HP 3000 Manuals

HP Data Entry and Forms Management System (VPLUS/V)

FORM FAMILIES 

A family of forms is a collection of forms that share a common
form layout but may have different field attributes, processing
specifications, or form sequencing options.  Use of form families may
improve VPLUS/V performance in some transaction processing applications;
since only the internal form characteristics are different among members
of a family, you do not have to wait for VPLUS/V to repaint the screen
when you change to another form in the same family.  Figure 3-14
illustrates some form family concepts.


          Figure 3-14.  Form Family Relationships 

Parent Form      Also called father or root form.  A parent form is a
                 standard VPLUS/V form created in FORMSPEC either by
                 designing it or by copying it from another form.  The
                 form layout of the parent form determines the layout of
                 all child forms that are reproduced from it.  Changing
                 the layout of the parent form causes the layouts of the
                 child forms to change.

Child Form       Reproduced from the parent form, the form layout of the
                 child form may not be modified.  You may change form
                 sequencing options, field attributes and processing
                 specifications.  As Figure 3-14 indicates, you may
                 reproduce a child form from another child form, although
                 VPLUS/V still considers the original root form to be the
                 parent of both forms.

Reproduce        Generate a related form by entering the name of an
                 existing form in the "Reproduced from" field of the Form
                 Menu.

Creating Child Forms 

You create child forms by following these steps:

   1.  Select A for "Add a form" at the Main Menu.  Press ENTER.

   2.  When the Form Menu comes onto the screen, specify the name of the
       child form you wish to create, and, in the "Reproduced from"
       field, specify the name of the form from which you wish to
       generate the child form.  You may change any of the other Form
       Menu fields.  Press ENTER.

   3.  The layout for the form you named in step 2 is displayed.  Then
       press NEXT. Since the form layout must be the same for parent and
       children, pressing ENTER causes the error message "Cannot change
       screen, the form is a family member." to appear in the window.

   4.  You may change any of the attributes or processing specifications
       on the Field Menus (except length and field number) to adjust the
       internal characteristics of the child form to your needs.  A child
       form continues to have all the characteristics of the parent if
       you do not modify the child's Field Menus.

To modify the form layout of a form family, you need to change only the
layout of the parent form, and recompile the forms file.  This changes
the layouts of the child forms automatically.  Deleting the parent form
deletes the entire form family.

Careful naming of forms and the use of the optional comment field of the
Form Menu makes relationships between forms of the same family more
apparent.  To make it easier to distinguish between forms of the same
family in ENTRY or in other applications, you may wish to add a field
reserved for the form name to the screen definition of the parent form,
and add processing specifications which set the value of that field to
the name of the current form.  Refer to the SET command in Section 4.

Although family relationships are not maintained after a copy operation,
they can be re-established using the R option "Relate child form to
parent form" at the Main Menu.  In order to use this method of creating
family relationships, certain criteria must be met.  The forms must
already exist and their form layouts must be identical.  The forms must
have identical field number sequences.  The forms must be distinct forms;
that is, one form cannot be both the parent form and the child form.
Furthermore, the child form cannot already be a child form or a parent
form.  Thus, it is also possible to relate forms which were never
previously related.

Users should note that if a new form is to be reproduced from a form
which is already a child, then its parent will be designated as the
actual parent.  For example, suppose that an existing forms file contains
three forms named PARENT, CHILD and NEWCHILD, where PARENT and CHILD
already maintain a relationship.  At the Main Menu, it is indicated that
NEWCHILD should become a child form of CHILD. If the forms meet the above
criteria, FORMSPEC actually creates the relationship with PARENT as the
parent form and NEWCHILD as its child.  The form named CHILD continues to
be a child form of PARENT.

Forms can also be related using the RELATE command from FORMSPEC in batch
mode.  (For further information see "Using FORMSPEC in Batch Mode",
Section 7.)

Form Family Example 

Suppose you have a VPLUS/V application which, after accepting a
customer's identification number, retrieves items of pertinent customer
information from a data base and displays them on a form.  It would be
convenient to have two forms, one on which the customer ID is required,
and the other on which the user views or alters the customer data.  If
you don't use the form family feature, the user who is alternating
between entering customer ID's and inspecting or modifying data
constantly has to wait for the form to be repainted each time the user
needs information on another customer.

The solution to this problem of long user waiting time is to create two
forms with the same form layout but different field attributes.

Suppose the root or parent form of this example is named CUSTPAR, and
that its form layout is as shown in Figure 3-15 below.  All of the fields
in this form are display only, except for the Customer ID Number field,
which is required.


          Figure 3-15.  Parent Form 

Create a child form, CUSTCHILD, by specifying CUSTPAR in the "Reproduced
from" field of the Form Menu.  Press NEXT until the Field Menu for CUSTID
appears and make it a display only field.  Make all other data fields in
the form optional.  Compile the forms file.


          Figure 3-16.  Child Form 

Now when the user types the customer ID and presses ENTER, the
application retrieves the related information from the data base and
displays it in the form immediately.  Once the form is on the screen, it
appears to remain there as long as the user uses the application, rather
than being repainted each time for every customer about whom the user
calls up data.

MPE/iX 5.0 Documentation