O1-v2-interface: Subscribe/Unsubscribe for VES events.

DRAFT!

Open: All the details about the NetConf operation (rpc, edit-config (Create-MOI, Modify-MOI)).

A new function should be defined by WG1 for O-RAN-OAM-Interface specification (O1-interface) version 2.

The function should provide the ability by the Management-Service-Consumer (MnS Consumer, NMS) to subscribe and unsubscribe for VES events.

According to the O-RAN-OAM-interface specification (O1) each MnS Provider (ME) implements a (TLS/)NetConf interface for Configuration Management and consumes TLS/HTTP-POST messages with a json body in VES message format.

The method for the VES subscription/un-subscription must be performed via NetConf, because VES itself does not provide such function. The MnS Consumer will use the NetConf interface for such an operation.

Click here to view PlantUml code...

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Copyright 2019 highstreet technologies GmbH
' Licensed under the Apache License, Version 2.0 (the "License");
' you may not use this file except in compliance with the License.
' You may obtain a copy of the License at
' 
'     http://www.apache.org/licenses/LICENSE-2.0
' 
' Unless required by applicable law or agreed to in writing, software
' distributed under the License is distributed on an "AS IS" BASIS,
' WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
' See the License for the specific language governing permissions and
' limitations under the License.
' 
' Author: martin.skorupski@highstreet-technologies.com

@startuml

' Diagram
title 
  O-RAN-SC 
  O1-Interface: VES Subscription architecture
end title

node "\nManagement-Service (MnS) Consumer\nOAM Controller" #8064A2 {
  interface "TLS/HTTP" as http
  [VES Server] -down-> http: provides
  [NetConf Client] as ncc
} 

node "\nManagement-Service (MnS) Provider\nManagedElement" #ED7D31 {
  interface "TLS/NetConf" as nc
  [NetConf Server] -up-> nc: provides
  [VES Client] .up.> http: <font color=#222222>use
  [VES Client] -[hidden]left- [NetConf Server]
} 
   ncc .down.> nc: <font color=#222222>use

' End Diagram
' Format
header
  <b><font color=#8888ff>License</font></b>
  <b><font color=#8888ff>Apache 2.0</font></b>
end header
'caption "\n UML Formatting"

right footer 
  VES Subscription
  Thanks to plantUml! 
  2019-07-16 | o-ran-sc.org
end footer

skinparam backgroundColor #fefefe

skinparam backgroundColor #fefefe
'skinparam handwritten true
skinparam roundcorner 15

skinparam componentStyle uml2

skinparam component {
  BorderColor #666666
  BackgroundColor #fefefe
}

skinparam interface {
  BorderColor #666666
  BackgroundColor #fefefe
  FontColor #fefefe
}

skinparam databaseBorderColor #666666
skinparam databaseBackgroundColor #fefefe
skinparam databaseFontColor #666666

skinparam node {
  FontColor #ffffff
}

skinparam sequence {
  MessageAlign left
  
  ArrowColor #fefefe
  ArrowFontColor #fefefe
  ArrowThickness 2.5 
  
  ActorBorderColor #666666
  LifeLineBorderColor #666666
  LifeLineBackgroundColor #eeeeee
 
  BoxBorderColor #666666
    
  GroupBorderColor #666666
  GroupBackgroundColor #eeeeee
  
  ParticipantBorderColor #666666
  ParticipantBackgroundColor #ffffdd
  'ParticipantFontName Impact
  'ParticipantFontSize 17
  ParticipantFontColor #666666
    
  ActorBackgroundColor #ffffdd
  'ActorFontColor DeepSkyBlue
  'ActorFontSize 17
  'ActorFontName Aapex
}

@enduml

Each NetConf session should be terminated as soon as possible. Therefore any solution requiring a permanent NetConf session (e.g. for NetConf Notification) should be avoided.
(TODO: add here the reasons for such requirement/expectation. It may have something to do with avoiding TCP connection for better scale. However, for the required event streaming functionality, a permanent session is necessary. To be continued)
The NetConf client should be informed about the status of the VES connection. In the case of missconfiguration, alarm events can not be sent to the MnS Consumer (alarm blindness). The only channel to troubleshoot such situation is via NetConf.

Due to the Design Guidelines above the status of the subscription can not be handled asynchronously. The status must be given in the NetConf response.

Establish a NetConf session
A secure communication channel is required to establish a NetConf session. This can be done via Secure Shell (SSH) connection (RFC6242) or via Transport Layer Security (TLS) (RFC5539).
Due to the fact that O-RAN-Alliance requires TLS for HTTP traffic, it is preferred and recommended to use also TLS for NetConf.
Subscribe for VES events
Open: The details about the NetConf operation and the exact data structure are currently (2019-07-28) under discussion. The results of this discussion will be updated later here.
Inform VES client about a new subscription
An MnS Provider internal mechanism is necessary to verify the VES configuration.
Check VES connectivity
The verification of the VES communication channel id done by sending a VES heartbeat.
Response from VES server
Based on the response from the VES-HTTPS-Server (TCP/TLS/HTTP-POST/VES) the status attribute value of Managed Object instance (MOI) representing the subscription will be updated and exposed as attribute value change to all subscribers.
1. SUCCESS
  The HTTP response codes 20x indicate that the VES connection can be established and the subscription status attribute will be changed to the value of the HTTP-status (integer).
2. FAILED
  The HTTP response codes different from 20x may require operator actions. Also, in this case, the subscription status attribute will be changed to the value of the HTTP-status (integer)
  
  Open: is a textual status attribute useful? e.g. status: ok and status: "failed" or status: "failed (connection refused)" - Assumption; no - such translation is not subject of an OAM interface, it is subject of customer documentation and/or user interface (UI).
Inform NetConf server about the status of the VES connection
The NetConf server must be triggered, to response the correct status back to the MnS Consumer.
NetConf response
The NetConf server sends a response including the VES connection status of the subscription.
Open: Shall the response also include all other attributes of the MOI representing the subscription?
Terminate NetConf session
Once the NetConf client received the NetConf response or the NetConf response timed out, the NetConf session should be actively terminated.
Note: All ODL based NetConf clients until release "Sodium" do not support such functionality yet - Also the ODL based implementation by ONAP CCSDK does not support such function.
It is currently (2019-07-28) under discussion, which of the involved open-source projects should implement such function - candidates are ODL, ONAP-CCSDK, ONAP-SDNC, ONAP-SDN-R, O-RAN-SC-NON-RT-RIC or O-RAN-SC-OAM. (TODO: add OAM Jira to track it). As a consequence, it is very likely that O-RAN-SC release A does not support the automated termination of the NetConf session after NetConf responses.

Click here to view PlantUml code...

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Copyright 2019 highstreet technologies GmbH
' Licensed under the Apache License, Version 2.0 (the "License");
' you may not use this file except in compliance with the License.
' You may obtain a copy of the License at
' 
'     http://www.apache.org/licenses/LICENSE-2.0
' 
' Unless required by applicable law or agreed to in writing, software
' distributed under the License is distributed on an "AS IS" BASIS,
' WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
' See the License for the specific language governing permissions and
' limitations under the License.
' 
' Author: martin.skorupski@highstreet-technologies.com

@startuml

' Diagram
title 
  O-RAN-SC 
  O1-Interface: VES Subscription procedure
end title

box "\nManagement-Service (MnS)Provider\nManagedElement" #ED7D31
  participant "<b>Client</b>" as vesc <<VES>> 
  participant "<b>Server</b>" as ncs <<NetConf>>
end box 

box "\nManagement-Service (MnS) Consumer\nOAMController" #8064A2
  participant "<b>Client</b>" as ncc <<NetConf>>
  participant "<b>Server</b>" as vess <<VES>>
end box

autonumber "<b>[00]"
  
group VES Subscription

  ncc <-> ncs: tcp/tls/netconf/830\nEstablish NetConf Session (hello, ...)
  ncc -> ncs: subscribe for VES events
  activate ncs
    ncs -> vesc: inform about a new subscription
    vesc -> vess: Check connectivity (e.g. tcp/tls/http/ves/heartbeat)
    vesc <- vess: expected response "SUCCESS" (http status: 200)
    vesc-> ncs: inform about status of the VES connection
    ncs -> ncc: Response (expected: success, unexpected: failure)
  deactivate ncs
  ncc -> ncs: Terminate NetConf Session
end group

' End Diagram
' Format
header
  <b><font color=#8888ff>License</font></b>
  <b><font color=#8888ff>Apache 2.0</font></b>
end header
'caption "\n UML Formatting"

right footer 
  VES Subscription
  Thanks to plantUml! 
  2019-07-27 | o-ran-sc.org
end footer

skinparam backgroundColor #fefefe

skinparam backgroundColor #fefefe
'skinparam handwritten true
skinparam roundcorner 15

skinparam databaseBorderColor #666666
skinparam databaseBackgroundColor #fefefe
skinparam databaseFontColor #666666

skinparam sequence {
  MessageAlign left
  ArrowColor #2277dd
  ArrowFontColor #666666
  ActorBorderColor #666666
  LifeLineBorderColor #666666
  LifeLineBackgroundColor #eeeeee
 
  BoxFontColor #ffffff
  BoxBorderColor #666666
    
  GroupBorderColor #666666
  GroupBackgroundColor #eeeeee
  
  ParticipantBorderColor #666666
  ParticipantBackgroundColor #ffffdd
  'ParticipantFontName Impact
  'ParticipantFontSize 17
  ParticipantFontColor #666666
    
  ActorBackgroundColor #ffffdd
  'ActorFontColor DeepSkyBlue
  'ActorFontSize 17
  'ActorFontName Aapex
}

@enduml

Establish a NetConf session
A secure communication channel is required to establish a NetConf session. This can be done via Secure Shell (SSH) connection (RFC6242) or via Transport Layer Security (TLS) (RFC5539).
Due to the fact that O-RAN-Alliance requires TLS for HTTP traffic, it is preferred and recommended to use also TLS for NetConf.
Un-subscribe from VES events
Open: The details about the NetConf operation and the exact data structure are currently (2019-07-28) under discussion. The results of this discussion will be updated later here.
Inform VES client about the un-subscription
An MnS Provider internal mechanism is necessary to verify the VES configuration.
Send corresponding VES event
Open: Config-change?
Response from VES server
Based on the response from the VES-HTTPS-Server (TCP/TLS/HTTP-POST/VES) the following scenarios will happen:
1. SUCCESS
  Ths HTTP response codes 20x indicate that the still subscribed MnS consumer has received the last VES message and "knows" that not more VES messages via this channel will be received.
2. FAILED
  Open: How to handle this situation? Release A: ignoring; Release B: x retries?!?!?!
Inform NetConf server about the status of the VES connection
The NetConf server must be triggered, to response the correct status back to the MnS Consumer (NetConf client).
NetConf response
The NetConf server sends a response including the VES connection status of the un-subscription.
Open: Shall the response also include all other attributes of the MOI representing the subscription?
Terminate NetConf session
Once the NetConf client received the NetConf response or the NetConf response timed out, the NetConf session should be actively terminated.
Note: All ODL based NetConf clients until release "Sodium" do not support such functionality yet - Also the ODL based implementation by ONAP CCSDK does not support such function.
It is currently (2019-07-28) under discussion, which of the involved open-source projects should implement such function - candidates are ODL, ONAP-CCSDK, ONAP-SDNC, ONAP-SDN-R, O-RAN-SC-NON-RT-RIC or O-RAN-SC-OAM. (TODO: add OAM Jira to track it). As a consequence, it is very likely that O-RAN-SC release A does not support the automated termination of the NetConf session after NetConf responses.

Click here to view PlantUml code...

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Copyright 2019 highstreet technologies GmbH
' Licensed under the Apache License, Version 2.0 (the "License");
' you may not use this file except in compliance with the License.
' You may obtain a copy of the License at
' 
'     http://www.apache.org/licenses/LICENSE-2.0
' 
' Unless required by applicable law or agreed to in writing, software
' distributed under the License is distributed on an "AS IS" BASIS,
' WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
' See the License for the specific language governing permissions and
' limitations under the License.
' 
' Author: martin.skorupski@highstreet-technologies.com

@startuml

' Diagram
title 
  O-RAN-SC 
  O1-Interface: VES Un-subscription procedure
end title

box "\nManagement-Service (MnS) Provider\nManagedElement" #ED7D31
  participant "<b>Client</b>" as vesc <<VES>> 
  participant "<b>Server</b>" as ncs <<NetConf>>
end box 

box "\nManagement-Service (MnS) Consumer\nOAMController" #8064A2
  participant "<b>Client</b>" as ncc <<NetConf>>
  participant "<b>Server</b>" as vess <<VES>>
end box

autonumber "<b>[00]"
  
group VES Un-subscription

  ncc <-> ncs: tcp/tls/netconf/830\nEstablish NetConf Session (hello, ...)
  ncc -> ncs: unsubscribe (which operation)
  activate ncs
    ncs -> vesc: inform about the deleted subscription
    vesc -> vess: send cooresponding event (which domain?)
    vesc <- vess: http status: 200
    vesc -> ncs: successful unsubscription
    ncs -> ncc: Done!
  deactivate ncs
  ncc -> ncs: Terminate NetConf session

end group

' End Diagram
' Format
header
  <b><font color=#8888ff>License</font></b>
  <b><font color=#8888ff>Apache 2.0</font></b>
end header
'caption "\n UML Formatting"

right footer 
  VES Unsubscription
  Thanks to plantUml! 
  2019-07-27 | o-ran-sc.org
end footer

skinparam backgroundColor #fefefe

skinparam backgroundColor #fefefe
'skinparam handwritten true
skinparam roundcorner 15

skinparam databaseBorderColor #666666
skinparam databaseBackgroundColor #fefefe
skinparam databaseFontColor #666666

skinparam sequence {
  MessageAlign left
  ArrowColor #2277dd
  ArrowFontColor #666666
  ActorBorderColor #666666
  LifeLineBorderColor #666666
  LifeLineBackgroundColor #eeeeee
 
  BoxFontColor #ffffff
  BoxBorderColor #666666
    
  GroupBorderColor #666666
  GroupBackgroundColor #eeeeee
  
  ParticipantBorderColor #666666
  ParticipantBackgroundColor #ffffdd
  'ParticipantFontName Impact
  'ParticipantFontSize 17
  ParticipantFontColor #666666
    
  ActorBackgroundColor #ffffdd
  'ActorFontColor DeepSkyBlue
  'ActorFontSize 17
  'ActorFontName Aapex
}

@enduml

O1-v2-interface: Subscribe/Unsubscribe for VES events.

Scope

O1 Component Architecture

Figure

PlantUml

Design guidelines

Subscription

Message flow

Figure

PlantUml

Un-subscription

Message flow

Figure

PlantUml