...
| Error Scenario | Expected behavior | Sign-off | |
|---|---|---|---|
| 1 | DMI Down | rejected | |
| 2 | DMI Not responding withing 30 sec | pending | |
| 3 | create for non-existing cm handle id | rejected | |
| 4 | delete for non-existing cm handle id | (silently?) ignore | |
| 5 | any operation on non-existing xpath | ignore? (no or minimal validation, see issue #5) | |
| 6 | delete for non existing name/client-id | TBD | |
| 7 | delete for no existing cm-handle id | TBD | |
| 8 | error upon error | An error scenario on a second subscription for the same cm-handle/xpath as a previous subscription which did not complete successfully (yet) to be discussed, see tabel below |
Characteristics
| # | Parameter | Expectation | Notes |
|---|---|---|---|
| 1 | Maximum number of cm data subscriptions | ||
| 2 | Maximum, Average CM Handles/subscription | ||
| 3 | Maximum, Average XPaths/CmHandles | ||
| 4 | Status update processing time limit | Based on the numbers above working out the current state of each cm handle/xpath combination could be slow! | |
| 5 |
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
...
| # | Issue | Notes | Decision |
|---|---|---|---|
| 1 | Is it intended that CM Notification subscription request cover (all) descendants of the given xpath too?! | e.g.. if a child is removed and there is a subscription for the parent node, will a notification be send (grandchild, child leaf updates etc.) I hope NOT! | |
| 2 | Could xpath point to an element that does not exist (yet) | if not how, how can I client be informed about a create event? | |
| 3 | Should NCMP support re-homing, moving of a CM Handle from one DMI to another? | assume only trough delete & create | |
| 4 | CM Handle Delete: Should DMI or Clients be sent a subscription update (assume no) | do NOT delete dmi-subscription entry until owning subscription is deleted (just ignore upon future delete if cm handle is gone altogether) | |
| 5 | Validation of xpath | options order of implement and also performance cost!
| |
| 6 | can DMI plugin 'reject' a subscription create (for a given cm-handel-xpath combination) | As NCMP might not validate as per issue#5 the DMI=plugin or component further down might have to reject an invalid xpath... | yes currently DMI can use response to say which cm handles are not accepted i.e. rejected' (but not 'pending') |
| 7 | implementation question: should 'rejected' DMI-subscriptions be stored | I would think not | |
| 8 | Dimensioning of DB depends on #cm handles, #subscrptions and #xpaths per subscription, this could be too big for fast processing of updates! | Need to agree maximum and possibly realistic average/total number of entries based on the characteristics above | |
| 9 | Maximum (error) message size, | theoretically all cm handles and all xpaths combinations could be rejected or pending leading to a very large error message! |
Solution Proposals
Current state handling for 'basic' (not merged) subscription create/delete (under development)
...