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ControlCommand » History » Version 2

Junxiao Shi, 01/23/2014 08:54 PM

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# NFD Control Command specification
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NFD management module exposes a command interface as Interest-Data exchange.
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Commands provided over this interface are useful for querying or changing the state of NFD forwarder.
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## Request format
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A request to the command interface is an Interest under `ndn:/localhost/nfd` prefix.
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A request Interest has at least four Name components.
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The first four components are:
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1. "localhost" in UTF-8
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2. "nfd" in UTF-8
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3. *verb*, the command verb in UTF-8
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4. *options*, the arguments to the command
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### Signed request and Unsigned request
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Most commands require a signature to be included in the Name.
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The signature format is defined in [[Signed Interests]] spec.
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A signed request Interest has seven Name components.
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Certain commands that do not change the forwarder state do not require a signature.
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An unsigned request Interest has four Name components.
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Each individual command specification defines whether a request Interest using that command verb should be signed or not.
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### Options
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The *option* component contains arguments to the command as a TLV.
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This component is required even if the command verb does not need any arguments.
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In that case, this component would have zero length.
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Each individual command specification defines the format of the options TLV.
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The TLV-TYPE numbers used in this TLV should be allocated from application range, and are not required to be unique across different command verbs.
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## Response format
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A response from the command interface is a Data that matches the request Interest.
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The payload in this Data should be a ControlCommandResponse element.
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    ControlResponse ::= CONTROL-RESPONSE-TYPE TLV-LENGTH
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                          StatusCode
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                          StatusText
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                          ...
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    StatusCode      ::= STATUS-CODE-TYPE TLV-LENGTH
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                          nonNegativeInteger
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    StatusText      ::= STATUS-TEXT TLV-LENGTH
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                          string in UTF-8
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**StatusCode** generally follows HTTP convention. Common codes include:
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StatusCode | Description
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-----------|------------------------
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200        | OK
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400        | Arguments are incorrect
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401        | Signed request is required for command, but unsigned request is passed
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403        | Signing key is not authorized for this command
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404        | Command verb is not supported
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Additional elements are allowed at the end of **ControlResponse**.
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Each individual command specification defines whether and what can present.
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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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StatusResponse                              | 130               | 0x82
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StatusCode                                  | 139               | 0x8b
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StatusText                                  | 140               | 0x8c