Page History

...

	Error Scenario	Expected behavior
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, should be handle in 'basic' solution
7	delete for no existing cm-handle id	ignore? (no or minimal validation, see issue #5)
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	Sign-off
1	Maximum number of cm data subscriptions	200	kieran mccarthy confirmed
2	Maximum, Average CM Handles

/subscription

3	Maximum, Average XPaths
per subscription	Max: TBD Avg: 200	kieran mccarthy to confirm Note: consider limit and future 'simple' ALL (wildcard) option when above that limit

/CmHandles

per CmHandle	Max: Avg: 10	kieran mccarthy
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

kieran mccarthy order of 30 seconds (NCMP side)
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.
Study shoudl consider compatibility with an 'ALL' cm handles options

Assumptions

#	Assumption	Notes
1	Targets is a collection of xpaths	can be implemented as a json array of strings
2	for the DMI plugin cm-handle-id and xpath are the key to a unique subscription	the client-id and subscription name are not relevant for the DMI (should not be included in the request) as this would break the concept of merging!

Issues & Decisions

...

update (assume no)options order of implement and also performance cost!
none
xpathimplementation question: I would think notHandled xpaths different subscriptions with different datastores, does that affect the cm data notifications send (which datastore applies)

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!
Consider:
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
24 Aug 2023 kieran mccarthy descendant not covered by 'basic' paths Wildcard will cover this kind of function in future
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?
24 Aug 2023 kieran mccarthy yes
3 Should NCMP support re-homing, moving of a CM Handle from one DMI to another? assume only trough delete & create
24 Aug 2023 kieran mccarthy out of scope
4 4 CM Handle Delete: Should DMI or Clients be sent a subscription update
do NOT delete dmi-subscription entry until owning subscription is deleted
(just ignore upon future delete if cm handle is gone altogether)
Note. LCM is already broadcast (today)

24 Aug 2023 kieran mccarthy re-use existing LCM event → also send it on topic for he subscription (currently fixed)
(might need to upgarde to CLoudEevent then too)
Note. need to add subscription if (name+client id) to header
5 Validation of xpath options order of implement and also performance cost!
none
xpath
5 Validation of xpath
-parser
model check
instance check
24 Aug 2023 kieran mccarthy not required right now
6 can DMI plugin 'reject' a subscription create (for a given cm-handle-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...

Priyank Maheshwari
yes currently DMI can use response to say which cm handles are not accepted i.e. rejected' (but not 'pending')

24 Aug 2023 kieran mccarthyconfirm DMI can reject whole subscrption
7 implementation question: 7 should 'rejected' DMI-subscriptions be stored not needed as whole subscription should be rejected
24 Aug 2023 kieran mccarthyconfirm
8 Dimensioning of DB depends on #cm handles, #subscriptions 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
The team is blocked until this becomes clear as it wil affect the way the data needs to be modelled exactly
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! no longer relevant given and max decided
10 can each CM- Handle have different set of xpath(s) per subscription the current 'basic' solution only supports a common set of datastore/xpaths (filter)
kieran mccarthy Yes
11 can the same cm handle/xpath have 12 will migration from 'basic' be supported Preferred to ask customers to create new subscriptions different subscriptions with different datastores, does that affect the cm data notifications send (which datastore applies)

12 will migration from 'basic' be supported Preferred to ask customers to create new subscriptions
24 Aug 2023 kieran mccarthy no need to support (migration) of 'basic' solution. Development of 'basic' solution can be stopped!
13 list v list instances filtering
/p/c1
/p/c1[@key=23] Might not always be supported, depending DMI Plugin impl.
considered different paths
24 Aug 2023 kieran mccarthy
14 confirm subscription id (currently name + client id)
kieran mccarthy to clarify ASAP

15 what subscription details should be send when theer is a change (in then union)
just delta
just union
union and delta (delta flagged)
24 Aug 2023 kieran mccarthy prefer option 3 despite the possible size of data (200 10 entries)

Solution Proposals

Current state handling for 'basic' (not merged) subscription create/delete (under development)

...

#

Existing Subscription A-10

Client Create Subscription B-52 Request

DMI Create RequestRequest
(union if changed)

Data Model Before (2nd) Create

Data Model After Create

1

CH-1, [ /p/c1, /p/c2 ]

CH-1, [ /p/c1 ]

None

Expand

title	Data Model...

Client Subscription		DMI Subscription
name	client-id	cm-handle	xpath	subscribers
A	10	CH-1	/p/c1	[ A-10 ]
		CH-1	/p/c2	[ A-10 ]

Expand

title	Data Model...

Client Subscription		DMI Subscription
name	client-id	cm-handle	xpath	subscribers
A	10	CH-1	/p/c1	[ A-10, B-52 ]
B	52	CH-1	/p/c2	[ A-10 ]

2

CH-1, [ /p/c1, p/c2 ]

CH-1, [ /p/c2, /p/c3 ]

CH-1, [ /p/c2, /p/c3c3 ]

Expand

title	Data Model...

Client Subscription		DMI Subscription
name	client-id	cm-handle	xpath	subscribers
A	10	CH-1	/p/c1	[ A-10 ]
		CH-1	/p/c2	[ A-10 ]

Expand

title	Data Model...

Client Subscription		DMI Subscription
name	client-id	cm-handle	xpath	subscribers
A	10	CH-1	/p/c1	[ A-10 ]
B	52	CH-1	/p/c2	[ A-10, B-52 ]
		CH-1	/p/c3	[ B-52 ]

3

CH-1, [ /p/c1]
CH-2, [ /p/c1]

CH-2, [ /p/c1]
CH-3, [ /p/c1]

Union
CH-1, [ /p/c1]
CH-2, [ /p/c1]
Added
CH-3, [ /p/c1]

Expand

title	Data Model...

Client Subscription		DMI Subscription
name	client-id	cm-handle	xpath	subscribers
A	10	CH-1	/p/c1	[ A-10 ]
		CH-2	/p/c1	[ A-10 ]

Expand

title	Data Model...

Client Subscription		DMI Subscription
name	client-id	cm-handle	xpath	subscribers
A	10	CH-1	/p/c1	[ A-10 ]
B	52	CH-2	/p/c1	[ A-10, B-52 ]
		CH-3	/p/c1	[ B-52 ]

4

CH-1, [ /p/c1]

CH-1, [ /p/c1/gc1 ]

CH-1, [ /p/c1/gc1 ] (see issue #1)

Expand

title	Data Model...

Client Subscription		DMI Subscription
name	client-id	cm-handle	xpath	subscribers
A	10	CH-1	/p/c1	[ A-10 ]

Expand

title	Data Model...

Client Subscription		DMI Subscription
name	client-id	cm-handle	xpath	subscribers
A	10	CH-1	/p/c1	[ A-10 ]
B	52	CH-1	/p/c1/gc1	[ B-52 ]

...

#

Existing Subscription A-10

Existing Subscription B-52

Client Delete A-10 Request

DMI Delete RequestUpdate

Data Model Before Before

Data Model After Delete

1

CH-1, [ /p/c1, p/c2 ]

CH-1, [ /p/c1 ]

CH-1, [ p/c2 ]

Expand

title	Data Model...

Client Subscription		DMI Subscription
name	client-id	cm-handle	xpath	subscribers
A	10	CH-1	/p/c1	[ A-10, B-52 ]
B	52	CH-1	/p/c2	[ A-10 ]

Expand

title	Data Model...

Client Subscription		DMI Subscription
name	client-id	cm-handle	xpath	subscribers
A	10	CH-1	/p/c1	[ A-10 ]
		CH-1	/p/c2	[ A-10 ]

2

CH-1, [ /p/c1]
CH-2, [ /p/c1]

CH-2, [ /p/c1]
CH-3, [ /p/c1]

Union
CH-2 [ /p/c1]
CH-3, [ /p/c1]

Deleted
CH-1, [ /p/c1]

Expand

title	Data Model...

Client Subscription		DMI Subscription
name	client-id	cm-handle	xpath	subscribers
A	10	CH-1	/p/c1	[ A-10 ]
B	52	CH-2	/p/c1	[ A-10, B-52]
		CH-3	/p/c1	[ B-52 ]

Expand

title	Data Model...

Client Subscription		DMI Subscription
name	client-id	cm-handle	xpath	subscribers
B	52	CH-2	/p/c1	[ B-52 ]
		CH-3	/p/c1	[ B-52 ]

3

CH-1, [ /p/c1]

CH-1, [ /p/c1]
CH-2, [ /p/c1]

None

Expand

title	Data Model...

Client Subscription		DMI Subscription
name	client-id	cm-handle	xpath	subscribers
A	10	CH-1	/p/c1	[ A-10 ]
B	52	CH-1	/p/c2	[ A-10, B-52 ]

Expand

title	Data Model...

Client Subscription		DMI Subscription
name	client-id	cm-handle	xpath	subscribers
B	52	CH-2	/p/c1	[ B-52 ]

...

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Versions Compared

Old Version 28

New Version 29

Key

Characteristics

Out-of-scope

Assumptions

Issues & Decisions

Solution Proposals

	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! Consider: 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	24 Aug 2023 kieran mccarthy descendant not covered by 'basic' paths Wildcard will cover this kind of function in future
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?	24 Aug 2023 kieran mccarthy yes
3	Should NCMP support re-homing, moving of a CM Handle from one DMI to another?	assume only trough delete & create	24 Aug 2023 kieran mccarthy out of scope
4	4	CM Handle Delete: Should DMI or Clients be sent a subscription	update	do NOT delete dmi-subscription entry until owning subscription is deleted (just ignore upon future delete if cm handle is gone altogether) Note. LCM is already broadcast (today)	24 Aug 2023 kieran mccarthy re-use existing LCM event → also send it on topic for he subscription (currently fixed) (might need to upgarde to CLoudEevent then too) Note. need to add subscription if (name+client id) to header
5	Validation of xpath	options order of implement and also performance cost! none xpath	5	Validation of xpath	-parser model check instance check	24 Aug 2023 kieran mccarthy not required right now
6	can DMI plugin 'reject' a subscription create (for a given cm-handle-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...	Priyank Maheshwari yes currently DMI can use response to say which cm handles are not accepted i.e. rejected' (but not 'pending')	24 Aug 2023 kieran mccarthyconfirm DMI can reject whole subscrption
7	implementation question:	7	should 'rejected' DMI-subscriptions be stored	not needed as whole subscription should be rejected	24 Aug 2023 kieran mccarthyconfirm
8	Dimensioning of DB depends on #cm handles, #subscriptions 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 The team is blocked until this becomes clear as it wil affect the way the data needs to be modelled exactly
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!	no longer relevant given and max decided
10	can each CM-	Handle have different set of	xpath(s) per subscription	the current 'basic' solution only supports a common set of datastore/xpaths (filter)	kieran mccarthy Yes
11	can the same cm handle/xpath have	12	will migration from 'basic' be supported	Preferred to ask customers to create new subscriptions	different subscriptions with different datastores, does that affect the cm data notifications send (which datastore applies)
12	will migration from 'basic' be supported	Preferred to ask customers to create new subscriptions	24 Aug 2023 kieran mccarthy no need to support (migration) of 'basic' solution. Development of 'basic' solution can be stopped!
13	list v list instances filtering	/p/c1 /p/c1[@key=23] *Might not always be supported, depending DMI Plugin impl. considered different paths	24 Aug 2023 kieran mccarthy
14	confirm subscription id (currently name + client id)	kieran mccarthy to clarify ASAP
15	what subscription details should be send when theer is a change (in then union)	just delta just union union and delta (delta flagged)	24 Aug 2023 kieran mccarthy prefer option 3 despite the possible size of data (200 * 10 entries)