Patterns for Building and Deploying Microservices

Managing microservices means looking afterlots of small systems talking to each other and automated provisioning as wellas infrastructure automation is crucial, James Lewis states when sharingtechniques and practices that
have helped him manage the increased operationalcomplexity a microservice architecture gives.

James, a consultant working for ThoughtWorks,describes the origin of microservices as a reaction to how we have beenbuilding big monolithic applications that are difficult to change, test andmanage; essentially big balls
of mud with tangled spaghetti code. The solutionbeing building smaller things and make them communicate in some way.

For James microservices means taking a largeapplication, identifying the bounded contexts and business capabilities withinand splitting them out, crucially taking data with them, i.e. applicationdatabases instead of one integration
database. The key thing is starting at thetop with a context map in order to understand the business domain and Jamesrefers to his colleague Ian Cartwright:

There should be business and architecture isomorphism. A business person should be able to look at a high level map of the architecture and see the business represented there and similarly as technologists we should be
able to look at the business and see the architecture represented there.

Animportant aspect of microservices is size and James sees Single ResponsibilityPattern (SRP) as a good measure. A service should have a single reason tochange which in practice means it should be small and focused enough
to bepossible to grasp conceptually.

Acore concept of microservices for James is the possibility to independentlydeploy and scale each service; a service may be deployed as several instancesand different services may be hosted on the same server. When building
anddeploying distributed systems, a focus on automated provisioning is crucialJames emphasizes, each service or application have to be built, deployed andscaled automatically. With microservices a lot of the complexity comes fromintegration but we can apply
patterns to solve this and refers to the bookContinuous Delivery for patterns of build pipelines.

Infrastructureautomation with tools like Chef and Puppet helping in automatic provisioning ofmachines is central in managing the complexity coming with lots of services.Phoenix infrastructure patterns describe how we by using
infrastructureautomation always should be able to recreate all infrastructure, e.g. we shouldbe able to wipe a box and run a script to rebuild it complete with alldependencies.

Related Topics:

1.Microservice
http://martinfowler.com/articles/microservices.html
2.Step by step to build microservice
http://www.simplicityitself.com/courses/1-day-tutorial-introduction-to-building-microservices/
3.Microservice and SOA
http://www.infoq.com/news/2014/03/microservices-soa/