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Given the following posts from Salesforce:

The way I'm understanding the behavior here is that during the connection to the /meta/subscribe channel, if I wish to replay prior durable events, I can use the following options:

  • -2: All events from the beginning of what is available/stored
  • -1: Everything going forward after subscription
  • Replay#: A previous 'replay' value from a prior message as starting point

I'm trying to pass the map value { "replay": { "/data/ChangeEvents": -2 } along when { "channel": "/meta/subscribe" } connection is going out but it is not replaying the 3 days prior changes as noted in the documentation for change data capture.

Is this the correct way to retrieve change data capture events for the retention period? I'm assuming I should see all events replayed after making the connection but nothing old is coming through, only new changes.

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  • The document you mentioned say events (pilot) for 72 hours , Being pilot you have to raise a case with SF to get it Commented Jan 14, 2019 at 0:16
  • @PranayJaiswal - do you mind letting me know where it says pilot? I'm unfortunately not seeing that.
    – Kyle B.
    Commented Jan 15, 2019 at 13:12

1 Answer 1

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I don't know if you are still looking for an answer for this but I was able to make it work. Here is how I did it:

First step was to add the replay extension to the bayeux client (please note that I am using C#)

var bayeuxClient = new BayeuxClient(endpoint, new [] {transport});
bayeuxClient.AddExtension(new ReplayExtension());

Next I added a listener to the meta/handshake channel. This is where I will do my subscriptions.

bayeuxClient.GetChannel("/meta/handshake").AddListener(new HandshakeListener(bayeuxClient));

The HandshakeListener implements the IMessageListener interface, so it has an OnMessage method where we can perform the channel subscriptions.

public void OnMessage(IClientSessionChannel channel, IMessage message)
{
    _bayeuxClient.GetChannel(channelName, replayId).Subscribe(new Listener());
}

You just need to find a way to store the replayId per channel so you can access it in the HandshakeListener's OnMessage method. I personally created a class that inherits from BayeuxClient and I added a Dictionary<string, long> which contains the channel name and its associated replayId. I then pass the instance of the class to the HandshakeListener who in turn passes it to all the channel listeners. When a message is received in a listener, I update the dictionary with the new replayId.

I still need to look into that because I feel there is an easier way to do this but it works. I tried hardcoding -2 and I received all the changes I had made that day, not just the new ones. I didn't try going back 3 days but I noticed the documentation is saying that this limit is for high-volume events as opposed to 24 hours for standard-volume events.

Hope this helps!

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  • Richard, Which package are you using for _bayeuxClient or COMETD. Is there a link for sample Code or Document ?
    – NSS
    Commented May 7, 2021 at 23:51
  • @NSS I used CometD.NetCore --> github.com/kdcllc/CometD.NetCore Commented May 13, 2021 at 14:20
  • @RichardCormier: This might be a naïve question but does this .net client also captures Change Data Capture vents as well? or it only works for Platform Events ?
    – SharpCoder
    Commented Jan 31, 2023 at 0:27
  • @SharpCoder it seems that it's the same principle for [Change Data Capture] (developer.salesforce.com/docs/…). You just need to listen to the /data/ChangeEvents channel but I never tried it. Commented Feb 1, 2023 at 13:30

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