Dr. Javier Gonzalez-Sanchez [email protected] www.javiergs.info o ffi ce: 14 -227 CSC 508/9 Software Engineering (Design & Deployment) Lecture 08. Distributed Systems 

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Assignment 01 Design 

Code (and Design) Review 5 https://github.com/javiergs/ADASIM • Draw the class 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. 

1. Java Desktop Application Eye Tr a cking Simul a tor (size, speed) 6 

Eye Tracking • Tobii Sp a rk https://www.tobii.com/products/eye-trackers/screen-based/tobii-pro-spark • Tobii SDK https://www.tobii.com/products/softw a re/ a pplic a tions- a nd-developer-kits/tobii-pro-sdk 7 

2. Java Desktop Application A ff ect Recognition (speed) 8 

Brain-Computer Interfaces • Emotiv He a dsets https://www.emotiv.com/ • D a t a S a mples https://emotiv.gitbook.io/cortex-api/data-subscription/data-sample-object 9 

3. Java Desktop Application He a d Movement 10 

4. Java Desktop Application Cobot Simul a tor 11 

Cobot • Univers a l Robotics e-Series https://www.universal-robots.com/media/1802432/e-series-brochure.pdf • Comm a nds th a t c a n be used https://s3-eu-west-1.amazonaws.com/ur-support-site/29983/Script command Examples.pdf 12 

5. Java Desktop Application Hub 13 

Distributed System Architecture 

Architecture 15 

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). WebSockets • - Wh a t: Full-duplex communic a tion protocol over a single TCP connection. • - How: En a bles persistent, bidirection a l communic a tion between client a nd server in re a l- time. • - Use C a se: Re a l-time a pplic a tions like live ch a ts, g a ming, a nd stock tr a ding pl a tforms. 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. 16 

Client-Server Sockets 

Client-Server 18 

Implementation :: Server 19 chrestomathy: https://www.javatpoint.com/socket-programming 

Implementation :: Client 20 chrestomathy: https://www.javatpoint.com/socket-programming 

Client-Server WebSockets 

Reference 22 https://shorturl.at/YHiBY 

Publisher-Subscriber MQTT 

Message Queuing 24 

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) org.eclipse.paho org.eclipse.paho.client.mqttv3 1.2.5 25 

https://github.com/CSC3100/MQTT 

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. 27 

https://github.com/CSC3100/MQTT 

Questions 29 

CSC 509 Software Engineering Javier Gonzalez-Sanchez, Ph.D. [email protected] Fall 2025 Copyright. These slides can only be used as study material for the class CSC509 at Cal Poly. They cannot be distributed or used for another purpose.