GD32F450_BMC_BaseCode/app/goahead-3.6.5/doc/contents/users/goactions.html

{
    title:  'GoActions',
    crumbs: [
        { "User's Guide": '../users/' },
    ],
}
            <h1>GoActions</h1>
            <p>The traditional Common Gateway Interface (CGI) is a slow technique for creating dynamic web pages
            because CGI processing results in the creation of a new process for every request. This is slow and cumbersome.
            GoAhead provides a high-performance replacement called GoActions&trade; that is a more suitable solution 
            for embedded systems that demand compact and efficient solutions.</p>
            <p>GoActions are "C" language functions that are directly bound to specific URIs. They respond to client
            requests without creating a new process for each request. By sharing the address space with GoAhead, GoActions
            can directly access the full request context. GoActions are serviced by the <i>action</i> handler.</p>
            <h2>Defining GoActions</h2>
            <p>GoActions are defined by the 
            <i><a href="../ref/api/goahead.html#group___webs_1gabadb35ad9084ca79783d0a63437d4959">websDefineAction</a></i> API.
            For example:</p>
<pre class="ui code segment">
static void buy(Webs *wp)
{
    websSetStatus(wp, 200);
    websWriteHeaders(wp, 0, 0);
    websWriteEndHeaders(wp);
    websWrite(wp, "Name %s", websGetVar(wp, "name", "")); 
    websWrite(wp,  "Age %s", websGetVar(wp, "age", ""));
    websDone(wp);
}
<b>websDefineAction("buy", buy);</b>
</pre>
            <h2>Calling GoActions</h2>
            <p>GoActions are bound to URIs that begin with <i>/action/</i>. 
            When a client requests a URI <i>/action/NAME</i>, the action handler is invoked which then
            looks for a GoAction by NAME. The function bound to NAME is then is invoked to service the request. For
            example:</p>
            <pre class="ui code segment">
/action/buy?name=John&amp;item=candy           
</pre>
            <p>This will invoke the GoAction <i>buy</i> which will run the bound C function. The action handler will
            automatically decode the query string "name=John&amp;age=30" and define GoAhead variables called "name" and "age".</p>
            <p>The GoAction is responsible for writing the HTTP header and HTML document content back to the user's
            browser.</p>