Replay 2025 took place March 3–5 in London under the banner "Modernise," bringing together engineers from fintech, logistics, pharma, telecom, and platform engineering to share how they're building production systems on top of Temporal. This wasn't a product launch event disguised as a conference. It was three days of teams who've already shipped talking about what worked, what broke, and what they'd do differently.
The timing matters. Distributed systems are no longer optional — they're the default. And with every team running microservices, event-driven pipelines, and now AI agents, the question has shifted from "should we orchestrate?" to "how do we orchestrate without losing our minds?" Replay 2025 answered that question with war stories from companies processing billions in payments, managing millions of IoT devices, and running drug discovery pipelines that used to take days.
The conference also marked a pivotal moment for Temporal itself: the GA of Nexus for cross-team workflow orchestration, a pre-release Ruby SDK, Worker Versioning APIs, and Temporal Cloud on Google Cloud. These aren't incremental improvements — they're the kind of capabilities that change how you architect systems.
Top 5 Talks (Most Impactful by Views)
1. Durable Execution: This Changes Everything — Tom Wheeler
Tom Wheeler poses a deceptively simple question: "How would you code if your application could not fail?" He contrasts the way senior engineers instinctively design for failure modes — retries, timeouts, partial completions — with how beginners assume the happy path is the only path. The talk builds a compelling case for Durable Execution as a paradigm shift, not just a feature. The practical takeaway: you can write business logic that reads like it runs on a single machine while the runtime handles crashes, restarts, and network partitions transparently.
2. Replay 2025 Keynote Demo: AI Agents Using Temporal
The keynote demo made the strongest case yet for Temporal as infrastructure for agentic AI systems. Rather than hand-waving about the future, the demo showed a working AI agent pipeline built on Temporal, demonstrating how durable execution solves the exact problems that make AI agents unreliable in production: long-running tasks, external API failures, and multi-step reasoning chains that need to recover from partial failures.
3. Getting Started with Worker Versioning — Drew Hoskins & Shahab Tajik
The new Worker Versioning APIs solve one of Temporal's biggest operational pain points — deploying changes to long-running workflows without breaking in-flight executions. Assignment rules, redirect rules, and a versioning model that gives teams fine-grained control. For teams running Temporal in production with frequent deployments, this session is required viewing.
4. Temporal and Spring Boot — Tihomir Surdilovic
A thorough walkthrough of the Temporal Spring Boot integration nearing GA status. Covers configuration, observability, scaling, and testing — the four pillars that determine whether a framework integration works in production. The testing section alone — workflow replay testing and Activity mocking — is worth the watch for Java teams.
5. Salesforce: Migrating a Monolithic Cloud — Trevor Grieger & Austin Deal
Migrating Marketing Cloud onto Hyperforce with 1,000+ engineers involved. Temporal powers the cross-substrate migration system with workflow-driven phases and rollback capabilities. Enterprise scale, proven in production. The architectural patterns are applicable far beyond Salesforce's specific use case.
The full issue covers all 27 talks with detailed summaries, speaker information, and direct YouTube links.
Read the complete article on Talk::Overflow: talkoverflow.substack.com/p/talkoverflow-19-replay-london-2025
Top comments (0)