What CometD streaming channels do communities support?

Question

Is there any documentation that says what streaming channels are allowed for communities?

(Note that in communities lightning-emp-api methods such as isEmpEnabled never resolve but it is possible to directly load and use CometD JavaScript.)

I'd like to use a StreamingChannel because that includes user id filtering. But using Comet D JavaScript for a "Customer Community Login" licensed user the response is:

{
    "clientId":"1n01i4ijc3vw89e11fi7leljv7xr2",
    "channel":"/meta/subscribe",
    "id":"2",
    "subscription":"/u/CvcpProgress",
    "error":"403::No access on channel",
    "successful":false
}

which is documented to mean:

The generic streaming channel can’t be accessed because the user doesn’t have permissions on the StreamingChannel object.

That object is not present in the profile, and granting rights through a permission set is not allowed:

The user license doesn't allow the permission: Read Streaming Channels

Trying a Platform Event "/event/cvcp__ProgressEvent__c" the subscribe works:

{
    "clientId":"1njst1mjwlem9r8t7qy9p8l9409",
    "channel":"/meta/subscribe",
    "id":"2",
    "subscription":"/event/cvcp__ProgressEvent__e",
    "successful":true
}

and the published values are received, but there is no user id filtering for this case. But perhaps this is my only option?

Answer 1

look heroku node.js with streaming channels https://developer.salesforce.com/blogs/2021/08/how-to-work-within-platform-events-delivery-limits

Answer 2

I suppose CometD version 3.1.0 or later is supported, as they are supported in the Streaming APIs. For more information please refer to this link. Please check if your user has access to the platform event object.