idms-adso

LEMURIA TECHNOLOGIES LTD 1

CA – IDMS / ADS

Overview


Dialog StructureAn ADS program is called a DIALOG.

A single dialog consists of the following:

1) one optional subschema

2) one optional map

3) one optional premap (process module)

4) one or more optional work records

5) one or more optional response processes (modules associated

with a PFkey or command)


Dialog Flow

1. Premap code (if any) begins executing. Database run-unit is started if there is any database I/O in the premap. The database run-unit is finished. The premap ends by displaying the MAP.

2. Program frees as many resources as possible, and waits for user to press the ENTER or a function key.

3. Program wakes up and does a map in.

4. Based on the function key pressed, the code in the appropriate response module is executed. A database run-unit is started at the time of the first database I/O.

5. The response code ends when a DISPLAY statement is executed (causes a MAP OUT) or when a statement such as RETURN or LEAVE ADS or a LINK to another DIALOG is encountered.


IDMS Mapping

Mapping Overview

The world of online mainframe systems has long been built around the IBM

3270 terminal. Mapping basically involves sending or receiving a data

stream to or from a 3270 terminal, and IDMS’s mapping was probably

modeled after IBM’s CICS BMS (Basic Mapping Support).

There are two ways of working with a terminal:

1) line mode - reading and writing one line at a time

2) mapping mode - the concept of sending and receiving an

entire screen at a time

Personal Computers continue the 3270 tradition by providing "terminal

emulators", which are software packages that allow a window on your PC to

look like a 3270 mainframe session.


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• Mapping became popular because it maximizes CPU time and transmission time.

• The user looks at the screen, fills in some fields, and then presses"ENTER" or a PFkey.

• The entire screen (map) is sent to the mainframe, a program is invoked to process the map, database I/O is done, the map is

reformatted (or a new map is built), then the data is returned to the terminal.

• Most mainframe sites use VTAM - Virtual Terminal Access Method as a layer between the terminal and the software.


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There is usually one additional layer between VTAM and the programmer

- and that is called a TP-monitor - where TP stands for Tele Processing.

IBM has long provided a TP monitor called CICS (Customer Information

Control? System) and its mapping language is called BMS (Basic

Mapping Support).

IDMS came out with a TP-monitor called DC (Data Communications). So

all IDMS online products use "DC" commands to communicate with maps

built by the Mapping Compiler. Some companies wanted to run IDMS

under CICS or TSO or other TP monitors, therefore IDMS provided UCF

(Universal Communications


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Error Message FieldDisplaying error messages: A maximum of one message field can bedefined on any given map; a message field can be of any length. Whenseveral data fields submit incorrect input, the message field displays asmany error messages as possible, in order of occurrence (from top tobottom and left to right) of the incorrect data fields.

Messages in the detail area: A message field that is defined in the detail area of a page able map is mapped out once in each occurrence ofthe detail occurrence in the detail area. Messages generated by the CA-DS DISPLAY MESSAGE statement are not displayed if the message field isdefined in the detail occurrence for the map.

Message sources: A message field displays messages generated fromeither of the following sources:

-The error-handling capability of the CA-IDMS mapping facility

- The CA-ADS dialog or application program that uses the map


Starting Task MAPC

Starting the Online Mapping Compiler

From the CA-IDMS DBDC "Enter NextTask Code Prompt:" type in MAPC (orany other name that your site may havedefined as the task code).


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When a new session is initiated, as when the online compiler isinvoked from CAIDMS, a new queue record is built. When asuspended session is invoked, the queue record from the suspendedsession is used.


Building a Map


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This course assumes that you already know about IDMS dictionaries. Allpieces of an ADS application are typically stored in the same dictionary.Often, your site administrators will automatically logon you on to the properdictionary. It is also possible that you might switch between multipledictionaries depending on the project you are working on.

You can type in the dictionary name on the screen above, or on the TCF(Transfer Control Facility) screen, or by using the DCUF command fromthe command prompt.

Adding, Copying, or Deleting a MapMAPC and ADSC follow the CUA (Common User Access), also called"ACTION BAR" or pull down menu.

To add a new map:

1) type in the map name (and optionally the dictionary name, otherwise the dictname will default).

NOTE: Check with your site standards for map naming conventions.

2) Move the cursor over the word "add" (upper left corner of the screen) and press enter.


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3) You can copy the map from another map by entering the source map name

or you can just press enter to create a new empty map.

Copy Option 1 "All" specifies to copy the entire map along with all records and

elements.

Copy Option 2 "Format" specifies to copy the format of the map, but not to copy

the element definitions.

For now, we don’t have any existing maps to copy from. This feature will be

demonstrated later.


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On the pull down menu that appears, type in 2 in order to delete the map.

You must confirm that you really want to delete the map before continuing.

This is shown on the next page.


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The "MODIFY" option on the action bar relates to map checkout.

"CHECKOUT" allows a developer to have sole access to a map.

The map is protect from additional updates until has been

checked in (released).

"RELEASE" - releases the developers hold on a map so that

other developers may modify it.

"LIST" - display a list of all maps checked out to the user signed

on.


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Other MAPC Menu Options

Other options exist on the ACTION BAR, but they will be covered later in thetutorial.

This section is designed primarily for beginners - so right now - you need tolearn the basics of building a simple map - and not get hung up on all theadvanced features.

Right now - a beginner needs to learn the following:

1) How to attach map work records to the map2) How to define the literals and fields to the map3) How to compile the map

Each of these topics will be covered in following sections.


Associated Records

Before building a map, usually the developer (or some other appointedperson) has built the necessary map work records on the IDD (IntegratedData Dictionary).

Building elements and records on the dictionary is covered in another partof this course.

Map Work Records are similar to a working-storage section of a COBOLprogram. A record is like an 01 level - with several fields or elements underit. The 01 level (or record-name) must be attached to your map before youadd any elements from that record to your map.


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NOTE: Most sites require that element names be unique. This isusually done by using a record prefix or suffix. For example, theelement name might be EMPNUM on the dictionary, but in one recordit might be EMP-NUM-M101 (where the suffix is '-M101') or MAP1-EMP-NUM (where the prefix is 'MAP1-'). Often times, a special maprecord will be built for each map, and the record name will containthe map-name, or the numerical part of the map name.

Example:

MAP-NAME= EMP0100M RECORD-NAME=EMP0100M-MAP-RECORD

or RECORD-NAME=EMP-MAP-RECORD-0100

Some sites have very strict naming conventions, other sites mayhave no naming conventions.


Mapping to Database Records?IDMS allows you to map directly to database records. While this makesthe programming somewhat easier by eliminating move statementsbetween the database fields and the map fields, there are complications.

If the database needs to be restructured, and the database record isassociated with several maps, the DBA has two options:

1) create a new version of the database record2) decompile all maps, change the record, then restore all maps

Check with your site's procedures as to whether you should map todatabase records. Some sites have standards that you should or shouldnot do so. The examples in this course will use intermediate MAP workrecords.


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Each site will have defined a special character to use to identify new and

changed fields.

The % sign is often used for this character.

Place one % sign in front of each literal, then just type in the literal.

Then press PF5 to proceed. PF5 is the "NEXT KEY" - and will usually take

you where you need to go next.


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You will see one "Literal Definition" screen for each literal that you defined.

A small part of your layout screen is shown, with the current literal

highlighted.

Each site will have its own screen design procedures. Usually the map name

goes somewhere on the top, often with the date/time. There are usually

standards as to how literals and variables should be displayed.

We will accept the defaults for now.

Display Intensity

1. Normal 2. Bright or 3. Hidden


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Hidden fields are available for such things as a password entry field.

Bright fields are usually shown brighter - or in a different color - depending on

your terminal emulation software. Many people now use Personal Computers

to emulate a 3270 session, and the PC has the power to re-interpret these

characteristics according to the PC users options.

Highlighting –

1. Blink 2. Reverse Video or 3. Underline

NOTE: not all 3270 terminals support these functions


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At end of field (for variable fields, not literals) - what happens if the user types

one character more than size of field?

1. Auto-tab - automatically tab to the next field, and insert that character as the

first character in the next field.

2. Lock keyboard - puts the "stick-man" or "X" at the bottom of the terminal,

prevents any further typing until the user presses the "RESET" key and manually puts the cursor in a valid position.

3. Take no action - just lets the user keep on typing.

Color - obviously sets the color of the field - but remember that a PC user may

have his colors re-mapped to some other set of colors.


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Notice how the literal fields all have the other field symbol preceding them.

Now prepare the screen for each variable field. Put a % mark at each

location where you wish to define a variable field.

Then press PF5 for NEXT.


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Be sure to include any prefix or suffix. We are using the map name as a

record element prefix (EMP0100M-).

After typing in the field name, press ENTER - and the results are shown

on the next screen.


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The mapping compiler automatically fills in the picture and the other fields

from information on the IDD.

You may now change the fields as desired (shown on next page).


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The Edit Picture will allow employee-id to be displayed without leading

zeroes.

It is a common procedure to make input fields bright and all other fields

normal intensity, so "2" was entering for intensity.

We will use auto-tab as a standard for all input fields.

Since the user must type in the employee-id to do a query the field must be

unprotected.

Press PF5 to continue to the next variable field.


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If you are processing more than one variable field at a time, then the next

variable field is highlighted.

Note that that the length of the field is only one character until you type in

the element name (then the length is determined by the Edit Picture).


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On the prior screen, an invalid element name was entered.

Note the error message (in red) on this screen).

What did we do wrong?

The M was omitted from the element prefix.

It should have been EMP0100M-LAST-NAME, so we correct the element

name and try again.


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Adding a Message Field


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Batch Mapping


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Start Task ADSC


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TCF – Transfer Control Facility


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Initial Screen


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Dialog Options and Directives Screen



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Subschema/Database Specifications


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Work-Records


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Process Modules


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ADS PROGRAMMING LESSONS


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Program 2 - PFKey Enhancements


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