Transaction processing systems

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Transaction processing systems
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Characteristics of transaction processing systems

• Batch transaction processing
• Real-time transaction processing
• Data validation
• Historical significance of transaction processing
  systems
• Manual transaction systems

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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
• processed later (time delay)
• 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.

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TPS Characteristics

• They collect, store, modify and retrieve the
  transaction of an organisation.
• Directly support business operations
• Must be designed in conjunction w/ the
  organisations procedures.
• Main information processes collecting and
  storage.

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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 organisations
  operations)

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Examples of batch transaction processing

• Clearance of cheques
• Other forms of paper output

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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)
• Often run at night less demand for info sys

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3 disadvantages in batch processing

• Processing schedule predetermined
• Errors unable to be corrected during processing
• Sorting transaction data expensive and time
  consuming

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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.

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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
  dont get lost/corrupted.

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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 real-time.

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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.

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Historical significance and manual transaction
systems

• Historical significance UNIVAC 1950s
• Manual transaction systems business systems
  operating w/o use of machines.

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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

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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

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System flowchart for a POS system
Customer receipt
MIS
Inventory database
UPC/quantity
POS system
Server
UPC/quantity
Purchase database
UPC
Price
Inventory report
Product Database
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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 customers card

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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

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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

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Data warehousing

• Data warehouse collects info from different data
  sources
• Consolidated, subject-oriented, historical and
  read-only

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Backup procedures

• Backup another copy of data
• Recovery processes include backup, journal,
  checkpoint and recovery manager

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2 types of recovery

• Backward recovery back out or undo unwanted
  changes
• Forward recovery redo changes

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Recovery processes continued

• Magnetic tape stores large data quantities
  inexpensively. Uses sequential access
• Grandfather-father-son backup procedure refers
  to at least 3 generations of backup master files
• Partial backups parts of master file backed up

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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

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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

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Other information processes

• Collecting generating transaction data
• Analysing data meet users information needs.
  Output from TPS is input to other systems

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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

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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

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Decision support systems

• Assist people to make decisions by providing
  information, models and analysis tools
• Data mining used in DSSs to find relationships
  and patterns in the data

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Management information systems

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

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Key issues in designing an MIS or DSS

• How a system will be modeled
• How model of system will be handled by the
  computer
• What data will be used
• How far into the future trends will be
  extrapolated

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Issues related to transaction processing systems

• Nature of work
• Non-computer procedures
• Bias
• Importance of data
• Control in transaction processing

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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.

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Non-computer procedures

• Organisations rely on TPS
• Manual backup procedure if system crashes
• When system up running, user needs procedure to
  enter manual transactions

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Bias

• Data unfairly skewed or gives too much weight on
  particular result
• Data gathered can be presented in biased way
  using tables and charts
• Becomes ethical issue when relevant information
  is misrepresented

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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

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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 (see Chapter 2)

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Data integrity

• Describes reliability of data.
• Involves accuracy, currency and relevance of data

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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

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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

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Aspects of TPS relevant to A large retail
company

• Real-time transaction processing
• Manual transaction systems
• Components of a TPS
• Credit card sales transactions
• Database and files
• Updating in a batch, real-time
• Other information processes collecting
• Nature of work
• Non-computer procedures
• Bias

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Real-time transaction processing

• It is important in an organisation such as a
  large retail company for the immediate
  processing of data instant confirmation of a
  transaction (specifically needed in a retail
  environment where servicing a number of customers
  with a limited staff under a limited amount of
  time is usual). The 4 important characteristics
  of a TPS stresses this. They are rapid response,
  reliability, inflexibility and controlled
  processing. Also, the concerns of concurrency and
  atomicity are important in ensuring data is not
  mishandled or any procedures/steps taken are
  completed successfully as a group or not executed
  at all.

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Manual transaction systems

• 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.

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Components of a TPS

• People are obviously important in an operation of
  a TPS. They are usually classified as users,
  participants and people in the environment. This
  classification allows for easier role recognition
  within the retail chain organisation. Users do
  not interact w/ the TPS but use the data
  provided. They provide information about the
  system that is useful to the large retail chain.
  The participants are the shop workers which do
  the actual work conducted in a retail chain
  store. They enter the data into the TPSs. And the
  peole from the environment are the consumers, or
  people who buy goods from the shop front. They
  become participants when they use EFTPOS
  terminals located within the retail store to
  purchase goods and ATMS within or outside of it.
  They become participants in the sense that they
  directly enter transactions and perform
  validations.

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Examples of real-time transaction processing

• Reservation systems basically involve setting
  aside a product or service for future purchase or
  use. They are common in the retail industry.
  Lay-by is a good example. This involves the
  delaying of a valued item for future purchase. A
  minor monetary deposit, usually a small
  percentage of the overall purchase price of the
  product is then used to secure the customer the
  right to purchase this product at a later time.

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Examples of real-time transaction processing
continued

• POS terminals are used by retail stores to sell
  goods and services. In large retail
  organisations, POS terminals send inventory data
  to a central computer (sale made). We as users
  become participants when we use these machines to
  purchase items from the store. The data is
  converted for easier transmission. Relevant
  information and the price are displayed using
  barcode readers.

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Examples of real-time transaction processing
continued

• Credit card sales transactions can be done over
  the internet, at POS terminals or taking an
  impression of customers credit card. Both the
  POS system and the multi-page credit slip system
  rely on batch processing. We use them as an
  alternative to money, to pay for retail store
  purchases.

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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.

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Databases and files

• Good data placementDatabase is designed to
  efficiently gain access to frequently used data
  data patterns
• Short transactions transactions can be processed
  fast
• Real-time backup saving data during low usage or
  idle time

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Databases and files continued

• High normalisation data redundancy is minimised
  to increase update speed. Also improves backup
  speed.
• Archiving of historical data old data stored in
  chronological order in separate databases.
• Good hardware configuration the setup must be
  able to handle a number of users and provide
  rapid response

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Files

• Master file info about a retail chains
  business. This is where the data is stored
• Transaction file audit trails and history for
  the retail chain
• Report file formatted user presentable data
• Work file temporary file
• Program file data processing instructions.

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Backup procedures

• Backups provide safety nets for data restoration
  in case of a system crash/malfunction. Without
  these, the retail chain will cease to make
  profits as a result of data loss. They are
  usually stored in a safe location.

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Recovery process

• When a TPS fails, data must be recovered
  immediately for restoration.
• Journal keeps track of company records on a
  physical medium.
• Checkpoint are like signposts. Indicate where,
  when, what data was saved in a daily period.
  Syncs files and journals together for smoother
  transaction reviewing

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Recovery process

• Backward recovery undo database changes
• Forward recovery redo database changes
• Recovery manager restores database to a previous
  condition

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Magnetic tape

• Often used. Inexpensive. Appropriate for storing
  large amounts of data. An alternative to hard
  disk drives.
• Data is read from the beginning until the end.
• Suitable for most transaction backups