Transcript Week # 2

Week 2
The System
• The AS/400 is a multi-user, multi-tasking
system -- a system on which many users can
perform many tasks concurrently.
• The basic unit of work on the AS/400 is a
job -- generally a unit of work, including all
programs, files, and instructions necessary
to perform that work.
Mastering the AS/400, Third Edition, author
Jerry Fottral
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Week 2
Sub Systems
• All jobs are run in areas of the computer
called Sub systems. A Sub system is where
the system brings together the resources
needed to process work.
– Sub system characteristics determine how the
system uses resources within the Sub system.
– The AS/400 operating system supports multiple Sub
systems that can be User-defined, each having a
separate Sub system description.
Mastering the AS/400, Third Edition, author
Jerry Fottral
2
Week 2
Sub Systems (continued)
• Some attributes of Sub systems whose
values are defined in the Sub system
description include:
–
–
–
–
Sub system name
How many jobs can run in a Sub system at one time
Which storage pools the Sub system will use
Which job queues the Sub system will work from
Mastering the AS/400, Third Edition, author
Jerry Fottral
3
Week 2
Sub Systems (continued)
• Different Sub systems are necessary because of the
many different types of jobs with different
characteristics and often conflicting needs.
• The system administrator can tailor the existing Sub
system descriptions and create new Sub systems to
handle the needs of different types of jobs.
• Within Sub systems, individual jobs can be prioritized
to begin execution sooner or later and, after they begin,
can be given a higher or lower runtime priority.
Mastering the AS/400, Third Edition, author
Jerry Fottral
4
Week 2
Types of Jobs
• On the AS/400 there are only two types of
‘jobs’ that can be initiated on the system. In
general, the two types are:
–Interactive
–Batch
Mastering the AS/400, Third Edition, author
Jerry Fottral
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Week 2
Types of Jobs (continued)
Interactive Job:
• Begins when a user signs on to an AS/400
• Terminates when the user signs off the
AS/400 or the job has ended
• Runs in conversational mode (i.e., dialogue
of sorts between user and program, utility,
or operating-system function)
Mastering the AS/400, Third Edition, author
Jerry Fottral
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Week 2
Types of Jobs (continued)
Interactive Job (continued):
• Because of the conversational mode (back-andforth nature of interactive jobs), any such requests
could lock up the workstation keyboard until the
request is completed.
• It is advisable to direct job requests to the
appropriate Sub system for that job – either to run
Interactively or submit them as batch jobs.
Mastering the AS/400, Third Edition, author
Jerry Fottral
7
Week 2
Types of Jobs (continued)
Batch Jobs:
• Can execute without user intervention
• Do not require data or any other information to be
input through the workstation once they have
started
• Are sent to a job queue until they can begin
execution. A job queue is a staging area, managed
by the Sub system, where batch jobs wait in line
for their turn at processing.
Mastering the AS/400, Third Edition, author
Jerry Fottral
8
Week 2
Types of Jobs (continued)
Batch Jobs (continued):
• Each batch subsystem can execute only a limited
number of batch jobs concurrently.(This is
programmable).
• Depending on the settings, a batch job can start
right away or wait it’s turn in the queue.
Mastering the AS/400, Third Edition, author
Jerry Fottral
9
Week 2
Types of Jobs (continued)
Batch Jobs (continued):
• A typical batch job submission would be a
report program or a program compile.
• If such a program were run interactively, the
DASD (Direct Access Storage Device, or
hard disk) access time required could cause
the program to run for a long time, locking
up the interactive session.
Mastering the AS/400, Third Edition, author
Jerry Fottral
10
Week 2
Types of Jobs (continued)
• To minimize disruption of work flow,
certain tasks during an interactive session
can be sent as batch jobs -– Programmer could submit a compilation or
report as a batch job from the interactive job
– While the submitted job runs in a batch
subsystem, the programmer could go on to
other tasks.
Mastering the AS/400, Third Edition, author
Jerry Fottral
11
Week 2
Types of Jobs (continued)
• An active job can be identified by the
Qualified Job Name. A Qualified Job
Name is made up of three distinct parts:
- Job Name > based on the Terminal I.D.
- User I.D. > The User I.D. that initiated the
job.
- Job Number > assigned by the system
(For a batch job it is the program name)
Mastering the AS/400, Third Edition, author
Jerry Fottral
12
Week 2
OS/400
• OS/400 is the AS/400’s operating system
• It is a robust, complex, functionally rich set
of programs
– It Controls traditional computer system
functions.
– It Incorporates features that normally require
separate software components
– It supports two other operating systems –
System/36 and System /38
Mastering the AS/400, Third Edition, author
Jerry Fottral
13
Week 2
OS/400 (continued)
All AS/400s are shipped with basic OS/400
support, including predefined system
settings for work management functions
Mastering the AS/400, Third Edition, author
Jerry Fottral
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Week 2
OS/400 (continued)
OS/400 is an object-based operating system:
An object is anything on the system that has a
name and takes up space in storage.
A large number of objects are supplied by
IBM through OS/400, and they typically have
names beginning with Q. Other objects usually are
named according to shop naming convention.
The system locates an object by its name.
Mastering the AS/400, Third Edition, author
Jerry Fottral
15
Week 2
OS/400 (continued)
Objects are grouped into types, and an object type
determines how the object is used on the system.
Common types include:
*PGM
Programs
*FILE
Files
*CMD
Commands
Other types also include user-profile objects and
subsystem-description objects.
Object type is always assigned by the system and is
determined by the command used to create the object.
Mastering the AS/400, Third Edition, author
Jerry Fottral
16
Week 2
Control Language
OS/400 provides a single, consistent user
interface to its functions through Control
Language (CL) commands.
• CL is flexible, powerful, and allows direct
access to OS/400 functions.
• More than 1,500 commands are available.
• Each command is an object on the AS/400.
Mastering the AS/400, Third Edition, author
Jerry Fottral
17
Week 2
Control Language (continued)
Most CL commands consist of a command
name and one or more command
parameters.
A Command Parameter has an associated
value, specified along with a command, that
controls and limits the operation of the
command and names the files, programs, or
other objects the command will work on.
Mastering the AS/400, Third Edition, author
Jerry Fottral
18
Week 2
Control Language (continued)
Individual commands can be entered on a command
line.
A command line is a line beginning with the
symbol ===> that appears near the bottom of
certain types of display screens.
Mastering the AS/400, Third Edition, author
Jerry Fottral
19
Week 2
System Values
System values are control and configuration
attributes that let you customize certain
operating-system functions.
– They define critical aspects of the environment and
general rules that jobs must follow.
– They are not objects.
– They describe characteristics of the system that can be
displayed or changed with CL commands.
– Many come preset or others need to be set.
Mastering the AS/400, Third Edition, author
Jerry Fottral
20
Week 2
User Profile
User: any person who is signed on to the system.
Each user requires a user profile.
User profile: identifies a user and describes the
user’s authority; the profile is the source of several
operational characteristics of that user’s job and
defines:
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•
•
•
user class (e.g. programmer, system operator)
special authorities
initial program to execute
group profile
Mastering the AS/400, Third Edition, author
Jerry Fottral
21
Week 2
User Profile (continued)
The two user-profile values necessary to sign on are:
user name (or user ID)
(1-10 characters long; security administrator determines its value
according to standards of the installation; user name may be
simple first initial and last name combination or more symbolic
code such as department; the user name or user ID must match
the name of user-profile object or sign-on attempt will fail)
password
(must match the current password stored in the corresponding user
profile)
Mastering the AS/400, Third Edition, author
Jerry Fottral
22
Week 2
User Profile (continued)
Sign-on screen:
Upper right area of screen shows
information identifying system, subsystem,
and display device (or display station).
A display device is the workstation
hardware (monitor and keyboard) that you
use to communicate with the system.
Mastering the AS/400, Third Edition, author
Jerry Fottral
23
Week 2
User Interface
The AS/400 Main menu:
• Most AS/400 interactive jobs begin by displaying
the Main menu.
• This menu is the highest-level task-oriented menu
on the AS/400.
• It can be the starting point to define a menu path.
• Menus are connected in such a way that a menu
choice at a higher level can take you to a lowerlevel menu.
Mastering the AS/400, Third Edition, author
Jerry Fottral
24
Week 2
Menu Screens
Primary sections of a menu screen:
• Screen header (includes menu ID--the menu object
name, menu description, and system name)
• Numbered list of menu options
• Selection or command line, indicated by
===>
• List of active function keys (and below this list
are: a message line showing the IBM copyright notice and
a status line showing cursor coordinates)
Mastering the AS/400, Third Edition, author
Jerry Fottral
25
Week 2
Menu Screens (continued)
From a menu display, you can:
– Type and enter a menu choice and go on to the
next screen
– Ask for Help
– Type a CL command and either prompt for
parameters or run the command
– Use a function key
Mastering the AS/400, Third Edition, author
Jerry Fottral
26
Week 2
Menu Screens (continued)
To create a library, take the menu path to:
DATA menu
From the DATA menu, you can take choice 2
(Libraries) by typing a 2 on the command
line and then pressing Enter. This takes you
to the LIBRARY menu.
The system displays an entry screen to request
information from a user.
Mastering the AS/400, Third Edition, author
Jerry Fottral
27
Week 2
Entry/Command Prompt Screens
• Note different heading -- Create Library
(CRTLIB) is the name of a CL command
followed by its AS/400 abbreviation in
parentheses.
• The entry screen does not identify the
system--you see a list of command
parameters.
• A list of active function keys is displayed.
Mastering the AS/400, Third Edition, author
Jerry Fottral
28
Week 2
Entry/Command Prompt Screens
Command prompt screen:
Is an entry screen; you need to enter required
parameter value(s). When you enter these, e.g.,
OPS234SB for Library name of the CRTLIB
command, the system can create a library. Thus
the system prompts for a parameter value to run a
command, and the screen is referred to as a
command prompt screen (one kind of entry
screen).
Mastering the AS/400, Third Edition, author
Jerry Fottral
29
Week 2
Entry/Command Prompt Screens (continued)
To request additional parameters:
Press function key F10
The Create Library (CRTLIB) Command
Prompt Screen appears and provides:
• Description
• Entry field showing parameter’s current value, if
any
• List of valid values (for most parameters)--to view
the entire list, position cursor on the line containing
the parameter in question and press Prompt function
key F4.
Mastering the AS/400, Third Edition, author
Jerry Fottral
30
Week 2
Entry/Command Prompt Screens (continued)
Required parameters:
– Value must be provided to run a command.
– Always appear as empty input fields at the top
of the command prompt parameter list.
For other parameters, use the default values
provided, or you can type over any default
value you need to change.
Mastering the AS/400, Third Edition, author
Jerry Fottral
31
Week 2
Using Help
Information screens:
• Provide information that you request and
provide a way back to where you were
when you asked for the information.
• Help screen is a good example: the Help
key is F1.
Mastering the AS/400, Third Edition, author
Jerry Fottral
32
Week 2
Field or Context-Sensitive Help
General (Field) Help or Specific (contextsensitive) Help:
When you are requesting information about a
particular area on a screen, you are requesting
what is referred to as General Help or Specific
(context-sensitive) Help.
Information window appears -- which can be
enlarged by pressing function key F20 or
cancelled by pressing function key F12.
Mastering the AS/400, Third Edition, author
Jerry Fottral
33
Week 2
Extended Help
To access more information about the field
Help window screen, press function key
F12 for extended Help. You would see
command parameters, for example, and
their possible values, parts of the screen,
and any entry fields or options available on
screen.
Mastering the AS/400, Third Edition, author
Jerry Fottral
34