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:
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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 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.
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Introduction to On-Line
Maintenance
Provides 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:
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Ease of Use
Performance
File Integrity
Security
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Online System Considerations
Ease of Use
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Common User Access (CUA)
 Entry Model (Dumb Terminals)
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Mainframe CICS, etc.
 Graphical Model (Workstations, PC’s)
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Windows, Linux, etc.
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Online System Considerations
Performance
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Response Time (Measurement)
 Time for screen update to occur
 Factors affecting response time
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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
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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
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Logon Procedure (Name/Password)
Multi-level Security
 RACF Security profile
 Alternate Logon’s (Supervisor, etc)
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Call Back Security, etc.
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Terminal Networks
Network connects terminal to host
Terminals can be ‘local’ or ‘remote’
Local
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Short distance (Usually same building)
Remote
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Further distance (Different cities)
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Terminal Networks
Local Connection
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Terminal
3270 Family Controller
Multiplexor (Optional)
Channel attachment
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Terminal Networks
Remote Connection
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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
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3270 Information Display System
 3270 Display Stations
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3278 – Monochrome
3279 – Seven Color (w/intensity also)
 3270 Printers
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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)
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Options
 Light pens, extended keyboards (languages),
extended attributes (highlighting, blinking, etc.)
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Terminal Networks
3270 Emulators
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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 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
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Introduction to CICS
CICS is interface between O/S & prog
CICS acts like an Operating System
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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
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CICS allows multiple tasks to operate
Uses its own method (not regular O/S)
Works same regardless of O/S
Multithreading allows program sharing
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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 run
TRANS-ID is 4 character unique code
Once loaded into CICS storage, it stays.
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(Unless external request received)
Each user is assigned a TASK
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Task active until RETURN is issued
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Introduction to CICS Tables
Each TRANS-ID is defined in PCT
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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 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
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Intro to CICS Services
Three main categories of CICS Services:
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Data Communications Services
Data Management Services
CICS Management Services
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Intro to CICS Services
Data Communication Services
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Basic mapping Support (BMS)
 Assembler program to handle screen formats.
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Terminal Control
 Interface with VTAM
 Send/Receive text to/from terminal
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Intro to CICS Services
Data Management
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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
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Program Control
 Allows TASK to call other programs
 Some RETURN and some don’t
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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 specs
Design the program
Create required CICS table entries
Create the BMS Mapset
Code the program
Compile and Test program
Document the program
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Introduction to CICS - Columbus State University