Cloud ClassroomRui Chen, Hao-Yu Hsieh, Jen-Chieh Huang

Outline• Motivation & Goals• Technical Details• iOS App Architecture• EC2 Server Architecture

• Demo & Conclusion & Future work

Motivation• You find yourself in a presentation, and …• You just have no slides, and you don’t know what the guy is

talking about.• You’re just late, and too far to read the screen…• And …

• In a code review/discussion meeting,• How do people exchange code pieces?

The Cloud Classroom includes• Class management

• User sign-in and sign-up• Create/delete class• Join/leave class• Instructor privileges

• Material sharing• Real-time material sharing• Support for various material types• Presentation privilege transferring

• Multi-platform support• Mobile devices – iOS• Desktop platform – OS X, Windows

System Overview

iOS App Architecture

iOS App Architecture - View Controllers

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iOS App Architecture - Model• Multiple views/view Controllers share a single model -

Message Center. • Since our application logic is almost based on the responses from

the server and instructors, we use a single model as control center to deal with all communication between server and iOS app. In this way, we can easily implement the app in different type of iOS device.

• Model (3 layers)• Message Center: it’s the interface to view controllers• Communication Handler: it deals with message sending, receiving,

queuing, and error checking• Socket Connection: it handles socket connection

• iOS SDK only supports to Core Foundation level

iOS App Features• Energy Saving• After receiving all expected responses, the app will close

socket connection and switch to push notification mode until having another request to send.• Use timeout mechanism to avoid the case that it doesn’t

disconnect because of missing any expected response.

• High tolerance for incorrect states• Since push notification is not reliable, the app is able to be

recovered from most incorrect states that caused by missing messages from server.

Server Software Architecture

Conclusion• By all the entities, we successfully create a real-time

material sharing system.• Students and Instructor can share the materials to one

another.• All operations are performed in real-time.• Access control and privilege control are also supported.

• Toward a more efficient system• Use passive update to reduce power consumption.• Separate data server and signaling server to enhance the

system capacity.• Introduce database system (SQLite) to increate the

scalability.

Future Work• Toward a more security classroom• Secure messages• Anonymous access• Content watermarking

• Enabling a more active participation• Online discussion• Instant question

• Full multimedia experience• Read-time multimedia experience• Courseware anywhere anytime