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Introduction to On-Line

Introduction to On-Line. BATCH – Transactions are accumulated into groups (batches) before processing. ON-LINE – Interactive Transactions entered one at a time via terminals and processed while you wait. Introduction to On-Line.

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Introduction to On-Line

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  1. Introduction to On-Line • BATCH – Transactions are accumulated into groups (batches) before processing. • ON-LINE – Interactive Transactions entered one at a time via terminals and processed while you wait. CICS-Int

  2. Introduction to On-Line • The main Advantage of On-Line over batch is responsiveness. Batch response time is usually measured in days where On-Line response time is usually measured in seconds! • Another advantage is immediate error correction. • Disadvantage – COST! CICS-Int

  3. Introduction to On-Line • Four main TYPES of On-Line programs: • Menu • Inquiry • Maintenance • Data Entry CICS-Int

  4. Introduction to On-Line • Menu Program: Shows list of functions available and allows user to choose which one to perform. Sometimes other NAVAGATION options are presented also, like HELP or EXIT. CICS-Int

  5. Introduction to On-Line • Inquiry Program Shows a response to a user’s inquiry. For example: A customer number is entered and a list of Video Tapes currently rented is displayed. CICS-Int

  6. Introduction to On-Line • Maintenance Provides for updates by allowing changes, deletions, and additions of data. For example: Changing the address of a customer. CICS-Int

  7. Introduction to On-Line • Data Entry Provides for transaction entry. For example: Entry of an order for a customer. The Customer Number and the required details of an order can be entered and validated. CICS-Int

  8. Online System Considerations • Four Main Areas of Concern: • Ease of Use • Performance • File Integrity • Security CICS-Int

  9. Online System Considerations • Ease of Use • Common User Access (CUA) • Entry Model (Dumb Terminals) • Mainframe CICS, etc. • Graphical Model (Workstations, PC’s) • Windows, Linux, etc. CICS-Int

  10. Online System Considerations • Performance • Response Time (Measurement) • Time for screen update to occur • Factors affecting response time • System load (Number of programs running) • Communication traffic load • Data traffic (Number of I/O operations required) • File activity (Number of files accessed/updated) CICS-Int

  11. Online System Considerations • File Integrity • Simultaneous file activity • Shared files (Batch program ‘owns’ file) • Multiple users with conflicting needs • File (Record/Block) locking CICS-Int

  12. Online System Considerations • Security • Logon Procedure (Name/Password) • Multi-level Security • RACF Security profile • Alternate Logon’s (Supervisor, etc) • Call Back Security, etc. CICS-Int

  13. Terminal Networks • Network connects terminal to host • Terminals can be ‘local’ or ‘remote’ • Local • Short distance (Usually same building) • Remote • Further distance (Different cities) CICS-Int

  14. Terminal Networks • Local Connection • Terminal • 3270 Family Controller • Multiplexor (Optional) • Channel attachment CICS-Int

  15. Terminal Networks • Remote Connection • 3270 Family Terminal • 3270 Family Controller • Modem - SDLC (or BSC) • Communication Link • Modem - SDLC (or BSC) • 3270 Family Controller • Channel Attachment CICS-Int

  16. Terminal Networks • IBM’s 3270 family of terminals • 3270 Information Display System • 3270 Display Stations • 3278 – Monochrome • 3279 – Seven Color (w/intensity also) • 3270 Printers • Dot matrix Printers • Line Printers • Laser Printers CICS-Int

  17. Terminal Networks • IBM 3270 Family (Continued) • 3270 Controllers • Connect up to 32 devices to controller • Coaxial cables • Multiplexors (8 units via single cable) • Options • Light pens, extended keyboards (languages), extended attributes (highlighting, blinking, etc.) CICS-Int

  18. Terminal Networks • 3270 Emulators • PC Programs emulate Mainframe Terminal • Adds: upload and download of files • Translation from/to EBCDIC/ASCII • Also allows screen/file printing • Changes PC to ‘FULL SCREEN’ device CICS-Int

  19. Introduction to CICS • Customer Information Control System • IBM Product of the 70’s (Intro in 1969) • 490 of Fortune 500 use CICS • Over 1 billion lines of CICS (COBOL) code • Nearly 15 million CICS terminals • Nearly 1 million CICS programmers • Allows BATCH O/S to handle ONLINE CICS-Int

  20. Introduction to CICS • CICS is interface between O/S & prog • CICS acts like an Operating System • Manages its own storage • Provides its own file and D/B management • Has its own TASK manager • Runs in its own ADDRESS SPACE CICS-Int

  21. Introduction to CICS • Multitasking is basic feature of CICS • CICS allows multiple tasks to operate • Uses its own method (not regular O/S) • Works same regardless of O/S • Multithreading allows program sharing • Program must be reentrant • No code modification allowed! CICS-Int

  22. Introduction to CICS • Assembler can be used (carefully!) • CICS/COBOL produces reentrant code. • Users share same program code. • Each user gets separate copy of W/S. • Users invoke a TRANSACTION CICS-Int

  23. Introduction to CICS • TRANSACTION specifies prog to run • TRANS-ID is 4 character unique code • Once loaded into CICS storage, it stays. • (Unless external request received) • Each user is assigned a TASK • Task active until RETURN is issued CICS-Int

  24. Introduction to CICS Tables • Each TRANS-ID is defined in PCT • TRANS-ID is four chars (w/trailing spaces) • PCT = Program Control Table • PCT is list of valid TRANS-ID’s • Paired with ‘Program Name’ to use • Program names are eight characters (wts) • IBM TRANS-ID’s start with ‘C’ CICS-Int

  25. Introduction to CICS Tables • PPT = Processing Program Table • List of all valid program names • Used by CICS to determine if in storage. • IF not in storage, CICS loads NEW COPY • Tables created by programmer with CEDA • RDO = Resource Definition OnLine - CEDA CICS-Int

  26. Intro to CICS Services • Three main categories of CICS Services: • Data Communications Services • Data Management Services • CICS Management Services CICS-Int

  27. Intro to CICS Services • Data Communication Services • Basic mapping Support (BMS) • Assembler program to handle screen formats. • Terminal Control • Interface with VTAM • Send/Receive text to/from terminal CICS-Int

  28. Intro to CICS Services • Data Management • No COBOL READ/WRITE Permitted! • CICS handles all data requests • VSAM, DL/1, and DB/2 • Files defined in FCT • FCT = File Control Table • List of available files, status, type, security CICS-Int

  29. Intro to CICS Services • CICS Management Services • Program Control • Allows TASK to call other programs • Some RETURN and some don’t • Temporary Storage Control • Transient Data, Interval, Storage Control • Task, Dump, Trace and Journal Control CICS-Int

  30. Intro to Program Development • Develop complete program specs • Design the program • Create required CICS table entries • Create the BMS Mapset • Code the program • Compile and Test program • Document the program CICS-Int

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