include/Session.h

   1 /***************************************************************************
   2  *   Copyright (C) 2007 by www.databasecache.com                           *
   3  *   Contact: praba_tuty@databasecache.com                                 *
   4  *                                                                         *
   5  *   This program is free software; you can redistribute it and/or modify  *
   6  *   it under the terms of the GNU General Public License as published by  *
   7  *   the Free Software Foundation; either version 2 of the License, or     *
   8  *   (at your option) any later version.                                   *
   9  *                                                                         *
  10  *   This program is distributed in the hope that it will be useful,       *
  11  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  13  *   GNU General Public License for more details.                          *
  14  *                                                                         *
  15   ***************************************************************************/
  16 #ifndef SESSION_H
  17 #define SESSION_H
  18 #include<DatabaseManager.h>
  19 #include<UserManager.h>
  20 #include<ErrorType.h>
  21 class Session;
  22
  23 enum IsolationLevel
  24 {
  25     READ_UNCOMMITTED,
  26     READ_COMMITTED,
  27     READ_REPEATABLE
  28 };
  29
  30 /**
  31 * @class Connection
  32 *
  33 * @brief Represents a database connection.
  34 * All database operations shall be done within the context of the connection. <br>
  35 * Application should first create object of this class for accessing the database.<br/>
  36 * Each connection has only one active transaction at any given point of time, all <br/>
  37 * operations which happen using this connection object will be done as part of that <br/>
  38 * transaction.<br/>
  39 * <br/>
  40 * Functionality: <br/>
  41 *     1.Connection Management (connect and disconnect) <br/>
  42 *     2.Transaction Management (start, commit, abort) <br/>
  43 *     3.Provides getter methods for database manager and user manager <br/>
  44 * <br/>
  45 * TODO: <br/>
  46 * 1.Isolation Level support needs to be added. Currently it supports REPEATABLE READ <br/>
  47 *   isolation level as the default. It will soon support READ COMMITTED and <br/>
  48 *   READ UNCOMMITTED isolation levels<br/>
  49 * 2.AutoCommit mode<br/>
  50 * <br/>
  51 *  Note: <br/>
  52 *  SERIALIZABLE isolation level is not supported.
  53 * @author Prabakaran Thirumalai
  54 */
  55
  56 class Connection
  57 {
  58     Session *session;
  59     public:
  60     Connection() { session = NULL; }
  61     ~Connection();
  62
  63     /** opens connection to the database
  64     *   @param username username for authentication
  65     *   @param password password for authentication
  66     *   @return DbRetVal
  67     */
  68     DbRetVal open(const char*username, const char*password);
  69
  70
  71     /** closes connection to the database and releases all the resources
  72     *   @return DbRetVal
  73     */
  74     DbRetVal close();
  75
  76     /** gets the database manager object.
  77     *   @return DatabaseManager
  78     */
  79     DatabaseManager* getDatabaseManager();
  80
  81     /** gets the user manager object.
  82     *   @return UserManager
  83     */
  84     UserManager* getUserManager();
  85
  86     /** Starts a transaction.
  87     *   The previous transaction should be either committed or rollback <br/>
  88     *   before startTransaction is called. <br/>
  89     *   Application are required to start transaction before they attempt any <br>
  90     *   database operation.
  91     *   @return DbRetVal
  92     */
  93     DbRetVal startTransaction(IsolationLevel level = READ_COMMITTED);
  94
  95     /** Commits active transaction.
  96     *   It makes all the changes made in the current transaction permanent and <br/>
  97     *   it also releases the locks held by the current transaction.<br/>
  98     *   After a transaction commits, application is required to start another <br/>
  99     *   transaction for further database operations.
 100     *   @return DbRetVal
 101     */
 102     DbRetVal commit();
 103
 104     /** Aborts the active transaction.
 105     *   undo all the changes made in the current transaction and it also <br/>
 106     *   releases the locks held by the current transaction.<br/>
 107     *   After a transaction rollback, application is required to start another <br/>
 108     *   transaction for further database operations.
 109     *   @return DbRetVal
 110     */
 111     DbRetVal rollback();
 112 };
 113
 114
 115 class Session
 116 {
 117     public:
 118     virtual DbRetVal open(const char*username, const char*password)=0;
 119     virtual DbRetVal close()=0;
 120
 121     virtual DatabaseManager* getDatabaseManager()=0;
 122     virtual UserManager* getUserManager()=0;
 123
 124     virtual DbRetVal startTransaction(IsolationLevel level)=0;
 125     virtual DbRetVal commit()=0;
 126     virtual DbRetVal rollback()=0;
 127     //TODO:: virtual int setAutoCommit(bool flag)=0;
 128     //TODO::support for save points
 129     virtual ~Session() { }
 130
 131 };
 132
 133 #endif