ControlCommand » History » Revision 7
Revision 6 (Alex Afanasyev, 01/30/2014 04:27 PM) → Revision 7/53 (Alex Afanasyev, 01/30/2014 04:48 PM)
# NFD Control Command specification
NFD management module exposes a command interface as Interest-Data exchange.
Commands provided over this interface are useful for querying or changing the state of NFD forwarder.
## Request format
A request to the command interface is an Interest under ``ndn:/localhost/nfd/<management-module>/...`` prefix.
A request Interest has at least four Name components.
The first four components are:
1. "localhost" in UTF-8
2. "nfd" in UTF-8
3. *management-module* in UTF-8, management module to which the command needs to be dispatched
4. *...*, the arguments to the command, defined for each management module in separate specifications:
- [[FibMgmt|FIB Management specification]]
- [[FaceMgmt|Face Management specification]]
### Signed request and Unsigned request
Most commands require a signature to be included in the Name.
The signature format is defined in [[Signed Interests]] spec.
A signed request Interest has seven Name components.
Certain commands that do not change the forwarder state do not require a signature.
An unsigned request Interest has four Name components.
Each individual command specification defines whether a request Interest using that command verb should be signed or not.
### Options
The *option* component contains arguments to the command as a TLV.
This component is required even if the command verb does not need any arguments.
In that case, this component would have zero length.
Each individual command specification defines the format of the options TLV.
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.
## Response format
A response from the command interface is a Data that matches the request Interest.
The payload in this Data should be a ControlCommandResponse element.
ControlResponse ::= CONTROL-RESPONSE-TYPE TLV-LENGTH
StatusCode
StatusText
<StatusBody>?
StatusCode ::= STATUS-CODE-TYPE TLV-LENGTH
nonNegativeInteger
StatusText ::= STATUS-TEXT TLV-LENGTH
string in UTF-8
<StatusBody> ::= <TLV block defined by the specific control protocol>
**StatusCode** generally follows HTTP convention. Common codes include:
StatusCode | Description
-----------|------------------------
200 | OK
400 | Arguments are incorrect
401 | Signed request is required for command, but unsigned request is passed
403 | Signing key is not authorized for this command
404 | Command verb is not supported
Additional elements are allowed at the end of **ControlResponse**.
Each individual command specification defines whether and what can present.
## TLV-TYPE assignments
(Types are assigned from the range reserved for forwarding daemon.)
Type | Assigned value | Assigned value (hex)
------------------------------------------- | ----------------- | --------------------
ControlResponse | 101 | 0x65
StatusCode | 102 | 0x66
StatusText | 103 | 0x67