Support batched CloudEvent content mode in dispatcher

[antoineco]

Problem

Sending a batch of CloudEvents with datacontenttype: application/cloudevents-batch+json results in the creation of a single CloudEvent - composed of an aggregation of multiple CloudEvents serialized as a JSON document - instead of individual CloudEvents.

Persona:: Event producer

Exit Criteria

Dispatchers accept batched CloudEvents (example of payload used in a real application) and know how to split their contents into individual events.

Time Estimate (optional): ?

Additional context (optional)

[antoineco]

It's been raised in #2880 already but this issue hasn't seen much activity.

I think part of the job could be delegated to the CloudEvents SDK, where a Message with a batch content type could be split by calling e.g. batchMessage.Events(), but I haven't seen any support for batch events in the SDK. cc. @slinkydeveloper @n3wscott

[slinkydeveloper]

Hi @antoineco, the sdk doesn't have batch support, we never came out with a proper interface definition and, most important, with how to model the behaviours of the client around an incoming batch. Look at cloudevents/sdk-go#301 for more details

[slinkydeveloper]

We're also now looking at implementing the new Websockets protocol binding, which solves similar issues of batched CloudEvent but it's more efficient cloudevents/sdk-go#598

[antoineco]

Sounds good! 🙏

I'll close this issue then, and people who use the search and stumble upon it can refer to your links to track support for batching.

[lionelvillard]

@aslom @dug @cr22rc any thoughts?