$Web Api

Determine whether web API is available

This method was first avaliable in Model 204 7.8.

$Web_APi indicates whether the current processing is the result of a request to Janus Web Server. The difference between $Web_Api and $Web is that the latter returns 0 on the transactional daemon child (or any transactional descendant) of a web thread whereas the former returns 1, indicating that the $web API is available to the threads.

$Web_Api takes no arguments and returns either a 0 or a 1.

Syntax

%rc = $Web_Api

Return codes

Code	Meaning
0	Web API not available.
1	Web API available.

Usage notes

• The $Web function is most useful for:
  • Preventing code that should only be run for a web request from running for 3270 (or other non-web) requests.
  • Ensuring that non-web, possibly 3270 specific code, is not run for web requests.
  • While $web functions are available on transactional daemon descendants of web threads, "terminal" output is not captured to the web output buffer as it is for the web thread itself. If a transactional daemon wishes to add data to the web output buffer it should use $Web_Put_Text or $Web_Put_Bin.

  In the example below, the variable %district is set from a form field when running a web request and from a screen field otherwise:

  if $web_api then %district = $web_form_parm('DISTRICT') else %district = %query:district end if

• $web_api has several advantages over other techniques for determining whether a request is running a web request, such as checking $Web_Port or doing a $VIEW('IODEV'):
  • It is syntactically simple and easy to understand.
  • It works correctly even when a request is being debugged using JANUSDEBUG.
  • It works correctly and does not cause a "CONNECTION WAS LOST" user restart after the connection was closed either with a $Web_Done or by the browser. This can be especially useful if there is web-specific processing, like APSY navigation code, that happens after a $Web_Done.