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This is an example of transaction processing system. This document is useful in conducting transaction processing system.
This is an example of transaction processing system. This document is useful in conducting transaction processing system.
Transaction Processing Systems A. Introduction A transaction is any event that generates or modifies data that is eventually stored in an information system. Transaction processing systems collect, store, modify and retrieve the transactions. 1. Four characteristics of a TPS are: Rapid response Fast performance with a rapid response time is critical for business Reliability A breakdown will disrupt operations or even stop the business. Inflexibility Every transaction is processed in the same way regardless of the user. Controlled processing The processing in a TPS must support an organisation’s operations. 2. Batch Processing Batch transaction processing collects the transaction data as a batch and processes it later. Its kept for processing at a convenient time. Features processing large volume of similar data lowers costs processing a batch may take several minutes, hours or days. used when a time delay will not decrease the usefulness of the results. involves a large batch of an identical data type. Disadvantages: The processing schedule is predetermined. Will halt immediately if an error occurs in any one of the tasks. Errors cannot be corrected during processing. If an error occurs during a batch process, then the error must be corrected and the batch process restarted from the beginning. Must have exclusive access and control over its data files. Sorting the transaction data is expensive and time consuming. Does not provide data that are fully current. 1 E/Transaction Processing Systems RK 3. Real Time Processing Real Time Transaction processing is the immediate processing of data. It provides instant confirmation of a transaction. Involves using a terminal to enter data and display results. Computer network links terminals to mainframe Involves large number of users performing transactions simultaneously. Also called online transaction processing Two main concerns : Concurrency: ensures that two users cannot change the same data at the same time. Atomicity : ensures that all of the steps involved in a transaction are completed successfully. If any step fails the system ceases. 4. Monitor It is a software that allows the transaction processing application programs to run efficiently. It provides a standard interface between terminals, application programs and DBMS. is ready to receive the transaction data. It is used in real-time processing to eliminate a number of possible errors. Some TPS add an entry time to the transaction data in an attempt to trace the data if it is lost. 5. Data Validation Validation can be achieved in several ways: The correct data type . alphanumeric, numeric, alphabetic. Verification at data entry time, so that only the correct format and number of characters may be entered. Field checking occurs when the transaction data is entered into a database. The data is organised into files, records, fields and characters. Data validation is carried out by checking the files, using a range check, list check, type check or check digit. 2 E/Transaction Processing Systems RK 6. Batch Processing Vs Real Time Processing Real time processing Batch processing Each transaction is unique. It is not part of The database is not a group of transactions accessible all of the Requires the master file to be available time for batch more often for updating and reference processing. Has fewer errors as transaction data is The data is organised validated and entered immediately. and stored before the More computer operators are required, as master file is updated. the operations are not centralised. Errors can occur during more difficult to maintain these steps. 7. Manual transaction Vs Automated Transaction Clerk manual systems included: Gathering data on paper application forms Transferring the data to their own system for storage Storing data in records in a sequence so that they could be easily retrieved Transcribing information to invoices, orders and accounts Updating records with additions, deletions and editing Automated transaction processing: Automated transaction processing can achieve much more than any number of clerks manually sorting, transferring, sorting and copying data in the creation of accounting documents. Punched cards and tapes were used when batch was the only method of transaction processing. Transaction Processing was the first to utilise the power of the computer back in the 1950’s, with UNIVAC Costs for computer time was high, and there was a need for a greater processing speed. People are used to record the data about the business activities. Computerisation of a manual transaction processing system provides significant benefits to the business: Increases the rate at which products are sold. There is less time taken for a customer to purchase a product. 3 E/Transaction Processing Systems RK It provides information on which products are in demand. The business knows what products are selling from the inventory database. Determine purchasing habits. Automated transaction processing is faster than any number of clerks manually sorting, transferring, sorting and copying data in the creation of accounting documents. 8. Components of TPS Users These are people within the company that run and use the TPS. These individuals will access the data from the online system to check inventory, orders, find and retrieve data to use in other planning systems and so on. Participants The people who perform the transaction processing, either as real-time or as batch. The types of actions they perform will therefore vary depending on the type of TPS. People People from the environment are becoming participants in real- time processing systems as they directly enter transactions and perform validation. B. 1 Examples of Real Time TPS a. Reservation systems are used in many businesses to put aside a service or product for a customer.Eg. Travel Agents. b. Point of Sale Terminals are used by retail stores to sell goods and services. The product is generally identified by its barcode, and price and other relevant data about the product can be found form the database. c. A library loan system is used to keep track of items borrowed from the library. 2. Examples of Batch TPS a. Cheque clearance involves checking that the person who wrote the cheque has enough money in his/her account to cover the cheque. b. Bill generation . organisations create a bill, or invoice, for goods or services that have been supplied to a customer. They usually generate a group of bills at a scheduled time and done as a group. c. Credit cards are performed in real-time, but the only online check are that the card is not listed as lost, stolen, cancelled or over the card limit. d. The printing of documents from the print queue (both network and non- network) is a batch process. The document is written to a file before being printed at the printer. 4 E/Transaction Processing Systems RK 3. Reservation System Data Flow Diagram/ System Flow Chart Purpose Environment Data/ Information Participants and Users Information and Technology Issues arising 5 E/Transaction Processing Systems RK 4. Point-of-Sale Data Flow Diagram/ System Flow Chart Purpose Environment Data/ Information Participants and Users 6 E/Transaction Processing Systems RK Information and Technology Issues arising 5. Library Loan Data Flow Diagram/ System Flow Chart Purpose Environment Data/ Information 7 E/Transaction Processing Systems RK Participants and Users Information and Technology Issues arising 6. Generation of Bills (Batch) Data Flow Diagram/ System Flow Chart Meter Reading Customer Database Calculate Bill Charge rates Print Bill Update Consumer Database Database 8 E/Transaction Processing Systems RK Purpose Environment Data/ Information Participants and Users Information and Technology Issues arising C. Storing and Retrieving 1. File types in database for TPS A file is a block of data containing related records. Every TPS uses files to organize and store its transactions. files Characteristics Master keep permanent data such as data about employees or customers. It is completely rewritten whenever any records in the file are changed (inserted, modified, deleted). Transaction contain records about events. When these records are processed, changes are made to the master files. For example sales 9 E/Transaction Processing Systems RK information used to update product database or customer database. Report contains data that has been formatted for presentation. Work temporary file in the system used during processing Program contains instruction for processing data. 2. Searching for Files Linear Search Linear search starts from the beginning, and works its way one by one (sequentially) until it finds it’s specific target. This search will work ordered or random. Binary Search Divides the array into two parts: Upper and Lower part. The process is continued until either the value is found or there are no more elements in the data set to be checked. At each division there are three possibilities for the target to exist (if it exists in the data set) 1. the target lies at the division point 2. the target lies to the left of the division point 3. the target lies to the right of the division point 3. Paper Storage Data for transactions are normally stored in a digital form in databases and files for processing and updating. Paper copies of invoices, delivery dockets are also a part of the system as manual filing systems still operate in many companies for the batch paperwork of each days transactions. Paper records in their original hard-copy format have several disadvantages: The storage of paper is bulky requiring enormous physical space It is difficult to manually find all the occurrences of text in multiple documents A separate index or catalogue system must be maintained to allow documents to be located Sorting large quantities of paper documents is a slow and unreliable process Examples Document Imaging 1 E/Transaction Processing Systems RK 0 Documents scanned and saved as images Cannot be searched Cannot be edited Identical to original but in digital form Saves storage space Separate indexing systems are required to access the scanned documents as searches cannot be done on the text contained in them Optical Character Recognition (OCR) Pages containing text are scanned and saved as image files Character recognition software then processes the images to identify the different shapes of the characters Support hyperlinks Type Advantage Disadvantage HTML Public domain format Not platform dependent Standardised format Text and images are separate files PDF Text and images in same file Copyrighted format Contents, index lists, bookmarks, Specialised software required thumbnails, Needs browser plug-in for comments viewing Documents can be locked 4. Data warehouse Businesses use computerised database to handle all transactions. Large amount of data from accounting, sales, distribution, personnel, etc can all have separate database. Data warehousing brings together all the information stored in the various data formats and structures from an organisation into a single data store. A data warehouse provides data that is: Consolidated- Data is organised using consistent naming conventions, measurements, attributes and semantics. Subject-oriented Data that is irrelevant for executing reporting and making searching difficult is removed. Only key information is available for analysis. 1 E/Transaction Processing Systems RK 1 Historical Data stored is historical. It was accurate when it was collected. The data stored in a data warehouse represents a particular point in time and never updated. Read-only After data has been moved to the data warehouse successfully, it does not change unless the data was incorrect. 5. Data Mining A class of database applications that look for hidden patterns in a group of data that can be used to predict future behavior. For example, data mining software can help retail companies find customers with common interests. The term is commonly misused to describe software that presents data in new ways. True data mining software actually discovers previously unknown relationships among the data. D. Backup Procedures A backup is a copy of files or a file system created in case the originals are damaged or lost. The backup is stored on media such as a tape or disk that is generally portable and removable. Backup is one of the most important procedures that a system administrator must perform because it is usually their first line of defence against data loss. The DBMS will contain both backup and recovery capabilities for getting the database up and working ask quickly and accurately as possible after hardware failure or a system crash. Backup is the storing of additional copies of the database and transaction records, so that in case of hardware failure, user error, vandalism or natural disaster, a copy of the data will survive and can be restored. The more valuable the data the: More often the files should be backed-up More copies should be made Greater the number of locations where the back-ups should be stored. 1. Full Backups This week Last week Week before last 1 E/Transaction Processing Systems RK 2 Son Father Grandfather Grandfather, father, son is three generations of the kept files for successive backups. This allows for two previous versions of the files to be stored in case some error has been passed on from one generation to the next. 2. Partial backups Differential backups, which have a full copy of the files from time to time, as well as a regular copy of those files that have changed since the last full backup. Incremental backups, which are copies of all files that have changed since the last backup of any kind, not just since a full backup. Type Advantages Disadvantages Differential The full backup and only the Slow by the end of the week last daily backup have to be Each backup needs more space loaded to restore all the data Incremental Faster backups The full backup plus all the Uses less space daily backups have to be loaded to restore all the data 3. Storage 1 E/Transaction Processing Systems RK 3 Offsite Storage It refers to a location that is physically separated from the main system. In case of vandalism or a natural disaster that might destroy the premises and all the files stored out of site will be safe. On-site Storage Requires several levels of security including a fire-proof backup storage safe, generally in a different location or preferably a different building to the operation files. It refers to a location that is physically close to the system and gives faster access to the backup data but requires extra precautions. Storage Media ranges from Zip disks to Magnetic tape. Tape media, though sequential, is quite commonly used since it is economical for large backups. 4. Backup Software Backup Software is designed to manage the copying of selected files to backup media, generally offers automated scheduling as well as options for full, differential or incremental backups. Features of backup software: Combinations of full and incremental or full and differential backup procedures Backup of all or selected files Selection of files for backup by date, size, type Restoration of all or selected files to their original or other directories Optional compression Optional password to access a backup set Unattended backup Scheduled backup allowing overnight operation Encryption of the backup, requiring a decryption key to unlock the backup set Logs the success of the backup Tolerates files being left open, by prompting the user to close them rather than aborting the backup 5. Recovery Recovery . recovery testing is done to devise the most appropriate method of regaining data loss. Backward recovery is used to undo unwanted changes to the database, due to aborted transactions. 1 E/Transaction Processing Systems RK 4 Forward recovery begins with the backup copy and processes all the transactions from the partial backups in order, through to the most recent. This method is faster and more accurate than the backward method. Recovery TYPE STORAGE PERIOD SPEED/ACCESS COST Floppy 1.4MB Short term Slow/direct expensive 6mm tape 2GB Long term Slow/sequential Noisy/inexpensive 12mm tape 60-400MB Long term Slow/sequential Inexpensive tape Drive expensive 4mm DAT 1-4GB Long term Slow/sequential inexpensive 8mmDAT 250MB Long term Slow/sequential inexpensive Digital linear 20GB Long term Fast/sequential Inexpensive tape Tape Drive expensive M O disks 650 to 10GB Long term Slow/direct inexpensive CD-RW 650 Medium Slow/direct inexpensive DVD 17GB Medium Slow/direct Inexpensive tape Drive expensive 1 E/Transaction Processing Systems RK 5 Hard disk 80GB Medium Very fast/ direct inexpensive ZIP/JAZ 100MB-%GB Short term Very fast/direct inexpensive 6. Updating in Batch In batch processing paper invoices and records were collected in batches. Transactions were then updated on a fixed basis. Batch processing done today When transactions are recorded onto paper or stored on a magnetic tape. There are two steps: Transaction File is created to collect and store data. Data must be sorted and put in a sequential order. Master File is updated. The data is read sequentially and additions, deletions and updates are made. Data Entry What actually happens Retrieving the transaction from a magnetic tape. Reads all data in the order it was stored Transaction File The transaction file would be sorted in the same sequence as the master file. Transaction records will be matched with corresponding master file records. Batch run Both files are read in sequential order. Some master file records will have no transactions, in which case, the program will simply copy the old master file record to the new master file. When a match occurs, the applicable update processing Master File is performed and a record written to a new output master file. Points to consider when batch processing The source documents which are grouped together as a lot. The total number will be predetermined but rarely exceeds 100. Each batch should contain only one transaction type: debit, credit, monthly installments. Source documents specially designed with data entry considerations where data is requested in a logical manner as used in processing. Each batch will contain another document, a batch header on which batch number, data and transaction type and number of records in batch will be calculated. 1 E/Transaction Processing Systems RK 6 Data entry: For data entry, batches would normally be keyed in twice: one initially, and by another operator to validate the entry. Editing An edit computer program would read the transaction file and validate its content. The validation would involve: ensuring only valid data types were contained in relevant fields(e.g. numbers, dates). Data value range (e.g. between 1 to 12) in terms of months of year. Check digits on codes( e.g. 4 digits for post code). The number of records in a batch to be equal to the number of records in the batch header record. Creating an edit report of all transaction records and errors. Corrections would be re-keyed in and edit program re-run. 7. Updating in Real-time Real-time is the immediate processing of data usually online. It provides for immediate editing and correcting. Also provides instant confirmation of a transaction and requires access to an online database. Features It reflects the current situation, rather than an out- of-date one. It is not fast, but all of the processing takes place during the transaction. It allows for a quicker response resulting in the movement of objects displayed. Using a terminal to enter data and display the results of the TPS Large number of users who are simultaneously performing transactions to change data. Data Entry Transaction file Master File Steps: Enter data Retrieve the appropriate record from the master file 1 E/Transaction Processing Systems RK 7 Update the record Send the appropriate response back to the participant. IT Required The hardware required for real-time processing includes large capacity secondary storage with direct access files so that response times is very quick. The software must enable online work for multiple simultaneous use, as well as a simple user-friendly interface. E. Information Processes 1. Collecting. Hardware MICR (Magnetic Ink Character Recognition) MICR systems are used by banks to read account numbers on cheques. Characters are printed using magnetic ink. When MICR occurs, signals are sent to the computer identifying each cheque as presented. MICR Fonts ATM (Automatic Teller Machine) An ATM is a banking terminal that performs common banking transactions, such as deposits, withdrawals, obtaining account balances or transferring money from one account to another. When people complete a transaction using an ATM, they are participants in a real-time transaction processing system. Barcode Readers Barcode readers are used in retail industries to collect product information at point of sale. 2. Collecting Forms A form is a document used to collect data from a person. When the form is completed, it is processed in batch or real-time. Forms minimise data entry errors by providing the correct format for the user or by using checkboxes, radio buttons, etc. 1 E/Transaction Processing Systems RK 8 Browse Dairy / Frozen : Cheese : Creamed Cheese Showing items 1 to 22 of 22 Page 1 Paper Forms Paper forms are written to provide the data and then batch processed at a later time. Advantages They can be stored and processed in batches The can be signed, unlike electronic forms The customer does not have to be computer literate Disadvantages They can accept data that is invalid The customers may miss required details. Copies of a large number of paper forms are expensive to make. They are difficult and bulky to store. A customer’s writing may be difficult to read. 3. Online Data Collection The screen forms are completed to populate databases, and can be processed in real- time or batch. Web Forms Web forms are for users wanting to purchase products from Internet companies. The user details will go into in a database, and may be processed as either batch or real-time. Analysing Data Once the transaction data is processed and stored, it may be analysed. The output from one TPS becomes input for other information systems such as DSS (Decision Support Systems) and MIS (Management Information Systems). Decision Support Systems (DSS). DSS help people to make decision by providing information, models and analysis tools. It supports the decision-maker by providing tools such as spreadsheets to assist in the examination of the data 1 E/Transaction Processing Systems RK 9 Management Information Systems (MIS) MIS provides information for the organization’s managers. It shares the data from the TPS, which is then manipulated to create reports. These reports can assist managers in their decision-making. 4. Reports Types Report Types Characteristics 1 Periodic provided on a regular basis, used by all levels of management 2 Detail list relating to a product or an activity to be performed 3 Forecasting make projections about business trends. Also known as planning reports 4 On-demand Generated usually in response to a specific need 5 Summary Combination of data showing totals over different areas 6 Exception alerts management to unexpected situations that need special handling F. Social and Ethical Issues 1. Changing Nature of Work Automation of jobs TPSs has made businesses more efficient by offering a range of new services. This has caused many jobs to change. Multi-skilling, de-skilling and up-skilling taking place with the improvements in technology. Workers are required to do ongoing training or lose the job. 2. Clerical Work Typing and clerical duties are gone due to real-time processing. TPS allow user to enter and retrieve data which a clerk used to do. 3. Bias data collection Bias means that the data is unfairly skewed or gives too much weight to a particular result. Can be in the form of methods used in the collecting, processing or presenting of data. 4. Security 2 E/Transaction Processing Systems RK 0 Security refers to the protection of the data once it has been collected. Business rivals and former employees may wish to steal, destroy data belongings to a business. There is a greater risk when the data is accessible to multiple users in a real-time transaction processing system. Passwords and biometric methods such as fingerprint and eye scan. Encryption: Data is coded, transmitted and then converted back into its original form. Firewalls check the password of anyone trying to access a network. 5. Accuracy Despite the importance of accurate data collection and processing, errors may occur at many states. Data Collection Errors – errors due to poor handwriting, misreading of questions, etc. Data Entry Errors - takes information from the wrong form. Out-of-date Errors - a person moves, changes their name on marrying. Mismatching Errors - different person, maybe with a similar name. Improvements to Data Accuracy Careful design/ wording will helps limit possible errors Checking data for accuracy through data validation 6. Integrity This refers to the correctness and reliability of the data. Data should be current ie must be updated constantly. It must pass an ACID test. Atomicity - when all steps in a transaction are completed. If one fails the transaction is aborted. Consistency- when the tps transforms the system and the database from one state to another. E.g. always crediting and debiting the same amount. Isolation- transaction is processed independently even though other people are using the same database. It should not interfere with each others updates. Durability- the changes made to the database remain permanent when completed. 2 E/Transaction Processing Systems RK 1
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