$Web: Difference between revisions
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<span class="pageSubtitle">Determine whether running a web request</span> | <span class="pageSubtitle">Determine whether running a web request</span> | ||
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<li>The <var>$Web</var> function is most useful for: | <li>The <var>$Web</var> function is most useful for: | ||
<ul> | <ul> | ||
<li>Preventing code that should only be run for a web request from running for 3270 (or other non-web) requests. | <li>Preventing code that should only be run for a web request from running for 3270 (or other non-web) requests.</li> | ||
<li>Ensuring that non-web, possibly 3270 specific code, is not run for web requests. | <li>Ensuring that non-web, possibly 3270 specific code, is not run for web requests.</li> | ||
<li>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]].</li> | |||
</ul> | </ul> | ||
In the example below, the variable %DISTRICT is set from a form field when running a web request and from a screen field otherwise: | In the example below, the variable %DISTRICT is set from a form field when running a web request and from a screen field otherwise: | ||
<p class="code"> | <p class="code">if $web then | ||
% | %district = $web_form_parm('DISTRICT') | ||
else | |||
% | %district = %query:district | ||
end if | |||
</p> | </p> | ||
Latest revision as of 19:34, 20 January 2020
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.