Build a Price Aggregator Service in Java | Learn CompletableFuture with Real Example (Part 1)

In this video, we build a **real-world Price Aggregator in Java** and compare **sequential vs asynchronous API calls** using `CompletableFuture`. Instead of just theory, we **simulate real response times** from multiple vendors and measure how performance changes when we move from blocking calls to parallel execution. You’ll learn: * Why sequential API calls slow down your application * How `CompletableFuture` enables parallel execution in Java * Real latency comparison (with simulated vendor delays) * How this pattern is used in **microservices and system design interviews** This is **Part 1** of a series where we evolve a simple Java program into a **highly scalable distributed system**. Perfect for: * Java developers (freshers to experienced) * Backend engineers preparing for system design interviews * Anyone building high-performance APIs **Next part**: handling failures, timeouts, and scaling this into microservices. *Complete Playlist* - https://youtube.com/playlist?list=PLq3uEqRnr_2Ek7y2U3UAiQZCPzr0a82CX&si=RBeq-7RG5kQ_W7bs --------------------------------------------------------------- 📚 Popular Playlists 🔥 System Design https://www.youtube.com/playlist?list=PLq3uEqRnr_2F6vigodG2KdvQTmt9Gim83 🔥 Spring Boot Interview Questions https://www.youtube.com/playlist?list=PLq3uEqRnr_2HNEhqdeiSslXYR7mojWGPY 🔥 Java Interview Questions https://www.youtube.com/playlist?list=PLq3uEqRnr_2E8fpzIaHTfKJWvAAMq7s0c 🔥 Scaling from 0 to Billion https://www.youtube.com/playlist?list=PLq3uEqRnr_2H2B9kK2g9-7_-rn2uXMdRa 🔥 Kafka Basics https://youtu.be/w0PvkFfbtZs 🔥 Kafka with Spring Boot https://www.youtube.com/playlist?list=PLq3uEqRnr_2FxD5iPebGYs7ploRFFOG1I 🔥 Microservices Architecture https://www.youtube.com/watch?v=uPndlp0kbok&list=PLq3uEqRnr_2EDsuxPboP9_WtVRR_TaMrF 🔥 Microservices Demo https://www.youtube.com/watch?v=Uw8Qicia3H0&list=PLq3uEqRnr_2He0bLb7XW8Mq7egwQZ-V8n 🔥 Microservices Testing https://www.youtube.com/watch?v=1vWWgwELQWM&list=PLq3uEqRnr_2GuTTkLZL5GU1wZH2FqJRRP 🔥 Wiremock for API Testing https://www.youtube.com/watch?v=VouscOgOmZE&list=PLq3uEqRnr_2FKs8K3_kIG9g93Uy9dVdtR 🔥 Circuit Breaker Demo https://www.youtube.com/playlist?list=PLq3uEqRnr_2FZpfjnp_jol_F0mFFogo_S 🔥 Caching with Spring Boot https://www.youtube.com/playlist?list=PLq3uEqRnr_2HY6LMQsbvsK4btj51sWhBS 🔥 Unit Testing in Java https://www.youtube.com/playlist?list=PLq3uEqRnr_2GYMK6_WEYRlT5kyD8qx98M --------------------------------------------------------------- 🌐 Connect with Codefarm *LinkedIn* https://www.linkedin.com/in/codefarm0/ *Medium* https://codefarm0.medium.com/ *GitHub* https://github.com/codefarm0 *Twitter* https://twitter.com/arvind4gl --------------------------------------------------------------- ⚠️ *Disclaimer* The content and opinions expressed on this channel are personal. Code samples shared here are for educational purposes and can be reused for learning. --------------------------------------------------------------- #Java #CompletableFuture #AsyncProgramming #JavaDeveloper #BackendDevelopment #SystemDesign #Microservices #PerformanceOptimization #CodingInterview #SoftwareEngineering #SpringBoot #Concurrency #TechEducation #codefarm