microservices

microservices

1. definition

   • architecture
     • breaks code into chunks
     • instanciate code as needed
   • properties

2. topology

   • exists some patterns. 3 are the commonly used
   • Elements
     • API (gateway)
       • acts as a controller, handling and directing request
       • locate individual microservices
         • can be used to discover services
       • message oriented
       • interact with other APIS but not directly to microservices
     • microservices
       • small pieces of code that do only one thing
       • know about each other's existence, but not what they do
       • receives input from API, other microservice or the back end
       • runs its own process
     • back end
       • dont know anything of API and client
       • can be a database, webservice, or any other destination
       • should have messaging and logging capabilities
       • talks to the API
       • Never communicates directly with microservices (encapsulated)
   • mS communication
     • based in IPC (Interprocess communication mechanism)
     • first dimension
       • one to one
         • a single service instance handle the request
         • interactions
           • request/response (maybe syn)
           • notification
           • request/response asyn
       • one to many
         • multiple service instances handle the request
         • interactions
           • publish/subscribe
           • publish/response asyn
     • second dimension
       • synchronous
       • asynchronous
     • IPC technologies
       • http or thrift
         • Synchronous
           • should be used for external requests
       • AMQP or STOMP
         • Asynchronous
           • should be used for microservices intercommunication
       • JSON or XML
         • Should be used for external messaging
       • Avro or protocol buffer

3. disadventages, considerations

   • considerations
     • distribuited system can be hard to work with
     • high complexity because its arch. includes glue elements
     • network congestion and latency
     • data consistency when passing data between services

4. infrastructure

   • open source
     • OS
       • CoreOS
       • Atomic (Red hat)
       • Canonical
       • VMware
     • container
       • Docker
       • Swarm
       • Kubernetes
       • Azure
         • Service Fabric ( container orchestration)
       • each container run in a thread
     • monitoring
       • prometheus
       • ELK
       • cAdvisor
     • virtualization

5. Netflix

   • Open Source Software (OSS)
     • main components
       • Eurieka
         • Service Registry (its just a service which coordinates another mS)
         • ensure mS are always reachable
         • handles
           • self- registration
           • thid part registration
         • load balancer
       • Hystrix
         • latency tolereace enforced library
         • controls the interactions between microservices
         • contains the microservice which is having issues and avoid the propagation
       • Ribbon
         • client side technology
         • reduces the number or hops needed for services to communicate( load balancer)
         • handle communication between services
       • Zuul Api Gateway
         • Mains functions is be the Gateway
         • handle over 2 billion request per day
         • dinamic route, stress testing,
     • other netflix and 3rd part libraries
       • netflix nebula
         • is a collection on gradle plugins
         • allows package and deploy application faster
       • Spinnaker
         • multi cloud continous delivery platform
         • manages deployment pipelines

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