Should there be a CreateOrUpdateStreamAsync

[alberk8]

There is a CreateOrUpdateConsumerAsync, is it possible to have CreateOrUpdateStreamAsync ?.

[mtmk]

They currently map to JetStream API call and AFAIK STREAM.CREATE does not allow for updating existing streams but it is idempotent and would return the stream if already created with the same configuration so I don't think you can update a stream with this call if you provided different config, can you? Whereas consumer API would allow some of the configuration to be changed.

[alberk8]

Would this be some sort of an equivalent?

StreamConfig streamConfig = new StreamConfig("EVENTS", new[] { "data.>" })
 {    
 };

INatsJSStream stream;

var evnt = await jsContext.GetStreamAsync("EVENTS");

if (evnt != null)
{
    Debug.WriteLine("UpdateStreamAsync");
    streamConfig.MaxAge = TimeSpan.FromMinutes(30);
    stream = await jsContext.UpdateStreamAsync(streamConfig);
}
else
{
    Debug.WriteLine("CreateStreamAsync");
    stream = await jsContext.CreateStreamAsync(new StreamConfig("EVENTS", new[] { "data.>" }));
}

[mtmk]

It's a good idea which would make the API more uniform. Of course it's not the same as consumers i.e. consumer 'upsert' is probably done atomically etc. on the server side. @caleblloyd wdyt?

edit: some other points; it's an expensive call with stream info, it has race conditions. it should really be done on the server to be same as consumers. Maybe it belongs to a higher level api?

[alberk8]

What you are saying is that changing the stream config can cause existing consumer of the stream elsewhere (on another service/app) to experience error?

[mtmk]

AFAIU getting the stream info quite an expensive operation for the server, collecting stats etc. that would be the main issue.

[caleblloyd]

I think you may be able to achieve upsert-like functionality with:

INatsJSStream stream;
try
{
    stream = await js.UpdateStreamAsync(config);
}
catch (NatsJSApiException e) when (e.Error.Code is 404)
{
    stream = await js.CreateStreamAsync(config);
}

I have mixed feelings about putting this in the library as CreateOrUpdateStreamAsync though because as @mtmk points out this is not an atomic server-side operation.