Repo Protocol Specification » History » Revision 30
Revision 29 (Shuo Chen, 02/21/2014 09:35 AM) → Revision 30/136 (Shuo Chen, 02/21/2014 03:48 PM)
Repo Protocol Specification
===========================
Repo is persistent storage of data objects model in NDN. The NDN repo protocol is a specification of repo operations including reading, insertion and deletion of data objects in repo.
Repo semantics is based on [Command Interests](http://redmine.named-data.net/projects/nfd/wiki/Command_Interests) with signed commponents an the end of the name and basic common semantics of NDN.
When some operation of repo including insertion and deletion of data objects is requested, a command interest is sent. The command interest is the interest as command of insertion and deletion and signed as form of command interest for access control. The repo will response the command with the data object.
The repo protocol can be categorized in three sections of reading, insertion and deletion of data objects.
## Repo Reading Specification
The repo could be viewed as the data container of the data objects. It will register some specific prefixes of data objects it holds into NFD (NDN Forwarding Deamon) and the repo will respond the data with such prefixes.
A standard interest is used to fetch content from the repo. The repo will respond when the name of the interest matches the prefix it registered in NFD. If the content in repo matches the interests, it will respond with the data object. When the interest is not matched, it will not respond.
The protocol is listed as bellow
If there is a matching data object:
Requester Repo
| |
| |
| Interest |
t1 |-------------------------->|
| |
| Data Object |
t2 |<==========================|
| |
| |
| |
If there is no matching data object:
Requester Repo
| |
| |
| Interest |
t1 |-------------------------->|
| |
| |
| |
## Repo Command
For insertion, deletion and other operations of repo, these commands are encoded in the form of [sigend command interest](http://redmine.named-data.net/projects/nfd/wiki/Command_Interests). The semantics of repo command interest is as follows:
The name semantics is defined to have following components:
* ``<name of repo>`` refers to specific name of repo
* ``<command verb>`` refers to the name of command
* ``<RepoCommandParameters>`` refers to parameters of repo command
The folloing components are components of singed interest for access control:
* ``<timestamp>``
* ``<random-value>``
* ``<SignatureInfo>``
* ``<SignatureValue>``
For name of the repo /ucla/cs/repo/, the command will be defined as this:
/ucla/cs/repo/<command verb>/<RepoCommandParameters>/<timestamp>/<random-value>/<SignatureInfo>/<SignatureValue>
### RepoCommandParameters
RepoCommandParameters ::= SEGMENTATIONINFO-TYPE TLV-LENGTH
Name?
StartBlockId?
EndBlockId?
Name ::= NAME-TYPE TLV-LENGTH NameComponent*
NameComponent ::= NAME-COMPONENT-TYPE TLV-LENGTH BYTE+
StartBlockId ::= STARTBLOCKID-TYPE TLV-LENGTH
nonNegativeInteger
EndBlockId ::= ENDBLOCKID-TYPE TLV-LENGTH
nonNegativeInteger
## Repo Command Response
Repo command response is the response data packet of repo command interest. The response contains statuscode to indicate the status of command process and other information. A TLV-encoded block called ``RepoCommandResponse`` is encoded in content of the data packet.
RepoCommandResponse ::= INSERTSTATUS-TYPE TLV-LENGTH
StatusCode?
StartBlockId?
EndBlockId?
InsertNum?
DeleteNum?
StatusCode ::= STATUSCODE-TYPE TLV-LENGTH
nonNegativeInteger
StartBlockId ::= STARTBLOCKID-TYPE TLV-LENGTH
nonNegativeInteger
EndBlockId ::= ENDBLOCKID-TYPE TLV-LENGTH
nonNegativeInteger
InsertNum ::= INSERTNUM-TYPE TLV-LENGTH
nonNegativeInteger
DeleteNum ::= DELETENUM-TYPE TLV-LENGTH
nonNegativeInteger
## Repo Insertion Specification
Insertion specification is for some client and application to insert data objects into certain NDN repo. A command interest as insertion command will be sent to the repo. This command interest is a signed interest and will be validated with access control policy defined by the repo. When the interested is validated and name of the data is not existed in the repo. The repository will reponse with a data object containing OK status and start to send the interest to fetch the data to insert.
Segmented data insertion is also supported in the insertion protocol. Segmantation info is defined as a TLV-encoded SegmantationInfo block. If the content is segmented, the final segment id will be encoded in this block.
### Insertion command interest semantics
The name semantics is follows defined to have following components:
* ``<name of repo>`` refers to specific name of repo
* ``<command verb>`` refers to the format command of the repo command.
* ``<RepoCommandParameters>`` refers to specific name of data that will be inserted
The <command verb> is defined as ``insert``. folloing components are components of singed interest for access control:
* ``<timestamp>``
* ``<random-value>``
* ``<SignatureInfo>``
* ``<SignatureValue>``
<name of repo> and <data name> can be divided by serveral continious ``/`` according to specific defination.
For example, for ``<name of repo>`` as ``/ucla/cs/repo``, ``/ucla/cs/repo`` and ``<data name>`` as ``/vedio/Forrest Gump``, the following data object is an example:
/ucla/cs/repo/insert/<RepoCommandParameters>/<timestamp>/<random-value>/<SignatureInfo>/<SignatureValue>
defined as following:
/ucla/cs/repo/insert/<RepoCommandParameters>/........................
### RepoInsertParameters
RepoCommandParameters ::= SEGMENTATIONINFO-TYPE TLV-LENGTH
Name?
StartBlockId?
EndBlockId?
Name ::= NAME-TYPE TLV-LENGTH NameComponent*
NameComponent ::= NAME-COMPONENT-TYPE TLV-LENGTH BYTE+
StartBlockId ::= STARTBLOCKID-TYPE TLV-LENGTH
nonNegativeInteger
EndBlockId ::= ENDBLOCKID-TYPE TLV-LENGTH
nonNegativeInteger
### Insertion status check
During the insertion progress, the requester could send insertion status check command to check the status of the insertion progress. This status check command is also signed interest. The semantics of insertion status check command is shown as follows:
<command verb> equals The name semantics is defined to have following components:
* ``<name of repo>`` refers to specific name of repo
* ``insert check``. For example:
/ucla/cs/repo/insert check/<RepoCommandParameters>/<timestamp>/<random-value>/<SignatureInfo>/<SignatureValue>
check`` refers to insert data objects
* ``<insert option>`` refers to insert options
* ``<data name>`` refers to specific name of data that will be inserted
The folloing components are components of singed interest for access control:
* ``<timestamp>``
* ``<random-value>``
* ``<SignatureInfo>``
* ``<SignatureValue>``
### Insertatation status response
This insert status data object could be the response data object of both insert command and insert check command. It will follow The name of data packet is the same as that of command. The insertion status is enocoded as a TLV echoded block in content block in data packet. The TLV block format of repo command response. is as follows:
InsertStatus ::= INSERTSTATUS-TYPE TLV-LENGTH
StatusCode?
StartBlockId?
EndBlockId?
InsertNum?
StatusCode ::= STATUSCODE-TYPE TLV-LENGTH
nonNegativeInteger
StartBlockId ::= STARTBLOCKID-TYPE TLV-LENGTH
nonNegativeInteger
EndBlockId ::= ENDBLOCKID-TYPE TLV-LENGTH
nonNegativeInteger
InsertNum ::= INSERTNUM-TYPE TLV-LENGTH
nonNegativeInteger
StatusCode indicates the status of insertion. InsertNum represents how many data has been intersted into the repo. StartBlockId and EndBlockId is the start and end segment id of data inserted. InsertNum is the how many data segments have been inserted.
For insert cammand, status code will be set according to definition below, StartBlockId and EndBlockId will be set according to the insert command.
For insert check command, status code will be set according to definition below, StartBlockId and EndBlockId will be set according to the insert command, insertnum will be set according to insertion progress.
StatusCode Definition:
``StatusCode`` | Description
-------------- | ----------------------------------------------
``100`` | The command is OK. can start to fetch the data
``200`` | All the data has been inserted
``300`` | This insertion is in progress
``401`` | This insertion check is invalidated
``404`` | No such this insertion is in progress
``505`` | status check command is not supported
### Protocol Process
1. start to authorize the command; if authorization does not fail immediately, go to step 3
2. send a negative response indicating authorization failure, and abort these steps
3. if both StartBlockId and EndBlockId are missing, go to step 6
4. if both StartBlockId and EndBlockId are present, and StartBlockId is less than or equal to EndBlockId, go to step 6
5. send a negative response indicating malformed command, and abort these steps
6. wait for authorization completion
7. if authorization fails, go to step 2
8. send a positive response indicating insert is in progress
9. if both StartBlockId and EndBlockId are present, go to step 15
10. start to retrieve Name
11. wait for retrieval completion
12. if retrieval fails, abort these steps
13. store retrieved Data packet
14. abort these steps
15. append StartBlockId to Name
16. start to retrieve Name
17. wait for retrieval completion
18. if retrieval fails, abort these steps
19. store retrieved Data packet
20. if retrieved Data packet contains FinalBlockId, and FinalBlockId is less than EndBlockId, let EndBlockId be FinalBlockId
21. if the last component of Name is greater than or equal to EndBlockId, abort these steps
22. increment the last component of Name
23. go to step 16
Implementation MAY pipeline the Interests.
### Repo command progress report
Implementation MAY publish a notification of status regarding insert progress. The process of status check is as follows:
1. start to authorize the insert status command
2. send a negative response indicating authorization failure, and abort these steps
3. start to check the progress of the insert with the data name in the command. If no such progress is found, go to 4. or go to 5.
4. reponse status with status code of 404
5. ckeck te status of insertion. return the status data content
### Protocol diagram:
Requester Repo Data producer
| | |
| | |
+---+ Insert command +---+ |
| | --------------------> | | |
+---+ | | |
| | | |
+---+ Confirm start | | |
| | <==================== | | |
+---+ Reject command +---+ |
| (with status code) | |
| +---+ Interest for Data +---+
| | | --------------------------> | |
| +---+ | |
| | | |
| +---+ Data segment | |
| | | <========================== | |
| +---+ +---+
| | |
| ~ ~
| ~ ~
| | |
| +---+ Interest for Data +---+
| | | --------------------------> | |
| +---+ | |
| | | |
| +---+ Data segment | |
| | | <========================== | |
| +---+ +---+
| | |
| | |
| ~ ~
| ~ ~
| | |
| | |
| | |
+---+ Status interest +---+ |
| | --------------------> | | |
+---+ | | |
| | | |
+---+ Status response | | |
| | <==================== | | |
+---+ +---+ |
| | |
| | |
## Repo Deletion Specification
Deletion of one content object or content objects under certain prefix are both supported in repo specification. Selectors are used to select multiple content objects. These selectors are different from conventional [selectors](http://named-data.net/doc/ndn-tlv/interest.html#selectors) of interest packet. The conventional selecors of interest would select one data packet of repo. Selecors of delete command will return any data packets which applies for these selectors.
### Deletion command interest semantics
Deletion command The name semantics is defined to have following components:
* ``<name of repo>`` refers to specific name of repo
* ``delete`` refers to insert data objects
* ``<data name>`` refers to specific name of data that will be inserted
The folloing components are components of singed interest follows the format for access control:
* ``<timestamp>``
* ``<random-value>``
* ``<SignatureInfo>``
* ``<SignatureValue>``
<name of repo> and <data name> can be divided by serveral continious ``/`` according to specific defination.
For example, for ``<name of repo>`` as ``/ucla/cs/repo`` and ``<data name>`` as ``/vedio/Forrest Gump``, the repo command. For example: data object is defined as following:
/ucla/cs/repo/delete/<RepoCommandParameters>/<timestamp>/<random-value>/<SignatureInfo>/<SignatureValue> /ucla/cs/repo/delete/vedio/Forrest Gump/<timestamp>/<random-value>/<SignatureInfo>/<SignatureValue>
### Deletion Command Selectors
Selectors ::= SELECTORS-TYPE TLV-LENGTH
MinSuffixComponents?
MaxSuffixComponents?
PublisherPublicKeyLocator?
Exclude?
MinSuffixComponents ::= MIN-SUFFIX-COMPONENTS-TYPE TLV-LENGTH
nonNegativeInteger
MaxSuffixComponents ::= MAX-SUFFIX-COMPONENTS-TYPE TLV-LENGTH
nonNegativeInteger
PublisherPublicKeyLocator ::= KeyLocator
Exclude ::= EXCLUDE-TYPE TLV-LENGTH Any? (NameComponent (Any)?)+
Any ::= ANY-TYPE TLV-LENGTH(=0)
The definitions of delete command selectors is the same as the selectors of conventional [selectors](http://named-data.net/doc/ndn-tlv/interest.html#selectors). The difference is that this delete command selectors will return any data packets that comforms to the selectors. If selectors are not presented, the repo will just delete the data of exact name. So, for example, if somebody wants to delete all the data under certain prefix, at least, MinSuffixComponents should be set to 0.
### Deletion status check
During the deletion progress, the requester could send deletion status check command to check the status of the deletion progress. This status check command is also signed interest. The semantics of deletion status check command follows the format is shown as follows:
The name semantics is defined to have following components:
* ``<name of repo>`` refers to specific name of repo command. ``<command verb>`` equals
* ``delete check`` refers to ``delete check``. For example:
/ucla/cs/repo/delete/<RepoCommandParameters>/<timestamp>/<random-value>/<SignatureInfo>/<SignatureValue>
insert data objects
* ``<data name>`` refers to specific name of data that will be inserted
The folloing components are components of singed interest for access control:
* ``<timestamp>``
* ``<random-value>``
* ``<SignatureInfo>``
* ``<SignatureValue>``
### Deletion status response
This delete status data object could be the response data packet of both delete command and delete check command. The name of data packet is the same as that of command.The deletion status is enocoded as a TLV echoded block in content block in data packet. The TLV block format follows RepoCommandResponse. is as follows:
DeleteStatus ::= DELETESTATUS-TYPE TLV-LENGTH
StatusCode?
DeleteSum?
DeleteNum?
StatusCode ::= STATUSCODE-TYPE TLV-LENGTH
nonNegativeInteger
DeleteSum ::= INSERTNUM-TYPE TLV-LENGTH
nonNegativeInteger
DeleteNum ::= INSERTNUM-TYPE TLV-LENGTH
nonNegativeInteger
StatusCode indicates the status of deletion. DeleteSum is the sum of the deletion. DeleteNum represents how many data has been deleted.
StatusCode Definition:
``StatusCode`` | Description
-------------- | --------------------------------------
``200`` | All the data has been deleted
``300`` | This deletion is in progress
``401`` | This deletion check is invalidated
``404`` | No such this deletion is in progress
``505`` | status check command is not supported
### Protocol process
1. start to authorize the command; if authorization does not fail immediately, go to step 3
2. send a negative response indicating authorization failure, and abort these steps
3. check whether selectors are presented. If selectors are presented, go to step 4, or select the data packet of the exact name of command. If some data is selected, go to step 6. If no data selected, go to step 5
4. select all the data packets that comforms to data name of the command and the selectors. If some data packets are selected, go to step 6. Or no data selected, go to step 5.
5. send a negative response and abort the delete transaction.
6. wait for authorization completion
7. if authorization fails, go to step 2
8. start to delete the selected data. If deletion success, return positive reponse, or return negative response and abort the deletion.
Implementation MAY publish a notification of status regarding delete progress. The process of status check is as follows:
1. start to authorize the delete status command
2. send a negative response indicating authorization failure, and abort these steps
3. start to check the progress of the delete with the data name in the command. If no such progress is found, go to 4. or go to 5.
4. reponse status with status code of 404
5. ckeck te status of delete. return the status data content
### Protocol diagram:
Requester Repo
| |
| |
+---+ Delete command +---+
| | --------------------> | |
+---+ +---+
| |
| |
| |
+---+ Status interest +---+
| | --------------------> | |
+---+ | |
| | |
+---+ Status response | |
| | <==================== | |
+---+ +---+
| |
| |
| |
+---+ Confirm Deletion +---+
| | <==================== | |
+---+ Reject command +---+
| (with status code) |
| |