QueryEvaluator


1   /**
2    * MEDOR: Middleware Enabling Distributed Object Requests
3    *
4    * Copyright (C) 2001-2004 France Telecom R&D
5    * Contact: alexandre.lefebvre@rd.francetelecom.com
6    *
7    * This library is free software; you can redistribute it and/or
8    * modify it under the terms of the GNU Lesser General Public
9    * License as published by the Free Software Foundation; either
10   * version 2.1 of the License, or (at your option) any later version.
11   *
12   * This library is distributed in the hope that it will be useful,
13   * but WITHOUT ANY WARRANTY; without even the implied warranty of
14   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15   * Lesser General Public License for more details.
16   *
17   * You should have received a copy of the GNU Lesser General Public
18   * License along with this library; if not, write to the Free Software
19   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
20   *
21   * Initial developers: M. Alia, A. Lefebvre
22   */
23  
24  package org.objectweb.medor.eval.api;
25  
26  import org.objectweb.medor.api.EvaluationException;
27  import org.objectweb.medor.datasource.api.WrapperFactory;
28  import org.objectweb.medor.eval.prefetch.api.PrefetchBuffer;
29  import org.objectweb.medor.expression.api.ParameterOperand;
30  import org.objectweb.medor.query.api.QueryTree;
31  import org.objectweb.medor.tuple.api.TupleCollection;
32  
33  import java.util.Map  ;
34  
35  /**
36   * This interface represents the MEDOR evaluator. It permits to evaluate an
37   * evaluable (optimized) query Tree.
38   *
39   */
40  public interface QueryEvaluator {
41  
42      /**
43       * Launch the evaluation of a query.
44       * @param parameters is the array of query parameter (never null).
45       * @param ressources is a ConnectionResources containing associations between
46       * the DataStore names used in the QueryTree and the connection objects to
47       * use for the evaluation. It can be null.
48       * @param evalMDMap contains a map associating an EvaluationMetaData object
49       * to each of the query nodes of the query tree currently associated to the
50       * QueryEvaluator.
51       */
52      TupleCollection evaluate(ParameterOperand[] parameters,
53                               ConnectionResources ressources,
54                               Map   evalMDMap)
55              throws EvaluationException;
56      /**
57       * Launch the evaluation of a query. This method is able to prefetch data
58       * of the query in a prefetch buffer.
59       * @param parameters is the array of query parameter (Never null).
60       * @param ressources is a ConnectionResources containing associations between
61       * the DataStore names used in the QueryTree and the connection objects to
62       * use for the evaluation.It can be null.
63       * @param pb is the prefetch buffer which must be fill with query results.
64       * If this parameter is null then no data prefetching is done.
65       */
66      TupleCollection evaluate(ParameterOperand[] parameters,
67                               ConnectionResources ressources,
68                               PrefetchBuffer pb,
69                               Map   evalMDMap)
70              throws EvaluationException;
71  
72      ConnectionResources getRequiredConnectionResources();
73  
74      /**
75       * @return the cache size used in different node of the QueryNode tree.
76       */
77      long getCacheSize();
78  
79      /**
80       * @return the evaluable (optimized) query tree associated to the current
81       * QueryEvaluator.
82       */
83      QueryTree getQueryTree();
84  
85      /**
86       * Returns the associated WrapperFactory. This is used to be able to
87       * bind specific Wrappers to DataStore types.
88       * @return the associated WrapperFactory
89       */
90      WrapperFactory getWrapperFactory();
91  }
92
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags