NewMemoryBroker is build a Broker implement by memory.

WithTimeout is set subscriber receive message timeout.

WithTopic is set message topic or set subscriber only subscribe some topic.

the timeout key name in options.

the topic key name in options.

ErrBrokerClosed is defined broker close error.

MemoryBroker is a Broker implement by Memory use map and channel.

Broker is defined a message queue broker.

Option is callback function to edit Options.

Options is used to extend for subscribe method.