Distributed Application Framework
MassTransit is a framework for building distributed applications using asynchronous messaging in .NET. It provides a consistent API and behavior across supported transports.
MassTransit
MassTransit is a distributed application framework for .NET for building message-based systems that are reliable under load, testable during development, and observable in production.
MassTransit gives .NET teams a consistent way to build message-based applications on brokers such as RabbitMQ, Azure Service Bus, Amazon SQS, ActiveMQ, and SQL (PostgreSQL or SQL Server).
MassTransit is more than an abstraction layer. It defines the programming model and supports operational patterns needed for building long-lived distributed systems: message contracts, consumers, retries, redelivery, outbox, scheduling, workflows, and a unit test harness.
What MassTransit Is
Section titled “What MassTransit Is”Message-Driven Programming Model
Define contracts, produce messages, consume messages, and compose workflows. Use command, event, and request/response patterns without rebuilding plumbing for each service.
Production-Oriented by Default
Reliability and operability concerns are first-class: retries, delayed redelivery, outbox support, fault handling, scheduling, and observability.
Built for .NET Applications
MassTransit integrates with dependency injection and hosted services, so consumers and workflows run as part of your application without custom bus lifecycle code.
Why Teams Use It
Section titled “Why Teams Use It” Contract-First Design Use explicit message contracts to keep boundaries clear and reduce coupling across services and teams.
Transport Portability Use the same programming model across supported transports, while still tuning behavior for each broker.
Testability Use the test harness and focused patterns to verify message flows, consumers, sagas, and activities.
Resilience Controls Apply retries, redelivery, outbox, rate limiting, partitioning, and circuit protection in the receive pipeline.
Operational Visibility Capture telemetry and runtime behavior so distributed systems can be monitored and diagnosed in production.
Workflow Coordination Model long-running processes with saga state machines, routing slips, and job consumers.
Feature Map
Section titled “Feature Map” Messaging Patterns Send, publish, and request/response patterns for service communication.
Reliability Patterns Retry, redelivery, outbox, fault handling, and pipeline controls.
Workflow Saga state machines, routing slips, and job consumers for complex processes.
Transports and Riders RabbitMQ, Azure Service Bus, Amazon SQS, ActiveMQ, SQL Transport, plus Kafka and Event Hub riders.
Topology and Serialization Configure message topology, serialization, and broker-specific behavior.
Testing and Diagnostics Validate distributed behavior with tests and observe runtime behavior with telemetry.
Golden Path
Section titled “Golden Path” 1. Learn the Concepts Understand contracts, consumers, producers, workflows, and transport semantics before implementation.
2. Build with Guides Create contracts, consumers, tests, and workflows using focused, working examples.
3. Configure for Production Apply transport, middleware, and operational configuration for reliable runtime behavior.
Architecture Mindset
Section titled “Architecture Mindset”Treat messages as your boundary, and keep behavior behind consumers, state machines, and activities.
Contracts Define Boundaries Use message contracts as stable ports between services so implementations can evolve without breaking integration.
Consumers Are Adapters Keep transport and endpoint concerns in consumers, while domain behavior stays in application services.
Topology Is Explicit Make exchanges, topics, queues, and bindings intentional so routing behavior is observable and maintainable.
Failure Is a First-Class Concern Design retries, redelivery, outbox, and fault handling up front to keep behavior predictable under failure.
Start Here
Section titled “Start Here”If you are new to MassTransit, start with contracts and consumers, then add reliability patterns.
Massient, Inc. Over the past fifteen years, MassTransit has grown to become the most popular distributed application framework for building message-based applications with .NET. Massient is the new company behind the commercial release of MassTransit v9. Learn more on our website.
Additional Resources
Section titled “Additional Resources”YouTube Channel
Be sure to check out PhatBoyG’s YouTube channel for videos on MassTransit.
Discord
The Discord server is a great place to ask questions and discuss implementation details with other users.