The first page will be the usual Hello World, which is very straight forward. Just insert a couple of lines into a flat file and run it from a browser. The source can be found at helloworld. However, the following section focuses on the HelloWorld page with the intention of providing a little more explanation as to how the Net.data CGI interface works.

• Net.data is an interpretative language, as is PHP or ASP. It performs the tasks you want by running a script, otherwise known as a macro in Net.data terminology.
• Scripts or macros are just source files. These can be regular source physical files in some user library, accessible via SEU, or flat files residing in an IFS folder. We will presume to use flat files. Thus we can use any text editor to enter the code for our script. While there may exist some text editors that can be configured to offer some support for Net.data syntax, the language is simple enough that NotePad will suffice.
• We will assume that you already have an HTTP server which has been correctly configured to map url requests for Net.data pages to a specific IFS folder, namely the folder in which you wish to keep your Net.data source files. For example, a request for a Hello World page would be http://mysite/cgi/hello/macro Where each component has the following meaning - mysite : the name of your host domain (and port if required). cgi : the token in the url that tells the HTTP server to pass control to the Net.data CGI interface. hello : the name of the source file containing the Net.data source code for this request. macro : the name of the code block (within the source file) that will be used to generate the hello world page. Let us assume that name home of the folder chosen to contain the Net.data macro source files is in the home directory for mydemo in a sub-folder named macros. /home/mydemo/macros So we will begin by using NotePad to create a file named hello this folder. We enter the following code into file /home/mydemo/macros/hello

  %html(macro) {                                    
  Hello World from Net.data on @dtw_rdate() at @dtw_rtime()
  %}

• Now we can request this Hello World page by entering the following url into the browser address line - http://mysite/cgi/hello/macro The result should appear as below with the current date and time.

  Hello World from Net.data at 17 Aug 2008 20:24:11

• Here is a brief explanation of what occurred to generate this page.
  1. The HTTP server received a url from the browser containing the following string
     /cgi/hello/macro
  
  
  2. Since the string begins with /cgi, the HTTP server identified that it matches a directive in the HTTP configuration which causes it to pass control to Net.data. The matching directive should normally be a ScriptAlias directive like ScriptAliasMatch ^/cgi/(.*) /QSYS.LIB/MYDEMO.LIB/DB2WWW.PGM/home/mydemo/macros/$1
  3. The ScriptAlias directive will cause the program MYDEMO/DB2WWW to be invoked. The other thing it does is to map everything after /cgi to the end of the path string that follows the .PGM. In other words, the path now becomes home/mydemo/macros/hello/macro
  4. So now Net.data is running (DB2WWW) and it knows the exact location of the source code that you have asked it to interpret. Each line in the source file is interpreted, attempting to find an %html block named macro (the last component of the url string).
  5. Once the statement

     %html(macro) { 

     has been located, Net.data will begin generating a line of output for each subsequent line encountered until the %html block ends when the a closing statement

     %}

     has been located.
  6. Net.data will ignore all content within the %html block unless it is a word whose syntax identifies it as being a Net.data language element. Content that is ignored will be written verbatim back to the browser. Content that is Net.data syntax will be removed or replaced by dynamic content which may be returned at the point in the source at which the language element was encountered.
  7. Thus, in the Hello World macro, there are 2 language elements identified. One, @dtw_rdate(), returns the current date while the other, @dtw_rtime, returns the current time. Everything else is returned as is to the browser, irrespective of its format. Thus, although the source may contain content which could in fact be any form of markup, that is, html or xml, or some other scripting language like javascript, this will be totally disregarded by Net.data.
  8. The disregarding of browser based markup language is a very important concept since it is often misunderstood by developers who a new to Net.data. The only code that gets executed at the HTTP server is that which is a Net.data language element. In effect, Net.data does not see any markup language such as html or javascript since this is only understood by, and executed by, the browser. In reality, the browser does not see any Net.data language elements since these would have been removed when Net.data processes the source back at the server.
  9. All Net.data development is essentially just an extension of the source code employed to deliver the Hello World page. It is just a matter of understanding a larger set of Net.data language elements. These are all documented in the Net.data Reference which is also accessible from the home page at dtwdude.com via the Net.data Manuals button.