124170940 Introduction to OS 400 Concepts

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OS400 Concepts


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Sales Transaction Processing on AS400

CL

Hard Disk RAM/Buffer

S/W Appl.

COBOL

/RPG

CICS

Business

Data

DB2 400

Files

OS/400


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Store1

Store2

Store5

Store3

Store4

Store6

CL


S/W Appl.

COBOL

/RPG

CICS

Business

Data

DB2 400

Files

OS/400


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CL


S/W Appl.

COBOL

/RPG

CICS

Business

Data

DB2 400

Files

OS/400

Store1

Store2

Store5

Store3

Store4

Store6


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How to connect a PC to the AS400


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Follow these steps to connect a PC to the AS400 :


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Follow these steps to connect a PC to the AS400 :

1. Install an Emulation S/W (Emulator) on the PC.Eg : Mocha, Attachmate, Telnet, etc.

2. Specify the IP Address of the AS400 on the Emulator.

3. Thru Internet Connectivity, we can connect a PC to the AS400.


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CL


S/W Appl.

COBOL

/RPG

CICS

Business

Data

DB2 400

Files

OS/400

Store1

Store2

Store5

Store3

Store4

Store6


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OS400 Objects

On the AS/400, everything that can be stored or retrieved is stored in an

object.

Eg : Libraries, files, executable programs, queues, and more.

Objects share some common attributes such as name, type, size,

description, date created, and owner.

The concept of an object allows the system to perform certain standard

operations, such as authorization management, on all objects types. Theobject types that we will be primarily concerned are:

*LIB Libraries

*FILE Files

*PGM Compiled programs

*OUTQ Output queues


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OS400 Objects

QSYS library (*LIB) Special system Library

Programs(*PGM)

(Executable)

Outqueues

(*OUTQ)Files (*FILE) Other Objects

Contains Spooled files for

printer

Physical Files Logical Files

Data

Physical FilesSource

Physical Files

Contains

Actual Data

Contains

Source Programs

User Defined Libraries (*LIB)


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Libraries

Every object is contained in a library. A library is an object, of type *LIB,that contains a group of objects. We can term it as a root.

A library cannot "contain" other libraries (with the exception of QSYS, the

system master library, which "contains" all libraries on the system).

Note : Two users cannot have libraries with the same name. There are

basically three general categories of libraries:

1. QSYS - the library that contains all other libraries,

2. System supplied libraries (NOTE:all IBM-supplied library names begin

with the letter "Q" or "#")3. User-created libraries.

OS400 Objects


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Files

A file is an object, of type *FILE, that contains data in the form of adatabase, device data, or a group of related records that are

handled as a unit.

There are two types of database files:

1. Physical files2. Logical files.

A physical file contains actual data stored on the system. It has a

fixed-length record format. There are two kinds of physical files:

1. Data physical files2. Source physical files.

OS400 Objects


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OS400 Objects

QSYS library (*LIB) Special system Library

Programs(*PGM)

(Executable)

Outqueues

(*OUTQ)Files (*FILE) Other Objects

Contains Spooled files for

printer

Physical Files Logical Files

Data

Physical FilesSource

Physical Files

Contains

Actual Data

Contains

Source Programs

User Defined Libraries (*LIB)


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1. It contains physical data such as

an input file to a program likeEmployee Master file.

2. It cannot be compiled.

3. It has a record format defined

using DDS(Data Description

Specifications a language that is

used to describe database files to

system).

4. It has an attribute PF-DTA.

OS400 Objects

Data Physical File

1. It contains source statements

such as statements of COBOLPASCAL, etc.

2. It must be compiled.

3. It is created using CRTSRCPF

command/F6 with a default record

length 92(80 for the source data

field, 6 for the sequence number

field, and 6 for the date field).

4. It has an attribute PF-SRC.

Source Physical File


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Note : The data physical file and source physical file can have members. But these

members are not objects themselves but only the subsets of an object.

Use of specifying attribute :

Specifying attribute will allow the system programs like editors/compilers to

recognize the type of source file.

For example, a member has been specified as having an attribute of CBL (for

COBOL program,) the AS/400 editor, SEU, will format the program as a COBOLprogram, and when PDM (Program Development Manager) is given the instruction

to compile the file, it "knows" that it should invoke the COBOL compiler.

CBL indicates it is a COBOL program

RPG indicates it is a RPG program

CLP indicates it is a Control Language program

DSPF indicates it is a DISPLAY file(online screen)PGM indicates it is a compiled code

PF indicates it is a Physical file

LF indicates it is a Logical file

OS400 Objects


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1. It contains both structure and

physical data such as an inputfile or a program.

2. It can be compiled but each

time file is compiled, data is

deleted.

3. It has a record format defined

using DDS(Data Description

Specifications a language that

is used to describe database

files to system) or using CL

command CRTPF/CRTSRCPF.

4. It has an attribute PF-DTA.

OS400 Objects

Physical File

1. It is just a structure and a view

of physical file data.

2. It can be compiled any number

of times and no data loss as is

does not contain any data.

3. 3. It has a record format

defined using DDS(Data

Description Specifications a

language that is used to

describe database files to

system) or using CL command

CRTLF.

4. It has an attribute LF.

Logical File


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The Program Development Manager (PDM) is a set of utilities under OS/400

designed to simplify the creation and development of software. It automates file and

member creation, editing, compilation and program execution, and allows the

programmer to manage their environment from a set of standard menus.

PDM can be used in 2 ways.

1. Use the command STRPDM (for Start PDM,) which will produce a menu of

options for the level on which the user wishes to work (libraries, objects, or

members,) .

2. Use one of three commands which indicate the level at which the user would like

to work:

WRKLIBPDM -- Work with libraries using PDM

WRKOBJPDM -- Work with objects using PDM

WRKMBRPDM -- Work with file members using PDM

Program Development Manager(PDM)


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Source Entry Utility (SEU) is used to work with source members in source

physical files, and the records contained in source members.

With SEU, you can do operations such as:

Create members

Edit members (code programs)

Print members

Copy records into a member from another member or spooled file

Source Entry Utility(SEU)


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Screen Design Aid (SDA) is used to perform the following tasks:

1. Design a menu to present a list of options from which the user makes a

Selection

2. Design a display to help the user navigate through an application

program

3. Create online help information for displays and menus.

Screen Design Aid(SDA)


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D t D i ti S ifi ti (DDS)


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Data Description Specifications (DDS) describe data attributes in file

descriptions that are external to the application program that processes the

data.

File Types that use DDS :

1. Physical and logical files

2. Display files

3. Printer files

4. ICF files (Intersystem communications function files)

Data Description Specifications(DDS)


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End of Day 2 session

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124170940 Introduction to OS 400 Concepts

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