Remove USubscription CreateTopic() and DeprecateTopic() APIs

[stevenhartley]

The topic lifecycle APIs were added as an optimization early on so that subscribers could know if the topic they are subscribing to is valid and the producer is alive however this optimization has given us nothing but heartburn in production as it forces all publishers to call the API when then are initialized and it causes race conditions on initial boot-up. Furthermore, validation of topics could already be done by calling UDiscovery so there was no added benefit of adding the extra states to the subscription service.

#96

[sophokles73]

LGTM

[sophokles73]

@AnotherDaniel this might be of interest to you as well, since you are working on an implementation ...

[lynn2009]

@stevenhartley , The uSubscription still requires verification of whether the requested topic is valid. By removing the createTopic method, this implies a strong dependency on uDiscovery for its functionality.

[stevenhartley]

@stevenhartley , The uSubscription still requires verification of whether the requested topic is valid. By removing the createTopic method, this implies a strong dependency on uDiscovery for its functionality.

@lynn2009 , why do you need to check the topic is valid or not?

[lynn2009]

If uSubscription does not check the topic is valid or not, we will run into the case the subscriber can subscribe an invalid topic and get success response.

[stevenhartley]

If uSubscription does not check the topic is valid or not, we will run into the case the subscriber can subscribe an invalid topic and get success response.

correct

[mayureshkar]

@stevenhartley @lynn2009 with createTopic removed, what constitutes an 'invalid topic'?

[stevenhartley]

invalid UUri