SD Social App

Overview

Developed for the Distributed Systems course, SD Social App is a Twitter-like desktop social platform built to demonstrate core computer networking models and communication protocols.

The project was designed around two distinct network architectures:

• Client/Server Architecture: A centralized server manages persistent user accounts, authentication, online presence tracking, and queues messages for offline users.
• Peer-to-Peer (P2P) Architecture: Nodes establish direct socket connections to bypass the central server whenever both users are online, enabling direct real-time messaging and friend request handling.

Core Features & Network Logic

• Hybrid Routing & Persistence: Built custom logic using Java Sockets for direct peer communication and Java RMI (Remote Method Invocation) for central server operations. File-based logging ensures account credentials and friend lists persist across server restarts.
• Offline Message Queueing: If a recipient is offline, private messages and friend requests are automatically routed to the central server, flagged as “pending delivery,” and pushed to the recipient upon their next login.
• Friends Boards & Group Feeds: Implemented shared message boards accessible across mutual friend networks, functioning as shared feeds where board posts are propagated to authorized peers.
• Presence & Notification Management: Real-time online/offline monitoring allows peers to query network state, with toggleable client notification modes (such as “Do Not Disturb”).

Challenges & Key Learnings

Building a distributed system from scratch without high-level framework abstractions provided deep insight into low-level socket management and async networking:

• Low-Level Socket Architecture: Mastered multi-threaded socket handling, connection pooling, and payload serialization across disparate network nodes.
• JavaFX UI Integration: Created a desktop UI using JavaFX and Scene Builder, synchronizing state updates between background network threads and the main application thread.
• Self-Reliant Implementation: Built raw protocol logic without relying on third-party networking libraries, gaining a thorough understanding of network protocols, edge cases, and thread synchronization.