ESB Patterns & Implementation with MassTransit

Origins:

Last year at Alt.NET there was a discovered need for a bus systems.  Rather than developing two proprietary messaging systems, work together to build framework and open source it.

If nothing else is gotten out of MassTransit, MassTransit is easier than working with System.Messaging

Resources:

• Gregor Hohpe - http://www.eaipatterns.com/ramblings.html
• integrationpatterns.com - http://integrationpatterns.com/
• Fowler, Patterns of Enterprise Application Architecture - http://martinfowler.com/books.html
• SOA Patterns - Arnon Rotem-Gal-Oz - http://www.manning.com/rotem/
• Enterprise Service Bus (David Chappell, not THAT David Chappell) - http://www.amazon.com/Enterprise-Service-Bus-David-Chappell/dp/0596006756
• Saga paper (from Cornell, need author info here)

Moving from Batch to Trickle processing, why is this valuable - If you have to carry inventory a batch processing between systems introduces lag.  The more systems, the greater the lag.  In this example, inventory will be off by an amount that affects inventory and costs.

Where is MassTransit at in Dev. lifecycle

• 0.1 -> 0.2 contained a lot of pain, learned a lot about maintaining backward compatibility
• Currently working on refactoring various bits in the core
• Following apache model and are solidifying interfaces before releasing a 1.0 version.  Once a version goes 1.0 the interface should not change.

     

Testability of MassTransit -

• MassTransit uses a lot of interfaces.  You can "new up" a new Saga and set a few properties and call methods.

Bus systems, allow for extensibility.  If you want to put a new solution in place, it becomes very easy to do so.

YAGNI or Extensibility?

Publishing messages which are not yet consumed or asked for (in terms of business need), is this breaking YAGNI?  Depends on how much you adhere to YAGNI.  The publish call, is a call to a HashSet (so it is a very quick call).  Ultimately the implementor, you, must decide.

Asked from the crowd: Does ESB negate the need for WCF? - MassTransit supports of WCF Transport, if you have legacy code that uses WCF, you may not be able to rip out legacy code in favor of ESB.

Private queues are recommended, since the integration story with ActiveDirectory (for public queues) is not very good.

Actions from Sunday

From our actions on Sunday, the wiki for MassTransit has been created.