diff -r ea12a3bb4b33 -r 4ce38f21f4cd launcher/api/src/main/java/org/apidesign/bck2brwsr/launcher/InvocationContext.java
--- a/launcher/api/src/main/java/org/apidesign/bck2brwsr/launcher/InvocationContext.java	Tue Feb 24 11:12:53 2015 +0100
+++ b/launcher/api/src/main/java/org/apidesign/bck2brwsr/launcher/InvocationContext.java	Tue Jan 26 04:36:23 2016 +0100
@@ -19,7 +19,6 @@
 
 import java.io.IOException;
 import java.io.InputStream;
-import java.net.URI;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.CountDownLatch;
@@ -38,6 +37,7 @@
     private Throwable exception;
     String html;
     final List<Resource> resources = new ArrayList<>();
+    private int time;
 
     InvocationContext(Launcher launcher, Class<?> clazz, String methodName) {
         this.launcher = launcher;
@@ -65,11 +65,27 @@
     
     /** Invokes the associated method. 
      * @return the textual result of the invocation
+     * @throws java.io.IOException if execution fails
      */
     public String invoke() throws IOException {
         launcher.runMethod(this);
         return toString();
     }
+
+    /** Invokes the associated method.
+     * @param time one element array to store the length of the invocation
+     *    - can be <code>null</code>
+     * @return the textual result of the invocation
+     * @throws java.io.IOException if execution fails
+     * @since 0.20
+     */
+    public String invoke(int[] time) throws IOException {
+        launcher.runMethod(this);
+        if (time != null) {
+            time[0] = this.time;
+        }
+        return toString();
+    }
     
     /** Obtains textual result of the invocation.
      * @return text representing the exception or result value
@@ -90,7 +106,8 @@
         wait.await(timeOut, TimeUnit.MILLISECONDS);
     }
     
-    void result(String r, Throwable e) {
+    void result(String r, int time, Throwable e) {
+        this.time = time;
         this.result = r;
         this.exception = e;
         wait.countDown();