No, this isn't necessary to simply publish and subscribe.
AMPS doesn't have any requirement to predefine topics for publish and subscribe. You can publish to whatever topic name your application needs to, and subscribe to any topic your application needs to subscribe to (including regular expression topics).
To persist messages, though, a configuration must explicitly specify the topic or topics to be persisted.
Defining a Topic in the
SOW section of the configuration file enables record-based current value caching for a topic. (This also allows AMPS to provide out-of-focus messages, provide a view over the topic, allow queries for the current state of records, and so on).
Specifying a Topic in the
TransactionLog section of the configuration file enables record and replay for that topic. (This also allows AMPS to replicate the topic, provide subscriptions that can be resumed at the correct point in time after server or application failover, use that topic as the message source for a queue, and so on.)
Most AMPS configuration files include topic definitions.
However, these definitions aren't required for simply publishing and subscribing to topics -- they are only required to enable features that require retaining messages.