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Ankur in Spring

Zuul to Spring Cloud Gateway Migration: Routes, Filters, and the Blocking-Call Traps

The first time I ported a Zuul gateway to Spring Cloud Gateway, the routes took an afternoon — and the filters took two weeks. That ratio surprises every team that attempts this migration, because the route configuration looks superficially similar while the filter model is a different universe: Zuul 1 is a blocking servlet filter chain, Spring Cloud Gateway runs on Netty with Project Reactor, and a single hidden blocking call in a ported filter can stall your entire gateway. This guide covers the route conversion, the filter-by-filter port, and the blocking-call traps, in that order.

1 min read
Ankur in Spring

Spring Cloud Netflix to Modern Alternatives: The Complete Migration Guide (2026)

In 2020 I published a dozen tutorials on this site covering Eureka, Hystrix, Zuul, Ribbon, and Feign — the Spring Cloud Netflix stack. They were accurate then. Today, most of that stack is dead: Netflix put Hystrix into maintenance mode back in 2018, Zuul 1 and Ribbon followed, and the Spring team removed them from the Spring Cloud release train entirely. If you are still running any of these libraries on Spring Boot 2.x, this guide maps every Netflix component to its modern replacement and shows you the actual migration steps — including the parts that break.

1 min read
Ankur in JUnit

JUnit 6

Complete guide to JUnit 6 with links to all articles covering getting started, core patterns, advanced techniques, mocking, extensions, integration testing, and best practices.

5 min read
Ankur in Java

20 AI Prompts for Java Concurrency and CompletableFuture

20 copy-paste AI prompts for Java concurrency and CompletableFuture — from basics to advanced production patterns and debugging. Covers thread pools, ExecutorService, CompletableFuture chaining, fan-out/fan-in, timeout handling, virtual threads, deadlock diagnosis, thread dump analysis, and full concurrency audits.

2 min read
Ankur in 8086

8086 Flag Register: All 9 Flags, Conditional Jumps, and Critical Traps

All 9 flags of the 8086 flag register explained: CF, PF, AF, ZF, SF, OF (status) and TF, IF, DF (control) with exact set/clear conditions, the CF vs OF unsigned/signed distinction, the four traps that catch every beginner, and a complete conditional jump reference.

1 min read
Ankur in 8086

8086 Microprocessor Architecture: BIU, EU, Pipeline, Pin Diagram, and I/O

How the Intel 8086 splits work between the Bus Interface Unit (BIU) and Execution Unit (EU) to create a two-stage pipeline, with the complete 40-pin signal reference (minimum and maximum mode), T-state bus cycle timing, even/odd memory banks, and the full I/O subsystem including 8255 PPI, 8259 PIC, and 8253 timer.

1 min read