File Based System

Definition of file based system:-

  A collection of application programs that perform services for the end-uses, such as the production of reports. Each program defines and manages its own data.

Traditional file processing system or simple file processing system refers to the first computer-based approach of handling the commercial or business applications. That is why it is also called a replacement of the manual file system. Before the use computers, the data in the offices or business was maintained in the files (well in that perspective some offices may still be considered in the pre-computer age). Obviously, it was laborious, time consuming, inefficient, especially in case of large organizations.

But file processing environment simply transformed manual file work to computers. So processing became very fast and efficient.

Example:-

Consider DreamHome example for file-based systems

1.        Sales Department : responsible for selling and renting of properties
2.     Contract Department: responsible for handling lease agreements

 Sale Department:

·  Property For Rent

       (PropertyNo, Street, City, Postcode, Type, Rooms, Rent,  OwnerNo)

·  Client

      (ClientNo, fName, lName, telNo, preftype, maxRent)

·       Private Owner

       (OwnerNo, fName, lName, address, telNo)

·       Property For Rent:-

propertyNo	street	city	postcode	type	rooms	rent	ownerNo
PA14	…	Aberdeen	…	House	6	650	CO46
PL94	…	London	…	Flat	4	400	CO87
PG4	…	Glasgow	…	Flat	3	350	CO40
PG36	…	Glasgow	…	Flat	3	375	CO93
PG21	…	Glasgow	…	House	5	600	CO87
PG16	…	Glasgow	…	Flat	4	450	CO93

     

Private Owner:-

ownerNo	fName	lName	address	telNo
CO46	Joe	Keogh	…	01224-861212
CO87	Carol	Farrel	…	0141-357-7419
CO40	…	…	…	…
CO93	…	…	…	…

   

Client:-

clientNo	fName	lName	telNo	prefType	maxRent
CR76	John	Kay	0207-774-5632	Flat	425
CR56	Aline	Stewart	0141-848-1825	Flat	350
CR74	Mike	Ritchie	01475-392178	House	750
CR62	Mary	Tregear	01224-196720	Flat	600

Contract Department:-

• Lease

(leaseNo, propertyNo, clientNo, rent , paymentMethod,  deposit, paid, rentStart, rentFinish, duration)

• PropertyForRent

        (propertyNo, street, city, postcode, type, rooms, rent)

• Client

         (clientNo, fName, lName, telNo, preftype, maxRent)

Property For Rent:-

propertyNo	street	city	postcode	type	rooms	rent
PA14	…	Aberdeen	…	House	6	650
PL94	…	London	…	Flat	4	400
PG4	…	Glasgow	…	Flat	3	350
PG36	…	Glasgow	…	Flat	3	375
PG21	…	Glasgow	…	House	5	600
PG16	…	Glasgow	…	Flat	4	450

Lease:-

Client:-

clientNo	fName	lName	telNo
CR76	John	Kay	0207-774-5632
CR56	Aline	Stewart	0141-848-1825
CR74	Mike	Ritchie	01475-392178
CR62	Mary	Tregear	01224-196720

 

File-based processing:-

Limitations of File-Based Approach:-

There are some problems of file based system.

1).  Separation and isolation of data

•  Each program maintains its own set of data.

• Users of one program may be unaware of potentially useful data held by other programs.

2).  Duplication of data

• Decentralized approach taken by each department.
•  Same data is held by different programs and wasted space.

3). Data dependence

• File structure is defined in the program code.

4).  Incompatible file formats

• Programs are written in different languages, and so cannot easily access each other’s files.

5.)   Fixed Queries/Proliferation of application programs

• Programs are written to satisfy particular functions.

• Any new requirement needs a new program.