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eFaps is a framework used to map objects with or without attached files to a relational database and optional file systems (only for attaches files). Configurable access control can be provided down to object and attribute level depending on implementation and use case. Depending on requirements, events (like triggers) allow to implement business logic and to separate business logic from user interface. The framework includes integrations (e.g. webdav, full text search) and a web application as 'simple' configurable user interface. Some best practises, example web application modules (e.g. team work module) support administrators and implementers using this framework.

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/*
 * Copyright 2003 - 2012 The eFaps 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.
 *
 * Revision:        $Rev: 7483 $
 * Last Changed:    $Date: 2012-05-11 11:57:38 -0500 (Fri, 11 May 2012) $
 * Last Changed By: $Author: [email protected] $
 */

package org.efaps.db.store;

import java.io.InputStream;
import java.io.OutputStream;

import javax.transaction.xa.XAResource;

import org.efaps.db.Instance;
import org.efaps.util.EFapsException;

/**
 * Interface for the StoreResource used to archive files in eFaps.
 *
 * @author The eFaps Team
 * @version $Id: Resource.java 7483 2012-05-11 16:57:38Z [email protected] $
 */
public interface Resource
    extends XAResource
{
    /**
     * Store resource could implement the possibility to compress and uncompress
     * data while writing to and reading from files.
     */
    enum Compress
    {
        /** File should not be compressed.*/
        NONE,
        /** File should be compressed using zip.*/
        ZIP,
        /** File should  be compressed using gzip.*/
        GZIP
    };

    /**
     * The store resource could handle three different
     * events:
     * 
     * delete
     * write
     * read
     * 
     * These three events are defined here and set in instance variable
     * {@link #storeEvent}.
     */
    enum StoreEvent
    {
        /** delete. */
        DELETE,
        /** write. */
        WRITE,
        /** read. */
        READ,
        /** not known yet.    **/
        UNKNOWN;
    };

    /**
     * Method to open the Resource.
     *
     * @param _event Event the store is opened for
     * @throws EFapsException on error
     */
    void open(StoreEvent _event) throws EFapsException;

    /**
     * The input stream with the attached content of the object returned.
     *
     * @return input stream with the content of the file
     * @throws EFapsException if an error occurs
     */
    InputStream read() throws EFapsException;

    /**
     * Writes the file with the given input stream.
     *
     * @param _in       input stream
     * @param _size     size of the data to write (or negative if the size is
     *                  not known)
     * @param _fileName name of the file
     * @return length of the file which is stored
     * @throws EFapsException if an error occurs
     */
    long write(final InputStream _in,
               final long _size,
               final String _fileName)
        throws EFapsException;

    /**
     * Will delete the file.
     *
     * @throws EFapsException if an error occurs
     */
    void delete() throws EFapsException;

    /**
     * Method to commit the Resource.
     *
     * @throws EFapsException on error
     */
    void commit() throws EFapsException;

    /**
     * @return if the Resource was opened.
     */
    boolean isOpened();

    /**
     * Method to open the Resource.
     *
     * @throws EFapsException on error
     */
    void abort() throws EFapsException;

    /**
     * The output stream is written with the content of the file. From method
     * {@link #read()} the input stream is used and copied into the output
     * stream.
     *
     * @param _out    output stream where the file content must be written
     * @throws EFapsException if an error occurs
     */
    void read(final OutputStream _out) throws EFapsException;


    /**
     * Get the name of the file.
     * @return filename
     * @throws EFapsException on error
     */
    String getFileName() throws EFapsException;

    /**
     * Get the Length of the file in byte.
     * @return filelength
     * @throws EFapsException on error
     */
    Long getFileLength() throws EFapsException;

    /**
     * Method called to initialize this StoreResource.
     * @see org.efaps.db.store.Resource#initialize(org.efaps.db.Instance,
     *  java.util.Map, org.efaps.db.store.Resource.Compress)
     * @param _instance     Instance of the object this StoreResource is wanted
     *                      for
     * @param _store        Store this StoreResource belongs to
     * @throws EFapsException on error
     */
    void initialize(final Instance _instance,
                    final Store _store)
        throws EFapsException;
}