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/CdbBase/CdbStateControl.hh

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#ifndef CDB_STATE_CONTROL_HH
#define CDB_STATE_CONTROL_HH

#include "CdbBase/CdbCommon.hh"

/// The state control interface for the API classes
/**
  * This interface incorporates external controls for the API components,
  * whose instances maintain dynamic relaishionship with the corresponding
  * persistent entities.
  *
  * In the current design of the API only the following groups
  * of controls are defined:
  *
  * - the one providing opening, closing and enquiering the current state of
  *   a connection with the corresponding persistent entity.
  *
  * - the one providing the "validity" of an interface's instance. Here the idea
  *   is that at some point of time an API component may become "invalid" (which
  *   means non-usable in given context) even if this component was created
  *   "valid" at the beginning.
  *
  */
class CdbStateControl {

protected:

  /// The destructor.
  /**
    * Is only available for the derived classes and friends to prevent accidental
    * deletion of objects.
    */
    virtual ~CdbStateControl( );

public:

  /// Check if the current API context is valid.
  /**
    * The precise definition of the "valid" depends on an API component
    * implementing this interface. However the general assumption is that
    * it is "usable" to communicate with the corresponding persistent
    * counterpart.
    *
    * @return true if a component is valid
    */
    virtual bool isValid( ) = 0;

  /// Check if the current API component is open.
  /**
    * This flag makes a sense only if the database is "valid".
    * It's role is to indicate if the current API component has
    * established reliable and consistent communication with
    * the corresponding persistent entity.
    *
    * @return true if the component is open
    */
    virtual bool isOpen( ) = 0;

  /// Open the component.
  /**
    * This will connect the API component with the corresponding
    * persistent entity.
    *
    * @see CdbStatus
    *
    * @return the completion status
    */
    virtual CdbStatus open( ) = 0;

  /// Close the component.
  /**
    * Drop the open onnection with the corresponding persistent entity.
    *
    * @see CdbStatus
    *
    * @return the completion status
    */
    virtual CdbStatus close( ) = 0;
};

#endif  // CDB_STATE_CONTROL_HH

 

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Last Update: October 04, 2002