Issue 12430: Dynamic configuration of components                                                                                                                                                                     (qos4ccm-rtf)
Source: THALES (Mr. Olivier Hachet, olivier.hachet2@fr.thalesgroup.com)
Nature: Uncategorized Issue
Severity: 
Summary: Dynamic configuration of components :
In the Scope section of QoS4CCM specification, the following is mentionned: 
"Dynamic configuration and re-configuration is also an essential point of
distributed systems, because in order to adapt an application to a specific
execution environment, one has to be aware that the QoS of the execution
environment evolves during execution. There is a strong need to be able to
make on-the-fly adaptation. That is why it is very important to provide an
architecture, mechanisms, and monitoring concepts that allow dynamic
adaptation of a running application, explicitly by an administrator, but
also automatically. The specification addresses this problem domain in the
context of the CORBA Component Model (CCM) [CCM]."


For example reading/writing component's attributes or installing or
uninstalling non-functional properties is necessary. This issue propose to
address this topic which is not concretly resolved in the current
specification. 


To achieve this goal, a small evolution is needed.  The existing CCM
specification allows some application specific means like home user defined
operations or 'configurator' setting but such mechanisms don't work without
respectively using home finder or dynamic invocations. The necessity to
develop applications that can dynamically reconfigure components and get
knowledge of component configuration in a generic way, bring us to consider
a new configuration mechanism at runtime to facilitate dynamic adaptation of
running application.
We propose to add configuration ability with access of special
'configurator' implementation using component's home interface. We also
propose to improve StandardConfigurator to get component configuration.This
will allow to configure easily non-functional properties at run-time.

Resolution: If the component is created dynamically, or configured at runtime, the QoS value needs to be configured either via application specific means or by using configurator. Sections are added to support dynamic adaptation of a running application. This implies the modification of the CCM interface StandardConfigurator to be able to retrieve configuration values. HomeConfiguration interface is also modified to be able to retrieve a configurator.
Revised Text: ·	The section 6.1 is modified to support dynamic configuration elements:
6.1 Changes to Adopted OMG Specifications
...
·	Extension of the context interface to retrieve reference to container services.
·	Extension of the StandardConfigurator interface to get component configuration.
·	Extension of the HomeConfiguration interface to retrieve reference to Configurator.
...

·	The section 7.1 is modified to support dynamic configuration elements:
7.1 Scope of QoS Properties
...
If a QoS property is bound to a component or connection instance, its actual scope depends on their lifetime. If a component instance is already declared during the assembly and never deleted until application shutdown, its lifetime - and that of the QoS property as well - is identical with that of the application. In this case, the value of the QoS property may be configured during the deployment and configuration phase. However, if the component is created dynamically or configured at runtime, the QoS value needs to be configured either via application specific means or by using configurator. The latter mechanism is modified by this specification, see section 8.11, "Dynamic adaptation of a running application" for details.
...

·	The following sections are added to the specification:
8.12 Dynamic adaptation of a running application
In a most general way, the QoSEnabler life cycle may need to be managed over the component life cycle. This means that creation, deletion and configuration of QoSEnabler have to be done independently of corresponding component means. Container vendor are free to exploit CCM capacities to add specific operations for QoSEnabler configuration, however configuration at run-time may become constraining :
·	client may have to manage QoSEnabler owned by components with heterogeneous configuration  interface.
·	client implementation may be generic code and not be aware about specific component definition.
·	client  in an embedded environment may not be allowed to use CORBA dynamic capacities.
To help container vendors to implement standard and homogeneous dynamic configuration mechanisms the StandardConfigurator and the HomeConfiguration definition has been extended.
8.12.1 Modification of StandardConfigurator interface
module Components {
  interface StandardConfigurator : Configurator 
  { 
    void set_configuration (in ConfigValues descr);
    /* QoS4CCM */
    ConfigValues get_configuration( in CCMObject comp ) 
                                  raises (WrongComponentType);

  };
};

8.12.1.1 get_configuration
This operation returns a sequence of ConfigValue instances containing the configuration of the target component. If the target component is not of the type expected by the configurator, the get_configuration operation shall raise the WrongComponentType exception.

8.12.2 Modification of HomeConfiguration interface
module Components {
  interface HomeConfiguration : CCMHome {
    void set_configurator ( in Configurator cfg); 
    /* QoS4CCM */
    Configurator get_configurator();
    void set_configuration_values ( in ConfigValues config); 
    void complete_component_configuration (in boolean b); 
    void disable_home_configuration(); 
  };
};


8.12.2.1 get_configurator
This operation returns a Configurator reference to the standard configurator that manages this home. This one may be able to process particular configuration values and to call specific user interface of component and component's home.

Actions taken:
May 7, 2008: received issue
Discussion: 

End of Annotations:=====

m: olivier.hachet2@fr.thalesgroup.com
To: qos4ccm-rtf@omg.org
Cc: issues@omg.org
Subject: QoS4CCM issue
Date: Wed, 7 May 2008 16:51:17 +0200 
X-Mailer: Internet Mail Service (5.5.2655.55)


Hello RTF members,


Please find here a new issue:


Dynamic configuration of components :
In the Scope section of QoS4CCM specification, the following is mentionned: 
"Dynamic configuration and re-configuration is also an essential point of
distributed systems, because in order to adapt an application to a specific
execution environment, one has to be aware that the QoS of the execution
environment evolves during execution. There is a strong need to be able to
make on-the-fly adaptation. That is why it is very important to provide an
architecture, mechanisms, and monitoring concepts that allow dynamic
adaptation of a running application, explicitly by an administrator, but
also automatically. The specification addresses this problem domain in the
context of the CORBA Component Model (CCM) [CCM]."


For example reading/writing component's attributes or installing or
uninstalling non-functional properties is necessary. This issue propose to
address this topic which is not concretly resolved in the current
specification. 


To achieve this goal, a small evolution is needed.  The existing CCM
specification allows some application specific means like home user defined
operations or 'configurator' setting but such mechanisms don't work without
respectively using home finder or dynamic invocations. The necessity to
develop applications that can dynamically reconfigure components and get
knowledge of component configuration in a generic way, bring us to consider
a new configuration mechanism at runtime to facilitate dynamic adaptation of
running application.
We propose to add configuration ability with access of special
'configurator' implementation using component's home interface. We also
propose to improve StandardConfigurator to get component configuration.This
will allow to configure easily non-functional properties at run-time.



best regards,


Olivier
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Olivier HACHET      
THALES Communications DLJ/FR/OPS-F/SAT/SC2
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