$Web: Difference between revisions

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Revision as of 21:45, 17 October 2012

<section begin="desc" />Determine whether running a web request<section end="desc" />

$Web indicates whether the current processing is the result of a request to Janus Web Server.

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

Syntax

<section begin="syntax" />%rc = $Web <section end="syntax" />

Return codes

Code Meaning
0 Not running a web request.
1 Running a web request.

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.

    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 THEN %DISTRICT = $Web_Form_Parm('DISTRICT') ELSE %DISTRICT = %QUERY:DISTRICT END IF

  • $Web 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.