001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements. See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache license, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License. You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the license for the specific language governing permissions and
015     * limitations under the license.
016     */
017    package org.apache.logging.log4j.nosql.appender;
018    
019    import java.io.Closeable;
020    
021    /**
022     * Represents a connection to the NoSQL database. Serves as a factory for new (empty) objects and an endpoint for
023     * inserted objects.
024     *
025     * @param <T> Specifies which implementation of {@link NoSqlObject} this connection provides.
026     * @param <W> Specifies which type of database object is wrapped by the {@link NoSqlObject} implementation provided.
027     */
028    public interface NoSqlConnection<W, T extends NoSqlObject<W>> extends Closeable {
029        /**
030         * Instantiates and returns a {@link NoSqlObject} instance whose properties can be configured before ultimate
031         * insertion via {@link #insertObject(NoSqlObject)}.
032         *
033         * @return a new object.
034         * @see NoSqlObject
035         */
036        T createObject();
037    
038        /**
039         * Creates an array of the specified length typed to match the {@link NoSqlObject} implementation appropriate for
040         * this provider.
041         *
042         * @param length the length of the array to create.
043         * @return a new array.
044         * @see NoSqlObject
045         */
046        T[] createList(int length);
047    
048        /**
049         * Inserts the given object into the underlying NoSQL database.
050         *
051         * @param object The object to insert.
052         */
053        void insertObject(NoSqlObject<W> object);
054    
055        /**
056         * Closes the underlying connection. This method call should be idempotent. Only the first call should have any
057         * effect; all further calls should be ignored. It's possible the underlying connection is stateless (such as an
058         * HTTP web service), in which case this method would be a no-op. This method should also commit any open
059         * transactions, if applicable and if not already committed.
060         * <p>
061         * If this connection is part of a connection pool, executing this method should commit the transaction and return
062         * the connection to the pool, but it should not actually close the underlying connection.
063         * </p>
064         */
065        @Override
066        void close();
067    
068        /**
069         * Indicates whether the underlying connection is closed. If the underlying connection is stateless (such as an
070         * HTTP web service), this method would likely always return true. Essentially, this method should only return
071         * {@code true} if a call to {@link #insertObject(NoSqlObject)} <b>will</b> fail due to the state of this object.
072         *
073         * @return {@code true} if this object is considered closed.
074         */
075        boolean isClosed();
076    }