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Why Service Oriented Architecture? Sean Farmar @farmar

The Evolution Small monolith Success == growth == features ++ Scaling Maintenance nightmare == high risk So we end up with …

Big Ball of Mud

So I went to my master

Solve the problem you want? Coupling your problem is… Hmmmm SOA your solution will be

Why SOA? SOA's tenets are about reducing coupling.

Coupling Afferent (dependents) Efferent (depend on) Temporal (time, synchronous communication) Spatial (deployment, endpoint address) Platform (protocols, .Net Remoting)

Coupling: Afferent & Efferent Afferent (dependents) Efferent (depend on) Afferent & Efferent solutions: Attempt to minimize Zero coupling is not possible

Coupling: Temporal Temporal (time, synchronous communication) Temporal solutions: Asynchronous messaging Publish Subscribe

Coupling: Spatial Spatial (deployment, endpoint address) Spatial solutions: Delegate service location to the infrastructure, not in application code

Coupling: Platform Platform AKA Interoperability (protocols, .Net Remoting) Platform solutions: XML on the wire. Use standards based transfer protocol like http “Share contract and schema, not class or type”

Fallacies of Distributed Computing The network is reliable. (Bill Joy and Tom Lyon) Latency is zero. (Bill Joy and Tom Lyon) Bandwidth is infinite. (Bill Joy and Tom Lyon) The network is secure. (Bill Joy and Tom Lyon) Topology doesn’t change. (Peter Deutsch) There is one administrator. (Peter Deutsch) Transport cost is zero. (Peter Deutsch) The network is homogeneous. (James Gosling) The fallacies of distributed computing describe common assumptions that are made by developers and architects in distributed systems. In 1994 Peter Deutsch wrote down seven fallacies. In 1997 James Gosling added another fallacy. These fallacies are known as “The eight fallacies of distributed computing”. In the year 2006 Ted Neward added three more fallacies, which are not so widely known. The system is atomic/monolithic. (Ted Neward) The system is finished. (Ted Neward) Business logic can and should be centralized. (Ted Neward)

Fallacies of Distributed Computing Three more... The system is atomic/monolithic The system is finished Business logic can and should be centralized Ted Neward’s blog: http://blogs.tedneward.com/post/enterprise- computing-fallacies/ The fallacies of distributed computing describe common assumptions that are made by developers and architects in distributed systems. In 1994 Peter Deutsch wrote down seven fallacies. In 1997 James Gosling added another fallacy. These fallacies are known as “The eight fallacies of distributed computing”. In the year 2006 Ted Neward added three more fallacies, which are not so widely known.

The Fallacies EBook Go to: http://go.particular.net/developerdays16 1 min.

In practice

In practice Business domain decomposition (entity fields) Vertical Slicing Using asynchronous messaging for state changing operation Publish subscribe Explicit intentions [naming, context] Single Responsibility Command Query Separation “Clean Code” (Uncle Bob)

Monolith Tight Coupling Loose Coupling UI BL DAL DB

Referential Integrity Vertical Slicing Tight Coupling Loose Coupling UI BL DAL Sales Content CRM Ops DB Referential Integrity Re-introduces Coupling

Publish Subscribe [pub/sub]

Publish Subscribe [pub/sub]

Sales Marketing Customer Care Place Order Save status locally Save pricing locally Subscribe to Product Pricing Updated Subscribe to Customer Status Updated Publish Product Pricing Updated Publish Customer Status Updated Marketing Customer Care Publish Order Accepted

Summary SOA/Microservices not a cookie cutter Be Pragmatic, sometimes a monolith is a great solution Avoid all aspects of coupling NServiceBus Particular.net Just do it

Q&A Thank You! Sean Farmar twitter: @farmar Particular.net

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