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<title>WaitFor Task</title>
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<h2>Waitfor</h2>
<h3>Description</h3>
<p>Blocks execution until a set of specified conditions become true. This is intended to be used
with the <a href="parallel.html">parallel</a> task to synchronize a set of processes.</p>
<p>The conditions to wait for are defined in <a href="waitfor.html#nested">nested elements</a>, if
multiple conditions are specified, then the task will wait until all conditions are true.</p>
<p>If both <var>maxwait</var> and <var>maxwaitunit</var> are not specified,
default <var>maxwait</var> is 3 minutes (180000 milliseconds).</p>
<p>If the <var>timeoutproperty</var> attribute has been set, a property of that name will be created
if the condition didn't come true within the specified time.</p>
<h3>Parameters</h3>
<table class="attr">
  <tr>
    <th>Attribute</th>
    <th>Description</th>
    <th>Required</th>
  </tr>
  <tr>
    <td>maxwait</td>
    <td>The maximum amount of time to wait for all the required conditions to become true before
      failing the task.</td>
    <td>No; defaults to 180000 <var>maxwaitunit</var>s</td>
  </tr>
  <tr>
    <td>maxwaitunit</td>
    <td>The unit of time that must be used to interpret the value of the <var>maxwait</var>
      attribute.  Valid values are
      <ul>
        <li><q>millisecond</q></li>
        <li><q>second</q></li>
        <li><q>minute</q></li>
        <li><q>hour</q></li>
        <li><q>day</q></li>
        <li><q>week</q></li>
      </ul>
    </td>
    <td>No; defaults to <q>millisecond</q></td>
  </tr>
  <tr>
    <td>checkevery</td>
    <td>The amount of time to wait between each test of the conditions.</td>
    <td>No; defaults to 500 <var>checkeveryunit</var>s</td>
  </tr>
  <tr>
    <td>checkeveryunit</td>
    <td>The unit of time that must be used to interpret the value of the <var>checkevery</var>
      attribute.  Valid values are
      <ul>
        <li><q>millisecond</q></li>
        <li><q>second</q></li>
        <li><q>minute</q></li>
        <li><q>hour</q></li>
        <li><q>day</q></li>
        <li><q>week</q></li>
      </ul>
    </td>
    <td>No; defaults to <q>millisecond</q></td>
  </tr>
  <tr>
    <td>timeoutproperty</td>
    <td>the name of the property to set if <var>maxwait</var> has been exceeded.</td>
    <td>No</td>
  </tr>
</table>

<h3 id="nested">Parameters specified as nested elements</h3>
<p>The available conditions that satisfy the <code>&lt;waitfor&gt;</code> task are the same as those
for the <a href="condition.html"><code>&lt;condition&gt;</code></a>
task. See <a href="conditions.html">here</a> for the full list.</p>

<h3>Examples</h3>
<pre>
&lt;waitfor maxwait="30" maxwaitunit="second"&gt;
    &lt;available file="errors.log"/&gt;
&lt;/waitfor&gt;</pre>
<p>waits up to 30 seconds for a file called <samp>errors.log</samp> to appear.</p>
<pre>
&lt;waitfor maxwait="3" maxwaitunit="minute" checkevery="500"&gt;
    &lt;http url="http://localhost/myapp/index.html"/&gt;
&lt;/waitfor&gt;</pre>
<p>waits up to 3 minutes (and checks every 500 milliseconds) for a web server
on <samp>localhost</samp> to serve up the specified URL.</p>
<pre>
&lt;waitfor maxwait="10" maxwaitunit="second"&gt;
    &lt;and&gt;
        &lt;socket server="dbserver" port="1521"/&gt;
        &lt;http url="http://webserver/mypage.html"/&gt;
    &lt;/and&gt;
&lt;/waitfor&gt;</pre>
<p>waits up to 10 seconds for a server on the <samp>dbserver</samp> machine to begin listening on
port 1521 and for the <samp>http://webserver/mypage.html</samp> web page to become available.</p>

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