Topic at a Glance
Transaction – an event
that involves multiple
actions that must all
succeed or all fail. The
transaction performs
actions which create
and/or modify data.
4 Characteristics of a
TPS:
1. Rapid Response –
the system must
respond quickly to
data requests.
2. Reliability – the TPS
must be reliable eg.
In a bank example,
24/7 up-time is
critical.
3. Inflexibility – the TPS
should complete the
same processing for
each transaction,
irrespective of the
user.
4. Controlled Processing
– the processing in a
TPS must support
and compliment an
organisation’s
operations.
4 Properties of a TPS
1
2
3
4
Batch Transaction
Processing: is a method
used, whereby data is
collected and stored for
later processing. Data is
processed when there is
sufficient time eg. Nonworking hours, and is
usually an automated
process. Examples
include, bill generation,
clearance of cheques,
payroll runs etc.
Advantages:
 Reduced costs
 Standardisation – all
data is in the correct
format prior to
processing
 Control – the
organisation has
control over what
data is processed.
Disadvantages:
 Time delay – this
could be a few
minutes, a few hours
or a few days
 Identical data must
be processed in a
batch eg. Payroll
batch processing
would occur at a
different time to Sales
batch processing
 Errors – if an error
occurs during the
batch, it cannot be
corrected
 Cost – some forms of
batch processing can
be more expensive.
Atomicity – the
transaction should
be conducted
completely or
‘undone’ completely.
Remember it’s “All or
Nothing”
Consistency – The
data should be
entered into the TPS
consistently and
should be entered
into a database
consistently.
Isolation – Each
transaction should
be completed in
isolation and stored
in isolation.
Concurrency
ensures a piece of
data can be only
edited by the one
user at any time.
Durability – the
effects of a
completed
transaction should
always be durable –
eg. Money deposited
at a bank.
Real-Time Transaction
Processing (or Online
Transaction Processing:
is the immediate
collection, processing
and storage of data. This
is also often referred to
as online transaction
processing as the data is
often collected by a POS
(point of sale terminal)
and transmitted across a
network (WAN or LAN) to
a DBMS (Database
Management System).
Examples include
EFTPOS (debit cards), Ecommerce sites (Roses
Only), Police checking
licenses after pulling a
driver over.
Transaction Processing Systems
Advantages:
 Response time is
reduced; may not be
immediate, however
very little delay.
 Data is processed
immediately and
provides immediate
feedback eg.
Withdrawal from an
ATM issues a receipt
detailing balance etc
 Errors can be
immediately corrected
– eg ATM advises
user of incorrect pin –
they can then correct
the error.
Disadvantages:
 Hardware and
software can be
expensive – need for
a central mainframe
that processing
 Security and backups
are critical – any
system downtime
could be disastrous to
business activity. Eg.
Real time bill
generation in a busy
restaurant. Backups of
the system are critical
to its success.
 Standardisation – all
data must contain the
same format etc
Credit Card transactions are an example that
carries out both real-time
transaction processing
and batch transaction
processing. The real time
aspect is where the
amount is above or below
the customers credit limit
or the card is stolen. The
updating of the transaction
on the user’s card is batch
(up to 3 days post
transaction).
Transaction Processing
Systems : were actually
the first information
systems invented. When
the first computer systems
were invented, their
purpose was to calculate
and process transactions.
Data Validation: this is the
most critical action
performed in a TPS,
irrespective of whether in
a real-time or batch
system. Data validation
ensures that the data to be
entered or entered is of
the correct data type and
that its value is sensible.
Eg. Post code does not
contain 10 numbers or a
PIN number contains
letters.
Storing and Retrieving
Data in a TPS:
A TPS uses different types
of files:
1
Program file – this is
an application and is
stored as a single
unit. Eg Cole’s
registers would run a
program file to begin
their day.
2
Work File – is a
current file that is
open and is in the
process of being
created.
3
Transaction File - is
a temporary holding
file that stores the
changes that need to
be made to the
master file. Eg At
MacDonald’s, each
register would create
a transaction file that
would update the
master file stored on
the main computer at
the end of the day.
4
Master File – is a
data file containing
relatively permanent
records that are
generally updated
periodically.
3 main methods of
Storage and Retrieval in
DBMS:
1
Sequential data
storage – data is
stored as a
sequence, one
character after
another. When
searching, it begins
and searches through
the file until found.
2
Indexed Sequential
Data Storage - The
data block is made of
a main data file and a
separate smaller
index file.
Data Integrity – a measure
of how correct and
accurately data reflects its
source. The quality of the
data,
3 Hashed File Storage –
this method divides the total
storage space into
locations and gives each
location a
number.
The record is then identified
by this number.
Backup Methods –
1 Grandfather, Father Son –
this is used to refer to
generations of backup files.
Each generation is the new
set of backup data i.e. Son,
with the previous version
being the father, and the
version previous to father is
Grandfather. Data recovery
is generally from the most
recent backup (Son),
however this could be
corrupted, and hence the
Father would be used.
2 Partial Backup –
Differential Backup –
updates all added or
amended files since the last
full backup.
Incremental Backup –
updates all added or
amended files since the
previous day’s backup.
3 Offsite Backup – this
occurs when an
organisation employs an IT
firm to retrieve data from
their servers and backup
on servers off-site. This
prohibits the chance of
human error – eg forgetting
a backup tape.
4 Secure On-site storage the data back-up is stored in
a
secure fire-proof,
water-proof safe.
Data Warehouse – a large
database that includes
historical copies of the
organisation’s databases from
each of the operational
databases.