CSC364 Lecture 10

Introduction to Networked, Distributed, and Parallel Computing
Publisher-Subscriber
(202602)

Transcript

1. Dr. Javier Gonzalez-Sanchez javiergs@calpoly.edu www.javiergs.info o ffi ce: 14 -227 CSC 364 Introduction to Networked, Distributed, and Parallel Computing Lecture 10. Publisher-Subscriber 1
2. Communication Protocols Sockets • - Wh a t: Low-level communic a tion mech a nism for exch a nging d a t a between two systems. • - How: Utilizes TCP/UDP protocols for reli a ble/unreli a ble d a t a tr a nsfer. • - Use C a se: Direct communic a tion between client-server a pplic a tions (e.g., f ile tr a nsfer a nd ch a t). MQTT (Mess a ge Queuing Telemetry Tr a nsport) • Wh a t: Lightweight mess a ging protocol designed for low-b a ndwidth, high-l a tency networks. • How: Uses a publish-subscribe p a ttern for e ff icient communic a tion between devices. • Use C a se: Ide a l for IoT a pplic a tions, sm a rt home devices, a nd sensor networks. 2
3. MQTT Wh a t is MQTT? • MQTT (Mess a ge Queuing Telemetry Tr a nsport) is a lightweight, publish-subscribe network protocol. • Designed for constr a ined devices a nd low-b a ndwidth, high-l a tency, or unreli a ble networks. Key Fe a tures • Simple a nd e a sy to implement. • Low b a ndwidth consumption. • Reli a ble mess a ge delivery. • Sc a l a ble to millions of devices. 3
4. Message Queuing 4
5. MQTT Architecture Broker • The centr a l server th a t h a ndles mess a ge distribution. • Ex a mples: Mosquitto, HiveMQ, EMQX, AWS MQ. Clients • Devices or a pplic a tions th a t publish (send) a nd subscribe (receive) mess a ges. • Ex a mples: Sensors, mobile a pps, a nd IoT devices. Topics • Hier a rchic a l n a mesp a ces for org a nizing mess a ges. • Ex a mple: home/livingRoom/temper a ture. 5
6. Code MQTT
7. Eclipse Paho for Java Wh a t is Eclipse P 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> 7
8. https://github.com/CSC3100/MQTT
9. Quality-of-service options • 0 – "at most once": A.K.A. "fire-and-forget." 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. 9
10. https://github.com/CSC3100/MQTT
11. Game 11
12. Dependencies
13. Library • A collection of resources (cl a sses) • A J a v a Archive, or JAR f ile, cont a ins a ll of the v a rious components th a t m a ke up a self- cont a ined, execut a ble J a v a a pplic a tion or, most commonly, a J a v a libr a ry to which a J a v a Runtime Environment c a n link. 13
14. jar-download.com 14
15. • Build m a n a gement tool • M a ven a utom a tes dependency m a n a gement by a utom a tic a lly downlo a ding required libr a ries a nd their dependencies, ensuring consistent builds with speci f ied versions. • In contr a st, m a nu a lly downlo a ding JARs is l a bor-intensive a nd error-prone. 15
16. • The project object model (POM) f ile describes a project a nd its dependencies. • A st a nd a rdized directory form a t. • Repositories where third-p a rty softw a re is stored a nd discovered. 16
17. Create a project with Maven support 17
18. Or Add Framework Support 18 Do one of these
19. Or Add Framework Support 19
20. Maven File and Directories 20
21. POM.xml 21
22. Maven Repository 22
23. Adding a New Dependency 23
24. Multiplayer Brokerverse
25. MultiPlayer Game 25
33. Questions 33
34. Lab.
35. 35 To be continued… "tcp://broker.hivemq.com:1883"
36. Chat 36 Remote: Local: ABC Remote: ABC Local:
37. Game 37
38. CSC 364 Introduction to Introduction to Networked, Distributed, and Parallel Computing Javier Gonzalez-Sanchez, Ph.D. javiergs@calpoly.edu Winter 2026 Copyright. These slides can only be used as study material for the class CSC 364 at Cal Poly. They cannot be distributed or used for another purpose. 38