#messaging
messaging

Critter Stack in Review: message loss fixes, clean shutdown and multi-tenancy

JasperFx shipped 72 tagged releases across Wolverine, Marten and shared libraries between October 12 and 30. The headline theme is a durable inbox and outbox hardening pass that closed about a dozen ways messages could go missing or run twice, much of it driven by community bug reports. For .NET developers running durable messaging, the review also covers performance fixes, cleaner shutdown and multi-tenant Marten changes.

CritterWatch 1.1 groups dead letters by failure cause and acts on each group at once

CritterWatch 1.1 groups dead letters by the failure that produced them, merging matches across every monitored service and database into one row. An operator can replay, archive, restore or discard a whole group as a single tracked operation with a required reason. The release also exposes the same loop through MCP, so teams running Wolverine can handle incidents faster and check whether replayed messages failed again.

Wolverine Best Practices Revisited: A-Frame and Handler Design

JasperFx rewrote the Wolverine best practices guide from scratch, replacing the 2023 version. The new guide centers on the A-Frame Architecture and gives concrete advice on splitting handlers, error handling, and at-least-once messaging rules. It is a practical reference for .NET teams building messaging systems with Wolverine.

CritterWatch 1.1, Bobcat 1.0 and AI Skills 1.17 ship; Stoat preview arrives

JasperFx shipped a coordinated Critter Stack release wave: CritterWatch 1.1, Bobcat 1.0, AI Skills 1.17 and a Stoat 0.5.0 preview. CritterWatch's MCP server now exposes 83 tools, and Bobcat 1.0 turns existing test methods into executable specifications. Worth a look if you run Wolverine or Marten in production or write integration tests on the .NET stack.

Seven emails later: duplicate messages are not a theoretical problem

Mauro Servienti uses a shipping notification that arrived seven times to explain how duplicate messages happen in messaging systems. The post separates duplicates caused by sending, receiving and processing, and lists practical defenses for each. It is a useful read for any .NET developer building queue-based systems.

Wolverine 6.52.0 adds named connections and timer agents

Wolverine 6.52.0 is a feature release adding connection-string-name registration for every transport and message store, timer agents for recurring schedules under 15 minutes, and groundwork for Wolverine 7.0. It also changes behavior: frequent schedules now run on timer agents, and unmappable outgoing envelopes are dead-lettered. Developers running Wolverine messaging should review these changes before upgrading.

Wolverine 6.51.3: durable inbox and outbox hardening

Wolverine 6.51.3 is a durability release that fixes a run of problems in the durable inbox and outbox. A new receiver compliance suite exercised PostgreSQL, SQL Server, Marten, EF Core, RabbitMQ and SQS, and the fixes cover transactions, deduplication, retries and dead lettering. There are no breaking API changes, and the one schema addition is optional.

Kafka Consumer Recovery: Resuming Processing After a Crash

Kafka consumers must pick up where they left off after a restart, crash or network failure. This article explains how committed offsets, consumer groups and manual commits govern recovery, using a C# example built on Confluent.Kafka. It also covers duplicate deliveries, poison messages and the monitoring signals that reveal a consumer quietly falling behind.

A weekend Node.js library with transactional outbox and NServiceBus compatibility

Mauro Servienti released Zusammen, an alpha Node.js library that brings the NServiceBus transactional session idea to Node.js. Business data and outgoing messages are committed together in one MongoDB transaction, with a control message and tombstone guarding dispatch to RabbitMQ. It is also a useful case study in AI-assisted development, and a concrete look at the outbox pattern for .NET developers.

Rebuilding Marten Projections Without Downtime with Wolverine 6.51 Warm-up Nodes

Wolverine 6.51 adds a warm-up node role for blue/green deployments. New nodes join the cluster only to rebuild new projection versions in Marten or Polecat, without handling messages or subscriptions. Combined with versioned projections and a side-effect gate, teams can catch up read models before switching traffic. This is a practical path to zero-downtime releases for event-sourced systems.

Serverless Wolverine Gets a Transactional Outbox in Wolverine 6.51

Wolverine 6.51 adds the DurabilityMode.ServerlessWithOutbox mode, letting handlers running on Cloud Run, AWS Lambda or Azure Functions keep the transactional outbox without always-on background agents. An externally triggered durability pass recovers messages that failed to send, and push receivers accept broker deliveries over HTTP. It is a useful option for teams on tight serverless budgets.