CPS Events Structure

Overview

CPS-1628 - Getting issue details... STATUS

This page gives a description of CPS events including their fields
Events will be split into events and Headers

Issues & Decisions

#	Description	Notes	Decision
1	No Event properties defined for DMI AVC Event	Priyank Maheshwari will need to specify and agreed event structure for DMI AVC Event with stakeholders ie. provide Jira ticket	Event Body should be compatible with RFC8641 kieran mccarthy has confirmed. Priyank Maheshwari created JIRA to create the event body schema.
2	Bulk Operation events details have not yet be defined (just headers)	Sourabh Sourabh to provide Jira tickets	CPS-1658 - Getting issue details... STATUS
3	Should all the events have same Headers		kieran mccarthy 26 Apr 2023 Possibly Common (base) set of headers but mandatory aspect might differ. In practice we might need a separate headers (schema?) for each event
4	Clarify the format of the version eventSchemaVersion	~~v1 or 1.0~~ ex: 1.0.0 (without 'v')	kieran mccarthy to check ORAN preference kieran mccarthy confirms through email on 12 May 2023 to use semantic versioning which ORAN follows https://semver.org.
5	What to do with additional event headers (from DMI Plugins)		kieran mccarthy 26 Apr 2023 if DMI produce additional headers NCMP will discard those i.e. not included in forwarded events
6	Event(Content) field in DMI Async Request Response Event has inconsistent name (compared with other schemas)	Add V2 file Deprecate V1 Support both versions for a while Delete the V1 version (after some time)	CPS Team 27 Apr 2023 Create a V2 of the schema and rename eventContent as ~~event~~ `data`. Do it as part of the schema addition.
7	NCMP Async Request Response Event (#5) contains both an Event and ForwardedEvent	ForwardedEvent is not wrapped inside Event but question now is if we need 2 events at all?! Sourabh Sourabh and RAVITEJA KARUMURI (EST) can check how it is actually working and then we decide (create a JIRA ticket) Wiki for the Study on NCMPAsyncRequestResponse event schema Conclusion: events not designed as proposed, very inconsistent. Never go a bug because these async events aren't used at all (confirmed by Csaba Koscis) Instead bulk request wil be used for topology use cases.	10 May 2023 kieran mccarthy and team agreed to: Temporary disable the legacy async request feature (task created: CPS-1694 - Getting issue details... STATUS ) As part of a lower priority work items (but during Montreal) fiX related events with learnings from the new batch-usecase. (task created CPS-1693 - Getting issue details... STATUS )
8	Dmi Data AVC Event, use of eventSource field	Priyank Maheshwari wanted to store 'datastore' in this field but kieran mccarthy explained it to use for different purposes	kieran mccarthy Clients can use this field as per their requirements.
9	~~Can Headers be described with 'schema's owned and managed by NCMP~~	~~POC to follow. CPS-1657 - Getting issue details... STATUS~~ ~~Defining header schema.~~ ~~Integration of header with kafka.~~ ~~Naming and versioning convention for the header schemas. 'id'~~ ~~Does the headers schema have a version too?!~~	03 May 2023 ~~Priyank Maheshwari confirmed headers can be described with a separate schema.~~ ~~Both header schema's and event schemas will be published on https://docs.onap.org/projects/onap-cps/en/latest/cps-events.html~~ ~~Header schema name and version will be maintained in the 'id' metadata field of header's schema .~~
10	Depending #10 can schema inherit/extend a common schema for common headers	Commonly define them and then define what are mandatory(required) or optional as per the schema extending it. If a field is not used in the extended schema then it should be able to handle it. extend the POC (on #9) to cover this. 09 May 2023 Priyank Maheshwari did the POC and the conclusion of that was that :- One schema can extend the other schema. We cannot override the mandatory/optional parameter from the Parent schema.	09 May 2023 Toine Siebelink agrees to go ahead with separate schema/headers per event. There will be some duplication but it will have its advantage when versioning.
11	Is anyone using Async Request feature?	See CPS-1660 - Getting issue details... STATUS we need to re-design event #4 (Covers Point 6 as well) and #5 in a backward incompatible way. If no-one is using this feature right now (suspected) we can do this more easily/cheaper!	03 May 2023 Csaba Kocsis confirmed this is not used by Ericsson currently. No plans to use soon for single-cmhandle requests either (TBC). Need to decide priority (Csaba Kocsis to find out of fiXing the legacy schema(s) See decision on issue #7
12	Do we need additionalProperties for DMI ASync Data Request respondes (events #4, #5)	The original code populates a framework defined 'additionalProperties' field with a singel key-value pair: "response-data",{<json data>}. No other (private) properties are added either in DMI PLugin or NCMP code. The name is just coincidence and misleading. In fact this 'additionalProperties' field should NOT have been used at all!	No, the new schema should NOT add 'additionalProperties' field at all use 'additionalProperties:no' in the schema
13	AVC Subscription Event (DMI → NCMP) (events #3)	Want to understand what 'data' is datatype referring to under Subscription Event? What value comes under 'schemaName' & 'SchemaVersion' of Datatype definition under AVC Subscription Event? Reconfirmation needed on 'schemaName' & 'SchemaVersion' should be in the payload?	kieran mccarthy 07 Jun 2023 this issue is now no longer relevant as the decision was to use CNCF Cloud Events instead as per decision #14
14	Align headers with CNCF Cloud Events	Using standard headers as defined by Cloud Events and possibly common header extension See Table below, CNFC Cloud Event alignment CPS will use Cloud Events 3PP for all current and legacy events to ensure common format	23 May 2023 kieran mccarthyand Toine Siebelink agreed on general idea but exact list of common headers need to be agreed Jira (first impl.) to be added! CPS-1717 - Getting issue details... STATUS
15	During the meeting we saw that the Header fields were prefiXed with "ce_" so we need to check if we are ok with that.	assume "ce_" can be used as all user of the CNCF lib will get this behavior, will check if it can be replaced with no prefix at all. Sourabh Sourabh and Priyank Maheshwari concluded a cloud events specific serializer is used that add this prefix and cannot easily be changed (also that would be inconsistent use of this library) CPS Team recommend to accept this prefix and simply document that this prefer is required when filtering on kafka headers defined by CloudEvenst standard.	07 Jun 2023 team agreed with kieran mccarthy to accept "ce_" prefix on serialzied CE defined headers. Note. Event(s) documentation in RTD should mentioned this clearly too
16	Do will still need/ can we still use schemas for header details with CNCF library ?!	How to publish info about non-standard headers like `correlationid` ?	Meeting on 31 May 2023 Team agreed refer to CNFC doc. and add list of extensions in RTD documentation. (key and value constraints)
17	Inconsistent casing convention for header fields v. json data fields	Just observing. All header ion CNCF are lowercase whereas json field are camelCase. Don't want to change but want to make sure agree...	Meeting on 31 May 2023 Team agreed this is the way it is and Toine Siebelink will update to CPS Style section: Contribution and Development#CommonStyleConventions
18	Confirm 'source'. is to be added to ALL events (declared mandatory for CNFC events)		kieran mccarthy 07 Jun 2023 confirm is is compulsory and a value will need to be set for all event definition. in NCMP a default value of 'ncmp' can be used if no other source is applicable. Toine Siebelink will update this page were needed to add this field and default value

Event Overview

#	Short Name	Source	Destination	Impl. Status	Notes	Full Schema Name	Diagram Ref.
1	LCM Event	NCMP	Client Apps	In Use	Life Cycle Management Events, when cmHandles are added or removed	cps:org.onap.ncmp.cmhandle.lcm-event:v1	CM-Handle State Changes and Notifications Overview#Notificationhandlingincode
2	DMI Data AVC Event	DMI	NCMP	Implemented, Not in use	Attribute Value Change in configuration management (CM) data.	cps:org.onap.cps.ncmp.events:avc-event-schema:v1	5 in CPS Data Notifications Overview#ComponentDiagram
3	AVC Subscription Create Event	Client	NCMP & DMIs	Implemented, Not in use	Create Event Only	cps:org.onap.cps.ncmp.events:avc-subscription-event:v1	7 in CPS Data Notifications Overview#ComponentDiagram
4	DMI Async Request Response Event	DMI	NCMP	In Use	DMI passes response onto Kafka topic specified by client.	cps:org.onap.cps.ncmp.events:dmi-async-request-response-event-schema:v1	3b → 4a in CPS-821 Spike: Support Async read-write operations on CPS-NCMP interface#ProposedDesign
5	NCMP Async Request Response Event	NCMP	Client Apps	In Use	Forward No.4 to client specified topic	cps:org.onap.cps.ncmp.events:ncmp-async-request-response-event-schema:v1	4b → 5 in CPS-821 Spike: Support Async read-write operations on CPS-NCMP interface#ProposedDesign
6	Bulk Response Event (Internal)	DMI	NCMP	In Progress	Internal Kafka topic	cps:org.onap.cps.ncmp.event:dmi-async-bulk-response-event-schema:v1	5 in CPS-1515: Spike: Support Multiple CM-Handles for NCMP Get Operation (batch operations)
7	Bulk Response Event (Client)	NCMP	Client Apps	In Progress	Forwarding the DMI responses to the client topic	cps:org.onap.cps.ncmp.event:ncmp-async-bulk-response-event-schema:v1	6 in CPS-1515: Spike: Support Multiple CM-Handles for NCMP Get Operation (batch operations)

#1 LCM Event (NCMP → Client Apps)

Description

LCM (Life Cycle Management) Event. Sent by NCMP when the state of a CM Handle changes. For diagram see CM-Handle State Changes and Notifications Overview#Notificationhandlingincode

LCM Event Details

Current LCM Event Object

Field	Type	Description	Header	Payload	Notes	CloudEvents Mapping
eventID	string	The unique id identifying the event	X		Mandatory	standard (`id`)
eventCorrelationId	string	The id identifying the event. In LCMEvent this is always a cmhandleId	X		Optional (extension fields will be optional now)	extension (`correlationid`)
eventTime	string	The timestamp when original event occurred	X		Mandatory	standard (`time`)
eventSource	string	The source of the event	X		Mandatory	standard (`source`)
eventType	string	The type of the event	X		Mandatory	standard (`type`)
eventSchema	string	The schema that this event adheres to.	X		Mandatory e.g. cps:org.onap.ncmp.cmhandle.lcm-event:1.0.0	standard (`dataschema`)
~~eventSchemaVersion~~	~~string~~	~~The version of the schema that this event adheres to~~	X		~~Mandatory e.g v1.0~~	~~N/A included in 'dataschema'~~
event	Event	The payload of an event		X	Mandatory	standard (`data`)
N/A	N/A	The version of CNCF Specification	X		Specified by CNCF (value hardcoded)	standard (`specversion`)

Type:Event (cps:org.onap.ncmp.cmhandle.lcm-event:v1)

Field	Type	Description	Payload	Notes
cmHandleId	string	cmHandle id	X
oldValues	Values	Values that represents the state of a cmHandle	X	Defined by values object below
newValues	Values	Values that represents the state of a cmHandle	X	Defined by values object below

Type:Values

Field	Type	Description	Payload	Notes
dataSyncEnabled	string	cmHandle id	X
cmHandleState	string	State of cmHandle	X	Enum: ["ADVISED", "READY", "LOCKED", "DELETING", "DELETED"]
cmHandleProperties	object	cmHandle properties	X	List of Java <String, String> Maps

#2 DMI Data AVC Event (ONAP DMI → NCMP)

Description

A normalized AVC Event that ONAP DMI Plugin will send to NCMP. NCMP can process the event and update cached data if needed. See 5 in CPS Data Notifications Overview#ComponentDiagram
Other DMI Plugin might snet similar events, using same headers but different payload and value for 'eventSchema' Depending on the AVC subscription details those events might or might not be forwarded to the Client Apps.

DMI Data AVC Event

AVC Event Object

Field	Type	Description	Header	Notes	CloudEvents Mapping
eventID	string	The unique id identifying the event	X	Mandatory	standard (`id`)
eventCorrelationId	string	The id identifying the event	X	Optional	extension(`correlationid`)
eventTime	string	The timestamp when original event occurred	X	Optional	standard (`time`)
eventSource	string	The source of the event	X	Optional	standard (`source`)
eventType	string	The type of the event	X	Mandatory (e.g. cps:org.onap.cps.ncmp.events:avc-event)	standard (`type`)
eventSchema	string	The schema that this event adheres to	X	Mandatory (e.g. cps:org.onap.cps.ncmp.events:avc-event-schema)	standard (`dataschema`)
~~eventSchemaVersion~~	~~string~~	~~The version of the schema that this event adheres to~~	X	~~Mandatory~~	~~N/A included in 'dataschema'~~
event	Event	The payload of an event		Mandatory	standard (`data`)

Type: Event (cps:org.onap.cps.ncmp.events:avc-event-schema:v1)

Field	Type	Description	Header	Payload	Notes
No Properties defined (entire event treated as single object) See open issue #1 Priyank Maheshwari This is how the event will look like. CPS-1065 Spike: CM data notifications from NCMP to applications including subscriptions#EventPayloadExample

#3 AVC Subscription Event (DME → NCMP)

Description

AVC Subscription Event (external Clients Apps → NCMP)

Priyank Maheshwari We need to revisit this schema and include the cloud events fields. (At the moment this doesn't have proper fields)

AVC Subscription Event

Subscription Event Object

Field	Type	Description	Header	Notes	CloudEvents Mapping
~~version~~	~~string~~	~~The event type version~~	X		~~included in dataschema~~
eventType	string	The event type	X		standard (`type`)
source			X	NEW see decision #18, value <clientId> (same as in payload) TBC	standard (`source`)
event	Event	The payload for an event	X	Defined by event object below	standard (`data`)

Event Object (cps:org.onap.cps.ncmp.events:avc-subscription-event:v1)

Field	Type	Description	Payload	Notes
subscription	Subscription	The subscription details	X	Defined by subscription object below
dataType	DataType	The datatype content	X	Defined by dataType object below
predicates	Predicates	Additional values to be added into the subscription	X	Defined by predicates object below

Type: Subscription

Field	Type	Description	Payload	Notes
clientID	string	The client ID	X
name	string	The name of the subscription	X
isTagged	boolean	optional parameter, default is false	X	default: false

Type: DataType

Field	Type	Description	Payload
dataspace	string	The dataspace name	X
dataCategory	string	The category type of the data	X
dataProvider	string	The provider name of the data	X
schemaName	string	The name of the schema	X
schemaVersion	string	The version of the schema	X

Type: Predicates

Field	Type	Description	Payload
targets	array	CM Handles to be targeted by the subscription	X
datastore	string	datastore which is to be used by the subscription	X
Xpath-filter	string	filter to be applied to the CM Handles through this event	X

#4 DMI Async Request Response Event (DMI → NCMP)

Description

This event is for the asynchronous responses from DMI to NCMP following (synchronous) requests (from NCMP) specifying a (response) topic. See 3b → 4a in CPS-821 Spike: Support Async read-write operations on CPS-NCMP interface#ProposedDesign

DMI Async Request Response Event

DmiAsyncRequestResponse Event Object

Field	Type	Description	Header	Notes	CloudEvents Mapping
eventID	string	The unique id identifying the event generated by DMI	X		standard (`id`)
eventCorrelationId	string	The request id passed by NCMP	X		extensions (`correlationid`)
eventTime	string	The timestamp when original event occurred	X		standard (`time`)
eventTarget	string	The target of the event	X		extensions (`target`)
eventType	string	The type of the event	X		standard (`type`)
eventSchema	string	The event schema for async request response events	X		standard (`dataschema`)
~~eventSchemaVersion~~	~~string~~	~~The event schema version for async request response events~~	X		~~N/A included in 'dataschema'~~
eventSource	string	The source of the event	X		standard (`source`)
eventContent	EventContent	The payload of an event		The name of this fields is inconsistent with all other event schemas, see issue #6	standard `(data)`

Type: EventContent (cps:org.onap.cps.ncmp.events:dmi-async-request-response-event-schema:v1)

Field	Type	Description	Payload	Notes
response-data-schema	string	The schema of response data	X
response-status	string	The status of the response	X
response-code	string	The code of the response	X
response-data	object	The data payload	X	contains payload of type object

#5 NCMP Async Request Response Event (NCMP → Client App)

Description

This event is for the asynchronous responses from NCMP to Client Apps following (synchronous) requests (from client) specifying a (response) topic. See 4b → 5 in CPS-821 Spike: Support Async read-write operations on CPS-NCMP interface#ProposedDesign

NCMP Async Request Response Event

NcmpAsyncRequestResponse Event Object

Field	Type	Description	Header	Payload	Notes	CloudEvents Mapping
eventID	string	The unique id identifying the event generated by DMI	X			standard (`id`)
eventCorrelationId	string	The request id passed by NCMP	X			extensions (`correlationid`)
eventTime	string	The timestamp when original event occurred	X			standard (`time`)
eventTarget	string	The target of the event	X			extensions (`target`)
eventType	string	The type of the event	X			standard (`type`)
source	string	The source of the event	X		NEW see decision #18, value 'ncmp' TBC	standard (`source`)
eventSchema	string	The event schema for async request response events	X			standard (`dataschema`)
~~eventSchemaVersion~~	~~string~~	~~The event schema version for async request response events~~	X			~~N/A included in 'dataschema'~~
event	Event	The payload of an event		X	Defined by event object below	standard (`data`)
forwardedEvent	ForwardedEvent	The payload of a forwarded event		X	Relation to Event field unclear, do we need 2 events at all see issue #7	standard (`data`) See new proposal below

Type: Event (cps:org.onap.cps.ncmp.events:ncmp-async-request-response-event-schema:v1)

Field	Type	Description	Payload	Notes
eventID	string	The unique id identifying the event generated by DMI	X	Only in payload in v1 of the payload schema. To be removed in v2 version (will be in the header only)
eventCorrelationId	string	The request id passed by NCMP	X	as above
eventTime	string	The timestamp when original event occurred	X	as above
eventTarget	string	The target of the event	X	as above
eventType	string	The type of the event	X	as above
eventSchema	string	The event schema for async request response events	X	as above
eventSource	string	The source of the event	X	as above
response-data-schema	string	The received schema of response data	X
response-status	string	The received status of the response	X
response-code	string	The received code of the response	X
response-data	object	The data payload	X	contains payload of type object

Type: forwardedEvent (cps:org.onap.cps.ncmp.events:ncmp-async-request-response-event-schema:v1)

Field	Type	Description	Payload	Notes
eventID	string	The unique id identifying the event generated by DMI	?	Can NCMP put these in the header and remove them from the 'forwardedEvent'
eventCorrelationId	string	The request id passed by NCMP	?	as above
eventTime	string	The timestamp when original event occurred	?	as above
eventTarget	string	The target of the event	?	as above
eventType	string	The type of the event	?	as above
eventSchema	string	The event schema for async request response events	?	as above
eventSchemaVersion	string	The event schema version for async request response events	?	as above
eventSource	string	The source of the event	?	as above
response-data-schema	string	The received schema of response data	X
response-status	string	The received status of the response	X
response-code	string	The received code of the response	X
response-data	object	The data payload	X	contains payload of type object

Proposed New Schema:

see CPS-1660 - Getting issue details... STATUS

Field	Type	Description	Header	Payload	Notes	CloudEvents Mapping
eventID	string	The unique id identifying the event generated by DMI	X			standard (`id`)
eventCorrelationId	string	The request id passed by NCMP	X			extensions(`correlationid`)
eventTime	string	The timestamp when original event occurred	X			standard (`time`)
eventSource	string	The source of the event	X		What value should contain in this? Needs clarification, see issue #8	standard (`source`)
eventType	string	The type of the event	X			standard (`type`)
eventSchema	string	The event schema for async request response events	X			standard (`dataschema`)
~~eventSchemaVersion~~	~~string~~	~~The event schema version for async request response events~~	X			~~N/A included in '`dataschema`'~~
event	Event	The payload of an event		X	Defined by event object below	standard (`data`)

Type: Event (cps:org.onap.cps.ncmp.events:ncmp-async-request-response-event-schema:v1)

Field	Type	Description	Header	Payload	Notes
eventCorrelationId	string	The request id passed by NCMP	X		as above @Toine asked to add this property.
responseStatus	string	The received status of the response		X
responseCode	string	The received code of the response		X
responseData	object	The data payload		X	contains payload of type object

#6 Batch Response Event (DMI → NCMP)

Description

Batch (data) request will always result in asynchronous events (responses) sent to the client. This event is the response from DMI to NCMP. See 5 in CPS-1515: Spike: Support Multiple CM-Handles for NCMP Get Operation (bulk / batch operations)#BulkRequestMessageFlow

DMI Async Batch Response Event

BatchResponseEvent Object

Field	Type	Description	Header	Payload	Notes	CloudEvents Mapping
eventID	string	The unique id identifying the event generated by DMI	X		Mandatory. Generated by DMI-Plugin	standard (`id`)
eventCorrelationId	string	The request id passed by NCMP	X		Mandatory. This is requestId that NCMP sent to client as an ACK. example : “request-1234" (UUID)	extension (`correlationid`)
eventTarget	string	The destination topic of the client	X		Mandatory. TBC example: my-topic	extension (`destination`)
source	string	The source of the event			Mandatory. example : dmi-plugin:enm-1 (dmi service name)	standard (`source`)
eventTime	string	The timestamp when original event occurred	X		Optional. The timestamp should follow that on https://www.rfc-editor.org/rfc/rfc3339#section-5. This follows ISO 8601 and is what is used/referenced in 3GPP standards example: 1985-04-12T23:20:50.52Z this represents 20 minutes and 50.52 seconds after the 23rd hour of April 12th, 1985 in UTC.	standard (`time`)
eventType	string	The type of the event	X		Mandatory. NCMP owns eventType that would be used by dmi-plugins The Convention of eventType and Schema names is under discussion, see open issue #17 on CPS-1515 Spike	standard (`type`)
eventSchema	string	The event schema for async request response events	X		Mandatory. The Convention of eventType and Schema names is under discussion, see open issue #17 on CPS-1515 Spike	standard (`dataschema`)
~~eventSchemaVersion~~	~~string~~	~~The event schema version for async request response events~~	X			~~N/A included in '`dataschema`'~~
event	Event	The payload of an event		X	java object not yet defined by schema, see issue #2	standard (`data`)
specversion	String	Version of CNCF spec	X		hardcoded value of 1.0	standard (`specversion`)

Type: Event (cps:org.onap.cps.ncmp.event.async:dmi-async-batch-response-event-schema:v1)

Field	Type	Description	Header	Payload	Notes
No Properties defined (Entire event treated as single object)

#7 Batch Response Event (NCMP → Client App)

Description

Batch (data) request will always result in asynchronous events (responses) sent to the client. This event is the response from DMI to NCMP. See 6 in CPS-1515: Spike: Support Multiple CM-Handles for NCMP Get Operation (bulk / batch operations)#BulkRequestMessageFlow

NCMP Async Batch Response Event - Client Topic

BatchResponseEvent Object

Field	Type	Description	Header	Payload	Notes	CloudEvents Mapping
eventID	string	The unique id identifying the event generated by DMI	X			standard (`id`)
eventCorrelationId	string	The request id passed by NCMP	X			extensions (`correlationid`)
eventTime	string	The timestamp when original event occurred	X			standard (`time`)
eventType	string	The type of the event	X			standard (`type`)
eventSchema	string	The event schema for async request response events	X			standard (`dataschema`)
~~eventSchemaVersion~~	~~string~~	~~The event schema version for async request response events~~	X			~~N/A included in '`dataschema`'~~
event	Event	The payload of an event		X	Java object not yet defined by schema, see issue #2	standard (`data`)

Type: Event (cps:org.onap.cps.ncmp.event.async:ncmp-async-batch-response-event-schema:v1)

Field	Type	Description	Header	Payload	Notes
No Properties defined (Entire event treated as single object)

CNCF Cloud Event alignment

Introduction

CNCF CloudEvents is a specification for describing event data in common formats to provide interoperability across services, platforms and systems.

These cloud events will be applied to all the internal and external events we have in CPS , NCMP and DMI Plugin.
Cloud events will be taking care of the fields which are part of Headers or part of the actual payload (fields other than "data" are sent as Headers)
These CNCF cloud events will be applied to all the events listed in above sections (LCM , DMI Data AVC etc.)

Library References

Common Header Mapping

The table below shows how previously proposed headers should be mapped to pre-defined CNFC headers.

Before	After¹	CloudeEvent builder method	Example Value	Notes
eventId	(ce_)id	.withId()		Mandatory
eventSource	(ce_)source	.withSource()		Mandatory
N/A	(ce_)specversion (default 1.0)	.v1()	1.0	Mandatory - This is the version of the cloud events
eventType	(ce_)type	.withType()		Mandatory
eventTime	(ce_)time	.withTime()		Optional (could be Mandatory for
eventSchema	(ce_)dataschema	.withDataSchema()		Optional includes the version of the schema
	content-type²	withDataContentType()	application/json	Optional
eventCorrelationId	(ce_)correlationid	.withExtension()		Optional This will be part of the extensions field in the cloud events and all the restrictions of the attribute field naming applies to it. i.e these fields will be in the small case. This is marked as optional as it only applies to some events.
event	(ce_)data	.withData(json TBC)		Mandatory actual event/payload now would be under "data" field.

Note 1 all cloud-event headers will be prefixed during serialization with 'ce_' (this means when filtering on serialized Kafka-headers this prefix need to be applied)
Note 2 content-type is a a 'default' header name no 'wrapped' by CloudEvents and hence the inconsistency in names and that is does NOT have the 'ce_' prefix.