Distributed Computing

One 45-50 minute period

In this brief intro lesson, students will brainstorm and discuss how Distributed Computing is part of our daily lives. They will be introduced to fundamental ideas related to Distributed Computing (DC). They will create NetsBlox accounts in preparation for Unit 1.

Connect DC to students’ lives to motivate learning of this module.

Distributed Computing (DC), Remote Procedure Call (RPC), Message Passing, Heterogeneity, Latency, Concurrency, Transparency, Security, Privacy,  Scalability, Resiliency

• What is Distributed Computing?

• Distributed Systems Goals and Challenges
• Some Issues, Challenges and Problems of Distributed Software System

1-2 (45-50 min) periods

In this lesson, students will be introduces to the Services in NetsBlox (specifically GoogleMaps and Weather).

TSW understand what an RPC custom block does and how it can be used to access the Google Maps and weather service. TSW be able to use RPCs to create a map with weather information

Distributed Computing (DC), Remote Procedure Call (RPC), Network Latency

• GoogleMaps
• Weather
• Geolocation

• Slides
• Completed Project (Teacher Reference)
• Step-by-Step Guide (Teacher Version)
• Step-by-Step Video (Teacher Version)

Urge students to come up with their own ideas. Here are some examples:

• Translate to language of the region
• Give choice of Centigrade or Fahrenheit
• Display multiple temperature indicators on the map
• Temperatures at locations of interest
• "Which place is hotter?" guessing game
• Store or Service locator for your community

2-3 (45-50 min) periods

In this lesson, students will be Introduced to lists and gain more experience with Remote  Procedure Calls (RPCs)  Students will learn how to create applications that display images of lead cast members in popular movies, movie posters, and additional information about cast members using TheMovieDatabase (TMDb).

After this lesson, students will be able to:

• Create and manipulated lists
• Explain the difference between lists and primitive values
• Understand the need for unique identifiers

Array/List, Element, Iterate/Iteration, Index, Primitive Value, Remote Procedure Call (RPC), Unique Identifier, Service

• MovieDB

• Understanding Lists and Intro to MovieDB

• Walkthrough (in slides):  Create a list of 10 random numbers between 1 and 100
• Practice (in slides):  Find the largest number in a list
• Activity 1:  MovieDB Poster
• Activity 2:  MovieDB CastShow
• Activity 3:  Extend MovieDB project

• Movie Posters (completed)
• Movie Cast Show (completed)
• Movie Simple Cast Show (cycles through images of main actor/actress)

• Movie Posters Walkthrough Video
• CastShow Walkthrough Video

• MovieDB Pacing Guide
• MovieDB Summary
• MovieDB Activity Walkthrough

• Video of the TheMovieDB API – Get a sense for how NetsBlox is abstracting complexity for easy access to internet data sources

Urge students to come up with their own ideas. Here are some examples:

• Larger grid of images (using cloning)
• Movie trivia quiz game
• Learn more about a favorite actor/actress (date of birth, biography, filmograph, etc.)
• Create actor/actress guessing game as shown on Ellen’s Game of Games (“Hot Hands”)
• How many movies did both X and Y act in?

In this unit students will be introduced to a NetsBlox supported charting service called Chart which uses the gnuplot open source charting app. The charting service will allow students to create custom charts and graphs using two remote procedure calls (RPCs). Students will also be introduced to more useful ways of getting and storing collections of related data through the use of multidimensional lists/arrays.

Student will:

• Explore ways of charting data using the Chart service
• Create a custom chart/graph to plot real-world data
• Understand that a list/array can be used to store a collection of data to be used in a program
• Build upon prior knowledge of distributed computing through the use of RPCs to get real-world plottable data from other NetsBlox services, such as MovieDB, Science, and Maps introduced in prior lessons.
• Apply understanding of lists/arrays to store and access information to be plotted
• Evaluate whether the graph created accurately represents the data set chosen to plot/graph

Remote Procedure Call (RPC), Data Structure, Multi-dimensional List/Array, Indexed Variable, Element

• Chart (specifically the “draw” RPC)

• Understanding multi-dimensional lists/arrays
• Intro to basic plotting with the NetsBlox Chart service
• Plotting with NetsBlox using CO2 data
• Create your own graph using other RPCs in NetsBlox

• 5-Day Daily Pacing Guide
• Lists and Plotting Slides (includes student plotting activity)
• Climate Change Plotting (includes student covid-19 activity)
• Teacher Step-by-step Plotting Guide
• Completed CO2 Data Plotting Project (teacher reference)
• Interactive COVID-19 Map

• Historical Temperature
• Ice Core CO2 Data
• Compare CO2 vs Temp over the past 800,000 and 100 years
• Degree Days in Alaska
• Cumulative COVID-19 Data
• Daily COVID-19 Data

• Ice core data background info

In this lesson, students will be introduced to message passing and related networking abstractions in NetsBlox (specifically, the room and roles).

Students will be able to:

• Explain the difference between messages and events, both in terms of the use od the network and the data payload
• Demonstrate the ability to use message passing for basic communication in a NetsBlox application

Room, Role, Message, Message Type, Event

• Distributed Hello World!
• Dog Animation

Urge students to come up with their own extensions, but here are some examples:

• Add another role to the project so it runs across 3+ screens
• Enable the animation to change directions so it can be sent back to the previous screen
• Enable multiple animations simultaneously (using cloning)

• Completed Hello World! Project
• Completed Distributed Animation Project
• Daily Pacing Guide
• Distributed Animation Summary

• Hello World! Guide
• Distributed Animation Guide
• Distributed Animation Starter Project (also available

In this lesson, the students will create custom messages and will be able to create a collaborative whiteboard application where two users can draw on each other’s stage.

Students should:

• Gain more experience with message passing
• Be able to reason about the impact of protocol design on the granularity/smoothness of collaboration
• Gain more experience reasoning about the impact of design decisions in a distributed setting on the resultant application

Room, Role, Message, Message Types, Custom Messages, Latency, Concurrency

• Collaborative Whiteboard

• Completed Collaborative Whiteboard Project
• Collaborative Whiteboard Step-by-step Guide (also available: video guide)

• Collaborative Whiteboard Starter Project

In this lesson, students will create an application where users can message each other without a central server by passing messages among peers. Each peer in the network can send messages, receive messages, or simply pass messages along.

Students will:

• Create an application where students can pass messages through a mesh network
• Understand peer-to-peer and client-server network architectures and be able to tell the limits and benefits of each
• Experience what happens to messages in the network as changes are made and nodes are faulty

Nodes, Fault-Tolerance, Peer-to-Peer Networking, Redundancy, Resiliency

• Mesh Network Lab
• Written Activity: Identify uses of Mesh Networks in Everyday Life

• Mesh Networking Slides
• Mesh Network Lab Step-by-Step Guide (teacher reference)
• Completed Mesh Network Project (also available: video walkthrough)

• Misc. Resources

2-3 Days

In this lesson, students will be introduced to a new way to write a distributed program.  Instead of using multiple roles, it will use multiple instances of the client program, all communicating with the server program using project to project message passing.

Students will be able to:

• Pass data to another project using the rolename@projectname@username syntax
• Establish a basic communication protocol

Message Passing, Protocol, Global Address, Role, Project

• Chat Room

• Completed Simple Chat Server (teacher reference)
• Completed Simple Chat Client (teacher reference)
• Simple Chat Guide (teacher reference)

• Simple Chat Server (starter)
• Simple Chat Client (starter)

45 minutes x 5 – 10 days

In this project, students will come up with a project to work on for the entire unit (5-10 days, depending on scheduling), either as an individual or in teams of 2-4. Project ideas should be related to distributed computing and can use pieces and concepts from previous lessons. Note that students are not limited to only concepts that have been covered previously.

This is meant to be a creative unit where students come up with their own project concepts, but if students are struggling for ideas, here is a list of example directions:

• Turn-based games. The NPlayer service (demo) in NetsBlox makes it easy to set up distributed, multiplayer turn-based games that use message passing between projects to control the game state (the NPlayer service simply handles turn order, but not other aspects of the game logic). Students are free to come up with what kind of game to make, but we provide the 21 Pebbles game as an example. Starter Project. Step-by-Step Guide. Completed Project.
• Make your own service.
• Animation-based games.

• NetsBlox Service Documentation