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diff --git a/src/main/java/org/apache/commons/math3/ode/sampling/StepHandler.java b/src/main/java/org/apache/commons/math3/ode/sampling/StepHandler.java
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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.commons.math3.ode.sampling;
+
+import org.apache.commons.math3.exception.MaxCountExceededException;
+
+
+/**
+ * This interface represents a handler that should be called after
+ * each successful step.
+ *
+ * <p>The ODE integrators compute the evolution of the state vector at
+ * some grid points that depend on their own internal algorithm. Once
+ * they have found a new grid point (possibly after having computed
+ * several evaluation of the derivative at intermediate points), they
+ * provide it to objects implementing this interface. These objects
+ * typically either ignore the intermediate steps and wait for the
+ * last one, store the points in an ephemeris, or forward them to
+ * specialized processing or output methods.</p>
+ *
+ * @see org.apache.commons.math3.ode.FirstOrderIntegrator
+ * @see org.apache.commons.math3.ode.SecondOrderIntegrator
+ * @see StepInterpolator
+ * @since 1.2
+ */
+
+public interface StepHandler {
+
+    /** Initialize step handler at the start of an ODE integration.
+     * <p>
+     * This method is called once at the start of the integration. It
+     * may be used by the step handler to initialize some internal data
+     * if needed.
+     * </p>
+     * @param t0 start value of the independent <i>time</i> variable
+     * @param y0 array containing the start value of the state vector
+     * @param t target time for the integration
+     */
+    void init(double t0, double[] y0, double t);
+
+    /**
+     * Handle the last accepted step
+     * @param interpolator interpolator for the last accepted step. For
+     * efficiency purposes, the various integrators reuse the same
+     * object on each call, so if the instance wants to keep it across
+     * all calls (for example to provide at the end of the integration a
+     * continuous model valid throughout the integration range, as the
+     * {@link org.apache.commons.math3.ode.ContinuousOutputModel
+     * ContinuousOutputModel} class does), it should build a local copy
+     * using the clone method of the interpolator and store this copy.
+     * Keeping only a reference to the interpolator and reusing it will
+     * result in unpredictable behavior (potentially crashing the application).
+     * @param isLast true if the step is the last one
+     * @exception MaxCountExceededException if the interpolator throws one because
+     * the number of functions evaluations is exceeded
+     */
+    void handleStep(StepInterpolator interpolator, boolean isLast)
+        throws MaxCountExceededException;
+
+}