Information processes and technology option topic 1 ...



Characteristics of Transaction Processing SystemsTransactions:A transaction is a series of events important to an organisation that involve a request, an acknowledgement, an action and an outcome.E.g. A transaction may be; using a credit card to make a purchase of an item, reserving a hotel room, borrowing a library book, or making a cash withdrawal at an ponents of a transaction processing system:A transaction processing system collects, stores, modifies and retrieves records of transactions.Data:Payment approval, Service confirmation, Delivery Docket, Universal Product Code (UPC)Information technology:Database servers, database management software, barcode scanners, RFID readers, laser/receipt printers, backup magnetic tape, client workstations networked to internet (touch screen, Ethernet cable, modem, switches, operating system), client applications.Participants:People who perform processes for the TPS (e.g. data entry clerk, credit card company, customer)Batch and real time transaction processing: Batch transaction processing: The collection and storage of data for processing at a scheduled time or when there is sufficient data.Real time transaction processing: The immediate processing of data.Real Time Transaction ProcessingBatch Transaction ProcessingSimilaritiesCollects, stores and modifies records of transactionHas data integrity procedures (validation, verification, referential integrity and ACID properties)DifferencesTransactions are handled individuallyTransactions are handled as a groupProcessing and output is immediateProcessing and output is delayedSystem failure is critical as it prevents processing taking placeSystem failure is less critical as there may be time to restore the system before the next batch If one event fails, user is given opportunity to correct the data immediately. Errors stored on an error file and corrected at a later time. Data validation – a check at the time of data collection, to ensure the data is reasonable and meets certain criteria.Types of real time (online ) systemsReservation systemsReservation systems are transaction processing systems which are used extensively in hotels and airlines to help staff set services and book rooms for customers at certain times. Through these systems, future customers of the business or organisation can do searches under many criteria to find a service or product that suit them. Some of these criteria include, e.g. destination, cost, arrival times and departure times. Point of sale (POS) systemsPoint of sale systems is a real time transaction processing systems which are utilised at supermarket or retail outlets to track stock levels and sales. In point of sale systems, when a transaction occurs, information is received from a server (which does most of the processing). A real life example would be at the Woolworths, when the staffs passes items through the scanner, an interface comes up on the screen, where they can tell you the total cost of all the products.Library loan systemsLibrary loan systems are systems which utilise real time transaction processing to provide the availability of the library’s resources. If a person wants to borrow a book then this is the progress.The librarian scans the resource’s barcode.The laser scanner scans the barcode.The hardware analyses the signal.The barcode comes up, and the book title comes up in the database.The librarian changes the status, and records it under the correct ID.Transaction processing systems:Are significant because they were the first type of information systems (traders kept paper records of sales). Must have data integrity (ACID properties): Atomicity – transactions should occur completely or it should be undone completelyConsistency – each step of the transaction is carried out in the same way each time so data is correct for each part of the transactionIsolation – transactions must be independent of each other so the same data is not treated twice (locking the record being processed)Durability – changes should be written to permanent storage before the transaction is fully committed (so there is a permanent record)Manual and automated systems:Manual transaction systems are stored on paper Automation of manual systems is the process of converting the hard copy data into an electronic formClerks perform events in manual systems. These events are only suited to automation if they follow a strict sequence of events; and the data used across the events are the sameAutomation of manual systems is not beneficial to small business because it is unlikely profits will increase from the time saved through automation; and the costs to purchase and maintain IT may be unaffordableAutomation may benefit large businesses through increased efficiency; savings from less employees; higher customer satisfaction from quick service Benefits of automated systems:Quicker to process transactionsElimination of calculation errors and repetitive tasks for participants Easier to create backups and to analyse historical dataWeaknesses of automated systems:High cost for IT Staff will have to undergo extensive trainingTransaction will fail if one piece of IT does not functionTypes of Transaction Processing SystemsWeb based systems:Data entered via the web e.g. reservation systems (airline, hotel)Non-web based systems:E.g. library loans system, point of sale systemsOn-line real time systems:The immediate processing of dataBatch systems:The collection and storage of data for processing at a scheduled time or when there is sufficient dataE.g. clearance of cheques, bulk generation of billsSystems that appear real time, responding as the transactions occur, but where the actual updating is batch processed:E.g. credit card transactionsStoring & Retrieving in Transaction Processing SystemsThe digital data is stored in databases and files Stored data is retrieved to conduct further transaction processing such as printing invoicesPaper records of transactions may also be storedBackup and recovery:Backup is the process of making a copy of data in case the original is lost or damaged (fire, hard disk failure, hacking)Recovery is where the backup copy of the data is restored in the systemRecent backups are useful to recover to a point as close as possible to the failure (there is less re-processing needed)Older backups are useful because: You may have regretted the software upgrade so you can now revert to older version Viruses infect files at a particular point in time; you can recover the data before it was infectedHackers can alter data; the older version will be the unaltered versionOffsite Storage:To protect backup if the building is destroyed Secure onsite storage:To have quick access to backup Types of backupsFull backup:A complete copy of all the data within the system. Advantage: Feel assured that everything is backed-up, Data is quickly recoveredDisadvantage: Time consuming to back up; uses lots of storageMany techniques can be used, one example is the the grandfather, father, son, where three generations are kept for backups.Grandfather, Father, Son:This is a backup procedure where there are 3 time versions of a system. Each backup represents a version. The “grandfather “ is the oldest version, the father is the second oldest version and the son is the earliest version. The father is usually a magnetic tape or external hard drive. The existing “son“ becomes the “father” The existing “father “ becomes the grandfather. The “grandfather” is updated.If the update fails, the “father” is used as the “father” uses the “son” to create the “grandfather”.If the “son” fails, the “father” replaces the spot. This makes sure that the data and the system can be reconstructed.Differential Backup:A copy of all files that have been altered since the last full backupThe size of the differential backup therefore continues to grow until the next full backup. Recovery needs a full backup and any one differential backupIncremental backup:Making a copy of files that have changed since the last backup Advantages: Quicker to backup; less storage required Disadvantages: All incremental backups must work for complete recovery (if not, there could be loss of data as only the previous back up can be accessed); time consuming to recover.Suitable media:Magnetic Tape: For lots of data; cost effective for its storage capacity; portable; sequential access (slow recovery)Hard Disks: Only for small systems because of high cost and weightOptical Media: Only for single machines because hundreds of CDs would be required for a large system; low cost; portable; most computers have CD/DVD driveOnline Systems: Completely automates backup as data is transferred via the internet offsite; expensive to useDocumenting backup and recovery procedures:Required because backup can easily become a chore that is overlookedProcedures should specify which set of media to use for backup and where backup copies should be stored They should also specify how backup copies are to be verified to ensure they will actually work in the event of failureSpecialised backup software:Verifies all data on the media as the backup is being madeRecovery Testing:Test recoveries should be made at regular intervals to ensure recovery operates as expected.Transaction Logs:Contains historical details of each transaction performed as well as details of current transactions The log can be used in recovery: completed transactions can be recommitted and incomplete transactions can be rolled back.Mirroring:Automated process of writing data to two drives simultaneouslyProvides for faster recovery because if one drive fails, the redundant drive will continue to store the data and provide access to itRollback:Returns the database to a consistent state e.g. after a crash, any transaction which was active at the time of the crash can be rolled backUpdating in batch systems:Historical significance:Batch processing was the first type of transaction processing: cards were punched by an operator and loaded in stacks for batch input. Steps in a batch update:The transaction file (which contains all the collected data) is submitted for processingEach transaction is retrieved and successful transactions are committed to the master fileAny transactions that have a problem are rolled back. Details of the problem are written to an error log so further processing can continueLimitations of batch processing:The system is not fully current. Processing will only be carried out when real time processing demands are lowest. Technology required:Magnetic ink character recognition readers (thousands of cheques can be processed in minutes)Sorting machines for paper formsDistributed processing to reduce the processing timeSequential access to the transaction file to retrieve data in the order it was stored Suitable applications:When the data already exists in the system and therefore can be batch processed as no real time input is required (e.g. generating bills)When data is collected on paper forms because customers understand that transporting the forms take time so they don’t expect a real time response; and also because paper forms (e.g. cheques) involve a large number of repetitious data entry tasks so batch processing is cost and time efficient User interface:Should be designed for rapid data entry (e.g. accepts numerical code)Generation of a telephone bill:The transaction details (duration, source, destination, etc.) of each call are stored as it takes place.On a regular basis; once a month; the transactions are processed as a group.They are sorted by customers and a bill is generated for each customer.Updating in on-line real time systems:Relevance and impact:Allows multiple users to simultaneously process transactions The data is always current across the system Technology required:Fast and secure communication linksLarge processing powerClient-server system Hardware requirements:Large secondary storage with direct accessSoftware requirements:Online database with user friendly interfaceSteps in on-line real time processing: Each transaction is processed as it is initiatedSuccessful transactions are committed to the master fileAny transactions that have a problem can be corrected immediately by the participant or is rolled backSuitable applications: When there is a constantly high demand for transaction processing e.g. library loans system, point of sale systems, reservation systems (otherwise it will be inefficient as hardware and software requirements are expensive)User interface:Should be interactive and easy to follow because customers initiate real time processingOther Information Processes in TPSCollecting:Hardware:Automatic Teller Machines (ATMs):The card reader captures the account information stored on the magnetic stripe. The keypad lets the cardholder enter the PIN and tell the bank what kind of financial transaction is required. All data collected is transmitted to the bank in encrypted form. Barcode Readers:Operates by reflecting laser light off the barcode image; light reflects well off white but not very well off black. A sensor detects the amount of reflected light. This is converted to an electrical signal and then transformed into binary (by an analog to digital converter). The binary data is the Universal Product Code which is used in retail transactions to uniquely identify products Radio Frequency Identification Tags:Composed of a microchip and antenna that stores bits of data. When a tag passes through the sensor, it receives energy. A signal is then automatically transmitted.RFID tags can therefore communicate with the network (unlike barcodes which need scanning). They are used to collect product details and the data stored on it can be changed.Collection from forms:Should have consistency with other forms; e.g. round radio buttons Should be readable (fonts, alignment of fields, bold text for emphasis) Should have white space (to imply grouping and rest the eyes)Paper forms:Used for batch processingInstructions must be clearly stated (paper form cannot react to user input)Forms with larger font should be available.There should be appropriate space for answers (people use the space provided as an indicator)AdvantagesDisadvantagesThey can be stored and processed in batches.They can be signed.The user does not have to be computer literateThey can accept invalid data.The customer may miss some details.Copies of paper forms are expensive and timely to make.Difficult and bulky to store.Online screen design:Clearly show what functions are available (users like to explore all possibilities with new software)Feedback should be provided to actions (users may reinitiate the task in the belief nothing has happened)Warning messages must appear before dangerous changes are madeGrouping commands and controls together.Web forms (real time and batch):Data should be validated on the downloaded page If validation error occurs, users should be informed what the error is and how to fix it. They should not have to re-type all the data.Web pages should be tested with many combinations of web browsers and screen resolutions Financial data should be collected in encrypted formAnalysing data, in which output form transaction processing is input to different types of information systems, such as:Enterprise systems:Performs processes central to the overall operation of a large organisationManagement information systems:Summarises existing data into information (sales trends, profit and loss report) to assist in the management of a business.Decision support:Summarises existing data and also performs analysis on the data to present possible solutions and consequences of making a particular decisionData mining is a decision support technique that examines the data warehouse to uncover hidden patterns. This allows humans to make decisions that maximise profit.Data warehousing systems:A large database that includes historical copies of dataAdvantages: Old transaction data can be removed from the operational system and placed in a data warehouse. This improves the performance of the operational system as less data needs to be examined in processing.Data warehouses are independent from the operational system. Therefore they can be mined without degrading the performance of the operational system.Data warehouses centralise data from the entire organisation (sales, payroll, production, marketing, customers). This means analysis can take place of the entire organisation.Issues Related to Transaction Processing SystemsChanging nature of work and the effect on participants:The automation of jobs once performed by clerksThere are fewer clerks in banks because customers rarely visit the banks due to ATMsThe internet allows for a business to be entirely web based, so there is no need for retail assistants, shop managers etc. Shifting of workload from clerks to members of the publicCustomers enter data in online banking and retailers enter data in EFTPOS New jobs have been created that require higher skillsDatabase designers, hardware technicians and web designers for web-based systems. The expected reduction in work hours from computer based systems have not occurred Integrity- the concept of whether data is correct and can be relied upon. The need for alternative non-computer procedures when the TPS is not available:During recovery, smaller systems need alternative procedures if they are to operate. This involves switching to a paper based system. The alternative method should be tested at regular intervals and the participants trained to use the paper system to ensure they operate as planned.Bias in data collection:Bias can occur when deciding what data to collect and the collection method.The result of bias during collection is inaccurate data leading to inaccurate output from the system. For example, surveys from the internet are not a representative sample of the population because generally speaking, internet users are younger, have higher incomes and possess higher technology skills than the general population.Data security:ProblemSolutionUnauthorised accessPasswordsEncryption Hackers altering dataBack-up copies of dataFirewallsCriminals stealing hardwarePhysically lock away clients and servers Virus Anti-virus softwareData integrity:ProblemSolutionUnreasonable dataData validation Outdated dataData verification Records with no links to other parts of the system Referential integrity Incomplete, inconsistent, non-permanent dataEnforce ACID properties Data quality:How effective the data is to the organisation Data entered from forms may be accurate (the data has integrity) but if the data is dishonest, it has no quality.Control in transaction processing and its implications for participants:The issue of who owns and uses data from transaction processing remains unanswered (is it the individual or the organisation doing the processing?)Managers need to monitor the activities of their employees to limit access to sensitive transaction data, but what level of control is reasonable?Should management:Read e-mail messages?Remotely view a user’s desktop?Monitor phone calls?Excessive control reduces staff motivation and efficiency so they engage in other non-work related activities A successful management style allows employees to take responsibility for the work they completeCurrent and emerging trends in transaction processing:Data warehousing and data mining Online Analytical Processing (OLAP): quickly answers complex queries using a multidimensional database; it is used for data mining. Online Transaction Processing (OLTP): manages data entry and retrieval for a large number of users who will be simultaneously performing transactions that change real-time data; e.g. banking and ticketing systems. ................
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