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Table of Contents |
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Requirements
Functional
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Requirement
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- Prevent unnecessary subscription updates to nodes already involved in a subscription to the same path
- For possible combinations, see table below
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Last lights out: upon subscription Delete request only when there is no more subscription for a cm-handle & xpath combination a subscription-delete request wil be send to the relevant DMI(s)
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Error Handling
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An error scenario on a second subscription for the same cm-handle/xpath as a previous subscription which did not complete successfully (yet)
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Characteristics
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Out-of-scope
- CM Notification Forwarding Check: When forwarding CM Notification NCMP will not check the content to see if the is a valid active subscription. It is assumed that the DMI Plugin as acted on the 'delete subscription' request (that request is NCMPs responsibility). And of course there wil be timing issues it also possible a CM Notification was send just after the subscription-delete was send (from client) but before the whole change had acted upon that.
- Retry: NCMP wil only report when actions are pending or rejected. NCMP will not implement a retry mechanism
- Wildcards: Wildcards or similar functionality where one string represent 0 or more xpaths is not covered as part of this requirement but it should be kept in mind as a future possibility
- Dynamic Topic: Topic for CM Data Notifications back to client will be hardcode for now
Assumptions
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Issues & Decisions
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- Risk of client effectively subscribing to ALL data in a cm handle by specifying top level datanode(s)
- Complexity (i.e. cost of) of merge operation. It might even required NCMP to check relevant dat model
- Future use of wildcards, could be a viable alternative for including descendants
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- none
- xpath-parser
- model check
- instance check
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yes currently DMI can use response to say which cm handles are not accepted i.e. rejected' (but not 'pending')
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Solution Proposals
Current state handling for 'basic' (not merged) subscription create/delete (under development)
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Scenario 1
1) Create Sub from Client: CH-1, CH-2
2) All handled by DM1
3) NCMP to DMI request Create sub: CH-1, CH-2
DMI responds within 30 seconds: Status OK
NCMP Send message to client: Statsu OK (no list with Rejected/Pending)
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NCMP Send messge to client: Pending [CH-1, CH-2]
Scenario 3
1) Create Sub from Client: CH-1, CH-2
2) All handled by DM1
3) NCMP to DMI request Create sub: CH-1, CH-2
DMI responds within 30 seconds: Rejected [CH-2]
NCMP Send message to client: Rejected [CH-2]
Scenario 4:
4 diffrent DMIs each handling 2 Cm Handles, create sub for all CHs
Scenario 4-part a
DMI1 CH-1, CH-2 All accepted within 30 secs
DMI2 CH-3, CH-4 Mixed result witing 30 seconds e.g. Rejected [CH-4]
DMI3 CH-5, CH-6 No result after 30 seconds
DMI4 CH-7, CH-8 No result after 30 seconds
NCMP -> Client : Rejected [CH-4], Pending [ CH-5, CH-6, CH-7, CH-8 ]
4-part b
DMI3 PLugin responds after 40 seconds; status OK
NCMP -> Client : Rejected [CH-4], Pending [ CH-7, CH-8 ]
4-part c
DMI4 PLugin responds after 50 seconds; Rejected [CH-7]
NCMP -> Client : Rejected [CH-4, CH-7]
Note. The above algorithm depends ons storing (in DB using yang modelled data) a cm-handle status for each cm-handle for each subscription!
Merge → Split
- NCMP treats a Client Subscription as one or more (small) DMI Subscriptions, each of which wil have there own state.
Each DMI Subscription is related to 1 or more client subscriptions.
If there is no more related client subscription the DMI Subscription can be deleted (once accepted by DMI Plugin)!
Data Model (not a great diagram...)
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Create Combinations
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title | Data Model... |
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title | Data Model... |
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title | Data Model... |
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title | Data Model... |
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Delete Combinations
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Error-Upon-Error Combinations
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Proposed JIRAs
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This study is now included in CM Data Notification Subscription LCM (incl. merge)