How are .do files used in JSP for passing data between Java and front end web forms outside of the Struts framework?
<p>I am using JSP with an Apache Tomcat server for a web project.</p>

<p>I do not understand <code>.do</code> files or how they are used, but <a href="https://stackoverflow.com/questions/20555816/how-to-call-user-input-from-jsp-file-into-java-file">I see them come up</a> in answers describing how to do things I need to do.</p>

<p>My understanding thusfar is this:</p>

<ol>
<li>The Struts framework uses <code>.do</code> files, so many people think of these in relation to one another</li>
<li><code>.do</code> files are described in the <a href="http://wiki.apache.org/tomcat/Specifications" rel="noreferrer">Java Servlet Specification</a> and are thus not specific to Struts</li>
<li>At least one major use case of <code>.do</code> files (which I'm interested in) is for easily passing data between HTML/JS forms and Java/JSP.</li>
</ol>

<p>If I create a form such as the one in the first answer I linked:</p>

<pre><code>  &lt;form action="MyServlet.do" method="post"&gt;
      &lt;input type="text" name="nameThree" value="Enter a Name" onClick="if(this.value == 'Enter a Name'){this.value = '';}" /&gt; 
      &lt;input type="submit"&gt;
  &lt;/form&gt; 
</code></pre>

<p>It will throw a 404 error, unless I create the <code>.do</code> file it mentions. Once that <code>.do</code> file is created the code runs, but does not appear to do anything because of some missing piece.</p>

<p>I'm not sure if the <code>.do</code> file is supposed to be empty or if I am supposed to put code in it, etc, etc.</p>

<p>Thus my question is:  <strong><em>Outside of the context of the Struts framework, how are .do files used in JSP for passing data between Java and front end web forms?</em></strong></p>