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Revision 16 (Davide Pesavento, 03/04/2018 11:31 AM) → Revision 17/20 (Davide Pesavento, 03/06/2018 04:19 PM)
# Content Store Management
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**Content Store Management** is a module of [[Management|NFD Management protocol]].
It provides commands and datasets about the Content Store and its usage in forwarding.
Content Store Management commands and datasets are available under namespace `ndn:/localhost/nfd/cs`.
## Control Commands
[[ControlCommand]] **management-module**: `cs`
### Update configuration
**command-verb**: `config`
This command updates CS configuration.
To discover the current configuration, either retrieve the CS Information Dataset, or send an empty `config` command.
ControlParameters fields:
* Capacity (optional): maximum number of CS entries.
* Flags (optional): CS enablement flags (see below).
* Mask (optional): MUST be specified if *Flags* is present, and omitted if *Flags* is omitted.
*Flags* is the inclusive OR of the following CS enablement flags:
1=`CS_ENABLE_ADMIT`, enables the CS to admit new Data.
2=`CS_ENABLE_SERVE`, enables the CS to satisfy Interests using cached Data.
The initial value of *Flags* in NFD's CS is equivalent to `CS_ENABLE_ADMIT` | `CS_ENABLE_SERVE`.
If all fields are omitted, the command has no effect but is still considered successful.
If the command succeeds, \<Body> in ControlResponse block contains updated ControlParameters reflecting current configuration:
* Capacity (required)
* Flags (required)
Note to future protocol designers: when the CS is extended to have multiple storage tiers (such as RAM and SSD), ControlParameter shall have an optional *Name* field to indicate the storage tier being configured.
### Erase entries
**command-verb**: `erase`
This command erases entries from the CS.
ControlParameters fields:
* Name (required): name prefix to start erasing.
* Count NCsEntries (optional): maximum number of entries to erase, must not be zero; if omitted, indicates "no limit".
This command causes the forwarder to erase CS entries under the specified name prefix *Name*. The number of erased entries shall not exceed *Count*, *NCsEntries*, if specified. The forwarder is free to erase any entries under *Name*, and does not need to follow a particular order.
A forwarder MAY impose a non-zero upper bound on *Count*. *NCsEntries*. If *Count* *NCsEntries* in a request exceeds the upper bound (including when it is omitted, i.e. "no limit"), the forwarder acts as if *Count* *NCsEntries* was set to the upper bound.
If the command succeeds, \<Body> in ControlResponse block contains updated ControlParameters indicating the result:
* Name (required)
* Capacity (optional): upper bound of *Count*, *NCsEntries*, included only when *Count* *NCsEntries* in the request exceeds the upper bound AND there are more entries under *Name* after erasing.
* Count NCsEntries (required): actual number of erased entries.
If there are no CS entries under the specified name prefix, the command does nothing but is still considered successful.
## CS Information Dataset
The CS configuration and runtime performance are published as a [[StatusDataset|Status Dataset]] at `ndn:/localhost/nfd/cs/info`.
CsInfo ::= CS-INFO-TYPE TLV-LENGTH
Capacity
Flags
NCsEntries
NHits
NMisses
(TLVs have nonNegativeInteger as value)
Note to future protocol designers: in CsInfo element, fields that reflect configuration shall be placed before fields that reflect runtime counters.
Note to future protocol designers: when the CS is extended to have multiple storage tiers (such as RAM and SSD), each storage tier shall have separate counters, multiple CsInfo elements appear in the dataset and each has a *Name* field as the first child to indicate the storage tier.
## CS Enumeration
A subset of CS entries can be queried into a [[StatusDataset|Status Dataset]] under `ndn:/localhost/nfd/cs/query`.
CsQuery ::= CS-QUERY-TYPE TLV-LENGTH
Name
PacketSize
FreshnessPeriod
(TLVs have nonNegativeInteger as value)
## TLV-TYPE assignments
Type | Assigned number | Assigned number (hex)
------------------------------------------- | ----------------- | ---------------------
CsInfo | 128 | 0x80
Capacity | 131 | 0x83
Count | 132 | 0x84
Flags | 108 | 0x6c
NCsEntries | 135 | 0x87
NHits | 129 | 0x81
NMisses | 130 | 0x82