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/batchReal-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 real-time.

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

Server POS system

Customer receipt

Product Database

UPC Price

UPC/quantity

UPC/quantity

Inventory database

Purchase database

MIS

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

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 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.

by Julian Carpo

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.

Designing the new solution continued 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 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.