DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING. 2 Marks and 11 Marks for Unit - 3

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1 DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING Subject Name: Subject Code: Staff name: Software Engineering CS T55 Dr K. Shantha Kumari 2 Marks and 11 Marks for Unit - 3 Software Design and Function Oriented Software Design: Outcome of a Design Process Characteristics of a Good Software Design Coupling and Cohesion Approaches to Software Design Object Oriented Vs Function Oriented Software Design approaches Structured Analysis Data Flow Diagrams Applying DFD to Real time systems Structured and Detailed Design. 1

2 PART A 1. List the characteristics of a good software design [April 2016] Correctness: A good design should correctly implement all the functionalities identified in the SRS document. Understandability: A good design is easily understandable. Efficiency: It should be efficient. Maintainability: It should be easily amenable to change 2. Compare object-oriented and function oriented system[april 2016] Function Oriented Design In function-oriented design, the system is comprised of many smaller sub-systems known as functions. These functions are capable of performing significant task in the system. The system is considered as top view of all functions. Function oriented design inherits some properties of structured design where divide and conquer methodology is used. Object Oriented Design Object oriented design works around the entities and their characteristics instead of functions involved in the software system. This design strategy focuses on entities and its characteristics. The whole concept of software solution revolves around the engaged entities. 3. Define coupling [Nov 2015] Coupling between two modules/classes/components is a measure of the degree of interdependence or interaction between the two modules or mutual interdependence between modules. The lower the coupling, the better the program. Two modules are said to be highly coupled when: -function calls between two modules involve & shared large chunk of data. -interaction occurs through shared data. 4. What is cohesion? [Nov 2015] Cohesion is a measure that defines the degree of intra-dependability within elements of a module. The greater the cohesion, the better is the program design. When function of one module cooperates with another to perform single objective then module is said to be good cohesion. 5. Enumerate the different types of cohesion that a module might exist. Give examples of each There are seven types of cohesion, namely Co-incidental cohesion - It is unplanned and random cohesion, which might be the result of breaking the program into smaller modules for the sake of modularization. Because it is unplanned, it may serve confusion to the programmers and is generally not-accepted. Logical cohesion - When logically categorized elements are put together into a module, it is called logical cohesion. 2

3 Temporal Cohesion - When elements of module are organized such that they are processed at a similar point in time, it is called temporal cohesion. Procedural cohesion - When elements of module are grouped together, which are executed sequentially in order to perform a task, it is called procedural cohesion. Communicational cohesion - When elements of module are grouped together, which are executed sequentially and work on same data (information), it is called communicational cohesion. Sequential cohesion - When elements of module are grouped because the output of one element serves as input to another and so on, it is called sequential cohesion. Functional cohesion - It is considered to be the highest degree of cohesion, and it is highly expected. Elements of module in functional cohesion are grouped because they all contribute to a single well-defined function. It can also be reused. 6. Enumerate the different types of coupling that might exist between two modules. Give examples of each There are five levels of coupling, namely - Content coupling - When a module can directly access or modify or refer to the content of another module, it is called content level coupling. Common coupling- When multiple modules have read and write access to some global data, it is called common or global coupling. Control coupling- Two modules are called control-coupled if one of them decides the function of the other module or changes its flow of execution. Stamp coupling- When multiple modules share common data structure and work on different part of it, it is called stamp coupling. Data coupling- Data coupling is when two modules interact with each other by means of passing data (as parameter). If a module passes data structure as parameter, then the receiving module should use all its components. 7. What is meant by functional independence in the context of software design? (What are the advantages of functional independence?) (How can functional independence in a software design be achieved?)* A module that is highly cohesive and also has low coupling with other modules is said to be functionally independent of the other modules. Advantages of functional independence o Error isolation o Scope of reuse o Understandability 8. What is meant by decomposition in the context of software design? In this technique, a complex problem is divided into several smaller problems and then the smaller problems are solved one by one. The primary characteristics of neat module decomposition are high cohesion and low coupling. 3

4 The problem has to be decomposed such that each component of the decomposed problem can be solved independently and then the solution of the different components can be combined to get the full solution. 9. What is meant by abstraction in the context of software design? The function-oriented design mechanism divides the whole system into smaller functions, which provides means of abstraction by concealing the information and their operation. These functional modules can share information among themselves by means of information passing and using information available globally. 10. Define top-down decomposition in the context of function-oriented design Top-down design starts with a generalized model of system and keeps on defining the more specific part of it. Top-down design takes the whole software system as one entity and then decomposes it to achieve more than one sub-system or component based on some characteristics. Top-down design is more suitable when the software solution needs to be designed from scratch and specific details are unknown. 11. Define DFD Data flow diagram is a graphical representation of data flow in an information system. It is capable of depicting incoming data flow, outgoing data flow and stored data. The DFD does not mention anything about how data flows through the system. 12. What is functional cohesion & Logical cohesion? A module is said to possess functional cohesion, if different functions of the module cooperate to complete a single task. A module is said to be logically cohesive, if all elements of the module perform similar operations such as error handling data input, data output, etc. 13. What is Procedural cohesion? A module is said to possess procedural cohesion, if the set of functions of the module are executed one after that other, though these functions may work towards entirely different purposes and operate on very different data. 14. List the classification of coupling.(nov 2015) The classification of coupling are o Data Coupling o Stamp Coupling o Control Coupling o Common Coupling o Content Coupling 4

5 15. What is data coupling & control coupling? Two modules are data coupled, if they communicate using an elementary data item that is passed as a parameter between the two, e.g an integer, a float, a character, etc. Control coupling exists between two modules, if data from one module is used to direct the order of instruction execution in another. 16. What is Stamp coupling & content coupling? Two modules are stamp coupled, if they communicate using a composite data item such as a record in PASCAL or structure in C. Content coupling exists between two modules, if they share code. That is, a jump from ne module into the code of another module can occur. 17. Define coupling. (Nov 2013) The coupling between two modules indicates the degree of interdependence between them. The degree of coupling between two modules depends on their interface complexity and based on the data they share among them. 18. List the concepts and terminologies associated with a layered design. Super ordinate and subordinate modules Visibility Control abstraction Depth and width Fan-out Fan-in 19. What is Fan-out & Fan-in? Fan-out is a measure of the number of modules that are directly controlled by a given module. In fig, the fan-out of module M1 is 3. Fan-in indicates the number of modules that directly invoke a given module. The fan-in of the module M1 is 0, that of M2 is 1, and that of M5 is What is object-oriented design?(nov 2015) In the object-oriented design approach, the system is viewed as a collection of objects (i.e. entities). The system state is system state is decentralized among the objects and each object manages its own state information. 5

6 21. What is data abstraction? Any entity external to the object have no knowledge about how data is exactly stored, organized, and manipulated inside the object. The entities external to the object can access the data internal to an object only by calling certain well-defined methods supported by the object. 22. Write Object-oriented Vs Function-oriented design approaches? Object-oriented design approach The state information distributed among several objects of the system It group functions together on the basis of the data they operate on. The basic unit of designing objectorineted programs is objects. Objects appear as nouns Function-oriented design approach The state information in a centralized shared data store. It group functions together that constitute a high level function The basic unit of procedural design is functions. Function appear as verbs. 23. What is top-down decomposition? The top-down decomposition used to denote the successive decomposition of a set of high-level functions into more detailed functions. A function create-new-library member is refined into the following sub functions: o Assign-membership-number o Create-member-record o Print-bill 24. What is the role of Structured analysis(sa) and Structured design(sd)? During structured analysis, the SRS document is transformed into a DFD (Data Flow Diagram) model; functional decomposition of the system is achieved and capture the detailed structure of the system as perceived by the user. During structured design, the DFD model is transformed into a structure chart and all functions identified during structured analysis are mapped to a module structure that is suitable for implementation in some programming language. 25. What are the principles followed in structured analysis technique? Top-down decomposition approach Applications of divide and conquer principle. Through this, each high-level function is independently decomposed into detailed functions. Graphical representation of the analysis results using Data Flow Diagrams (DFDs). 6

7 26. What are the primitive symbols used for constructing DFDs? Function (process or bubble) symbol A function is represented using a circle. External entity symbol Physical entities which interact with the system by inputting data to the system or consuming data produced by the system. This is represented by rectangle. Dataflow symbol - The data flow occurring between two processes or between an external entity and a process in the direction of the data flow arrow. It is represented by directed arc(arrow). Data store symbol It is referred to either a data structure or a physical file on disk. It is represented by two parallel lines. Output symbol the output symbol is used when hard copy is produced. 27. What are synchronous and asynchronous operations? If two bubbles are directly connected by a data flow arrow, then they are synchronous. It means that they operate at the same speed. If two bubbles are connected through a data store then the speed of operation of the bubbles is independent called asynchronous operations. 27. Define Data dictionary. A data dictionary lists the purpose of all data items and the definition of all composite data items in terms of their component data items. A set of information describing the contents, format, and structure of a database and the relationship between its elements, used to control access to and manipulation of the database. 28. What is context diagram (Level 0 DFD)? The context diagram establishes the context in which the system operates. That is who are users, what data do they input to the system, and what data they received by the system. A context diagram (SCD) in software engineering and systems engineering is a diagram that defines the boundary between the system, or part of a system, and its environment, showing the entities that interact with it. 7

8 29. What are the aspects considered in design review? After a design is complete, the design is required to be reviewed. The review team checks the design documents especially for the following aspects: o Traceability o Correctness o Maintainability o Implementation 30. What are the strategies involved in structured design? Structured design provides two strategies to guide transformation of a DFD into a structured chart o Transform analysis o Transaction analysis Normally, one would start with the level 1 DFD, transform it into module representation using either the transform or transaction analysis and then proceed toward the lower level DFDs. 31. Differentiate between structured analysis and structured design in the context of function-oriented design STRUCTURE ANALYSIS The SRS Document is transformed into a DFD model Structured analysis focuses on the following High-level functions of the systems Data-flow among the identified high-level functions The Graphical representation used is the Data flow diagram (DFD) STRUCTURED DESIGN The DFD model is transformed into a structure chart Structured Design focuses on the following: Various modules making up the system Module dependency (Control Flow) Parameters that are passed among various modules The Graphical representation used is the Structure Chart 32. Differentiate between structure chart and a flow chart as design representation techniques STRUCTURE CHART A structure chart represents the software architecture, i.e. the various modules making up the system, the dependency (which module calls which other modules), and the parameters that are passed among the different modules. The procedural aspects (e.g. how a particular functionality is achieved) are not represented. Sequential ordering of tasks is suppressed in a structure chart. FLOW CHART Flow chart is a convenient technique to represent the flow of control in a program. Data interchange among different modules is not represented in a flow chart. Sequential ordering of tasks is available in a flow chart. 8

9 33. What is meant by balancing a DFD? The data that flow into or out of a bubble must match the data flow at the next level of DFD. This is known as balancing a DFD. The concept of balancing a DFD has been illustrated in the following diagram. In the level 1 of the DFD, data items d1 and d3 flow out of the bubble 0.1 and the data item d2 flows into the bubble 0.1. In the next level, bubble 0.1 is decomposed. The decomposition is balanced, as d1 and d3 flow out of the level 2 diagram and d2 flows in. 9

10 PART -B 1. Explain in detail Cohesion in Object Oriented Systems. (May 2014)(Nov 2015) Cohesion is a measure of functional strength of a module. o A cohesive module performs a single task or function. Coupling between two modules a measure of the degree of interdependence or interaction between the two modules. A module having high cohesion and low coupling functionally independent of other modules. A functionally independent module has minimal interaction with other modules. Advantages of Functional Independence Better understandability and good design. Complexity of design is reduced, Different modules easily understood in isolation: o modules are independent Functional independence reduces error propagation. o Degree of interaction between modules is low. o An error existing in one module does not directly affect other modules. Reuse of modules is possible. A functionally independent module: o Can be easily taken out and reused in a different program. o each module does some well-defined and precise function o The interfaces of a module with other modules are simple and minimal. Classification of Cohesiveness Classification is often subjective,yet gives us some idea about cohesiveness of a module. By examining the type of cohesion exhibited by a module: o We can roughly tell whether it displays high cohesion or low cohesion. 10

11 Coincidental cohesion The module performs a set of tasks which relate to each other very loosely, if at all. The module contains a random collection of functions. Functions have been put in the module out of pure coincidence without any thought or design. Logical cohesion All elements of the module perform similar operations: o e.g. error handling, data input, data output, etc. An example of logical cohesion: o a set of print functions to generate an output report arranged into a single module. Temporal cohesion The module contains tasks that are related by the fact that all the tasks must be executed in the same time span. Example: o The set of functions responsible for initialization, Start-up, shut-down of some process, Procedural cohesion The set of functions of the module: o all part of a procedure (algorithm) o certain sequence of steps have to be carried out in a certain order for achieving an objective, e.g. the algorithm for decoding a message. Communicational cohesion All functions of the module reference or update the same data structure. 11

12 Example: o The set of functions defined on an array or a stack. Sequential cohesion Elements of a module form different parts of a sequence, output from one element of the sequence is input to the next. o Example: Functional cohesion Different elements of a module cooperate: o to achieve a single function, o e.g. managing an employee's pay-roll. When a module displays functional cohesion,we can describe the function using a single sentence. Determining Cohesiveness Write down a sentence to describe the function of the module o If the sentence is compound, it has a sequential or communicational cohesion. o If it has words like first, next, after, then, etc. it has sequential or temporal cohesion. o If it has words like initialize, it probably has temporal cohesion. 2. Explain Coupling in Object Oriented Systems.(May 2014) Coupling Coupling indicates: o The degree of coupling between two modules depends on their interface complexity. o There are no ways to precisely determine coupling between two modules: o Classification of different types of coupling will help us to approximately estimate the degree of coupling between two modules. o Five types of coupling can exist between any two modules. Classes of coupling 12

13 Data coupling Two modules are data coupled,if they communicate via a parameter,an elementary data item, e.g an integer, a float, a character, etc. o The data item should be problem related: Not used for control purpose. Stamp coupling Two modules are stamp coupled, if they communicate via a composite data item such as a record in PASCAL or a structure in C. Control coupling Data from one module is used to direct order of instruction execution in another. Example of control coupling: o a flag set in one module and tested in another module. Common Coupling Two modules are common coupled, if they share some global data. Content coupling Content coupling exists between two modules: o if they share code, o e.g, branching from one module into another module. The degree of coupling increases from data coupling to content coupling. 3. Explain about DFD in detail. (Nov 2014) DATA FLOW DIAGRAMS (DFDs) The DFD (also known as the bubble chart) is a simple graphical formalism that can be used to represent a system in terms of the input data to the system. Various processing carried out on these data, and the output data generated by the system. The main reason why the DFD technique is so popular is probably because of the fact that DFD is a very 13

14 simple formalism. It is simple to understand and use. A DFD model is uses a very limited number of primitive symbols to represent the functions performed by a system and the data flow among these functions with a set of high level functions that a system performs. A DFD model hierarchically represents various sub-functions. External entity Process Data store output Data flow Simple to understand any hierarchical model of a system, different details of the system can be slowly introduced through different hierarchies. The data flow diagramming technique also follows a very simple set of initiative concepts and rules. We now first explain the different symbols and then elaborate the various concepts associated with building a DFD model of a system. PRIMITIVE SYMBOLS USED FOR CONSTRUCTING DFDs: Functional symbol: A functional symbol is represented using a circle. This symbol is called a process or a bubble. Bubbles are annotated with the names of the corresponding functions. External entity set: An external entity such as a librarian, a library member, etc. is represented by a rectangle. The external entities are essential those physical entities external to the software system which interact 14

15 with the system by inputting data to the system or by consuming the data produced by the system. In addition to the human users, the external entity symbols can be used to represent external hardware and software such as another application software. Data flow symbol: A directed arc or arrow is used as a data flow symbol. A data flow symbol represents the data flow occurring between two process, or between an external entity and a process in the direction of the data flow arrow. Data flow symbols are usually annotated with the corresponding data names. Data store symbol: A data store represents a logical file. It is represented using two parallel lines. A logical file can represent either a data store symbol which can represent either a data structure or a physical file on disk. Each data store is connected to a process by means of a data flows symbol. The direction of data flow arrow shows whether data is being read from or written into a data store. An arrow flowing in or out of a data store implicitly represents the entire data of the data store and hence arrows connecting to a data store need not be annotated with the name of the corresponding data items. Output symbol: The output symbol is used when a hard copy is produced and the user of the copies cannot be clearly specified or there are several users of the output. For example, the data store may look like a box with one end closed. Some Important Concepts Associated with Designing DFDs Before we describe how to construct the DFD model of a system, let us discuss some important concept associated with DFDs. Synchronous and asynchronous operations If two bubbles are directly connected by a data flow arrow, then they are synchronous. This means that they operate at the same speed. 15

16 However, if two bubbles are connected through a data store, then the speeds of operations of the bubbles are independent. The data produced by a producer bubble gets stored in the data store. The producer may store several pieces of data items in the data store before the consumer bubble consumes any of them. Data dictionary Every DFD model of the system must be accompanied by a data dictionary. A data dictionary lists all data items appearing in the DFD model of the system. The data items listed include all data flows and content of all data stores appearing on all DFDs in the DFD model of the system. It may be recalled that the DFD model of the system typically consists of several DFDs, namely level 0 DFD, level 1 DFD, level 2 DFDs, etc. However a single data dictionary should capture all the data appearing in all the DFDs constituting the DFD model of the system. A data dictionary lists the purpose of all data items and the definitions of all composite data items in terms of their component data items. Data definition: Composite data items can be defined in terms of primitive data items using the following data definition operators. +: denotes composition of two data items, e.g. a+b represents data a and b [,,]: represents selection, i.e. any one of the data items listed inside the square bracket can occur. For example, [a,b] represents either a occurs or b occurs. (): the content inside the bracket represent optional data which may or may not appear a+(b) represents that either a occurs or a+b occurs. {}: represents iterative data definition, e.g. {name}5 represents five name data, {name} * represents zero or more instances of name data. Context diagram = represents equilance, e.g. a=b+c means that a represents b and c / */: anything appearing within /* and */ is considered as commend The context diagram is the most abstract data flow representation of the system. 16

17 It represents the entire system as a single bubble. This bubble is labeled according to the main function of the system. The various external entities with which the system interacts and the data flows occurring between the system and external entities are also represented. The data input to the system and the data output from the system are representing as incoming and outgoing arrows. The data flow across should be annotated with the corresponding data name. the name context diagram is well justified because it represent the context in which the system is to exist. The bubble in the context diagram is annotated with the name of the software system being developed (usually a noun). This is in contrast with the bubbles in all other level which are annotated with the verbs. This is to be expected since the purpose of the context diagram is to capture the context of the system rather than its functionality. Level 1 DFD To develop the level 1 DFD, examine the high-level functional requirements. If there are between three to seven high-level functional requirements, then these can be directly represented as bubbles in the level 1 DFD. Decomposition: 4. Explain in detail about various approaches to Software Design.(Apr 2015) Design Approaches Two fundamentally different software design approaches: o Function-oriented design o Object-oriented design These two design approaches are radically different. o Each technique is applicable at different stages of the design process. Function-Oriented Design A system is looked upon as something o that performs a set of functions. Starting at this high-level view of the system: o each function is successively refined into more detailed functions. 17

18 o Functions are mapped to a module structure. Example The function create-new-library member: o creates the record for a new member, o assigns a unique membership number o prints a bill towards the membership Create-library-member function consists of the following sub-functions: o assign-membership-number o create-member-record o print-bill Function-Oriented Design o Each subfunction is split into more detailed sub functions and so on. The system state is centralized: o accessible to different functions, o member-records: available for reference and updation to several functions: create-new-member delete-member update-member-record Object-oriented design System is viewed as a collection of objects (i.e. entities). System state is decentralized among the objects: o each object manages its own state information. Object-Oriented Design Example Library Automation Software: o each library member is a separate object With its own data and functions. o Functions defined for one object: Cannot directly refer to or change data of other objects. Objects have their own internal data: defines their state. Similar objects constitute a class each object is a member of some class. 18

19 Classes may inherit features from a super class. Conceptually, objects communicate by message passing. Object-Oriented versus Function-Oriented Design Unlike function-oriented design, o in OOD the basic abstraction is not functions such as sort, display, track, etc., o but real-world entities such as employee, picture, machine, radar system, etc. In OOD: o software is not developed by designing functions such as: update-employee-record, get-employee-address, etc. o but by designing objects such as: employees, departments, etc. Grady Booch sums up this fundamental difference saying: o Identify verbs if you are after procedural design and nouns if you are after object-oriented design. In OOD: o state information is not shared in a centralized data,but is distributed among the objects of the system. Example: In an employee pay-roll system, the following can be global data: o names of the employees, o their code numbers, o basic salaries, etc. Whereas, in object oriented systems: o data is distributed among different employee objects of the system. Objects communicate by message passing. o one object may discover the state information of another object by interrogating it. Of course, somewhere or other the functions must be implemented: o the functions are usually associated with specific real-world entities (objects) o directly access only part of the system state information. Function-oriented techniques group functions together if: 19

20 o as a group, they constitute a higher level function. On the other hand, object-oriented techniques group functions together: o on the basis of the data they operate on. To illustrate the differences between object-oriented and function-oriented design approaches, o let us consider an example --- o An automated fire-alarm system for a large building. Fire-Alarm System: The fire alarm system should: o Flash an alarm message on the computer console, fire fighting personnel man the console round the clock. After a fire condition has been successfully handled, the fire alarm system should let fire fighting personnel reset the alarms. Function-Oriented Approach: /* Global data (system state) accessible by various functions */ BOOL detector_status[1000]; int detector_locs[1000]; BOOL alarm-status[1000]; /* alarm activated when status set */ int alarm_locs[1000]; /* room number where alarm is located */ int neighbor-alarms[1000][10];/*each detector has at most*/ /* 10 neighboring alarm locations */ The functions which operate on the system state: interrogate_detectors(); get_detector_location(); determine_neighbor_alarm(); determine_neighbor_sprinkler(); ring_alarm(); activate_sprinkler(); reset_alarm(); reset_sprinkler(); report_fire_location(); 20

21 Object-Oriented Approach: class detector attributes: status, location, neighbors operations: create, sense-status, get-location, find-neighbors class alarm attributes: location, status operations: create, ring-alarm, get_location, reset-alarm class sprinkler attributes:locations, status operations: create, activate-sprinkler, get_location, reset-sprinkler In the object oriented program, o appropriate number of instances of the class detector and alarm should be created. In the function-oriented program : o the system state is centralized o several functions accessing these data are defined. In the object oriented program, o the state information is distributed among various sensor and alarm objects. Use OOD to design the classes: o then applies top-down function oriented techniques to design the internal methods of classes. Though outwardly a system may appear to have been developed in an object oriented fashion, o but inside each class there is a small hierarchy of functions designed in a top-down manner. 5. Design DFD for hospital management system. Context Flow Diagram:- o A context flow diagram is a 0 th level DFD. o It only contains one process node that generalizes the functions of the entire system in relationship to external entities. 21

22 Level 0: 22

23 Level 1(1.4) Level 1 (1.5) 6. Design trading house automation software. 23

24 A trading house wants us to develop a computerized system that would automate various bookkeeping activities associated with its business. The following are the silent features the system to be developed: The trading house has a set of regular customers The customers of orders with it various kinds of commodities. The tradition house maintains the names with and address of its regular customers. Each of these regular customers should be assigned a unique customer identification number (CIN) by the computer. The customers quote their CN on every order they place. Once an order is placed, as per current practice, the accounts department of the trading house first checks the credit worthiness of the customer. The credit worthiness of the customer is determined by analysis the history of its payments to different bills sent to him in the past. After automation, this task has to be done by the computer. If a customer is not credit-worthy, his orders are not processed any further and an appropriate order rejection message is generated for the customer. If a customer is credit worthy, the items that he has ordered has checked against a list of items that the trading house deals with. The items in the order which the trading house does not deal with, are not processed any further and an appropriate apology message to the customer for these it is generated. The items in the customer s order that the trading house deals with are checked for available in the inventory. If the items are available in the inventory in desired quantity,then A bill with the forwarding address of the customer is printed. A material issue slip is printed. The customer can produce the material issue slip at the storehouse and take delivery of the items. Inventory data is adjusted to reflect the sale to the customer. If any of the ordered items are not available in the inventory in sufficient quantity to satisfy the order,then these out of stock items along with the quantity ordered by the customer and its 24

25 CIN are stored in a pending order file for further processing to be carried out when the purchase department issues the generate indent command. The purchase department should be allowed to periodically issue commands to generate indents. When a command to generate indent is issued, the system should be examine the pending order file to determine the order that are pending and to determine the quantity required for each of the items. It should find out the addresses of the vendors who supply these items by examining the file containing vendor details and them should print out indents to those vendors. The system should also answer managerial queries regarding the statistics of different items sold over any given period of time and the corresponding quantity sold and the prize realized. The context diagram for the trading house automation problem is shown in figure 6.10 and the level 1 DFD in figure Data dictionary for the DFD model response: [bill + material-issue-slip, reject-message] 25

26 query: period /* query from manager regarding sales statistics*/ date: year + month +day year: month: integer integer day: integer order: customer-id + {items + quantity}* + order# accepted-order: order /* ordered items available in inventory */ reject-message: order + message /* rejection message*/ pending-orders: customer-id +..etc 7. Design DFD and Structure chart for Personal library software? Level 0 DFD (context diagram) +3 Level 1 DFD 26

27 Level 2 DFD Data dictionary 27

28 Software Engineering CS T55 June 2016 V-Semester Structure Chart 8. Draw DFD for call center management. The Call Center Management system automates the operations of a call center by giving automatic replies to the customer queries. It is achieved by adding more entries to the data base store, the application can respond to more number of queries from the customers. CONTEXT LEVEL DIAGRAM Customer Call center management system View customer transaction details View Report Admin 28

29 Software Engineering CS T55 June 2016 V-Semester LEVEL 0 DATA FLOW DIAGRAM LEVEL 1 DATA FLOW DIAGRAM 1. Registration: Registration of new customer Customer Already exist Registered successfully Checking availability Customer details database 2. Authentication: 29

30 Software Engineering CS T55 June 2016 V-Semester Authentication Customer Valid user Customer details database 3. Query: Enter mobile number and password Customer Invalid login Verify mobile number & password Post Query database Query is stored Customer details database Post Query 4. Response: Enter user id and password Login request Login request customer Employee post query View query Query database Response query 30

31 Software Engineering CS T55 June 2016 V-Semester 5. Feedback and Report: Feedback database View Feedback Write Feedback customer View feedback View Report Admin Response feedback Employee Report database 31