Introduction to Transaction Processing Systems

1. Chapter 2 TPS Introduction to Transaction Processing

2. Objectives for Chapter 2 • Broad objectives of transaction cycles • Types of transactions processed by each of the three transaction cycles • The basic accounting records used in TPS • The traditional accounting records and their magnetic equivalents • Documentation techniques • Batch and real-time processing and the impact of these technologies on transaction processing

3. A Financial Transaction is... • an economic event that affects the assets and equitiesof the firm, is reflected in its accounts, and is measured in monetary terms. • similar types of transactions are grouped together into threetransaction cycles: • the expenditure cycle, • the conversion cycle, and • the revenue cycle.

4. Labor Customers Materials Physical Plant Expenditure Cycle Conversion Cycle Revenue Cycle Finished Goods Cash Finished Goods Cash Subsystems: Purchasing/Accts Pay Cash Disbursements Payroll Fixed Assets Subsystems: Production Planning and Control Cost Accounting Subsystems: Sales Order Processing Cash Receipts Cash Three Primary Transaction Cycles

5. Each Cycle has Two Subsystems • Expenditure Cycle: time lag between the two due to credit relations with suppliers: • physical component (acquisition of goods) • financial component (cash disbursements to the supplier) • Conversion Cycle : • the production system (planning, scheduling, and control of the physical product through the manufacturing process) • the cost accounting system (monitors the flow of cost information related to production) • Revenue Cycle: time lag between the two due to credit relations with customers : • physical component (sales order processing) • financial component (cash receipts)

6. Manual System Accounting Records • Source Documents - used to capture and formalize transaction data needed for transaction processing • Product Documents - the result of transaction processing • Turnaround Documents - a product document of one system that becomes a source document for another system

7. Manual System Accounting Records • Journals - a record of chronological entry • special journals - specific classes of transactions that occur in high frequency • general journal - nonrecurring, infrequent, and dissimilar transactions • Ledger - a book of financial accounts • general ledger - shows activity for each account listed on the chart of accounts • subsidiary ledger - shows activity by detail for each account type

8. Flow of Economic Events Into the General Ledger Journal Entry Post Purchase Request Purchases Journal General Ledger Purchase Order Post Periodically Reconcile Subsidiary Ledger to General Ledger Accounts Payable Subsidiary Ledger

9. Audit Trail Financial Statements Source Document General Ledger Journal Financial Statements Source Document General Ledger Journal Accountants should be able to trace in both directions. Sampling and confirmation are two common techniques.

10. Verifying Accounts Receivable - The Audit Trail Accounts Receivable Control Account-General Ledger Accounts Receivable Subsidiary Ledger (sum of all customers’ receivables) Sales Journal Cash Receipts Journal Sales Order Deposit Slip Shipping Notice Remittance Advice Example of Tracing an Audit Trail

11. Computer-Based Systems • The audit trail is less observable in computer-based systems than traditional manual systems. • The data entry and computer programs are the physical trail. • The data are stored in magnetic files.

12. Computer Files • Master File - generally contains account data (e.g., general ledger and subsidiary file) • Transaction File - a temporary file containing transactions since the last update • Reference File - contains relatively constant information used in processing (e.g., tax tables, customer addresses) • Archive File - contains past transactions for reference purposes

13. Documentation Techniques • Documentation in a CB environment is necessary for many reasons. • Five common documentation techniques: • Entity Relationship Diagram • Data Flow Diagrams • Document Flowcharts • System Flowcharts • Program Flowcharts

14. Entity Relationship (ER) Diagram • is a documentation technique to represent the relationship between entities in a system. • The REA model version of ER is widely used in AIS. REA uses 3 types of entities: • resources (cash, raw materials) • events (release of raw materials into the production process) • agents (inventory control clerk, vendor, production worker)

15. Cardinality • represents the numerical mapping between entities: • one-to-one • one-to-many • many-to-many

16. Cardinalities Entity Relationship Entity 1 1 Sales- person Car Assigned 1 M Places Order Customer M M Vendor Inventory Supply

17. Data Flow Diagrams (DFD) • use symbols to represent the processes, data sources, data flows, and entities in a system • represent the logical elements of the system • do not represent the physical system

18. Data Flow Diagram Symbols Entity Name Data Store Name N Process Description Direction of data flow

19. Documents Flowcharts • illustrate the relationship among processes and the documents that flow between them • contain more details than data flow diagrams • clearly depict the separation of functions in a system

20. Symbol Set for Document Flowcharts Terminal showing source or destination of documents and reports Calculated batch total Source document or report On-page connector Manual operation Off-page connector File for storing source documents and reports Description of process or comments Accounting records (journals, registers, logs, ledgers) Document flowline

21. Sales Department Credit Department Warehouse Shipping Department Customer Customer Order Prepare Sales Orders Sales Order #1 Sales Order #1 Sales Order #1 Sales Order #1 First Stages in Constructing Document Flowchart Showing Areas of Activity

22. Sales Department Credit Department Warehouse Shipping Department A Sales Order #1 Customer Sales Order2 Customer Order Checks Credit Sales Order 4 Credit Records Picks Goods Stock Records Sales Order3 Prepare Sales Orders Signed Sales Order #1 Picks Goods Customer Order Sales Order2 Sales Order #1 Sales Order #1 Sales Order #1 Sales Order #1 Sales Order 4 Sales Order3 Signed Sales Order #1 N Sales Order2 N Distribute SO and File A Customer Order Customer Sales Order 4 Signed Sales Order #1 Finished Document Flowchart Showing Areas of Activity Sales Order3 Sales Order2 N

23. System Flowcharts • are used to represent the relationship between the key elements--input sources, programs, and output products--of computer systems • depict the type of media being used (paper, magnetic tape, magnetic disks, and terminals) • in practice, not much difference between document and system flowcharts

24. Systems Flowchart Symbols Terminal input/ output device Hard copy Computer process Process flow Real-time (online) connection Direct access storage device Video display device Magnetic tape

25. Sales Department Computer Operations Department Warehouse Shipping Department Customer Edit and Credit Check Credit Hist File Customer Order Sales Orders Terminal AR File Update Program Inventory First Stages in Constructing System Flowchart Showing Areas of Activity

26. Sales Department Computer Operations Department Warehouse Shipping Department Customer A Sales Order1 Edit and Credit Check Credit file Customer Order Sales Order 3 Picks Goods Stock Records Sales Order2 Sales Orders Terminal AR File Update Program Picks Goods Sales Order1 Inventory Customer Order Sales Order2 Sales Order3 N A N Sales Order1 Sales Order 3 Sales Order2 Sales Order1 Customer Finished System Flowchart Showing All Facts Translated into Visual Symbols

27. Program Flowcharts • illustrate the logic used in programs Program Flowchart Symbols Terminal start or end operation Logical process Input/output operation Decision Flow of logical process

28. The Physical DatabaseData Hierarchy Database File Record Field Bit - usually magnetically encoded

29. Data Structures • allow records to be located, stored, retrieved and allow movement through the database. Two components: • The organization of a file is the physical arrangement of records. • The access method is the technique used to locate records and to navigate through the database or file.

30. Sequential Access Structure • All records lie in contiguous storage spaces in a specified sequence arranged by their primary key. • Data retrieval requires that all records before the desired record must be read in order first. • This structure does not allow for a record to be accessed directly.

31. Direct Access Structures • Records are stored at unique locations known as addresses. • Address tells operating system the exact location of record on the disk. • This structure allows for accessing a record without going through all preceding records.

32. Index Structure • A separate index exists that is a file of record addresses. • The records may be dispersed throughout the disk either randomly or sequentially. • A record is found by first searching the indexfor the address of the desired record. • VSAM is an example of using an indexed access method on a large database of sequentially stored records.

33. Inserting a Record into an VSAM File Key 223 Key 224 Key 225 Key 226 Key 228 Key 229 Key 231 Key 233 Key 234 Overflow Area Key 235 Key 238 Key 239 Index Key 240 Key 241 ... ... ... ... Key 237 ... ... ... Prime Area ... ... ... ... Key 269 Key 270 Insert New Record with Key Value = 237

34. Hashing Structure • employs an algorithm that converts the primary key of a record directly into a unique storage address • eliminates the need for a separate index --record retrieval is rapid • A disadvantage is that some disk locations will never be selected because they do not correspond to legitimate key values.

35. Pointer Structures • A linked-list file stores in a field of one record the address (pointer) of a related record. • The records are spread over the entire disk without concern for their physical proximity. • Pointers may also be used to link records between files.

36. Three Types of Pointers • Aphysical address pointer contains the actual storage location needed by the disk controller. It is a rapid retrieval method. • A relative address pointer contains the relative position of a record in the file. It must be converted to the actual physical address. • A logical key pointer contains the primary key of the related record which is then converted to the record’s physical address using a hashing algorithm.

37. Computer-Based Accounting Systems • Two broad classes of systems: • batch systems • real-time systems

38. Batch Processing • A batch is a group of similar transactions that are accumulated over time and then processed together. • The transactions must be independent of one another during the time period over which the transactions are accumulated in order for batch processing to be appropriate. • A time lag exists between the event and the processing.

39. Batch Processing/Sequential File Unedited Transactions Sales Orders Keying catches clerical errors Edit Run Errors correct errors and resubmit Edited Transactions rearranges the transaction data by key field so that it is in the same sequence as the master file Sort Run Transactions Old Master (father) AR changes the values in the master file to reflect the transactions that have occurred Update Run AR Transactions (eventually transferred to an archive file) New Master (son)

40. Steps in Batch Processing/Sequential File • Keystroke - source documents are transcribed by clerks to magnetic tape for processing later • Edit Run - identifies clerical errors in the batch and places them into an error file • Sort Run - places the transaction file in the same order as the master file using a primary key • Update Run - changes the value of appropriate fields in the master file to reflect the transaction • Backup Procedure- the original master continues to exist and a new master file is created

41. Advantages of Batch Processing • Organizations can increase efficiency by grouping large numbers of transactions into batches rather than processing each event separately. • Batch processing provides control over the transaction process via control figures.

42. Real-Time Systems • process transactions individually at the moment the economic event occurs • have no time lag between the economic event and the processing • generally require greater resources than batch processing since they require dedicated processing capacity; however, these cost differentials are decreasing • oftentimes have longer systems development time

43. Why Do So Many AISs Use Batch Processing? • Much of AIS processing is characterized by high-volume, independent transactions, such as recording cash receipts checks received in the mail or payroll. The processing of such high-volume checks can be done during an off-peak computer time, such as overnight.