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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements. See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache license, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License. You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the license for the specific language governing permissions and
15   * limitations under the license.
16   */
17  package org.apache.logging.log4j.core.appender.db.nosql;
18  
19  import java.io.Closeable;
20  
21  /**
22   * Represents a connection to the NoSQL database. Serves as a factory for new (empty) objects and an endpoint for
23   * inserted objects.
24   * 
25   * @param <T> Specifies which implementation of {@link NoSQLObject} this connection provides.
26   * @param <W> Specifies which type of database object is wrapped by the {@link NoSQLObject} implementation provided.
27   */
28  public interface NoSQLConnection<W, T extends NoSQLObject<W>> extends Closeable {
29      /**
30       * Instantiates and returns a {@link NoSQLObject} instance whose properties can be configured before ultimate
31       * insertion via {@link #insertObject(NoSQLObject)}.
32       *
33       * @return a new object.
34       * @see NoSQLObject
35       */
36      T createObject();
37  
38      /**
39       * Creates an array of the specified length typed to match the {@link NoSQLObject} implementation appropriate for
40       * this provider.
41       *
42       * @param length the length of the array to create.
43       * @return a new array.
44       * @see NoSQLObject
45       */
46      T[] createList(int length);
47  
48      /**
49       * Inserts the given object into the underlying NoSQL database.
50       *
51       * @param object The object to insert.
52       */
53      void insertObject(NoSQLObject<W> object);
54  
55      /**
56       * Closes the underlying connection. This method call should be idempotent. Only the first call should have any
57       * effect; all further calls should be ignored. It's possible the underlying connection is stateless (such as an
58       * HTTP web service), in which case this method would be a no-op.
59       */
60      @Override
61      void close();
62  
63      /**
64       * Indicates whether the underlying connection is closed. If the underlying connection is stateless (such as an
65       * HTTP web service), this method would likely always return true. Essentially, this method should only return
66       * {@code true} if a call to {@link #insertObject(NoSQLObject)} <b>will</b> fail due to the state of this object.
67       *
68       * @return {@link true} if this object is considered closed.
69       */
70      boolean isClosed();
71  }