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 * @brief Represents isolation level of the transaction.
  25 */
  26 enum IsolationLevel
  27 {
  28     READ_UNCOMMITTED = 1,
  29     READ_COMMITTED = 2,
  30     READ_REPEATABLE = 3,
  31     WRITE_OSYNC = 4 //this will work only from sqlapi
  32                     //for dbapi WRITE_OSYNC = READ_REPEATABLE
  33 };
  34
  35 /**
  36 * @class Connection
  37 *
  38 * @brief Represents a database connection.
  39 * All database operations shall be done within the context of the connection. <br>
  40 * Application should first create object of this class for accessing the database.<br/>
  41 * Each connection has only one active transaction at any given point of time, all <br/>
  42 * operations which happen using this connection object will be done as part of that <br/>
  43 * transaction.<br/>
  44 * <br/>
  45 * Functionality: <br/>
  46 *     1.Connection Management (connect and disconnect) <br/>
  47 *     2.Transaction Management (start, commit, abort) <br/>
  48 *     3.Provides getter methods for database manager and user manager <br/>
  49 * <br/>
  50 * TODO: <br/>
  51 * 1.Isolation Level support needs to be added. Currently it supports REPEATABLE READ <br/>
  52 *   isolation level as the default. It will soon support READ COMMITTED and <br/>
  53 *   READ UNCOMMITTED isolation levels<br/>
  54 * 2.AutoCommit mode<br/>
  55 * <br/>
  56 *  Note: <br/>
  57 *  SERIALIZABLE isolation level is not supported.
  58 * @author Prabakaran Thirumalai
  59 */
  60
  61 class Connection
  62 {
  63     Session *session;
  64     public:
  65     Connection() { session = NULL; }
  66     ~Connection();
  67
  68     /** opens connection to the database
  69     *   @param username username for authentication
  70     *   @param password password for authentication
  71     *   @return DbRetVal
  72     */
  73     DbRetVal open(const char*username, const char*password);
  74
  75
  76     /** closes connection to the database and releases all the resources
  77     *   @return DbRetVal
  78     */
  79     DbRetVal close();
  80
  81     /** gets the database manager object.
  82     *   @return DatabaseManager
  83     */
  84     DatabaseManager* getDatabaseManager();
  85
  86     /** gets the user manager object.
  87     *   @return UserManager
  88     */
  89     UserManager* getUserManager();
  90
  91     /** Starts a transaction.
  92     *   The previous transaction should be either committed or rollback <br/>
  93     *   before startTransaction is called. <br/>
  94     *   Application are required to start transaction before they attempt any <br>
  95     *   database operation.
  96     *   @return DbRetVal
  97     */
  98     DbRetVal startTransaction(IsolationLevel level = READ_COMMITTED);
  99
 100     /** Commits active transaction.
 101     *   It makes all the changes made in the current transaction permanent and <br/>
 102     *   it also releases the locks held by the current transaction.<br/>
 103     *   After a transaction commits, application is required to start another <br/>
 104     *   transaction for further database operations.
 105     *   @return DbRetVal
 106     */
 107     DbRetVal commit();
 108
 109     /** Aborts the active transaction.
 110     *   undo all the changes made in the current transaction and it also <br/>
 111     *   releases the locks held by the current transaction.<br/>
 112     *   After a transaction rollback, application is required to start another <br/>
 113     *   transaction for further database operations.
 114     *   @return DbRetVal
 115     */
 116     DbRetVal rollback();
 117 };
 118
 119
 120 class Session
 121 {
 122     public:
 123     virtual DbRetVal open(const char*username, const char*password)=0;
 124     virtual DbRetVal close()=0;
 125
 126     virtual DatabaseManager* getDatabaseManager()=0;
 127     virtual UserManager* getUserManager()=0;
 128
 129     virtual DbRetVal startTransaction(IsolationLevel level)=0;
 130     virtual DbRetVal commit()=0;
 131     virtual DbRetVal rollback()=0;
 132     //TODO:: virtual int setAutoCommit(bool flag)=0;
 133     //TODO::support for save points
 134     virtual ~Session() { }
 135
 136 };
 137
 138
 139
 140 #endif