Transaction Processing Systems

Transaction processing
systems

Characteristics of transaction
processing systems
 Transaction: event generating or modifying stored data
in an info sys.
 Batch transaction processing collects transaction data
as a group/batch
Real-time transaction processing: immediate data
processing
 Data Validation: used to check entry of transaction data
 Historical significance of transaction processing
systems: UNIVAC
 Manual transaction systems: business systems that
operate without the use of machines.

TPS Characteristics
 They collect, store, modify and
retrieve the transaction of an
organisation.
 Directly support business operations
 Must be designed in conjunction w/
the organisation’s procedures.
 Main information processes:
collecting and storage.

4 important characteristics
 Rapid response (fast performance, rapid
response time)
 Reliability (low failure rate, quick and
accurate recovery, backup and recovery
procedures)
 Inflexibility (every transaction processed in
same way regardless of conditions)
 Controlled processing (supports an
organisation’s operations)

Examples of batch transaction
processing
 Clearance of cheques
 Other forms of paper output

Large batch
 Mainframe PC and magnetic tape
 Payroll or stock info
 Employee: hours worked, overtime
earned
 Payroll master file updated
 Pay slips created (ALL employees)

3 disadvantages in batch
processing
 Processing schedule predetermined
 Errors unable to be corrected during
processing
 Sorting transaction data – expensive
and time consuming

2 concerns w/ real-time transaction
processing
 Concurrency: data cannot be changed
by 2 users at same time
 Atomicity: steps completed
succesfully as a group. If any step
fails, no other step should be
completed.

Transaction processing monitor
 Software (middleware) allowing
running of TP programs.
 Manages sequence of events
 Provides interface between input
devices and DBMS
 Provides data security, ensuring
transactions don’t get lost/corrupted.

Differences btween real-time and
batch
 Real time: each transaction is unique; transactions are
stand-alone; requires master file to be available more
often for updating; fewer errors – transaction data is
validated and entered immediately; infrequent errors
may occur – but often tolerated; not practical to shut
down whole system (infrequent errors); more computer
operators are required in real-time processing –
operations not centralised.
 Batch: each transaction part of a group; database not
accesible all of the time; more errors; data is organised
and stored before master file is updated – errors can
occur during these steps; easier to maintain than realtime.

Data validation
 Used to check the entry of transaction
data.
 Procedures ensure transactions are
correct and have been accurately
stored in the database.
 Involves transaction initiation and
field checking.

Historical significance and manual
transaction systems
 Historical significance: UNIVAC 1950’s
 Manual transaction systems: business
systems operating w/o use of
machines.

Components of a transaction
processing system
 Users: take data and use it in another
info system type
 Participants: conduct info processing
 People (from the environment):
directly enter transactions and
perform validation

Examples of real-time transaction
processing
 Reservation systems: set aside
service/product for future use
 Motels
 Point-of-sale (POS) terminals: sells
goods/services
 Library loan systems: keeps track of
items borrowed from library

System flowchart for a POS system
Customer
receipt

UPC/quantity

Server

Inventory
database

MIS

POS system
UPC/quantity
UPC

Price

Product
Database

Purchase
database

Inventory
report

Examples of batch transaction
processing
 Cheque clearance: written order
asking bank to pay money to a
person
 Bill generation: an invoice for
goods/services supplied to a
customer.
 Credit card sales transaction: takes
impression of customer’s card

Databases and files
 Database: collection of data
 Types: hierarchical, network,
relational
 Important features for design: good
data placement, short transactions,
real-time backup, high normalisation,
archiving of historical data and good
hardware configuration

File: block of data
 Master file: info about business
organisation
 Transaction file: collection of transaction
records
 Report file: data formatted for presentation
 Work file: temporary file in the system used
during processing
 Program file: instructions for processing of
data

Data warehousing
 Data warehouse: collects info from
different data sources

Backup procedures
 Backup: another copy of data
 Recovery processes include backup,
journal, checkpoint and recovery
manager

2 types of recovery
 Backward recovery: back out or undo
unwanted changes
 Forward recovery: redo changes

Updating in a batch
 Originally feasible: details were stored on
punch cards or magnetic tape
 2 stages – collecting and processing of
transaction data into file & updating master
file
 Sequential access: data accessed in a
sequence. Time consuming.
 Information technology: magnetic tape

Updating in real time
 Direct/random access: data is accessed
without accessing previous data items.
Stores data based on an algorithm, which
calculates data location. When index used,
called indexed access.
 Information technology: magnetic disk
 Software – online and user-friendly
 Rapid response time – few seconds or less

Other information processes
 Collecting: generating transaction
data
 Analysing data: meet user’s
information needs. Output from TPS
is input to other systems

Hardware
 MICR (Magnetic ink character
recognition): used by banks to read
account numbers on cheques
 ATM (Automatic teller machine):
banking terminal performing deposits
and withdrawals
 Barcode readers: used in retail to
collect product information

Forms
 Document used to collect data from a
person
 Examples include sign-on sheet for
payroll.
 On-screen forms: populates fields in
a database
 Web forms: used to purchase items
over the internet

Management information systems
 Provides information for the manager
 Different types of reports include
scheduled reports, forecasting
reports, on-demand reports and
exception reports

Issues related to transaction
processing systems
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Nature of work
Non-computer procedures
Bias
Importance of data
Control in transaction processing

Nature of work
 Automation of jobs: the use of
information technology to perform
tasks once performed by people
 People as participants: resulted in
fewer jobs in banks. People are
purchasing products by completing a
web form.

Importance of data
 Data security: involves series of
safeguards to protect data
 Encryption: coding data
 Decryption: changing it back
 Firewalls: used on networks to verify
and authenticate all incoming data

Importance of data continued
 Accuracy: extent data is free from errors.
Errors caused by mistakes in gathering
data, data entry, mismatch of data and
person, or out-of-date information
 Data validation: checks data entry. Checks
for missing data, too high or too low data
values, data values inconsistent with other
data, data in wrong format.
 Carried out using range checks, list checks,
type checks and check digits

Data integrity
 Describes reliability of data.
 Involves accuracy, currency and
relevance of data

ACID test
 Atomicity: all steps involved in transaction
completed successfully as a group
 Consistency: transaction successfully
transforms the system and database from
one valid state to another
 Isolation: transaction is processed
concurrently with other transactions. As if
only transaction executing the system
 Durability: all changes transaction makes to
database become permanent

Control in transaction processing
 Starts with collecting, includes
manner TPS manipulates data & way
errors are corrected
 Some people in management
positions are willing to falsify
transactions to promote careers

Manual transaction systems
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Manual transaction systems are imperative in the retail environment
because they were the conceptual basis for real-time TPS. They were used
long before the rise in technology allowed for easier data collection and
storage. Obviously, they have been around since trading and business took
its early strides. In smaller stalls who still cannot afford the technology
corporations use, it is necessary to use manual transaction systems to
record business activities. Manual transaction systems are based on a clear
set of rules followed by a person. They make it easier to transmit the data
into a format suitable for recording onto an information technology e.g. a
computer. Of course, computerisation of a manual T.S. brings benefits, when
used by a large retail organisation. It increases the rate at which products
are sold, which means more profit for the retail chain. The less time taken
for a customer to purchase a product is invaluable in customer satisfaction,
as there are lesser queues – therefore lesser time spent on waiting. Also
manual T.S.s provides the retail chain with information in what products are
on demand. The retail chain capitalises on this information on consumer
habits and they can tailor their products to attract more customers, thereby
meaning more profit.

Databases and files
 In any large retail chain/organisation,
the information processes often vary.
In the handling of data, the storage
and retrieval of data must be spot on.
Retail chains rely on this trait for the
success of their business.

by Julian Carpo

Designing the new solution
continued
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Context diagrams provide an easy way to visualise
information. Consulting this design tool will help in
simplifying the development of the new system, as it clearly
shows the flow of data in the system.
A DFD will be used to provide more detail into what the
participants can do in regards to this new solution. It has
greater detail than the context diagram.
Decision trees are very important in this retail context.
Almost anyone can immediately identify what will transpire
with this solution, what needs to be done in order to
accomplish the goals, etc. it represents all possible
decisions and the outcomes of those decisions.
A Data dictionary provides a comprehensive list of the data.

Implementing the new solution
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Participant training, as outlined before, will come in handy
in ensuring that our employees and workers can use the
system and understand its benefits. Training manuals will be
accessible. Technical support in troubleshooting problems
will be gained online through an always-on internet
connection.
Pilot conversion ensures that all our retail chain stores
across Australia will have the latest technology available to
them concurrently. This also ensures that the system can be
trialled in different regions e.g. rural as opposed to urban. If
successful, the new solution is guaranteed to be functioning
within acceptable standards and will be implemented
throughout the larger centres.
Of course, testing the new system ensures that it works.
Diagnostic software and general operation are examples of
testing. The reliability of the backup system is integral in
the new system’s success.