The concept of Data Processing
Input
Data
INPUT DESIGN
Persistent
Data
Process
Output
Why be concerned about INPUT DESIGN?
Garbage In - Garbage Out (GIGO)
Data Verification & Validation (V&V):
• Self-checking digits or check-digit
• Combination check
• Limit and Range checks
• Completeness checks
“Input” involves 3 steps:
1. Collecting
2. Entering
3. Processing
“Input” Methods:
• Batch
• On-Line (real-time)
• Hybrid
BATCH INPUT - ADVANTAGES
• Collecting and Entering can be done off-line.
• Entering data can be done by trained personnel.
• Processing can be done very quickly.
• Processing can be done during non-peak times.
BATCH INPUT - DISADVANTAGES
• Data collection usually has to be a centralized activity.
• Data entry usually needs to be done by specially trained personnel.
• The processing activity is delayed, hence the possibility exists for
data to be considered old or untimely when it finally gets processed.
• Since processing is usually done during off-hours, input errors
detected during processing would not get corrected until the next
regularly scheduled processing of input data.
• The off-hours computer operator may have to call the systems
analyst or programmer if the program malfunctions.
ON-LINE INPUT - ADVANTAGES
• The data can be entered by its owners.
• The data can be entered as close to their origination
as possible.
• Immediate feedback can usually be given regarding
the correctness and acceptability of the data.
• The input data can immediately update a database
thus making it as current as possible.
ON-LINE INPUT - DISADVANTAGES
• Equipment may be more costly to perform the input.
• Users are not always well trained to input data.
• User data entry procedural controls may be lacking.
• Software must have additional controls to handle it.
• Data is often only entered during business hours thus impacting
the normal computer load.
• The data entry activity could actually be slower than the
equivalent batch processing for the same data.
Batch vs. On-Line Transaction
Processing
•
Two types of TPS:
–
–
Batch processing
» A system whereby business transactions are
accumulated over a period of time and prepared
for processing as a single unit or batch
On-line transaction processing (OLTP)
» A system whereby each transaction is processed
immediately, without the delay of accumulating
transactions into a batch
Batch Schematic
Data entry
of accumulated
transactions
Input
(batched)
Output
On-line Schematic
Terminal
Terminal
Terminal
Output
Immediate
processin
g
of each
transactio
n
Terminal
Terminal
Terminal
Accessing Data

To access data means to retrieve it from storage and place it in RAM, so
that it is ready to be processed.

There are three main ways to access data, depending on the storage
device that has been used and the way that the data has been saved…
1. Direct Access
2. Serial Access
3. Sequential Access
Direct Access

Hard drives, optical drives, flash drives and almost all other storage
devices are direct access devices
(also know as random access). This means that data stored anywhere
on the device can be accessed
in an equally short period of time.

The location of each file is stored in a ‘table’ on the drive (called a FAT
– File Allocation Table), which enables the operating system to find the
file quickly.

Direct access devices are much quicker and more efficient than serial
access devices, such as magnetic tapes which are only used for backup
and archive purposes.
Serial or Sequential Access

Magnetic tape is a serial access or sequential access device. This
means that you have to wind through it to reach the data that you
require. Access time varies depending on where the data is located on
the tape.

Serial access is where the data is stored in the order that the data files
were created, one after the other.

Sequential access is where the data is stored in a logical order, e.g.
the records of a bank may be stored in numerical order by account
number, or in alphabetical order by surname of the account holder.
Data Processing

When data is stored in a computer system, there are two main things
you can do with it – you can process it in the CPU, then you can output
the results.

There are many different ways of processing data…
1. Real-Time Processing
2. Interactive Processing
3. Batch Processing
4. Transaction Processing
Real-Time Processing

Real-time processing involves processing the data immediately, e.g.
 Computer control, e.g. aircraft, robot, flight simulator

Processing the data immediately makes sure:
 That the flight data displayed on the instruments
is current, so that the pilot can operate the aircraft controls with
confidence.

Real-time processing gives instant feedback.
Interactive Processing

Interactive processing (also known as online processing) accepts and
processes data items piece by piece and may produce prompts in
response to each stage, e.g. booking a holiday…
 Departure Airport…
 Destination Airport…
 Departure Date…
 Arrival Date…

At this point the system may prompt the user, “There are no available
flights for those dates…”

As soon as all the data is entered, the holiday will be booked so that
no double-booking occurs.

The processing for booking systems is not as urgent as for real-time
processing – if the system is busy, the user can wait a little.
Batch Processing

Batch processing waits until a group of data files is ready to be
processed, then processes them all at once.

Batch processing is usually done at night or at weekends to avoid busy
system times, as batch processing uses the CPU intensively and will
slow down the system for other users.

Batch processing suits large volume tasks that have to be done at
regular intervals, e.g.
 A business sending overdue letters to its creditors.
 A council sending out council tax bills.
 A business sending out direct mail using a mail merge with its
customer database.
Transaction Processing

Transaction processing is where an individual file is processed as a oneoff, e.g.
 A library customer may return a book late.
The librarian will process the request to return the book. This
process cannot be done through batch processing because…
 The customer may owe money, and must pay before they
leave.
 The request is processed as a one-off transaction, and the amount
owing is calculated.

Credit and debit card expenditure uses transaction processing as the
bank needs to know straightaway when a customer has reached their
credit limit.
Chapter Summary
Processing Methods
• Online vs. Batch Processing
On-line processing
• System in which
transactions are processed
when and where they
occur, allows output
directly to end users
–also called online
transaction processing or
interactive processing
On-line processing
• workstation -- either a PC
or terminal connected to
online processing system
–online processing system
verifies the transaction
values and allows end
user to interactively enter
data and correct errors
On-line processing
• Online file -- data file with
direct or indexed organization
that allows random access
–sequential files not used for
online processing
• IS must be continuously available whenever
end users require processing of transactions
Batch Processing
• IS in which data is collected
and, at some later time, all the
data that has been gathered is
processed as a group, or
batch
• Used extensively in 1950’s60’s
• Still used today for many
applications
Batch Processing
• Any application that requires
periodic processing of a large
number of records is good
candidate for batch
processing
–payroll
–billing/invoicing
–hard copy reports
Today’s processing trends
• Online and batch processing
combined in single IS
–random access files are available for
transactions that require interaction
–actual files available off-line for large
batch processing
–copies of online files available for
batch reports that don’t require
update
Online vs. Batch
• Online Advantages
–data is entered and
validated as it occurs
–data is available sooner in
more accurate form
–data is up-to-date
That’s all folks!