Administration and Programming Guide for OS/400

Anatomy of a Net.Data Macro

The macro consists of two parts:

The declaration part, that contains definitions used in the presentation part. The declaration part uses two major optional blocks:
- DEFINE block
- FUNCTION block
The declaration part can also contain other language constructs and statements, such as EXEC statements, IF blocks, INCLUDE statements, and MESSAGE blocks. For more information about the language constructs, see the chapter about language constructs in Net.Data Reference.
Authorization Tip: Ensure that the Web server has access rights to files referenced by the EXEC and INCLUDE statements. See Granting Access Rights to Objects Accessed by Net.Data for more information.
The presentation part defines the layout of the Web page, references variables, and calls functions using HTML blocks that are used as entry and exit points from the macro. When you invoke Net.Data, you specify an HTML block name as an entry point for processing the macro. The HTML blocks are described in HTML Blocks.

In this section, a simple Net.Data macro illustrates the elements of the macro language. This example macro presents a form that prompts for information to pass to a REXX program. The macro passes this information to an external REXX program called ompsamp.mbr, which echoes the data that the user enters. The results are then displayed on a second HTML page.

First, look at the entire macro, and then each block in detail:

%{ **********************       DEFINE block        ************************%}
%DEFINE {
   page_title="Net.Data Macro Template"
%}
 
%{ ********************** FUNCTION Definition block ************************%}
%FUNCTION(DTW_REXX) rexx1 (IN input) returns(result)
{
  %EXEC{ompsamp.mbr %}
%}
 
%FUNCTION(DTW_REXX) today () RETURNS(result)
{
      result = date()
%}
 
%{ **********************      HTML Block: Input    ************************%}
%HTML (INPUT) {
<html>
<head>
<title>$(page_title)</title>
</head><body>
<h1>Input Form</h1>
Today is @today()
 
<FORM METHOD="post" ACTION="OUTPUT">
Type some data to pass to a REXX program:
<INPUT NAME="input_data" TYPE="text" SIZE="30">
<p>
<INPUT TYPE="submit" VALUE="Enter">
 
</form>
 
<hr>
<p>[<a href="/">Home page</a>]
</body></html>
%}
 
%{ **********************    HTML Block: Output     ************************%}
%HTML (OUTPUT) {
<html>
<head>
<title>$(page_title)</title>
</head><body>
<h1>Output Page</h1>
<p>@rexx1(input_data)
<p><hr>
<p>[<a href="/">Home page</a> |
<a href="input">Previous page</a>]
</body></html>
%}

The sample macro consists of four major blocks: the DEFINE, the FUNCTION, and the two HTML blocks. You can have multiple DEFINE, FUNCTION, and HTML blocks in one Net.Data macro.

The two HTML blocks contain text presentation statements such as HTML, which make writing Web macros easy. If you are familiar with HTML, building a macro simply involves adding macro statements to be processed dynamically at the server and SQL statements to send to the database.

Although the macro looks similar to an HTML document, the Web server accesses it through Net.Data using CGI. To invoke a macro, Net.Data requires two parameters: the name of the macro to process, and the HTML block in that macro to display.

When the macro is invoked, Net.Data processes it from the beginning. The following sections look at what happens as Net.Data processes the file.

[ Top of Page | Previous Page | Next Page | Table of Contents | Index ]