Microservices

12 factor app pattern

Four-tier application architecture

Two key attributes of microservice architecture:

1.     Loosely coupled:  means that you can update the services independently; updating one service doesn’t require changing any other services.

2.     bounded context: A microservice with correctly bounded context is self‑contained for the purposes of software development. You can understand and update the microservice’s code without knowing anything about the internals of its peers, because the microservices and its peers interact strictly through APIs and so don’t share data structures, database schemata, or other internal representations of objects.

Best practices for designing a microservices architecture:

1.     Create a separate data store for each microservice.

2.     Keep code at a similar level of maturity: if you need to add or rewrite some of the code in a deployed microservice that is working well, create a new microservice for the new or changed code.  Then deploy and test the new one.  Then merge/combine them.

3.     Do a separate build for each microservice.

4.     Deploy in containers.

5.     Treat servers as stateless.

More info: https://www.nginx.com/blog/microservices-at-netflix-architectural-best-practices/

API Gateway

·       Ngnix

·       Netflix Zuul 1

·       Spring Cloud Gateway

·       Linkerd

Their performance comparison:

https://engineering.opsgenie.com/comparing-api-gateway-performances-nginx-vs-zuul-vs-spring-cloud-gateway-vs-linkerd-b2cc59c65369

OpenAPI

OpenAPI Specification (formerly known as Swagger spec) is the industry standard for defining REST APIs.

Sample:

    swagger: "2.0"
    info:
      title: "Airport Codes"
      description: "Get the name of an airport from its three-letter IATA code."
      version: "1.0.0"
    # This field will be replaced by the deploy_api.sh script.
    host: "YOUR-PROJECT-ID.appspot.com"
    schemes:
      - "https"
    paths:
      "/airportName":
        get:
          description: "Get the airport name for a given IATA code."
          operationId: "airportName"
          parameters:
            -
              name: iataCode
              in: query
              required: true
              type: string
          responses:
            200:
              description: "Success."
              schema:
                type: string
            400:
              description: "The IATA code is invalid or missing."

API spec edit APICURIO:

https://www.apicur.io/

hapi-swagger:

https://github.com/glennjones/hapi-swagger