IPT Y12 Option Topic Transaction Processing Systems

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IPT Y12 Option TopicTransaction Processing
Systems
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Transaction processing systems are crucial to the
operation of most finance, banking and electronic
commerce organisations. Transaction processing
is primarily concerned with maintaining data
integrity. Such systems can operate at the
single database level, but they also operate at
higher levels where data in many databases and
even many different systems is involved. For
example transferring funds from one financial
institution to another. So what is a
transaction? A transaction is a series of events
that when performed together complete some unit
of work that is important to an organisation.
Each transaction has two possible outcomes,
either it is a complete success or it is
a complete failure.
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A Transaction Processing System (TPS) is a type
of information system that collects, stores,
modifies and retrieves the data transactions of
an enterprise or large business.

• the need to handle hundreds, even thousands of
  simultaneous Users
• the need to allow many Users to work on the same
  set of data, with immediate updating
• the need to handle errors in a safe and
  consistent manner

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Transaction Processing Systems

• Characteristics
• TPS collect, store, modify and retrieve
  transactions.
• It is also a unit of work composed of multiple
  operations that must all succeed or must all fail
  (Atomicity)
• Each operation generates and/or modifies data.
• Must pass the ACID test.
• Examples
• POS
• Processing credit cards
• Motel/Hotel reservations
• The main Information Processes are collecting
  and storing.

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The ACID properties of TPS

• Transactions are known as atomic, meaning that
  the
• transaction will either happen or not. If one
  account is
• debited, then another account has to be credited.
  
• Atomicity- all transactions/operations must
  succeed or fail as a group.
• Consistency- all parties must agree on the facts
  of the exchange
• Isolation- transactions must be independent of
  each other.
• Durability- the effects of a completed
  transaction should be lasting

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The ACID properties of TPS

• ACID is an acronym for atomicity, consistency,
  isolation and durability. The aim is to ensure
  all transactions comply with these four
  properties. They ensure that
• transactions are never incomplete (atomicity),
  the data is never inconsistent.
• (consistency), transactions do not intrude or
  affect each other (isolation) and that the
• results of a completed transaction are permanent
  (durability).
• All these properties combine to ensure the
  integrity of all data is maintained before,
  during and after each transaction.

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CHARACTERISTICS OF TPS

• Rapid processing/response- customers cannot wait
  for a TPS to respond. Speed from input to output
  must be in a few seconds.
• Reliability- Breakdown will disrupt or stop
  business. Failure rate must be low. Quick and
  accurate recovery. Backup and recovery procedures
  are essential.
• Inflexibility- Every transaction to be processed
  in the same way. Operation must be standardized.
  Transactions must be processed in the same way
  each time to maximise efficiency. To ensure this,
  TPS interfaces are designed to acquire identical
  data for each transaction, regardless of the
  customer.
• Controlled processing- must support the business
  operations. A TPS should enforce and maintain
  roles and responsibilities of an organisation.

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Advantages of a computer-based transaction over a
manual system.Manual transaction systems are
business systems that operate without the use of
machines

• Larger numbers of transactions can be processed
  in a shorter amount of time cheque processing.
• Greater reliability. Less prone to human error
  data is much more reliable
• Increased storage capacity and greater ease of
  retrieval of stored data. More efficient in terms
  of space and much more reliable. Paper records
  deteriorate over time digital data does not.
• Retrieval and sorting of data is more efficient
  than manual methods

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Transaction processing is easily computerised as
it is based on clear set of rules

• A manual POS system has 11 operational steps
• Examine the product and determine the price.
• Record the product price on sale slip and add it
  to the total price of product.
• Repeat steps 1 and 2 for subsequent products.
• Check the total price of all products.
• Informs customer of total price and wait for
  payment.
• Receive payment.
• Calculate the change owing to customer.
• Give customer products, copy of sales slip and
  change.
• Repeat steps 1 to 8 for next customer.
• At the end of day add total sales slips money
  collected
• Do a stocktake to count all products remaining.

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Real- time processing

• Transactions are handled individually.
• Processing and output is instant.
• Does not require access to an online database.
• Involves using a network to link terminal to
  mainframe.
• Involves a large number of users.
• E.g Airline reservation, banking transaction
  systems, library system, student enrolment
  systems
• System failure is critical- processing cannot
  take place.
• Difficult to maintain than batch processing

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Batch processing

• Transactions are handled as a group/batch and
  processes it later.
• Processing and output is delayed
• Processing occurs at a convenient time during
  evening when PCs are idle and networks are not
  busy
• Processing cost are lower per transaction
• Processing occurs without human interaction
• Occupy much of the network capacity.
• Data errors will stop a batch process
• E.g. Payroll, cheques, billing for electricity,
  E-way and telephone.
• The only feasible form of processing when data
  was stored on punch cards or tapes.
• System failure is less critical-time to restore
  system
• Database not always available.

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Two main concerns with real-time processing

• Concurrency
• Two user cannot change the same data at the same
  time.
• One user cannot change a piece of data before
  another user has finished with it.

• Atomicity
• Ensures that all of the steps involved in a
  transaction are completed successfully as a group
• If any steps fails, no other step should be
  completed.
• In order for transaction processing to work, all
  the operations must succeed or fail as a group.

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Real-time transaction processing
A Transaction processing monitor (TP monitor) is
software that allows the transaction processing
application programs to run efficiently.
Terminal
Terminal
Terminal

• It manages the sequence of events that are part
  of a transaction
• It provides a standard interface between the
  input devices(terminals), the TP application
  programs, and the DBMS
• It also provides data security

• It is used in conjunction with a operating system.

User Interface
TP Monitor
Application
DBMS
Database
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Differences between real-time and batch processing

• Each transaction in real-time is unique.
  Transaction are stand-alone both in the entry to
  the system and also in the handling of output.
• Real-time processing requires the master file to
  be available more often than batch processing
• The DB is not accessible all of the time for
  batch processing.
• Real-time processing has fewer errors than batch
  processing data is validated and entered
  immediately. With batch, data is organised and
  stored before the master file is updated. Errors
  can stop processing
• Infrequent errors may occur in real-time
  processing. Errors are tolerated.
• More operators required in real-time
  processing-operators are not centralised.
• Difficult to maintain real-time system than batch
  processing system.

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Credit Card Machines
EFTPOS
Manual impression
Real-time processing
Batch processing
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Data validation

• Data validation is used to check the entry of
  transaction data. It involves transaction
  initiation and field checking.
• Transaction initiation is used to acknowledge
  that the TP monitor is ready to receive the
  transaction data. It is used in real-time
  processing to eliminate errors. (ATM or Online
  shopping)
• Field checking occurs when the transaction data
  is entered into the database (files, records,
  fields and characters). Data validation is
  carried out by checking the fields, using a range
  check, list check, type check or check digit.
• Data validation in real - time systems allows
  corrections to be made as the data is entered.
• It is impossible to validate all data in a TPS

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Historical significance of TPS

• Transaction processing was the first type of
  information system.
• Much of modern data processing is still based on
  traditional pre- computing methods
• Clerk manual systems include
• Gathering data on paper application forms
• Transferring the data to their own system for
  storage.
• Storing data in records in sequence.
• Transcribing information to invoices, orders and
  accounts.
• Updating records with addition, deletions and
  editing.
• The first commercially available electronic
  computer was called UNIVAC (Universal Automatic
  Computer)

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The end of characteristics of TPS

• Outcomes
• After studying this unit, you should be able to
• Describe the historical importance of transaction
  processing.
• Identify types of transaction processing.
• Investigate data validation.