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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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Base class for managers of different parts of the system
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Managers are responsible for a certain aspect of the sytem. It is a logical
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grouping of code relating to a portion of the system. In general other
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components should be using the manager to make changes to the components that
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it is responsible for.
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For example, other components that need to deal with volumes in some way,
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should do so by calling methods on the VolumeManager instead of directly
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changing fields in the database. This allows us to keep all of the code
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relating to volumes in the same place.
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We have adopted a basic strategy of Smart managers and dumb data, which means
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rather than attaching methods to data objects, components should call manager
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methods that act on the data.
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Methods on managers that can be executed locally should be called directly. If
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a particular method must execute on a remote host, this should be done via rpc
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to the service that wraps the manager
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Managers should be responsible for most of the db access, and
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non-implementation specific data. Anything implementation specific that can't
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be generalized should be done by the Driver.
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In general, we prefer to have one manager with multiple drivers for different
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implementations, but sometimes it makes sense to have multiple managers. You
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can think of it this way: Abstract different overall strategies at the manager
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level(FlatNetwork vs VlanNetwork), and different implementations at the driver
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level(LinuxNetDriver vs CiscoNetDriver).
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Managers will often provide methods for initial setup of a host or periodic
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tasksto a wrapping service.
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This module provides Manager, a base class for managers.
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from nova import utils
added
removed
nova/manager.py
