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StrategyChoice » History » Version 13

Davide Pesavento, 02/09/2018 02:31 PM

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# Strategy Choice Management
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{{>toc}}
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**Strategy Choice Management** is a module of [[Management|NFD Management protocol]].
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It provides:
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* commands to choose the forwarding strategy for a namespace
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* a dataset of strategy choices
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Strategy Choice Management commands and datasets are available under namespace `ndn:/localhost/nfd/strategy-choice`.
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## Strategies
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A strategy is identified by a name.
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NFD currently supports the following strategies:
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* ndn:/localhost/nfd/strategy/best-route
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* ndn:/localhost/nfd/strategy/broadcast
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* ndn:/localhost/nfd/strategy/client-control
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* ndn:/localhost/nfd/strategy/ncc
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* ndn:/localhost/nfd/strategy/access
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* ndn:/localhost/nfd/strategy/asf
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Each strategy listed above may have one or more versions. Strategy version is increased when there is a major behavior change; bugfixes usually won't bump strategy version. The version component is appended to the strategy name.
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A strategy may accept parameters name components. Parameters are always optional. They may be appended to the strategy name after the version component. Whether a strategy accepts parameters and the syntax and semantics of the parameters are defined by each strategy.
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## Control Commands
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[[ControlCommand]] **management-module**: `strategy-choice`
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### Set the strategy for a namespace
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**command-verb**: `set`
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ControlParameters fields:
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* Name (required)
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* Strategy (required)
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**Name** is the name prefix on which the strategy is selected.
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NFD MAY impose a limit on the length of name prefix. The current limit is 32 name components.
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If Name exceeds this limit, the command fails with code 414.
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**Strategy** must be a Name that identifies a strategy.
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It could be either an unversioned name to instantiate the latest version of a strategy, or a versioned name to instantiate a specific version. If the chosen strategy accepts parameters, they may be appended after a versioned name.
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If **Strategy** does not match any registered strategy, the command fails with code 404.
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In case of an error during strategy initiation (such as unacceptable parameter), the command fails with code 409.
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If the command succeeds, \<Body> in ControlResponse block contains updated ControlParameters:
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* Name: unchanged
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* Strategy: strategy instance name, which always contains a version component and may contain parameters name components
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### Unset the strategy for a namespace
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**command-verb**: `unset`
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ControlParameters fields:
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* Name (required)
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After this operation, the effective strategy at **Name** is inherited from the parent.  
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If there is no strategy defined at **Name**, this command does nothing, but is still considered successful.
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**Name** must not be `ndn:/`, otherwise the command fails with code 400.
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## Strategy Choice Dataset
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Strategy choices for namespaces are published as a [[StatusDataset|Status Dataset]] at `ndn:/localhost/nfd/strategy-choice/list`.
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Each choice is represented by a **StrategyChoice** block:
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    StrategyChoice := STRATEGY-CHOICE-TYPE TLV-LENGTH
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                        Name
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                        Strategy
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* **Name** is the namespace on which a strategy is chosen.
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* **Strategy** is the strategy chosen for this namespace.
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## TLV-TYPE assignments
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Type                                        | Assigned value    | Assigned value (hex)
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------------------------------------------- | ----------------- | --------------------
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StrategyChoice                              | 128               | 0x80