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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.

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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!

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Introduction to On-Line

Four main TYPES of On-Line programs: Menu Inquiry Maintenance Data Entry

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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.

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Introduction to On-Line

Inquiry ProgramShows a response to a user’s inquiry.For example: A customer number is entered and a list of Video Tapes currently rented is displayed.

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Introduction to On-Line

MaintenanceProvides for updates by allowing changes, deletions, and additions of data.For example: Changing the address of a customer.

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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.

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Online System Considerations

Four Main Areas of Concern: Ease of Use Performance File Integrity Security

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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.

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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)

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Online System Considerations

File Integrity Simultaneous file activity Shared files (Batch program ‘owns’

file) Multiple users with conflicting needs

File (Record/Block) locking

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Online System Considerations

Security Logon Procedure (Name/Password) Multi-level Security

RACF Security profile Alternate Logon’s (Supervisor, etc)

Call Back Security, etc.

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Terminal Networks

Network connects terminal to hostTerminals can be ‘local’ or ‘remote’Local Short distance (Usually same

building)

Remote Further distance (Different cities)

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Terminal Networks

Local Connection Terminal 3270 Family Controller Multiplexor (Optional) Channel attachment

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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

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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

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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.)

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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

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Introduction to CICS

Customer Information Control SystemIBM Product of the 70’s (Intro in 1969)490 of Fortune 500 use CICSOver 1 billion lines of CICS (COBOL) codeNearly 15 million CICS terminalsNearly 1 million CICS programmersAllows BATCH O/S to handle ONLINE

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Introduction to CICS

CICS is interface between O/S & progCICS 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

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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!

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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

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Introduction to CICS

TRANSACTION specifies prog to runTRANS-ID is 4 character unique codeOnce loaded into CICS storage, it stays. (Unless external request received)

Each user is assigned a TASK Task active until RETURN is issued

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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’

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Introduction to CICS Tables

PPT = Processing Program TableList of all valid program namesUsed by CICS to determine if in storage.IF not in storage, CICS loads NEW COPYTables created by programmer with CEDARDO = Resource Definition OnLine - CEDA

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Intro to CICS Services

Three main categories of CICS Services: Data Communications Services Data Management Services CICS Management Services

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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

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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

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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

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Intro to Program Development

Develop complete program specsDesign the programCreate required CICS table entriesCreate the BMS MapsetCode the programCompile and Test programDocument the program