PROCESS PAGE

This document covers the following topics:

• Function

• Syntax 1 - PROCESS PAGE

• Syntax 2 - PROCESS PAGE USING

• Syntax 3 - PROCESS PAGE UPDATE

• Syntax 4 - PROCESS PAGE MODAL

• Examples

Function

The PROCESS PAGE statement constitutes a general interface description to an external rendering engine, such as Natural for Ajax, thus linking the Natural internal data representation with an external data representation. Via this link, data and events, but no rendering information, are sent to and returned from an external, browser-based application.

For further information, refer to the Natural for Ajax documentation. The latest Natural for Ajax documentation is always available at https://empower.softwareag.com/.

Syntax 1 - PROCESS PAGE

For an explanation of the symbols used in the syntax diagram, see Syntax Symbols.

Belongs to Function Group: Screen Generation for Interactive Processing

Syntax Description - Syntax 1

Syntax 1 of the PROCESS PAGE statement is normally only used inside a Natural adapter. An adapter is a Natural object that forms the interface between Natural application code and web page. It is automatically created/updated by Natural for Ajax when the layout is saved.

Note:

Operand Definition Table:

Syntax Element Description:

(CV=operand2)

(CV=operand5)

Example of an adapter which has been created by Natural for Ajax:

* PAGE1: PROTOTYPE       --- CREATED BY Natural for Ajax --- 
* PROCESS PAGE USING 'XXXXXXXX' WITH
* INFOPAGENAME RESULT YOURNAME
DEFINE DATA PARAMETER
1 INFOPAGENAME (U) DYNAMIC
1 RESULT (U) DYNAMIC
1 YOURNAME (U) DYNAMIC
END-DEFINE
*
PROCESS PAGE U'/njxdemos/helloworld' WITH
PARAMETERS
 NAME U'infopagename'
  VALUE INFOPAGENAME
 NAME U'result'
  VALUE RESULT
 NAME U'yourname'
  VALUE YOURNAME
END-PARAMETERS
*
*  TODO: Copy to your calling program and implement.
/*/*( DEFINE EVENT HANDLER
* DECIDE ON FIRST *PAGE-EVENT
*  VALUE U'nat:page.end'
*   /* Page closed.
*   IGNORE
*  VALUE U'onHelloWorld'
*   /* TODO: Implement event code.
*   PROCESS PAGE UPDATE FULL
*  NONE VALUE
*   /* Unhandled events.
*   PROCESS PAGE UPDATE
* END-DECIDE
/*/*) END-HANDLER
*
END

Syntax 2 - PROCESS PAGE USING

For an explanation of the symbols used in the syntax diagram, see Syntax Symbols.

Belongs to Function Group: Screen Generation for Interactive Processing

Syntax Description - Syntax 2

This syntax is used to perform rich GUI input/output processing using an object of type adapter that has been generated from a page layout created with Natural for Ajax or a similar tool.

Operand Definition Table:

Syntax Element Description:

PROCESS PAGE USING without Parameter List

The following requirements must be met when PROCESS PAGE USING is used without parameter list:

• The adapter name (operand6) must be specified as an alphanumeric constant (up to 8 characters).

• The adapter used in this manner must have been created prior to the compilation of the program which references the adapter.

• The names of the fields to be processed are taken dynamically from the adapter source definition at compilation time. The field names used in both program and adapter must be identical.

• All fields to be referenced in the PROCESS PAGE statement must be accessible at that point.

• In structured mode, fields must have been defined previously (database fields must be properly referenced to processing loops or views).

• When the page layout is changed, the programs using the adapter need not be recataloged. However, when array structures or names, formats/lengths of fields are changed, or fields are added/deleted in the adapter, the programs using the adapter must be recataloged.

• The adapter source must be available at program compilation; otherwise, the PROCESS PAGE USING statement cannot be compiled.

Note:
If you wish to compile the program even if the adapter is not yet available, specify NO PARAMETER. The PROCESS PAGE USING statement can then be compiled even if the adapter is not yet available.

PROCESS PAGE USING Fields Defined in the Program

By specifying the names of the fields to be processed within the program (operand7), it is possible to have the names of the fields in the program differ from the names of the fields in the adapter.

The sequence of fields in the program must match the sequence in the adapter. If you use Natural maps as adapter objects, note that the map editor sorts the fields as specified in the map in alphabetical order by field name. For more information, see the map editor description in your Editors documentation.

The program editor line command .I(adaptername) can be used to obtain a complete PROCESS PAGE USING statement with a parameter list derived from the fields defined in the specified adapter.

When the layout of the adapter is changed, the program using the adapter does not need to be recataloged. However, when field names, field formats/lengths, or array structures in the adapter are changed or fields are added or deleted in the adapter, the program must be recataloged.

A check is made at execution time to ensure that the format and length of the fields as specified in the program match the fields as specified in the adapter. If both layouts do not agree, an error message is produced.

Syntax 3 - PROCESS PAGE UPDATE

For an explanation of the symbols used in the syntax diagram, see Syntax Symbols.

Belongs to Function Group: Screen Generation for Interactive Processing

Syntax Description - Syntax 3

The PROCESS PAGE UPDATE statement is used to return to and re-execute a PROCESS PAGE statement. It is generally used to return from event processing, because the data input processing of the preceding PROCESS PAGE statement was incomplete.

Note:
No INPUT, WRITE, PRINT or DISPLAY statements may be executed between a PROCESS PAGE statement and its corresponding PROCESS PAGE UPDATE statement.

The PROCESS PAGE UPDATE statement, when executed, repositions the program status regarding subroutine, special condition and loop processing as it existed when the PROCESS PAGE statement was executed (as long as the status of the PROCESS PAGE statement is still active). If the loop was initiated after the execution of the PROCESS PAGE statement and the PROCESS PAGE UPDATE statement is within this loop, the loop will be discontinued and then restarted after the PROCESS PAGE statement has been reprocessed as a consequence of the PROCESS PAGE UPDATE statement.

If a hierarchy of subroutines was invoked after the execution of the PROCESS PAGE statement, and the PROCESS PAGE UPDATE is performed within a subroutine, Natural will trace back all subroutines automatically and reposition the program status to that of the PROCESS PAGE statement.

It is not possible, however, to have a PROCESS PAGE statement positioned within a loop, a subroutine or a special condition block, and then execute the PROCESS PAGE UPDATE statement when the status under which the PROCESS PAGE statement was executed has already been terminated. An error message will be produced and program execution terminated when this error condition is detected.

Operand Definition Table:

Syntax Element Description:

Example User Program Fragment:

PROCESS PAGE USING "HELLOW-A"
*
/*( DEFINE EVENT HANDLER
DECIDE ON FIRST *PAGE-EVENT
 VALUE U'nat:page.end'
  /* Page closed.
  IGNORE
 VALUE U'onHelloWorld'
  COMPRESS "HELLO WORLD" YOURNAME INTO RESULT
  PROCESS PAGE UPDATE FULL
 NONE VALUE
  /* Unhandled events.
  PROCESS PAGE UPDATE
END-DECIDE
/*) END-HANDLER

EVENT Option

AND SEND EVENT operand8
[WITH PARAMETERS
{[NAME] operand9 [VALUE] operand10 [		(EMU=value) (EM=value)		]}...
END-PARAMETERS]

With this option, you can advise the external I/O system to run specific functions. These functions are part of the external I/O system or implement special functions regarding the output processing as setting of focus, displaying message boxes, etc.

Operand Definition Table:

Syntax Element Description:

Syntax 4 - PROCESS PAGE MODAL

For an explanation of the symbols used in the syntax diagram, see Syntax Symbols.

Related Statements: ESCAPE | PROCESS PAGE

Belongs to Function Group:

• Loop Execution

• Screen Generation for Interactive Processing

Syntax Description - Syntax 4

The PROCESS PAGE MODAL statement is used to initiate a processing block and to control the lifetime of a modal rich GUI window.

Entering the PROCESS PAGE MODAL statement block causes the following actions to be performed:

• Data from Report 0, which is not displayed yet, will be displayed first;

• the system variable *PAGE-LEVEL is incremented;

• the opening of a modal page is prepared. The physical opening of the modal page will be performed with the next PROCESS PAGE USING operand6 WITH statement, where operand6 is the name of the adapter to be used.

Leaving the PROCESS PAGE MODAL statement block causes the following actions to be performed:

• If a modal page has been opened for this level, the closing of the modal page is prepared. The physical closing of the modal page will be performed with the next PROCESS PAGE UPDATE [FULL] statement;

• the system variable *PAGE-LEVEL is decremented, and the system variable *PAGE-EVENT is set back to the value it had before the statement block was entered;

• a nat:page.default event will be raised in the program that opened the modal page.

Note:
No PRINT, WRITE, INPUT or DISPLAY statements referring to Report 0 may be executed between a PROCESS PAGE MODAL statement and its corresponding END-PROCESS statement.

The PROCESS PAGE MODAL statement is not valid in batch mode.

Syntax Element Description:

Example:

* Name: First Demo/Open modal! 
*
PROCESS PAGE USING "EMPTY-A"
*
/*( DEFINE EVENT HANDLER
DECIDE ON FIRST *PAGE-EVENT
  VALUE U'nat:page.end', U'onClose'
    /* Page closed.
    IGNORE
  VALUE U'onNextLevel'
    PROCESS PAGE MODAL
      FETCH RETURN "EMPTY-P"
    END-PROCESS
    PROCESS PAGE UPDATE
  NONE VALUE
    PROCESS PAGE UPDATE
END-DECIDE
/*) END-HANDLER
END

Examples

Further examples of using the PROCESS PAGE statement are contained in library SYSEXNJX.