NonWordDataHandler.java

/***
 * Copyright 2002-2010 jamod development team
 *
 * Licensed 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 net.wimpi.modbus.io;

import java.io.DataInput;
import java.io.EOFException;
import java.io.IOException;

/**
 * Interface implementing a non word data handler for the
 * read/write multiple register commands (class 0).
 *
 * @author Dieter Wimberger
 * @version @version@ (@date@)
 */
public interface NonWordDataHandler {

    /**
     * Returns the intermediate raw non-word data.
     *
     * @return the raw data as <tt>byte[]</tt>.
     */
    public byte[] getData();

    /**
     * Reads the non-word raw data based on an arbitrary
     * implemented structure.
     *
     * @param in the <tt>DataInput</tt> to read from.
     * @param reference to specify the offset as <tt>int</tt>.
     * @param count to sepcify the amount of bytes as <tt>int</tt>.
     *
     * @throws IOException if I/O fails.
     * @throws EOFException if the stream ends before all data is read.
     */
    public void readData(DataInput in, int reference, int count) throws IOException, EOFException;

    /**
     * Returns the word count of the data.
     * Note that this should be the length of the byte
     * array divided by two.
     *
     * @return the number of words the data consists of.
     */
    public int getWordCount();

    /**
     * Commits the data if it has been read into an intermediate
     * repository.
     * This method is called by a <tt>WriteMultipleRegistersRequest</tt>
     * instance when finished with reading, for creating a response.
     *
     * @return -1 if the commit was successful, a Modbus exception code
     *         valid for the read/write multiple registers commands
     *         otherwise.
     */
    public int commitUpdate();

    /**
     * Prepares the raw data, putting it together from a
     * backing data store.
     * This method is called by a <tt>ReadMultipleRegistersRequest</tt>
     * instance when finshed with reading, for creating a response.
     *
     * @param reference to specify the offset as <tt>int</tt>.
     * @param count to sepcify the amount of bytes as <tt>int</tt>.
     */
    public void prepareData(int reference, int count);

}// NonWordDataHandler