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Software Engineering

Software engineering is the process of applying well-developed techniques and practices in order to create new software products. Questions about everything from design patterns to requirements and specification belong here.

1,663 Questions

What is data sub-language?

A data Sublanguage is a computer language used to define or manipulate the structure of a relational database management system(DBMS) e.g QBE, SQL.

What is the similarities between computer engineering and software engineering?

Computer Engineering students study the design of digital hardware and software systems including communications systems, other computer applications, Software engineering is a sub part of computer engineering.

Data flow diagram for railway reservation?

RAILWAY RESERVATION SYSTEM

This system is basically concerned with the reservation and cancellation of railway tickets to the passengers. The need of this system arose because as is the known fact that India has the largest railway network in the whole of the world and to handle it manually is quite a tough job. By computerizing it, we will be able to overcome many of its limitations and will be able to make it more efficient. The handling of data and records for such a vast system is a very complex task if done manually but it can be made much easier if the system is computerized.

To be more specific, our system is limited in such a way that a train starting from a particular source will have a single destination.

The basic functions being performed by our system are reservation and cancellation. These functions will be handled with the help of following sub functions: -

Ñ It reserves and cancels seats for the passenger.

Ñ It contains information about the trains.

Ñ It contains information about the passenger.

Ñ It contains the details of reservation fees, any concessions etc.

Ñ It makes entries for reservation, waiting, cancelled tickets.

Ñ It will update for uptime and downtime trains.

Index:-

· System Specification

§ Security

§ Limitation of Executing System

· Data Flow Diagrams

· Description of Flow Chart

· Entity Relationship Diagrams

· Feasibility Study

· Introduction of Feasibility study

· Summary

· Testing

· Debugging

· Conclusion

· Reference

SYSTEM SPECIFICATION

The railway network is a very vast system to be handled manually and its computerization will prove to be of great help to both the employees and the passengers.

SECURITY:-

From security point of view, authentication will be done by password checking. If correct password has been entered by the user, the user will get further access to the system, otherwise he will have to re-enter the password. The facility to change the password has also been provided but for that the user will have to first enter the old password. The password can be four characters long.

LIMITATIONS OF EXISTING SYSTEM: -

Ñ Data redundancy: It means that same data fields appear in many different files and often in different formats. In manual system, it poses quite a big problem because the data has to be maintained in large volumes but in our system, this problem can be overcome by providing the condition that if the data entered is duplicate, it will not be entered, otherwise, updating will take place.

Ñ Difficulty in accessing the data: In manual system, searching information is time consuming but in our system, any information can be accessed by providing the primary key.

Ñ Unsatisfactory security measures: In manual system, no security measures were provided but in this system, password security has been provided. The person can access the system by providing the correct password otherwise he is denied the access.

DATA FLOW DIAGRAMS

The data flow diagram is a graphical representation that depicts information flow and the transforms that are applied as data moves from input to output. The DFD may be used to represent a system or software at any level of abstraction. In fact DFD may be partitioned into levels that represent increasing information flow and functional detail.

The level 0 DFD or a context model represents the entire software element as a single bubble with input and output data indicated by incoming and outgoing arrows, respectively.

In level 0 diagram shown below, the passenger fills either the reservation or cancellation form as input. He gets the ticket as the output and the report is sent to the administration.

Up/down train info

Fill cancellation form

Passenger

Admin


Fill reservation form resva/cancle info

Ticket info passenger info

Waiting info


Level - 1 data flow diagram



Up Storage

Down Storage

A level 1 DFD is the furthur refinement of level 0 DFD showing greater details and functionalities. In this, the single bubble of level 0 DFD is refined furthur . Each of the processes depicted at level 1 is a subfunction of the overall system depicted in the context model.

As shown in the DFD above, the passenger either enquires about the trains or goes directly for the reservation or the cancellation processes as a result of which he gets the ticket generated. The reports are then sent to the administration.

Level 2 DFD



Cancel table

Reservation table

Waiting table

The level 2 DFD is the further refinement of the level 1 DFD. As shown in the DFD above the passenger has many options like he can directly go to the reservation counter or can first inquire and then go to the reservation counter or he can just inquire and return back. If the passenger wants reservation then the seats are checked for availability and if the seats are available the confirmation ticket is generated otherwise he is asked for waiting and waiting ticket is generated if he wants. If the user wants tickets to be cancelled he is given the cancellation ticket and the reports of all the transactions are sent to the administrator.

DESCRIPTION OF FLOW CHART

The program flowchart shows how the system proceeds from the input form to the output form of the system. It explains how the system is actually processed step by step .It represents the flow of control as the system is processed.

There are three types of program flow chart:

1. Input flow chart: This flowchart depicts the basic input operations in the system. In railway reservation system, first of all the password is checked then if the password is valid then we process the input form if the data is valid then the entries are updated in the data base otherwise the form is refilled.

2. Output flow chart: This flowchart depicts the basic output operations in the system. The user is required to enter t

he criteria for output. If it is for the reservation then the availability if seats is checked. If the seats are available then the confirmed ticket is generated otherwise the user is asked for waiting and if he wants then waiting ticket is generated. If the user wants the seat to be cancelled it is done and the cancelled ticket is generated for the user. The information about all the above transactions is then transferred to the related databases.

3. Report flow chart: This flowchart depicts the basic operations for the generation of reports. If the entries from the processed database are valid the concerned reports are generated otherwise the process will have to be repeated.


No

Yes


Reservation database is updated


INPUT FLOW CHART

ENTITY RELATIONSHIP DIAGRAM

Entity relationship diagram expresses the overall logical structure of a database graphically. It shows the relationship between different entities. The entities can have composite, multivolume or derived attributes. The entities and their attributes are: -

1 Passenger

#. Name

*. First name

*. Middle name

*. Last name

#. Gender

#. Address

*. House no.

*. Street

*. City

#. Age

#. Phone no.

2 Form

#. Form no.

3 Ticket

#. Ticket no.

*. Waiting

*. Confirmed

*. Cancelled

4 Reservation counter

5 Administrator

6 Train

#. Train no

#. Train name

#. Source

#. Destination

7 Seat

#. Seat no.

#. Compartment no.

The relationships between different entities are: -1. Fill: The passenger fills the form.

2. Submit: The form is submitted to the reservation counter.

3. Check: The reservation counter checks the seats.

4. Generate: Reservation counter generates the ticket.

5. Issue: Reservation counter issues ticket to the passenger.

6. Send info: The reservation counter sends information to the administrator.

7. Allotted: The seat is allotted in the train.

Symbols

Meanings

Data flow

Process

Data store

Entity

ENTITY RELATIONSHIP DIAGRAM


OUTPUT FLOWCHART



REPORT FLOWCHART

FEASIBILITY STUDY

An initial investigation in a proposal that determines whether an alternative system is feasible. A proposal summarizing the thinking of the analyst is presented to the user for review. When approved, the proposal initiates feasibility study that describes and evaluates candidate systems and provides for the selection of best system that meets system performance requirements.

To do a feasibility study, we need to consider the economic, technical factors in system development. First a project team is formed. The team develops system flowcharts that identify the characteristics of candidate systems, evaluate the performance of each system, weigh system performance and cost data and select the best candidate system for the job. The study culminates in a final report to the management.

By the end of this chapter you should know:

1. The steps in defining system performance.

2. What key considerations are involved in feasibility analysis?

3. How to conduct a feasibility study?

INTRODUCTION

1. Describe and identify characteristics of candidate systems.

2. Determine and evaluate performance and cost effectiveness of each candidate system.

4. Weigh system performance and cost data.

5. Select the best candidate system.

SUMMARY

1. A feasibility study is conducted to select the best system that meets performance requirements. This entails an identification description, an evaluation of candidate systems, and the selection of the best system for the job.

2. A statement of constraints, the identification of specific system objectives and a description of outputs define a system's required performance. The analyst is then ready to evaluate the feasibility of candidate systems to produce these outputs.

3. Three key considerations are involved in feasibility analysis: economic, technical and behavioral.

4. There are eight steps in feasibility study:

a. STATEMENT OF CONSTRAINTS

Constraints are factors that limit the solution of a problem. Some constraints are identified during the initial investigation

b. IDENTIFICATION F SPECIFIC SYSTEM OBJECTIVES

Once the constraints are spelled out, the analyst proceeds to identify the system's specific performance objectives. They are derived from the general objectives specified in the project directive at the end of the initial investigation. The steps are to state the system's benefits and then translate them into measurable objectives.

c. DESCRIPTION OF OUTPUTS

A final step in system performance definition is describing the output required by the user. An actual sketch of the format and contents of the reports as well as a specification of the media used, their frequency, size and numbers of copies required are prepared at this point.

d. FEASIBILITY CONSIDERATIONS

Three key considerations are involved in the feasibility analysis:

1. Economic feasibility

2. Technical feasibility

3. Behavioral feasibility

Testing and Debugging

Testing:

Testing is the process of exercising software with the intent of finding errors and ultimately correcting them. The following testing techniques have been used to make this project free of errors.

Content ReviewThe whole content of the project has been reviewed thoroughly to uncover typographical errors, grammatical error and ambiguous sentences. Navigation ErrorsDifferent users were allowed to navigate through the project to uncover the navigation errors. The views of the user regarding the navigation flexibility and user friendliness were taken into account and implemented in the project. Unit TestingFocuses on individual software units, groups of related units.

· Unit - smallest testable piece of software.

· A unit can be compiled /assembled / linked/loaded; and put under a test harness.

· Unit testing done to show that the unit does not satisfy the application and /or its implemented software does not match the intended designed structure.


Integration TestingFocuses on combining units to evaluate the interaction among them

· Integration is the process of aggregating components to create larger components.

· Integration testing done to show that even though components were individually satisfactory, the combination is incorrect and inconsistent.



System Testing Focuses on a complete integrated system to evaluate compliance with specified requirements (test characteristics that are only present when entire system is run)

· A system is a big component.

· System testing is aimed at revealing bugs that cannot be attributed to a component as such, to inconsistencies between components or planned interactions between components.

· Concern: issues, behaviors that can only be exposed by testing the entire integrated system (e.g., performance, security, recovery)


Each form encapsulates (labels, texts, grid etc.). Hence in case of project in V.B. form are the basic units. Each form is tested thoroughly in term of calculation, display etc.

Regression TestingEach time a new form is added to the project the whole project is tested thoroughly to rectify any side effects. That might have occurred due to the addition of the new form. Thus regression testing has been performed.

Debugging:

Debugging is a consequence of successful testing. That is when a test care uncovers an error, debugging is the process that results in the removal of errors. There are mainly two types of debugging.

BacktrackingBacktracking is a fairly common debugging approach that can be used successfully in small programs. Beginning at the site where a symptom has been uncovered, the source code is traced backward until the site of the cause is found. Brute ForcingThis is the most common category of debugging which involves loading the source code with write statements and tracking line by line execution to isolate possible errors.

Conclusion

Practical Training is a very important part of the curriculum as it strengthens the concepts and enhances knowledge about the practical implementation of all the theory concepts, we have learnt so far in different subjects.

This summer training helped us learn a lot. In this training we did the project on railway reservation system. This project is used to keep a track on reserving the seat to the passenger. It helps managing the system very efficiently and conveniently.

Finally, this gives us a lot of mental satisfaction that the project we have worked upon is a real time project, which will be installed at the customer site after some more session of regress testing.

Although the project work has been done in a complete and detailed manner but due to the constraint of time, we could not include some more features we wanted to. We left these features as a part of the future development. As soon as we'll get time we'll try to add them to my project.

Reference:-

v Henry F Korth, Abraham Silberschatz, ''Database system concepts'', McGrsw-Hill Internation editions, Computer Science Series (1991). Second Ed.

v Software Engineering ,McGrsw-Hill Internation editions

v www.Google.com.

Made By:-

Sunil Kumar Sharma

3rd Year (Computer Engineering)

Jaipur Engineering College, Kukas

E-mail: suniljoshi151@yahoo.in.

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I can only think of two ways you can connect two computers if they don't have network cards: 1. Use a serial cable. All computers have serial ports, so this would be the easiest solution, though it will be a little slow. Look up directions online on how to do this. 2. If both computers have an IR (infra-red) port you can use that to connect the two. More input from FAQ Farmers: * or you can do it with a usb cable thingy, see it is like $5.00 and it works great if both have usb ports. by parallel cable by usb cable For newer macbooks hold down the t key to make it a drive then connect it to the desktop You can also buy ethernet / usb connectors. Pretty much its a wire with USB on one end and ethernet on the other. You just plug the USB side into your computer and now you have a ethernet port.

How busy waiting occur?

I copied the answer from other place:while any process is in its critical section , any other process that tries to enter its critical section must loop continously in the entry code.this continue looping is clearly a problem in a real multiprogramming system. where a single CPU is shared among many processes. Busy waiting wastes CPU cycles that could have been used by some process in more productive way. This type of semaphore is also called a spinlock.

What is milestone chart?

A Milestone Chart is a Project Control Chart that graphically depicts key events along a timescale, usually with triangles representing each event. It can depict a single event or a culmination of events. It can mark specific points in the project where checks can be made to see if the project is on time and where it should be. The best place to locate milestones is at the completion of a major activity.

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What is constant variables?

Variables are items, which change their values during the execution of a program.

Constants do not change the value during the execution of a program.

What is an example of an aggregate object?

An aggregate object is an object that contains other objects for the

purpose of grouping those objects as a unit. It is also called a

container or a collection. Examples are a linked list and a hash table.

What are the boolean theorems?

Commutative x + y = y + x x . y = y . x Associative x+(y+z) = (x+y)+z = x+y+z x.(y.z) = (x.y).z = x.y.z Distributive x.(y+z) = x.y + x.z (w+x)(y+z) = wy + xy + wz + xz x + xy = x x + x'y = x + y where, x & y & z are inputs.

Top 10 college of engineering in Orissa?

well as per my opinion i think according to the placement the ranking list is # NIT # KIIT # CET # NMIET # UCE # SILICON # OEC # NIST # ITER # CV RAMAN # GITA NMIET is placed No:1 in giving 100% placement to all its students.

What are the two ways in which control structures can be combined?

Control Structures change the flow of a program.

Control Structures can be combined using what is known as Nesting.

In Nesting a control structure is put within another Control Structure

Example

If (x==y ) If (y==z) then do something

While(X is Not 0) While ( Y is Not 100 ) then do something.

Deference between prototype and incremental model?

In incremental model the real product is designed, implemented, integrated and tested as a series of incremental builds. while

In prototype model the prototype (not the real product) is designed, implemented, integrated and tested as a series of incremental builds

Iam not finding any difference between sdlc and rad please explain?

The reason why you might not find differences in the sdlc and rad is because RAD is a more sped-up version of the SDLC. RAD is typically used in small to medium size projects, while the SDLC is generally used for large projects. Another difference is that in the SDLC, one can control the scope creep of the project, whereas that is very limited when one implements RAD because you give it up for faster implementation times. In RAD you have alot of feedback from the user to refine the program more to the aspects of the user, whereas you dont get the same user input in the SDLC. This feedback loop is another reason that RAD is sometimes chosen over the SDLC

What is a default access specifier for variable in c sharp?

Default access specifier in c# is private.

if you don't specify it automaticaly takes it as private.

Which job pays better - a computer programmer or an HVAC technician?

The answer to this question may vary depending on the employer and responsabilities assigned to the specific position. As an example, a low level programmer for a mom-and-pop software company is not going to make as much money as the lead programmer for Microsoft. Nor would an HVAC technician employed by an appointment based home repair contracting company be paid as much as one responsible for, say, overseeing an entire university or large company campus. The lowest paid programmer may make less than the highest paid HVAC technician. But generally speaking, computer programmers tend to have higher salaries and better benafits and opportunities for advancement than HVAC technicians, depending on who they work for.

Difference between grant and revoke statements in sql?

grant will give permission to the user on database by using revoke we can remove the permission

Why do you use hexadecimal?

Hex is used by computers to store information because it is the most compact method to do so. Four lines of information can store 16 different conditions:

0000 is 0

0001 is 1

0010 is 2

0011 is 3

0100 is 4

0101 is 5

0110 is 6

0111 is 7

1000 is 8

1001 is 9

1010 is A (10)

1011 is B (11)

1100 is C (12)

1101 is D (13)

1110 is E (14)

1111 is F (15)

Pretty cool huh!? Your five fingers could store 32 separate counts.

What is physical dfd?

A Physical Data Flow Diagram is a diagram showing howparticular functions are performed within the data flow as opposed to a Logical DFD which only shows what functions are performed.