CRUDApi return values

[obermeier]

Some REST calls return messages. E.g. POST /api/v2/pipelines returns a SuccessMessage document.

This messages are currently not accessible by the Java-Api user. Since the interface does not return this information.

What do you think about the idea to extend the org.apache.streampipes.client.api.CRUDApi<K, V>to provide this Message to the developer?

void create(V element); vs. R create(V element);

This influences the other implementations of this Interface.
Does this Message make sense for DataLakeMeasurementApi, DataProcessorApi, DataSinkApi, DataStreamApi ...

[dominikriemer]

Good question - I think this makes sense and we could check that for the other classes as well. In addition, we should also think about returning ErrorMessage objects when something goes wrong in addition to the HTTP status.
Do the other APIs also return success messages or empty responses with an 200 status?

[obermeier]

@dominikriemer very good point

In the current implementation delete has a Message.class as response with subtypes SuccessMessage and ErrorMessage .

If delete is used jackson could not create the message becuase it is abstract.
Cannot construct instance of `org.apache.streampipes.model.message.Message` (no Creators, like default constructor, exist)

Is there a mechanism in jackson to instanciate the matching class?

Do you prefer to return the generic Message or a subtype (Adding some logic to find which type fits best)

The signature would be something like this.
org.apache.streampipes.model.message.Message create(V element);