AS400 - An Introduction (Part 2)

7/29/2019 AS400 - An Introduction (Part 2)

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HCL Technologies Ltd.

An Introduction to the

AS/400 / iSeries / i5

Mid-Range Sys tem

(Part 2)

Joy Patnaik


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Agenda

Commonly Used Terms


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Commonly Used Terms - 1

System The AS/400 is the system

The system is downorThe system is slow today

OS/400 AS/400s Object-Based Operating System

Controls all the activity on the AS/400

Incorporates many features that would be separatesoftware components on other systems (ex. Database)

IPL Initial Program Loading (Programs executed during

Boot-sequence)


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Licensed Internal Code (LIC)

Work Management Provides the hardware interface

Any changes to the hardware invite corresponding changes to the LIC. However, the application programs need not undergo any changes, thereby

reducing maintenance costs.

Users never interact directly with the LIC, and it cannot be

tampered by programmers or system operators.

Programming Languages Pascal, PL/1, Basic, RPG, C, C++, Cobol, Java, SQL, etc.


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System Values Control and Configuration attributes that allow you to customize the

operating environment to suit the company.

These values define what the default values will be. You cant changethem, but you can look at them.

Examples : QDATE, QTIME

Commands : DSPSYSVAL

User A person who uses the AS/400

A User-Id identifies you to the system when you sign-on User Class : *USER, *SYSOPR, *PGMR, *SECADM, *SECOFR

Each User-Id has a User Profile which describes the user and theirauthorities

Commands : CRTUSRPRF, DSPUSRPRF, etc


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Library Library is a container of Objects but cannot contain other Libraries

Exception : QSYS library contains other libraries

Commands :CRTLIB

File Contained in a Library

Data Container that can contain either

Application Data

Application program source code

Member One File can be made up of one or more members

Can be data or program source


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Library List List of commonly-used libraries (Short notation *LIBL)

Similar to PATH in Windows systems

Messages Message Queues

Work Station Queue

User Message Queue

Message Types

Information : *INFO

Inquiry : *INQ Commands :

SNDMSG - Sends Messages to user message queue.

SNDBRKMSG - Send Messages to work station.


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Important Libraries


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IBM-Supplied Libraries - 1

QSYS: Most important library on the AS/400. Contains OS/400, and master directory of

all libraries.

Dont delete or rename. Need to operate the system.

Some objects MUST be in QSYS.

User Profiles

Device descriptions

Authorization lists

Library object descriptions

QUSRSYS: Place user objects, considered more or lesssystem objects.

Typically message queues for user profiles.


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QHLPSYS: All help information Search Index Objects

QGPL: General Purpose Library. Contains objects used by the system or users.

Contains job queues, subsystem descriptions,

source physical files and output queues.

Dont store unnecessary objects in QGPLDo not delete or rename this library.


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QSPL: Spooling library. Contains several databases files in spooling

system.

Used to store reports and printed outputwaiting to print.

QDOC: Folders and documents created andmaintained in library QDOC.

Use Save Document Library Objects

(SAVDLO) and Restore Document Library

Objects (RSTDLO).


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QTEMP: Created for every active job automatically. Lasts only for the duration of the job.

Functions as a scratch pad, for temporary

objects.


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Working With Libraries


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Creating a Library

Create Library (CRTLIB)

Type choices, press Enter.

Library . . . . . . . . . . . . Name

Library type . . . . . . . . . . *PROD *PROD, *TEST

Text 'description' . . . . . . . *BLANK

Additional Parameters

Authority . . . . . . . . . . *LIBCRTAUT Name, *LIBCRTAUT, *CHANGE...

Auxiliary storage pool ID . . 1 1-16

Create authority . . . . . . . *SYSVAL Name, *SYSVAL, *CHANGE...

Create object auditing . . . . *SYSVAL Character value, *SYSVAL...

Bottom

F3=Exit F4=Prompt F5=Refresh F12=Cancel F13=How to use this display

F24=More keys


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Working with Libraries

Work with Libraries (WRKLIB)

Type choices, press Enter.

Library . . . . . . . . . . . . *LIBL Name, generic*, *LIBL...

Bottom

F3=Exit F4=Prompt F5=Refresh F12=Cancel F13=How to use this display

F24=More keys


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Using Library, File andMember


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How the AS/400 finds Objects When an object is created, it is created in a particular

library.

To access an object, the AS/400 needs to know what librarythe object is in.

The library is really a directory which contains pointers to theobjects in that library.

Usage of Library


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Library List - 1

What is a Library List List of commonly-used libraries (Short notation *LIBL)

OS/400 searches for the objects required for executing any

program or command in the LIBL that is enforced at the time ofrunning the program or command

Similar to PATH in Windows systems

Library list give the default list of libraries to be searched foran object.

Every job has a library list.

Library list has a maximum of 251 names.

Scanned from top to bottom.

Four library list types System (SYS), Product (PRD), Current (CUR), User (USR)


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Library List - 2

Library List Sections

Portion Values/Command Contents

System Library QSYSLIBL QSYS

1-15 libraries

Product

Library

Optional

Current

Library

CHGCURLIB From User

Profile

User

Library

QUSRLIBL QTEMP

1-25 Libraries


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Library List - 2

Usage of LIBL Library List is a convenience only

you can always access a library not on the list! (as long as your

user profile has proper authority to the library) We could have a program object named PROGA in two

different libraries!

Qualified Object Name: Library/Object(ex. CMOPS324/REVIEWS)

Library Descriptions, Device Descriptions and User Profiles are stored

in library QSYS. This means that you do not have to specify a library name when

you access these objects.


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LibraryList - 3

Each job has an attached Library List

Different Types of Libraries:

System: IBM SuppliedProduct: Added automatically when an IBM product is used

Current: Defined by an individual user IDUser IDs default Library

Dont rename or delete your current Library!

User: Non-IBM Supplied LibrariesCreated by Business to organize programs, files, etc.


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Library List Commands - 1

ADDLIBLE

Adds an entry to a library list to the USER portion of

the library list

RMVLIBLERemoves an entry from the USER portion of the

library list

EDTLIBL

Adds/Deletes/Changes entries on the USER portionof the library list


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Library List Commands - 2

CHGCURLIB

Changes the Current Library

CHGLIBL

Changes the Current Library and allowsAdd/Change/Delete to the USER portion of the

library list.

All Library List commands are listed on the CMDLIBLmenu.


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Library List contd


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Files

objects that store dataie. customer file: customer #, address, billing info etc. foreach customer

source file

special file that stores a programmers source codeeg. Judy stores all her source code in source file Judysrc (in

library Judylib)


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File Member

Source files have many membersone member for each source program

eg. Judysrc file has 3 members: RPGPGM1, RPGPGM2,

CLPROG, each contains a different program

PDM (Prog Dev Mgr)gives easy access to a programmers stuff (libs/files/mbrs)


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Database Files Types of *FILES

Physical File PF (Source and Data)

Logical File LF

Printer File PRTF

Display File DSPF

Data stored as EBCDIC - Extended Binary Coded Decimal Interchange

Code


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Source Physical File vs

Data Physical File

Source Physical File

Layout is fixed: 3 fields

programmers can only alter the length of the text

field

Used to store code

Data Physical File Layout is determined by Application Design

Used to store data


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What is Work Management ? Important building block of OS/400

Work enters the system

Gets Processed

Gets completed

Supports commands and internal system

functions


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Work Management - 1

Job A job is any and every piece of work on the AS/400

Commands : DSPJOB

Interactive Jobs

A job that begins when a user signs on to the system and ends when they

sign off. It is a job with interaction between the user and the AS/400, similar to a

conversation ( a polite conversation!).

Input for the job is entered via the screen.

Batch Jobs

A job that runs in the background.

They do not require input from the screen, but would read data from files. They are generally jobs that use a lot of resources and are lower priority

than interactive jobs.

Usually submitted by interactive jobs e.g. a program compile


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Work Management - 2

Subsystem Jobs run in subsystems.

An pre-defined operating environment in which systemresources (eg. main storage) are divided up and allocated for the

work to be done Described in subsystem descriptions.

Most subsystems are started at IPL (Initial Program Load) time. IPL can be equated to the processes that get executed when a PC boots up.

Subsystems (Examples) Interactive jobs run in subsystem QINTER

Batch jobs run in subsystem QBATCH

Commands : DSPSBSD


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Work Management - 3

Queue A queue is a line-up! A place where things wait.

Examples of AS/400 queues:

job queues: where batch jobs wait

message queues: where messages wait output queues: where spool files wait to print


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Work Management - 4

Job Description Defines the attributes of the job

Important parameters

Job queue Output Queue

Initial Library list

Job Priority

QDFTJOBD ( Default Job description)


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Most Often-used Work

Management Conceptsand Tasks


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A Jobs Life - 1 Submit a job

On submitting a job to an iSeries server, it (the job) iscreated and enters the system. At this time, the

properties of a job are given to the job. Once the properties have been defined, the job moves

to the job queue where it waits to enter the subsystem.

The job description holds properties the job will use togo through the work management life-cycle. These

properties include the user profile the job will start torun under, the request data (which tells the job what itwill do), and the initial user portion of the library list, aswell as others.


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A Jobs Life - 2 Job enters a job queue

Job queues are work entry points for batch jobs toenter the system. They can be thought of as "waiting

rooms" for the subsystem. A number of factors affect when the job is pulled off the

job queue into the subsystem, like job priority on thejob queue, the sequence number of the job queue, andthe maximum active jobs.

When all of these factors work together, the job will bepulled off the job queue to start running in thesubsystem.


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A Jobs Life - 3 Job enters the subsystem

When the job enters the subsystem it becomes active.

Until a job gets its activity level and memory from a

memory pool, it cannot run. The job uses several pieces of information before it can

receive memory to run.

The subsystem description, like the job description,carries information, such as the memory pool to use, the

routing entry, the maximum active jobs, and the numberof active jobs currently in the subsystem.


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A Jobs Life - 4 Memory pool allocates memory to

the subsystem

Memory is a resource from the memory pool that thesubsystem uses to run the job.

The amount of memory from a memory pool, as well ashow many other jobs are competing for memory affect

how efficiently a job runs.

The subsystem gives the memory pool the informationit needs to process the order in which jobs are allocatedmemory, and the memory pool allocates memory forthe job to run to completion.

Subsystems use different memory pools to supportdifferent types of jobs that run within them.


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A Jobs Life - 5 Job finishes


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Spooled File - 1 What is a Spooled File ?

When you print something, a spool file is created withthe data to be printed and stored in an Output Queue

WRKSPLF shows your spooled files (WRKSPLF groups allof YOUR spooled files together on one screen regardlessof the Output Queue)

What is an Output Queue (OUTQ) ? Output Queue is a queue of all spooled files awaiting

printing. (WRKOUTQ groups together all of the spooledfile in ONE output queue regardless of the USER)

To print a Spooled File, the file must be moved to anOutput Queue attached to a printer.


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Spooled File - 2 What is a Printer Writer ?

Printer Writer is a job that monitors a specified outputqueue

When a spooled file entry is placed in an output queue,the printer writer will direct the spooled file to printerdevice.

Commands DSPSPLF WRKOUTQ , CRTOUTQ

WRKWTR, STRPRTWTR, ENDWTR


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How Do Spooled Files get

Created?

Program/

Command

Data Report

Layout

Job Output Queue

*FILE*FILE

Spooled File

QINTER


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DC234X99

SPLF#1

SPLF#2

PRT01

SPLF#3

SPLF#4

WRKSPLF

option 2.

Changethe

Spooled

File

to OutQ

PRT01

How Do Spooled Files get

Printed?


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Working with Jobs - 1

How to get info about Jobs WRKJOB :

Display information about your current Interactive job

Display information about any other job, by entering JobName and User (Job Number is Optional)

WRKSBMJOB :

To display your Batch Jobs, use the Work with SubmittedJobs Commands

WRKUSRJOB : Shows you a list of all of the jobs that you own on the

system regardless of the subsystem


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Working with Jobs - 2

Job Status Active = Job is currently running

Outq = Job is finished

Jobq = Job is waiting to process.


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Work Management Summary Not every job follows this exact path; however, you can betterunderstand how other work is completed on the system by thebelow-mentioned flow :

The life of a simple batch job begins when you submit it tothe system.

The job is then sent to a job queue where it waits to entera subsystem where it can run.

Once the job moves to the subsystem it is allocated

memory in which to run. When the job is complete, it is sent to a printer output

queue to await further instruction on what to do (forexample, printing).


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Summary

The AS/400 is easy to use Menu driven

Lots of built-in help

Built-in security

Documents

AS400 - An Introduction (Part 2)