View source for $Web Api

<span class="pageSubtitle">Determine whether web API is available</span>

This method was first avaliable in Model 204 7.8.

<var>$Web_APi</var> indicates whether the current processing is the result of a request to <var class="product">[[Janus Web Server]]</var>. The difference between $Web_Api and [[$Web]] is that the latter returns 0 on the [[Daemon class#Transactional_daemons|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.

<var>$Web_Api</var> takes no arguments and returns either a 0 or a 1.

==Syntax==
<p class="syntax"><span class="term">%rc</span> = $Web_Api
</p>

===Return codes===
<table class="syntaxTable">
<tr><th>Code</th>
<th>Meaning</th></tr>
<tr><th>0</th>
<td>Web API not available.</td></tr>
<tr><th>1</th>
<td>Web API available.</td></tr>
</table>

==Usage notes==
<ul>
<li>The <var>$Web</var> function is most useful for:
<ul>
<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>
<li>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]].</li>
</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:
<p class="code">if $web_api then
   %district = $web_form_parm('DISTRICT')
else
   %district = %query:district
end if
</p>

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

[[Category:Janus Web Server $functions]]