This section describes the Object Maint code generator, which creates a subprogram that maintains complex data objects and updates all entities within an object. The generator also creates the local and parameter data areas.

This section covers the following topics:

• Generate the Object Maint Subprogram

• User Exits for the Object Maint Subprogram

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Generate the Object Maint Subprogram

To generate an object-maintenance subprogram and data areas

1. Open the context menu in the Navigator view for the NaturalONE project into which you want to generate the modules.

   Or:
   Open the context menu in the Navigator view for the library into which you want to generate the modules.

2. Select Code Generation > New Object Maint.

   The Define Object Maint Details panel is displayed. For example:

   

3. Type the location of the Natural library in which to generate the subprogram and associated modules in Library.

   The library must currently exist.

   Or:
   Select Browse to display a window listing the existing libraries for selection.

   Note:
   The libraries listed for selection are based on the current project.

4. Type the name of the object maint subprogram in Name.

5. Select the DDM for the object maint subprogram in DDM.

   Tip:
   The DDMs are typically located in the SYSTEM library.

   Using this panel, you can:

   Task	Procedure
   Select another NaturalONE project in which to generate the object maint modules.	Type the name of the project in Project or select Browse to display a window listing the existing projects for selection. The project must currently exist.
   Select a folder in which to generate the object-maintenance modules.	Type the name of the folder in Folder or select Browse to display a window listing the existing folders for selection. The folder must currently exist within the selected NaturalONE project. Note: This option allows you to generate modules into more complex library structures (for example, "Natural-Libraries/my library (MYLIB)/SRC"). When this option is not specified, the modules will be generated into the basic library folder (for example, "Natural-Libraries/MYLIB/SRC", "Natural-Libraries/MYLIB/Subprograms", etc.).
   Provide a description of the object maint subprogram.	Type a brief description in Description.

6. Select Finish to generate the object maint subprogram and associated modules with the default values.

   Or:
   Select Next to change the default specification values.

   The Change Defaults panel is displayed. For example:

   

   This panel displays the default specification values for the subprogram to be generated. Using this panel, you can:

   Task	Procedure
   Change the description of the subprogram to be generated.	Type the description in Object description.
   Change the name of the object.	Type the name in Object name.
   Change the primary key field used for maintenance operations.	Select the field in Primary key.

7. Select Finish to generate the object maint subprogram and associated modules.

   Or:
   Select Next to change the default parameter values.

   The Change Advanced Defaults panel is displayed. For example:

   

   This panel displays the default parameter values for the subprogram to be generated. Using this panel, you can:

   Task	Procedure
   Change the name of the parameter data area (PDA) for the object.	Type the name in Object PDA.
   Change the name of the local data area (LDA) for the object.	Type the name in Object LDA. Note: The local data area is only required when the hash-locking option is used for record locking.
   Change the name of the restricted parameter data area (PDA) for the object.	Type the name in Restricted PDA.
   Use a hold field to lock data for maintenance operations.	Select the hold field in Hold field. For more information, see Record-Locking Options. Note: By default, the hash-locking mechanism is used to lock data. If you select a hold field, the Hash locking field is automatically deselected.

   Note:
   If desired, a Generation Progress window can be displayed during generation. For information, see Set Code Generation Preferences.

8. Select Finish.

   The subprogram is generated using the current specifications. When generation is complete, the available user exits are displayed in the Outline view (see User Exits for the Object Maint Subprogram) and the generated modules are displayed in the Navigator view. For example:

   

   These modules are:

   Module	Description
   MYOBDM1.NSA	Parameter data area for the object maint subprogram
   MYOBJM.NSN	Object maint subprogram
   MYOBLM1.NSL	Local data area for the object maint subprogram
   MYOBPM1.NSA	Restricted parameter data area for the object maint subprogram

   The subprogram is displayed in the editor view. For example:

   

9. Save the subprogram and associated modules.

   At this point, you can:

   • Define user exits for the subprogram. For information, see Defining User Exits.

   • Use the NaturalONE Testing option to test the subprogram. For information, see Test a Subprogram Directly in Application Testing.

   • Use NaturalONE functionality to upload the generated subprogram to the server.

Record-Locking Options

In a client/server environment, data retrieved for maintenance is not locked initially. Instead, the object maint subprogram retrieves the data again and locks it prior to updating, storing, or deleting data from the database.

To ensure changes are not overwritten by another user during this process, the subprogram must determine whether the data has changed since the initial retrieval. To do this, the object maint subprogram has two record-locking options:

• Hash-locking

  This method is the most reliable. The subprogram retrieves the initial data and hashes it to a number. When it retrieves the data to lock it, the subprogram hashes it to a number again. Logical variables are stored in alphanumeric format in the local data area to process the hashed values. All data must hash to the same value as when it was requested. If it does, data has not changed and the changes are allowed.

• Timestamp

  The timestamp (or counter) method is the traditional record-locking mechanism. This method assumes that every time data changes, the timestamp also changes. This method is more efficient than the hash-locking method because the subprogram only has to check one field, but this assumption can be incorrect when the file is not maintained by an Object Maint-generated subprogram (for example, a programmer-coded subprogram may not change the timestamp when data is modified).

If the file is not normally maintained through an Object Maint-generated subprogram, the hash-locking option should be used. If the file is only maintained through an Object Maint-generated subprogram, the timestamp option should be used (as it is more efficient). For more information, see Natural Construct Object Models.

User Exits for the Object Maint Subprogram

The Outline view for the object-maintenance subprogram displays the available user exits. For example:

You can use these exits to define additional processing.

Notes:

1. All user exits are empty when generated.
2. For information about adding custom code within user exits, see Defining User Exits.