How to make an ANT build load a URL resource inside a waitfor task

Question

I am working on an ANT target for running tests, but I need to have the app server up and running before the tests start, so I'm using the "waitFor" task to ping a URL until it gets a response. This works great except that I need to not only make sure the URL is simply accessible, but also check that a particular status string is present. This second requirement is simple enough on its own with tasks like get or telnet and then doing a substring search, but the waitfor task doesn't accept any nested elements other than the standard ANT conditions or thing they can wrap (basically things that return booleans). I have tried loading the URL as a resource prior to the waitfor task and the using a resourceconatins condition within, but I found that it just caches the URL's response and doesn't refresh with the lastest response from the app server. Does anyone know of a way to force the URL to be loaded on each loop or some other way to achieve this?

Here is essentially what I want to achieve in pseudo-code:

<waitfor>
    <and>
        <!-- make sure the URL is accessible at all -->
        <http url="theurl.jsp"/>

        <!-- load the URL as a resource and make sure it contains a substring -->
        <!-- moving the "url" task before the waitfor works if all conditions are met the first time through, but does not refresh the URL if it has to loop over again. having it inside like this, fails because waitfor/and don't support nexted "url" tasks -->
        <url id="url.resource" url="url.jsp"/>
        <resourcecontains refid="url.resource" substring="status"/>
    </and>
    <!-- else, keep on trying until timeout -->
</waitfor>
<!-- continue on to the tests to be run -->

Answer 1

You can probably achieve the effect you're after using a scriptcondition element in waitfor.

I don't have an example to hand - but you can write a script that performs the get and string match, then embed it in waitfor instead of using url or resourcecontains.

See also the script task to determine how to use scriptcondition.

Answer 2

Usage:

   <typedef
      name="httpcontains"
      classname="HttpContains"
   />

  <waitfor maxwait="10" maxwaitunit="minute" checkevery="500">
    <httpcontains contains="Running" url="http://myurl"/&gt;
  </waitfor>

Code below allows for this:

import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.ProjectComponent;
import org.apache.tools.ant.taskdefs.condition.Condition;

/**
 * Condition to wait for a HTTP request to succeed. Its attribute(s) are:
 *   url - the URL of the request.
 *   errorsBeginAt - number at which errors begin at; default=400.
 * @since Ant 1.5
 */
public class HttpContains extends ProjectComponent implements Condition {
    private String spec = null;
    private String contains = null;
    /**
     * Set the url attribute
     *
     * @param url the url of the request
     */
    public void setUrl(String url) {
        spec = url;
    }

    public void setContains(String s){
       contains = s;
    }

    private int errorsBeginAt = 400;

    /**
     * Set the errorsBeginAt attribute
     *
     * @param errorsBeginAt number at which errors begin at, default is
     *                      400
     */
    public void setErrorsBeginAt(int errorsBeginAt) {
        this.errorsBeginAt = errorsBeginAt;
    }

    /**
     * @return true if the HTTP request succeeds
     * @exception BuildException if an error occurs
     */
    public boolean eval() throws BuildException {
        if (spec == null) {
            throw new BuildException("No url specified in http condition");
        }
        log("Checking for " + spec, Project.MSG_VERBOSE);
        try {
            URL url = new URL(spec);
            try {
                URLConnection conn = url.openConnection();
                if (conn instanceof HttpURLConnection) {
                    HttpURLConnection http = (HttpURLConnection) conn;
                    int code = http.getResponseCode();
                    log("Result code for " + spec + " was " + code,
                        Project.MSG_VERBOSE);
                    if (code > 0 && code < errorsBeginAt) 
                    {
                       if ( evalContents(url) )
                          return true;
                       else
                          return false;

                    } else {
                        return false;
                    }
                }
            } catch (java.io.IOException e) {
                return false;
            }
        } catch (MalformedURLException e) {
            throw new BuildException("Badly formed URL: " + spec, e);
        }
        return true;
    }

    public boolean evalContents(URL mUrl )
    {
       try
       {

          String contents;

          StringBuffer buffer = new StringBuffer();
          byte[] buf = new byte[1024];
          int amount = 0;
          InputStream input = mUrl.openStream();

          while ((amount = input.read(buf)) > 0) 
          {   
             buffer.append(new String(buf, 0, amount));
          }
          input.close();
          contents = buffer.toString();

          log("Result code for " + contents,
                Project.MSG_VERBOSE);

          if ( contents.indexOf(contains) > -1 )
          {

             log("Result code for " + contents.indexOf(contains),
                   Project.MSG_VERBOSE);
             return true;

          }






          return false;
       }
       catch ( Exception e )
       {
          e.printStackTrace();
          log("Result code for " + e.toString(),
                Project.MSG_VERBOSE);

          return false;
       }
    }
}