Chapter 9: Defining Program Specifications

In this chapter, you learn about Online Express, define program functions, and map screen fields.

Learn About Online Express

Goal

In this section you learn the concepts of processing logic in Online Express, and you access Online Express to specify the Parts Update program logic.

You complete your application by defining its processing logic using Online Express, a menu-driven painter that offers a fill-in-the-blanks approach. You use Online Express for any type of online application. Online Express references the information that you have specified in the other APS painters and importers, and prompts you to define the processing logic for those specifications. You do the following to define the program in Online Express:

Select predefined program functions. Online Express provides predefined program function logic, including teleprocessing and database read and write functions. You simply select the program function codes that you want.
Define custom program functions. You can define your own program functions to supplement the predefined functions. End users can execute custom functions just as they execute any predefined function.
Specify methods for executing functions. You specify the method by which the end user executes the functions. For example, the end user can either enter a code in a function field or press a key.
Map screen fields to database fields. Online Express automatically displays all screen fields that you have defined in the Screen Painter, so that you can map them to the appropriate fields in your database.

Procedure

Start this procedure where the last one ended -- in the Main Menu.

To transfer to the Painter Menu, type 1 in the Option field and press Enter. The APS Painter Menu displays.
Type e in the Command field to edit the application.
If necessary, type ap in the Type field to indicate Application Painter. To select the tutorial application, type the application name, apsappl, in the Member field and press Enter. The APS Application Painter screen displays.

Figure 9-1: Access Online Express
To access Online Express, type ox in the selection field to the left of the APSUPD program and press Enter. The Online Express menu screen displays.

Figure 9-2: Online Express Menu
To access the Program Definition screen, type 1 in the Command field and press Enter.

Checkpoint

You are in Online Express and are ready to begin specifying program logic by selecting the predefined function codes the program requires.

Help

Online Express has an extensive help facility that you can select from the action bar, or access from your screen by pressing PF1.

When you access the Online Express Menu and the warning message DEFAULT PROGRAM NOT FOUND displays, press PF3 to erase the message from the screen.

Hints

Other functions you can perform in Online Express are:

Test the teleprocessing functions. Without accessing a database, you can execute your teleprocessing functions to verify that they work as desired. In addition, you can enter test data to verify that your field edits are properly defined.
Customize the predefined functions. You can modify and supplement the default processing logic of the predefined functions by adding your own logic at predefined locations in your program, called control points.

Define Program Functions

Goal

In this section, you specify basic program information and select predefined functions, and then specify the method for executing the functions.

This program:

Reads database records and move data to screen fields -- the Query function.
Updates the records by moving data from screen fields to the records -- the Update function.
Deletes database records -- the Delete function.
Clears all screen fields of data -- the Clear function.
Terminates the program -- the Exit function.

The end user will execute these database and teleprocessing functions by entering a function code in the screen field named Function. Additionally, the end user will press the PF3 function key to return control to the Main Menu program, which displays the application Main Menu screen.

Procedure

Begin this procedure where the last one ended -- in the Program Definition screen.

Figure 9-3: Select Predefined Program and Database Functions

To select the Query, Update, Delete database functions, and the Clear and Exit teleprocessing functions, type qudce in the Function Codes field, as shown in Figure 9-3.
To specify that the end user will press a function key to transfer between application screens, type 3 in the Command field and press Enter. The PF Key Functions screen displays.

Figure 9-4: Assign Functions to PF Keys
To specify that the F3 key returns control to the Main Menu program, do the following:
- On the PFKEY03 input line, type x under the Function column.
- Type apsmnu under the Reserved Function or Function Name column.
Optionally, you can duplicate the actions for PF15 so your end user can use either row of function keys on the terminal. To do so, type * in the Command field and press Enter. Optionally, press Enter again to display function keys PF13 to PF24; the actions and functions are duplicated, with X assigned to PF15.

Checkpoint

You have defined your program specifications and specified how they are executed. Next, you map the screen fields to the appropriate fields in the imported VSAM database.

Help

Teleprocessing (TP) functions transfer screen data and program control from the current program to another screen or program. The APS predefined TP functions include the following:

TP Function	Description
S(end)	Transmit an input/output screen.
M(SG-SW)	Schedule a new program and optionally pass a screen record or other data record to it.
X(CTL)	Transfer control to another program.
C(all)	Call a subroutine or perform a CICS LINK.
C(lear)	Move spaces to all I/O fields.
E(xit)	Terminate the program.

Database functions read from and write to your application's database. The APS predefined database functions include the following:

Read Function	Description
Q(uery)	Obtain one or more records and display data on the screen.
B(ackward)	Page backward through a repeated record block.
F(orward)	Page forward through a repeated record block.
N(ext)	Retrieve the next sequential record and display data; not applicable to SQL.
R(efresh)	Re-read the database when the end user executes any database write function on one or more repeated record block rows, and re-display the record block to reflect the database updates.
A(dd)	Store records.
D(elete)	Erase records.
U(pdate)	Modify records.

The screen design dictates which functions act on which fields. The Parts Update screen displays data one occurrence at a time, displaying information about a particular part. To query the record in this tutorial, the end user will enter q(uery) in the Function field and a value in the record key field, Part Number -- you assigned the query function in step 1. Then, in step 3, you assigned the X(CTL) function to the F3 key so that the end user can press F3 to transfer to the Main Menu.

Any function that you define for this program acts on all fields. You can select any of the following functions:

A(dd)	D(elete)	N(ext)	S(end)
C(all)	E(xit)	Q(uery)	U(pdate)
C(lear)	M(SG-SW)	R(efresh)	X(CTL)

Hints

The function field on the Parts Update screen has the default name FUNCTION. If you assign the function field a different name, you would enter that name in the Function field on the Program Definition screen.

The system message field on the Parts Update screen has the default name SYSMSG. If you assign the system message field a different name, you would enter that name in the SYSMSG field on the Program Definition screen.

Map Screen Fields

Goal

In this section, you map the screen fields to the appropriate fields in the VSAM database. You specify each screen field's corresponding database field, and indicate whether the screen field is an input field, an output field, or both.

To help you do so quickly, Online Express displays all screen fields that you defined in the Screen Painter.

Procedure

Start this procedure where the last one ended -- on the PF Key Functions screen.

Type 4 in the Command field and press Enter. The Field Mapping screen displays, listing the screen fields you defined in the Screen Painter, prefixed by the screen name.

Figure 9-5: Initial Field Mapping Screen Lists Screen Fields
To enter the names of the database fields corresponding to each screen field and indicate that field data moves both from the screen to the database record and vice versa, type * (asterisk) in the Command field and press Enter. APS copies the field names from the Screen Field to Program Field for you and enters the default of B in the I/O/B column.

Figure 9-6: Map Screen Fields with the * Command
To assign the database record prefix to the program field names, type prefix pm- in the Command field and press Enter. APS assigns the PM- prefix to the program field names.

Figure 9-7: Assign a Prefix to Program Field Names

Checkpoint

You have completed field mapping and are ready to define program database access.

Help

Use the prefix command in any of the following formats:

pre[fix] fldprefix	Add fldprefix to fields on all lines.
pre[fix] fldprefix m n	Add fldprefix to fields from line m through line n.
*pre[fix] fldprefix n**	Add fldprefix to fields from line 1 through line n.
pre[fix] fldprefix n *	Add fldprefix to fields from line n through the last line.

Notice that the FUNCTION, SAVEKEY, and MESSAGE fields were not copied, because they don't correspond to database record fields -- they're defined only in your program and are reserved for special purposes in Online Express.

Hints

Use of the * command assumes the screen field names are the same as the database record names (except for the prefixes), which is true for this program.

To clear some or all of the values you entered, you can enter the reset command in any of the following formats in the Command field:

reset	Clear values on all lines.
reset m n	Clear values from line m through line n.
*reset n**	Clear values from line 1 through line n.
reset n *	Clear values from line n through the last line.