$Web

From m204wiki
Jump to: navigation, search

Determine whether running a web request

$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

%rc = $Web

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.
    • Under Model 204 7.8 and later, transactional daemon descendants of a web thread can also access the web API. However, $Web returns 0 on these threads. To check if the web API is available regardless of the thread type use $Web_Api.

    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.