and processes.data stores and flows are based on data structures that are composed of data elements. p 4.21 (components of the data elements description) 9. data flow- records are defined separately form the data flows and data stores, when records are defined more than one data flow or data can use the same record, volume and frequency describes the expected number of occurrences for the data flow per unit of time. data stores- volume and frequency describes the estimated number of records stored in the data store specifies any growth and changes statistics for the data store. processes description is filled only if the processes i a functional primitive ( in order for this to happen, the process description documents the processing steps and business logic) 10.modular design is based on combinations of three logical structures called control structures which are building blocks for the process- they are sequence, selection and iteration. modular design is analyzing a functional primitive you break the processing steps down into smaller units in a process sequence rectangle represents a step or process, diamond represents a condition of decision and the logic follows the lines in the direction indicated by the arrows. 11.second step- enter the condition under the heading with one condition per line to represent the customer status and availability of products. third- enter all potential combinations of Y/N for the conditions. each column represents a numbered possibility called a rule. fourth- place an x in the action entries area for each rule to indicate whether to accept or reject the order. decision trees and tables are equivalent but in different forms a graphic versus a table. 12.a decision tree is read from left to right with the conditions along the various branches and the actions at the far right. four terminating branches are at the right side of the tree. a matter of preference is used when deciding on a table versus vice versa. physical model follows the logical model and involved operational tasks and techniques. recommended sequence of models are physical model of current system, logical of current system, logical model of new system and physical model of new system CHAPTER 5 1. the patient is the object, the doctor is an object and the appointment itself is an object. the end product of object oriented analysis is an object model which represents the info system in terms of objects and object oriented concepts. object oriented analysis is a popular approach that sees a system form the viewpoint of the objects themselves as they function and interact with the system. objects represent a person, place, event, transaction UML represents an object as a rectangle with the object name at the top followed by the objects attributes and methods. 2. objects are similar to nouns and attributes are similar to adjectives that describe the characteristic of an object. the business requirements of the info system and its users determine how many attributes are needed. attributes are defined during the systems design process. inherit means to acquire certain attributes from other objects. examples of a state include future/current/past (all which describe student bc they are supposed to be adj). a method defines specific tasks that an object can perform. methods resemble verbs that describe what and how an object does something. number os steps vary when adding a new instance 3. view an object as a black box, encapsulation is when all data and methods are self contained, by limiting access to internal processes an object prevents its internal code from being altered by another object or process. objects send and receive messages but do not alter the internal methods of other objects. advantage of OO design is that systems analysts can save time and avoid errors by using modular objects and programmers can translate the designs into code working with reusable program modules that have been tested and verified. example being a sales transaction. 4. an object belongs to a group or category called a class. all objects share common attributes and methods. a subclass is a more specific category within a class. a more general category is a super class. relationships enable objects to communicate and interact as they perform business functions and transactions required by the system. they describe what objects respond to changes in other objects and the effects of membership in classes, superclass, subclass.weakest to strongest are dependency, association, aggregation and inheritance. figure 5-19 is broken down into more attributes and methods. bc all employees share certain attributes those attributes are assumed through inheritance and do not need to be repeated in the instructor object. 5. use case represents the steps in a specific business function or process, an external entity or actor initiates the case by representing the system to perform a function or process 6. an actor is the one who initiates the use case. can ask interact with other use cases 7. use case diagram is a visual summary of several related use cases within a system or subsystem. system boundary what is included in the system and what is not included in the system.after identifying it you pace the use cases on the diagram, add the actors, and show the relationships. class diagram represents a detailed view of a single use case. class diagram is a logical model which evolves into a physical model and finally becomes a functioning information system. class diagrams evolve into code modules, data objects and other system components. each class appears as as a rectangle with the class name at the top followed by the class attributes and methods. lines show relationships between classes and have labels identifying the action that relates the two classes. 8. sequence diagram graphically documents the use case by showing classes, and timing of the messages. a lifeline represents the time during which the object above it is able to interact with the other objects in the use case.focus is identified by a narrow vertical rectangle that cover the lifeline, it indicates when an object send or receives a message. state transition diagram shows how an object changes from one state to another depending on events that affect the object. all possible states must be documented in the state transition diagram. you read it from left to right the lines show direction and describe the action or event that causes a transition from one state to another. 9. you should organize your use cases and use case diagrams so they can be linked to the appropriate class, state transition, sequence, and activity diagrams. Object Oriented Thought Process CHAPTER 1 1. Object wrappers are object oriented code that includes other code inside 2. Businesses are gravitating toward objects because the technologies used for electric commerce are mostly OO in nature. Objects are defined by attributes and behaviors. Both is the key difference between OO programming and other programming methods because in OO design the attributes and behaviors are contained within a single object, where in a procedure the attributes and behaviors are normally separated. A black box is where inputs go in and outputs come out. 3. Global data is a problem in procedural programming because you have no control over who has access to the data, testing and debugging are much more difficult. This provides a high amount of data integrity in OO systems. 4. Data is referred to as attributes and functions are referred to as methods. data hiding is restricting access to certain attributes and or methods. 5. Procedural programming normally separates the data of a system from the operations that manipulate the data. Advantage of OO programming is that the data and the operations that manipulate the data are both encapsulated in the object. 6. concept of encapsulation example would be combining the attributes and methods in the same entity, which in OO parlance. Objects are the building blocks of an OO program.Behaviors are contained in methods in the OO program. 7. Getters and setters provide controlled access to an objects data. users need to know the name of the method, parameters passed to the method, return type of method for using OO methods. 8. Classes can be thought of as the templates for objects, higher level data type. an object cannot be instantiated without a class. 9. a class is a blueprint for an object, use a class for a basis for how the object is built. relational database, in the database table the definition of the table itself would be a class and the objects would be the rows of the table. a class might also be thought of as template or cookie cutter for objects 10.only the public methods, not the private methods of an object can be invoked by another object. internal behaviors are private methods that are not accessible by other objects. encapsulation enables data hiding. 11.*** 12.*** 13.Page 23 is example. Must specify a way for the user to invoke and obtain the square value and also provide the implementation that calculates the square. 14.plus sign designates public while minus sign designates private. can identify the interface by the methods prefaced with plus signs. 15.OO goes a step further and allows you to define relationships between classes that facilitate not only code reuse but also better overall design by organizing classes and factoring in commonalities of various classes. inheritance is a primary means of providing this functionality. inheritance allows a class to inherit attributes and methods of another class. this allows the creation of brand new classes by abstracting out common attributes and behaviors. When a dog or cat is instantiated it contains everything in its own class as well as everything from the parent class. 16.contains all the attributes and behaviors that are common to classes that inherit from it. an is-a relationship is when a circle, square and star all inherit directly from shape. 17.means many shapes, its it cited as one of the most powerful advantages to object oriented technologies- p28 for for the draw method example 18.when a method name is the same as the class and no return type is provided, the method is a special method. constructor is the entry point for the class, where the object is built, the constructor is a good place to perform start up tasks. 19.if a subclass inherits an abstract method from a superclass, it must provide a concert implementation of that method, or else it will be an abstract class itself 20.a has a relationship is a composition relationship CHAPTER 2 1. the fundamental unit of OO design is class. the desired end result is a robust and functional object model aka a complete system 2. *** 3. page 39 for example 4. change in implementation should not require change to users code, if interface does not change, the user does not care whether the implementation is changed. the interface is the application programming interface that the programmer will use the methods are in effect wrappers that enclose the functionality provided by the database system. public interface are plus signs next to the names of methods that are public interfaces. 5. initially provide the user with no public interfaces 6. dynamic loaded classes are loaded at runtime, not linked to an executable file, no user classes would have to be recompiled. static classes a link is required to bring in a new class. reusable classes tend to have interfaces that are more abstract than concrete. 7. our goal is to design an abstract highly reusable class and we will design highly abstract user interfaces to do this 8. much easier for one comment that to have separate interfaces with multiple steps, it is reusable 9. you must determine the behaviors of the objects. from the viewpoint of all the users, begin identifying the purpose of each object and what it must do to perform properly. 10.*** 11.anything that is not considered public interface is implementation, means the user will never see any of the methods that are considered part of the implementation including the signature and the code inside the method CHAPTER 3 1. constructors are structured programs 2. if you do not include a constructor the class will still compile and you can still use it 3. good to always include at least one constructor in a class. overloading allows a programmer to use the same method name over and over as long as the signature of the method is different each time. signature consists of the method name and a parameter list 4. you must know how the parent class is constructed, you must become intimately aware of all the parents data and behavior. each class attribute of the object is initialized. good practice to initialize all the attributes, if design is good you should practice to identify a stable state for all attributes and then initialize them to this stable state in the constructor. 5. ignore the problem, check for potential problems and abort the program when you find a problem, check for potential problems, catch the mistake, and attempt to fix the problem, throw an exception 6. primary directive for all applications is that the application should never crash, if you don't handle errors the application will eventually terminate ungracefully or continue in a mode that can be considered unstable state. good to check for problems and abort because the application can display a message indicating that a problem exists.a system exception will come up if a conditional statement is not included in the code. the better solution would be t prompt the user to reenter the proper input value 7. exceptions are unexpected events that occur within a system, provide a way to detect problems and then handle them. catch and throw is when a specific block of code is written to handle a specific exception. 8. you can catch exceptions at various levels of granularity, you can catch all or specific 9. exception parameter in the catch block is used to catch any exception that might be generated within a try block. each object is constructed separately and is allocated its own separate memory, some may be shared by all the objects instantiated from the same class, sharing memory allocated for these class attributes and methods. Shared/ loca/ object attributes 10.a compiler can tell which copy to count to access simply by recognizing which method it is in 11.*** 12.“this” directs the compiler to access object variable count and not the local variables within the method bodies 13.its possible for two or more objects to share attributes 14.Java decided that operator overloading was more of a problem than it was worth. problems with complex data structures is that they might contain references. deep copy occurs when all the references are followed and new copies are created for all referenced objects. shallow copy would copy reference and not follow the levels 15.only the references are copied, not any of the actual objects CHAPTER 4 1. when objects are instantiated, they almost always interact with other objects, they can be part of one another. 2. attributes represent the state of the object because they store the info about the object. making private keeps in with the design principle of keeping the interface design as minimal as possible- only accessible within declaring object. static keyword signifies that there will be one copy of this attribute for all the objects instantiated by this class 3. reference to another object, this class cab holds information about the cab such as its serial if number and maintenance records. 4. if an attribute is static and the class provides a setter for that attribute, any object that invoked the setter will change the single copy 5. public interface methods tend to be very abstract and the implementation tends to be more concrete. private methods are meant to be part of the implementation and not the public interface. these methods are called internally from the class itself (what calls these methods), private methods are strictly part of the implementation and are not accessible by other classes. CHAPTER 5 1. Primary goal is to model real world systems in ways similar to the ways in which people actually think. OO approach encapsulates the data and behavior into objects that interact with each other. 2. represent true behavior of the object. describes the service that the client wants accomplished. if designed with inheritance composition in mind a new class can utilize an existing class and create a new class with extended interface. 3. public interface provides users a way to get interface to do they job right but hides details. implementation should not involve user at all where as public interface revolves around users of class. a change to implementation should not necessitate a change in the users application code. “all fields shall be private” meaning none of the fields in a class are accessible from other objects. 4. constructor should put an object into an initial, safe state.destructors include proper clean up functions. destructor must free up memory that objects acquire during existence. if ignored, there is a memory leak. should anticipate potential errors and includes code to handle these conditions when encountered. 5. a class will service other classes, it will request the services of other classes or both 6. extensible means to add new features to a class, extending an existing class, adding new methods, modifying behavior. do not want to design a class so it contains behavior that prevents it from being extended by another class. guideline is abstract guideline. names should be descriptive and make sense. 7. non portable code should abstract the code out of the class. advantage includes the “wrapper class” which decides what codes to invoke. make sure class behavior has localized attributes. 8. good programing style is to minimize the scope of global variables and not specific to OO programming. appropriate attribute for temporary is to be local- small as possible. 9. p 96- print command passed to each shape as an argument. need a case statement to determine what to do for given shape. separate print routine for each shape. all calls are identical to it is the context of the shape that dictates how the system reacts. 10.class design forces you to keep a high level of paintability and to organize your code into many manageable pieces. high coupled classes are highly dependent on one another. couping level of classes should be kept as low as possible. 11.testing process includes creating code in small increments and building them and testing at each step. include walk throughs and other design techniques. stubs allow you to test the interfaces without writing any real code and it verifies interfaces are working properly. 12.keep stubs around for later use, they should be integrated into code 13. serializing is a system that deconstructs the object, send it over the wire and reconstructs it on the other end of the wire.
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