Project

General

Profile

Repo Protocol Specification » History » Version 128

Shuo Chen, 07/15/2014 11:32 PM

1 1 Shuo Chen
Repo Protocol Specification
2
===========================
3
4 36 Shuo Chen
A Repo supports the network by preserving content and responding to Interests requesting content that it holds. A Repo can exist in any node, and is recommended if applications in that node need to preserve data. The NDN repo protocol is a specification of repo operations including reading, insertion and deletion of data objects in repo.
5 2 Shuo Chen
6
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. 
7
8 11 Shuo Chen
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.
9 4 Shuo Chen
10
The repo protocol can be categorized in three sections of reading, insertion and deletion of data objects.
11
12
## Repo Reading Specification
13
14 36 Shuo Chen
Repo registers prefixes of data objects it holds into NDN fowarding deamon and the repo will respond the data with such prefixes.
15 6 Shuo Chen
16 11 Shuo Chen
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.
17 6 Shuo Chen
18
The protocol is listed as bellow
19
20
If there is a matching data object:
21
22 7 Shuo Chen
    Requester                     Repo
23
        |                           |
24
        |                           |
25
        |         Interest          |
26
     t1 |-------------------------->|
27
        |                           |
28
        |        Data Object        |
29
     t2 |<==========================|
30 1 Shuo Chen
        |                           |
31 7 Shuo Chen
        |                           |
32 1 Shuo Chen
        |                           |
33 7 Shuo Chen
34
If there is no matching data object:
35 6 Shuo Chen
36
    Requester                     Repo
37
        |                           |
38 1 Shuo Chen
        |                           |
39 7 Shuo Chen
        |         Interest          |
40
     t1 |-------------------------->|
41
        |                           |
42
        |                           |
43
        |                           |
44
45 74 Shuo Chen
46
### About Freshness
47
48
Solution to handle freshness by repo has not been clearly defined, so producer needs to take care of freshness when it puts things into repo, i.e. explicitly delete obsolete content. The mustbefresh selector will be ignored by repo when fetching content from repo or handling repo command by repo.
49
50 30 Shuo Chen
## Repo Command
51
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:
52 14 Shuo Chen
53 8 Shuo Chen
The name semantics is defined to have following components:
54 1 Shuo Chen
55 75 Shuo Chen
* ``<repo prefix>`` refers to specific prefix repo is listening
56 30 Shuo Chen
* ``<command verb>`` refers to the name of command
57 91 Shuo Chen
* ``<RepoCommandParameter>`` refers to parameters of repo command
58 1 Shuo Chen
59 38 Shuo Chen
The following components are components of singed interest for access control:
60 1 Shuo Chen
61
* ``<timestamp>``
62 8 Shuo Chen
* ``<random-value>``
63
* ``<SignatureInfo>``
64
* ``<SignatureValue>``
65
66 75 Shuo Chen
For prefix of repo /ucla/cs/repo/, the command will be defined as this:
67 33 Shuo Chen
68 91 Shuo Chen
    /ucla/cs/repo/<command verb>/<RepoCommandParameter>/<timestamp>/<random-value>/<SignatureInfo>/<SignatureValue>
69 14 Shuo Chen
70 91 Shuo Chen
### RepoCommandParameter
71 29 Shuo Chen
72 91 Shuo Chen
    RepoCommandParameter ::= REPOCOMMANDPARAMETER-TYPE TLV-LENGTH
73 118 Shuo Chen
                               Name?
74 42 Shuo Chen
                               Selectors?
75 1 Shuo Chen
                               StartBlockId?
76
                               EndBlockId?
77 62 Shuo Chen
                               ProcessId?
78 29 Shuo Chen
79 48 Shuo Chen
    Name                  ::= NAME-TYPE TLV-LENGTH NameComponent*
80
    NameComponent         ::= NAME-COMPONENT-TYPE TLV-LENGTH BYTE+
81 43 Shuo Chen
82
    Selectors             ::= SELECTORS-TYPE TLV-LENGTH
83
                               MinSuffixComponents?
84
                               MaxSuffixComponents?
85
                               PublisherPublicKeyLocator?
86
                               Exclude?
87 47 Shuo Chen
                               ChildSelector?
88 43 Shuo Chen
89
    MinSuffixComponents   ::= MIN-SUFFIX-COMPONENTS-TYPE TLV-LENGTH
90
                               nonNegativeInteger
91
92
    MaxSuffixComponents   ::= MAX-SUFFIX-COMPONENTS-TYPE TLV-LENGTH
93
                               nonNegativeInteger
94
95
    PublisherPublicKeyLocator ::= KeyLocator
96
97
    Exclude               ::= EXCLUDE-TYPE TLV-LENGTH Any? (NameComponent (Any)?)+
98
    Any                   ::= ANY-TYPE TLV-LENGTH(=0)
99 47 Shuo Chen
100
    ChildSelector         ::= CHILD-SELECTOR-TYPE TLV-LENGTH
101
                               nonNegativeInteger
102 1 Shuo Chen
    
103
    StartBlockId          ::= STARTBLOCKID-TYPE TLV-LENGTH
104 49 Shuo Chen
                               nonNegativeInteger
105 1 Shuo Chen
    
106
    EndBlockId            ::= ENDBLOCKID-TYPE TLV-LENGTH
107 49 Shuo Chen
                               nonNegativeInteger
108 1 Shuo Chen
109 62 Shuo Chen
    ProcessId            ::= PROCESSID-TYPE TLV-LENGTH
110
                               nonNegativeInteger
111
112 44 Shuo Chen
#### Repo Command Selectors
113 38 Shuo Chen
114 52 Shuo Chen
Repo command supports parts of interest selectors of interest to indicate which contents to process. The definition of standard NDN selectors is described in [NDN Selectors Doc](http://named-data.net/doc/ndn-tlv/interest.html#selectors). The concrete definitions of both standard NDN selectors and repo command selectors are the same.
115
116
The difference between standard NDN interest and Repo Deletion Command interest that, the standard NDN selectors just matches **one** data packet that conforms to the selector conditions, but repo command selectors would matches **any** data packets. For example, if Interest is expressed for /ndn/edu and Exclude specifies one name component ucla, in standard NDN interest, the data producers will first exclude all the data packets with prefix /ndn/edu but not /ndn/edu/ucla, and then just selects one data packet. In repo deletion command interest, it will select all the data packets with prefix /ndn/edu but not /ndn/edu/ucla. However, in repo insert command, the repo will fetch one data just like standard interest selectors.
117 38 Shuo Chen
118 124 Shuo Chen
Repo command supports parts of standard NDN interests including MinSuffixComponents, MaxSuffixComponents, PublisherPublicKeyLocator, and Exclude. ChildSelector is supported in insertion command but not deletion command. If command contains other selectors, repo will ignore these not supported selectors. In addition, selectors are just supported in delete command. If other commands contains selectors, repo will ignore selectors when processing these commands.
119 38 Shuo Chen
120
The form of selectors is as follows:
121
122
    Selectors             ::= SELECTORS-TYPE TLV-LENGTH
123
                               MinSuffixComponents?
124
                               MaxSuffixComponents?
125
                               PublisherPublicKeyLocator?
126 1 Shuo Chen
                               Exclude?
127 51 Shuo Chen
                               ChildSelector?
128 38 Shuo Chen
    
129
    MinSuffixComponents   ::= MIN-SUFFIX-COMPONENTS-TYPE TLV-LENGTH
130
                               nonNegativeInteger
131
132
    MaxSuffixComponents   ::= MAX-SUFFIX-COMPONENTS-TYPE TLV-LENGTH
133
                               nonNegativeInteger
134
135
    PublisherPublicKeyLocator ::= KeyLocator
136
    
137
    Exclude               ::= EXCLUDE-TYPE TLV-LENGTH Any? (NameComponent (Any)?)+
138 1 Shuo Chen
    Any                   ::= ANY-TYPE TLV-LENGTH(=0)
139 51 Shuo Chen
140
    ChildSelector         ::= CHILD-SELECTOR-TYPE TLV-LENGTH
141
                               nonNegativeInteger
142 46 Shuo Chen
143
#### StartBlockId, EndBlockId
144 38 Shuo Chen
145 54 Shuo Chen
StartBlockId and EndBlockId are used to process segmented data. StartBlockId indicate the first segment number and EndBlockId indicate the last segment number. Repo will process segment data whose segment id between StartBlockId and EndBlockId. If StartBlockId is missing, the first segment id the repo process is 0; If EndBlockId is missing, this scenario is described in specific process in Repo Insertion Command section and Repo Deletion Command section.
146 62 Shuo Chen
147 68 Shuo Chen
#### Conflict of Selectors and StartBlockId, EndBlockId
148 67 Shuo Chen
149 91 Shuo Chen
Repo cannot process command with both selectors and StartBlockId, EndBlockId in RepoCommandParameter. If the RepoCommandParameter carries both, repo will ignore this command interest and return with error code of 405.
150 67 Shuo Chen
151 62 Shuo Chen
#### ProcessId
152 53 Shuo Chen
153 63 Shuo Chen
ProcessId is used by insertion and deletion check command to indicate specific insertion and deletion process. The ProcessId is fetched by repo command response of insertion and deletion command.
154
155 30 Shuo Chen
## Repo Command Response
156 1 Shuo Chen
157 30 Shuo Chen
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.
158 1 Shuo Chen
159 30 Shuo Chen
    RepoCommandResponse   ::= INSERTSTATUS-TYPE TLV-LENGTH
160 61 Shuo Chen
                               ProcessId?
161 117 Shuo Chen
                               StatusCode
162 1 Shuo Chen
                               StartBlockId?
163
                               EndBlockId?
164
                               InsertNum?
165 117 Shuo Chen
                               DeleteNum?
166 1 Shuo Chen
167 61 Shuo Chen
    ProcessId            ::= PROCESSID-TYPE TLV-LENGTH
168 55 Shuo Chen
                                nonNegativeInteger 
169
    
170 1 Shuo Chen
    StatusCode            ::= STATUSCODE-TYPE TLV-LENGTH
171
                                nonNegativeInteger    
172
173
    StartBlockId          ::= STARTBLOCKID-TYPE TLV-LENGTH
174
                                nonNegativeInteger
175
    
176
    EndBlockId            ::= ENDBLOCKID-TYPE TLV-LENGTH
177
                                nonNegativeInteger
178 17 Shuo Chen
179
    InsertNum             ::= INSERTNUM-TYPE TLV-LENGTH
180
                                nonNegativeInteger
181
182 30 Shuo Chen
    DeleteNum             ::= DELETENUM-TYPE TLV-LENGTH
183
                                nonNegativeInteger
184 17 Shuo Chen
185 113 Shuo Chen
### Name
186
Name indicates the Name in repocommandparameter of repo command
187
188
189 61 Shuo Chen
### ProcessId
190
ProcessId is a random number generated by repo to indicate the number of the command process. Client could use this ProcessId to check the status of specific command.
191 59 Shuo Chen
192
### StatusCode
193
194 64 Shuo Chen
StatusCode indicates the status of repo command process. The statuscodes of insert and deletion command are described in following insertion and deletion specification.
195
196 59 Shuo Chen
### StartBlockId, EndBlockId
197
198 65 Shuo Chen
StartBlockId and EndBlockId are the same as those of RepoCommandParameter. If either of those in RepoCommandParameter is missing, repo will set them as the Id known for now. For example, if StartBlockId is missing in RepoCommandParameter, StartBlockId in response will be set 0. If EndBlockId is missing in RepoCommandParameter, EndBlockId will be set null untill Repo get FinalBlockId in data packet. If FinalBlockId in returned data packet is less than EndBlockId, the EndBlockId will be set FinalBlockId.
199
200 59 Shuo Chen
### InsertNum, DeleteNum
201 66 Shuo Chen
InsertNum is used in reponse of insertion status check to indicate how many data packets have been successfully inserted into the repo. DeleteNum is used in response of deletion command and deletion check command. DeleteNum indicates how many data packets have been successfully inserted from repo.
202 59 Shuo Chen
203 119 Shuo Chen
## Repo TLV Type Encoding Number
204 120 Shuo Chen
205
Type                  | Number
206
----------------------| -------
207
RepoCommandParameter  | 201
208
StartBlockId          | 204
209
EndBlockId            | 205
210
ProcessId             | 206
211
RepoCommandResponse   | 207
212
StatusCode            | 208
213
InsertNum             | 209
214
DeleteNum             | 210
215 119 Shuo Chen
216 58 Shuo Chen
## Repo Trust Model
217 57 Shuo Chen
218
The trust model of repo depends on people who deploy the repo service, such as PKI. Repo can specify their own verification policies, and data consumers can specify their own trust anchors. The NDN [FAQ](http://named-data.net/project/faq/#How_does_NDN8217s_8220trust_management8221_work) shows how NDN trust managment works.
219
220 30 Shuo Chen
## Repo Insertion Specification
221
222 69 Shuo Chen
Repo insertion command requests that the repo retrieve and store content. 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.
223 30 Shuo Chen
224 121 Shuo Chen
Segmented data insertion is also supported in the insertion protocol. Segmantation info is defined in RepoCommandParameter. If the content is segmented, the final segment id will be encoded in this block.
225 30 Shuo Chen
226
### Insertion command interest semantics
227
228 122 Shuo Chen
The name semantics follows the format of the repo command. The <command verb> is defined as ``insert``.
229 76 Shuo Chen
For example, for ``<repo prefix>`` as ``/ucla/cs/repo``, the following is an example:
230 1 Shuo Chen
231 92 Shuo Chen
    /ucla/cs/repo/insert/<RepoCommandParameter>/<timestamp>/<random-value>/<SignatureInfo>/<SignatureValue>
232 30 Shuo Chen
233
### Insertion status check
234
235
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:
236
237
<command verb> equals to ``insert check``. For example:
238 1 Shuo Chen
239 93 Shuo Chen
    /ucla/cs/repo/insert check/<RepoCommandParameter>/<timestamp>/<random-value>/<SignatureInfo>/<SignatureValue>
240 69 Shuo Chen
241
### RepoCommandParameter
242
243 70 Shuo Chen
RepoCommandParameter of insertion and insertion check command follows that in Repo Command section. Name, Selectors, StartBlockId, EndBlockId are used in insertion. Name and ProcessId are used in insertion check command.
244 69 Shuo Chen
245 70 Shuo Chen
In insertion command, Name represents the name or prefix of data for repo to fetch. If selectors are set, repo will use these selectors to fetch the data. If StartBlockId or EndBlockId is set, the repo will retrieve segmented data with segment number between StartBlockId and EndBlockId. If Repo Insert Command carries both Selectors and StartBlockId, EndBlockId, repo would ignore it and response with statuscode of 405.
246
247
In insertion check command, Name represents name or prefix of data for repo to fetch. ProcessId is set by the RepoCommandResponse to indicate specified process.
248 30 Shuo Chen
249
### Insertatation status response
250
251
This insert status data object could be the response data object of both insert command and insert check command. It will follow the format of repo command response.
252
253 77 Shuo Chen
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. ProcessId indicates an ID of process, a random number gernerated by repo.
254 30 Shuo Chen
255 77 Shuo Chen
For insert cammand, status code will be set according to definition below, StartBlockId and EndBlockId will be set according to the insert command. If StartBlockId in RepoCommandParameter is missing, it will be set 0 in response. If EndBlockId is missing, it will not be set.
256 30 Shuo Chen
257 77 Shuo Chen
For insert check command, status code will be set according to definition below, StartBlockId and EndBlockId will be set according to the StartBlockId and EndBlockId that repo is using, insertnum will be set according to insertion progress. ProcessId is set according to the ID of process checked. If EndBlockId has not been decided, this EndBlockId will not be set in response.
258 30 Shuo Chen
259 1 Shuo Chen
StatusCode Definition:
260 17 Shuo Chen
261
``StatusCode`` | Description
262
-------------- | ----------------------------------------------
263 19 Shuo Chen
``100``        | The command is OK. can start to fetch the data
264
``200``        | All the data has been inserted
265 17 Shuo Chen
``300``        | This insertion is in progress
266 102 Shuo Chen
``401``        | This insertion command or insertion check command is invalidated
267
``402``        | Selectors and BlockId both present
268 105 Shuo Chen
``403``        | Malformed Command
269 17 Shuo Chen
``404``        | No such this insertion is in progress
270 102 Shuo Chen
``405``        | EndBlockId Missing Timeout
271 17 Shuo Chen
272 83 Shuo Chen
### EndBlockId Missing Timeout
273
274
If StartBlockId presents but EndBlockId is missing, and returned data packets do not contain FinalBlockId, the repo will continuosly fetch the data. An EndBlockId missing timeout is set to prevent this ocassion. The repo will start a timer when StartBlockId presents but EndBlockId is missing. When timeout happens, repo will stop fetching data to store and end insert process. If an insert check command arrives during this insert process, the time of timer is set to 0. If data packet containing FinalBlockId arrives, this timeout timer will be dismissed.
275
276 22 Alex Afanasyev
### Protocol Process
277
278 20 Alex Afanasyev
1. start to authorize the command; if authorization does not fail immediately, go to step 3
279 17 Shuo Chen
280 107 Shuo Chen
2. send a negative response indicating authorization failure, and abort these steps, insert process ends (StatusCode: 401)
281 14 Shuo Chen
282 100 Shuo Chen
3. if  both StartBlockId and EndBlockId are missing, go to step 7
283 14 Shuo Chen
284 109 Shuo Chen
4. if either StartBlockId or EndBlockId is present, and one of supported selectors is present. send negative reponse back and abort steps, insert process ends (StatusCode: 402)
285 14 Shuo Chen
286 78 Shuo Chen
5. if both StartBlockId and EndBlockId are present, and StartBlockId is less than or equal to EndBlockId, go to step 7
287 14 Shuo Chen
288 107 Shuo Chen
6. send a negative response indicating malformed command, and abort these steps, insert process ends (StatusCode: 403)
289 14 Shuo Chen
290 78 Shuo Chen
7. wait for authorization completion
291 14 Shuo Chen
292 107 Shuo Chen
8. if authorization fails, go to step 2 (StatusCode: 401)
293 14 Shuo Chen
294 107 Shuo Chen
9. send a positive response indicating insert is in progress (StatusCode: 200)
295 14 Shuo Chen
296 78 Shuo Chen
10. if either StartBlockId or EndBlockId is present, go to step 16
297 14 Shuo Chen
298 78 Shuo Chen
11. start to retrieve Name with selectors in insert command
299 14 Shuo Chen
300 78 Shuo Chen
12. wait for retrieval completion
301 1 Shuo Chen
302 84 Shuo Chen
13. if retrieval fails, go to step 27
303 1 Shuo Chen
304 78 Shuo Chen
14. store retrieved Data packet
305 20 Alex Afanasyev
306 84 Shuo Chen
15. abort these steps, insert process ends
307 1 Shuo Chen
308 84 Shuo Chen
16. if StartBlockId is missing, set StartBlockId 0. If EndBlockId is missing, EndBlockId will be missing unless get FinalBlockId in comming data packets, start EndBlockId Misiing Timeout timer.
309 14 Shuo Chen
310 78 Shuo Chen
17. append StartBlockId to Name
311 1 Shuo Chen
312 78 Shuo Chen
18. start to retrieve Name
313 14 Shuo Chen
314 78 Shuo Chen
19. wait for retrieval completion
315 14 Shuo Chen
316 81 Shuo Chen
20. if retrieval fails, go to step 26
317 14 Shuo Chen
318 78 Shuo Chen
21. store retrieved Data packet
319
320
22. if retrieved Data packet contains FinalBlockId, and FinalBlockId is less than EndBlockId or EndBlockId is missing, let EndBlockId be FinalBlockId
321
322 84 Shuo Chen
23. if the last component of Name is greater than or equal to EndBlockId, abort these steps, insert process ends
323 1 Shuo Chen
324 82 Shuo Chen
24. increment the last component of Name
325 15 Shuo Chen
326 82 Shuo Chen
25. go to step 17
327 1 Shuo Chen
328 84 Shuo Chen
26. retrieve data with this data another 2 times. If these 2 retrieval both failes, abort these steps. if success, go to step 20
329 15 Shuo Chen
330 84 Shuo Chen
27. retrieve data with this data another 2 times. If these 2 retrieval both failes, abort these steps. if success, go to step 13
331
332
If EndBlockId Missing Timeout timer starts, repo will monitor this timer during step 17~26. If this timeout occurs, abort insert command process immediately.
333 15 Shuo Chen
334 20 Alex Afanasyev
Implementation MAY pipeline the Interests.
335 1 Shuo Chen
336 85 Shuo Chen
### Repo insert check command progress
337 16 Shuo Chen
338 20 Alex Afanasyev
Implementation MAY publish a notification of status regarding insert progress. The process of status check is as follows:
339 18 Shuo Chen
340 110 Shuo Chen
1. start to authorize the insert status command, if fails go to 2, if success, go to 3
341 1 Shuo Chen
342 110 Shuo Chen
2. send a negative response indicating authorization failure, and abort these steps (StatusCode: 401)
343 18 Shuo Chen
344 20 Alex Afanasyev
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.
345 18 Shuo Chen
346 110 Shuo Chen
4. reponse status with status code, abort check process. (StatusCode: 404)
347 18 Shuo Chen
348 110 Shuo Chen
5. ckeck the status of insertion. return the status of insertion progress. If a EndBlockId Missing Timeour timer is running, set this timer to 0. About check process. (StatusCode: 300)
349 20 Alex Afanasyev
350 17 Shuo Chen
### Protocol diagram:
351 10 Alex Afanasyev
352
    Requester                     Repo                          Data producer
353
        |                           |                                 |
354
        |                           |                                 |
355
      +---+  Insert command       +---+                               |
356
      |   | --------------------> |   |                               |
357
      +---+                       |   |                               |
358
        |                         |   |                               |
359
      +---+   Confirm start       |   |                               |
360
      |   | <==================== |   |                               |
361
      +---+   Reject command      +---+                               |
362
        |     (with status code)    |                                 |
363
        |                         +---+     Interest for Data       +---+
364 1 Shuo Chen
        |                         |   | --------------------------> |   |
365
        |                         +---+                             |   |
366 10 Alex Afanasyev
        |                           |                               |   |
367
        |                         +---+       Data segment          |   |
368
        |                         |   | <========================== |   |
369
        |                         +---+                             +---+
370
        |                           |                                 |
371
        |                           ~                                 ~
372
        |                           ~                                 ~
373
        |                           |                                 |
374
        |                         +---+     Interest for Data       +---+
375
        |                         |   | --------------------------> |   |
376
        |                         +---+                             |   |
377 1 Shuo Chen
        |                           |                               |   |
378
        |                         +---+       Data segment          |   |
379
        |                         |   | <========================== |   |
380
        |                         +---+                             +---+
381
        |                           |                                 |
382
        |                           |                                 |
383 17 Shuo Chen
        |                           ~                                 ~
384 1 Shuo Chen
        |                           ~                                 ~
385
        |                           |                                 |
386 30 Shuo Chen
        |                           |                                 |
387 19 Shuo Chen
        |                           |                                 |
388 30 Shuo Chen
      +---+   Status interest     +---+                               |
389 19 Shuo Chen
      |   | --------------------> |   |                               |
390
      +---+                       |   |                               |
391
        |                         |   |                               |
392
      +---+    Status response    |   |                               |
393
      |   | <==================== |   |                               |
394
      +---+                       +---+                               |
395
        |                           |                                 |
396
        |                           |                                 |
397
398
## Repo Deletion Specification
399
400 87 Shuo Chen
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 of segmented data is also supported.
401 19 Shuo Chen
402
### Deletion command interest semantics
403
404 1 Shuo Chen
Deletion command interest follows the format of the repo command. For example:
405 19 Shuo Chen
406 94 Shuo Chen
    /ucla/cs/repo/delete/<RepoCommandParameter>/<timestamp>/<random-value>/<SignatureInfo>/<SignatureValue
407 19 Shuo Chen
408 88 Shuo Chen
### Deletion Command RepoCommandParameter
409
410 96 Shuo Chen
Format of deletion command RepoCommandParameter follows that of Repo Command. Name, Selector, StartBlockId, EndBlockId, ProcessId are used to construct RepoCommandParameter.
411 88 Shuo Chen
412 96 Shuo Chen
Name is the name or the prefix of data repo will delete.
413
414 127 Shuo Chen
Selector is used to select data. ChildSelector is **not** supported in deletion command.
415 96 Shuo Chen
416
StartBlockId and EndBlockId are used to delete segment data. Data of segment id between StartBlockId and EndBlockId will be deleted by repo.
417
418
ProcessId is a random number generated by client to indicate the deletion process. Repo will match this ProcessId with this deletion process.
419 88 Shuo Chen
420 19 Shuo Chen
### Deletion Command Selectors
421
422 39 Shuo Chen
Deletion command selectors follows the [repo command selectors](http://redmine.named-data.net/projects/repo-ng/wiki/Repo_Protocol_Specification#Repo-Command-Selectors).
423
424 19 Shuo Chen
### Deletion status check
425
426 30 Shuo Chen
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 of repo command. ``<command verb>`` equals to ``delete check``. For example:
427 1 Shuo Chen
428 95 Shuo Chen
    /ucla/cs/repo/delete/<RepoCommandParameter>/<timestamp>/<random-value>/<SignatureInfo>/<SignatureValue>
429 19 Shuo Chen
430 97 Shuo Chen
### Deletion status check RepoCommandParameter
431
432
Name and ProcessId are used to indicate certain deletion process. Repo uses Name and ProcessId to match certain deletion process. If it matches, repo will respond progress of deletion. If just one of Name or ProcessId matches, it fails.
433
434 41 Shuo Chen
### Deletion Check Command Selectors
435
436
Selectors are not supported. Repo will ignore selectors when processing deletion status check command.
437
438 19 Shuo Chen
### Deletion status response
439
440 98 Shuo Chen
Deletion status response is used as response of repo deletion command and repo deletion check command.
441 1 Shuo Chen
442 99 Shuo Chen
Name, StatusCode, Selector, StartBlockId, EndBlockId, ProcessId, DeletenNum are used in deletion status response. Name, ProcessId, Selector is the same as that of delete command. StatusCode indicates the status of deletion. DeleteNum indicates how many data packets have been deleted.
443 98 Shuo Chen
444
In Repo Deletion Command, if just StartBlockId presents, EndBlockId may be the largest segment ID repo holds. If just EndBlockId presents, StartBlockId will be set 0
445 19 Shuo Chen
446
StatusCode Definition:
447
448
``StatusCode`` | Description
449
-------------- | --------------------------------------
450
``200``        | All the data has been deleted
451
``300``        | This deletion is in progress
452 104 Shuo Chen
``401``        | This deletion or deletion check is invalidated
453
``402``        | Selectors and BlockId both present
454 106 Shuo Chen
``403``        | Malformed Command
455 30 Shuo Chen
``404``        | No such this deletion is in progress
456 19 Shuo Chen
457 17 Shuo Chen
### Protocol process
458 1 Shuo Chen
459 101 Shuo Chen
1. start to authorize the command; if authorization does not fail, go to step 3
460 1 Shuo Chen
461 108 Shuo Chen
2. send a negative response indicating authorization failure, and abort these steps, end deletion process. (StatusCode: 401)
462 1 Shuo Chen
463 101 Shuo Chen
3. check whether a deletion process of same RepoCommandParameter exists, waiting for deletion process ends.
464 1 Shuo Chen
465 108 Shuo Chen
4. If selectors and one of StartBlockId and EndBlockId presents, send a negative response and abort these steps, end deletion process. (StatusCode: 402)
466 1 Shuo Chen
467 101 Shuo Chen
5. If selectors present, go to step 8
468 1 Shuo Chen
469 108 Shuo Chen
6. check whether StartBlockId or EndBlockId presents. If both presents but StartBlockId is larger than EndBlockId, return negative response and end deletion process. (StatusCode: 403) Or go to step 9
470 1 Shuo Chen
471 101 Shuo Chen
7. If StartBlockId, EndBlockId and selectors are all missing, go to step 10
472 1 Shuo Chen
473 101 Shuo Chen
8. delete all the data that conforms to the name and selectors, go to step 11
474
475
9. delete all the data packets of segment id between StartBlockId and EndBlockId. If StartBlockId is missing, StartBlockId is set to be 0. If EndBlockId is missing, EndBlockId is set to be the largest segment id that repo holds. go to step 11
476
477 128 Shuo Chen
10. delete all the data with prefix same as name. got to step 11
478 101 Shuo Chen
479 108 Shuo Chen
11. If lifetime of interest does not expire, return status response of positive statuscode. If lifetime of interest has expired, wait for interest the same RepoCommandParameter and return this status response. End Deletion process. (StatusCode: 200)
480 101 Shuo Chen
481
Client will set deletion command with big lifetime. If life time expires, client will re-express the command.
482 19 Shuo Chen
483 21 Alex Afanasyev
Implementation MAY publish a notification of status regarding delete progress. The process of status check is as follows:
484 19 Shuo Chen
485 21 Alex Afanasyev
1. start to authorize the delete status command
486 19 Shuo Chen
487 108 Shuo Chen
2. send a negative response indicating authorization failure, and abort these steps (StatusCode: 401)
488 19 Shuo Chen
489 21 Alex Afanasyev
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.
490 19 Shuo Chen
491 108 Shuo Chen
4. reponse status with status code of 404 (StatusCode: 404)
492 21 Alex Afanasyev
493 108 Shuo Chen
5. ckeck te status of delete. return the status data content (StatusCode: 300)
494 19 Shuo Chen
495
### Protocol diagram:
496
497
    Requester                     Repo 
498
        |                           |                                 
499
        |                           |                                 
500
      +---+  Delete command       +---+                               
501
      |   | --------------------> |   |                               
502
      +---+                       +---+                               
503
        |                           |                                 
504
        |                           |                                 
505
        |                           |                                 
506
      +---+   Status interest     +---+                               
507
      |   | --------------------> |   |                               
508
      +---+                       |   |                               
509
        |                         |   |                               
510
      +---+    Status response    |   |                               
511
      |   | <==================== |   |                               
512
      +---+                       +---+                               
513
        |                           |                                 
514
        |                           |                                 
515
        |                           |                                 
516
      +---+   Confirm Deletion    +---+                               
517
      |   | <==================== |   |                               
518
      +---+   Reject command      +---+                               
519
        |     (with status code)    |    
520 20 Alex Afanasyev
        |                           |