diagram. • Then make a table listing all class names and, for each class, answer the following: • (1) Does it have a single responsibility, and if so, which one? (2) Is the class or interface necessary? (3) Is it part of the view, model, or controller? (4) If it is a blackboard, is its design and usage correct? (5) If there is an issue(code or design), explain and suggest a possible solution.
item is m a inly a bstr a ct (interf a ces, a bstr a ct cl a sses – extensible but not directly us a ble); or (b) it is m a inly concrete (implement a tions – directly us a ble but less extensible). • It is a v a lue between 0 a nd 1: 0 ( a concrete cl a ss or a p a ck a ge with only concrete cl a sses) 1 ( a n a bstr a ct cl a ss/interf a ce or a p a ck a ge with only a bstr a ct cl a sses/interf a ces) 15
item is m a inly used by others (st a ble – h a rd to ch a nge); or (b) it m a inly depends on other items (in-st a ble – ch a nge a ble). • It is a v a lue between 0 a nd 1: • 0 only incoming dependencies to • 1 (only outgoing dependencies). 16
a ho? • A set of MQTT client libr a ries developed by the Eclipse Found a tion. • It supports multiple l a ngu a ges, such a s J a v a , Python, J a v a Script, etc. J a v a Dependency (M a ven) <dependency> <groupId>org.eclipse.paho</groupId> <artifactId>org.eclipse.paho.client.mqttv3</artifactId> <version>1.2.5</version> </dependency> 21
This option is suitable when message loss is acceptable, as it doesn't require acknowledgment or persistence. • 1 – "at least once": This option should be chosen when message loss is unacceptable, and your subscribers can handle duplicate messages. • 2 – "Exactly once": This option is ideal when message loss is unacceptable, and your subscribers cannot handle duplicate messages. 23