Spring Cloud

Spring Cloud Function

• Spring cloud function is a project with the following high-level goals.
• Promote the implementation of business logic via functions.
• Decouple the development cycle of business logic from any specific runtime target so that the same code can run as a web endpoint, a stream processor, or a task.
• Support a uniform programming model across serverless providers, as well as the ability to run standalone(locally in a PaaS).
• Enable spring boot features like auto configuration, dependency injection, metrics on server less providers.
• We don’t need to maintain or manage server.
• It abstracts away all of the Transport details and infrastructure, allowing the developer to keep all the familiar tools and processes, and focus firmly on business logic.
• Spring Cloud uses supplier, predicate, consumer and function functional interfaces.
• Spring cloud also uses Lambda expressions.
• Using functional interface we can expose our Endpoints as a function.
• Deploying an AWS function application jar in Lambda.
• Open service AWS lambda
• Go to functions dashboard and create a function
• Select “Auther from scratch”.
• Give function name
• Choose Java 8 as runtime or depending on the runtime you want to deploy on.
• Click create function.
• Once function is created edit its basic function
• Provide your request handler information here
• Example “hello.handle request”.
• com.spring implant.awslambda.SpringAws LambdaApplication.
• Packagename.classname.
• Click save.
• Edit environment variables
• Key is FUNCTION_NAME.
• Value is function name that is orders here.
• Next click on actions and click upload zip or jat file.
• Upload your jar file here.
• Next click on select a test event and configure test events.
• Give an event name.
• Give parameters as per need.
• Click on create.
• Click on test
• this will execute the function.
• Change function name in environment variables and we can test the second function too similarly.
• AWS lambda can be used for server less programming.
• AWS lambda is a server less computing service provided by Amazon to reduce the configuration of servers.
• AWS lambda lets you run code without provisioning or managing servers, it scales automatically and only charges for the time your code is running.
• It is used when we want to expose a Web end point, a Stream processor, Or a task to cloud without depending on server and operating system.
• Spring cloud function is a project with the following high-level goals
• Promote the implementation of business logic via functions.
• In Java 8 We have functional interfaces like supplier, function, consumer, predicate etc.
• We make use of these to create call back functions.
• Decouple that development lifecycle Of a business logic from any specific runtime target So that the same code can run as a web endpoint, a stream processor, or a task.
• Support a uniform programming model across server-less providers, as well as the ability to run standalone (locally or in a PaaS).
• PaaS is platform as a service.
• Enables spring boot features (auto configuration, dependency injection, metrics) on serverless providers.
• Advantages
• Zero server management.
• Flexible scaling
• No ideal capacity.
• Source Code for Spring AWS Cloud app : springmvc/springboot-aws-lambda at master · gauravmatta/springmvc (github.com)
• Source Code: springmvc/spring-cloud-function-example at master · gauravmatta/springmvc (github.com)

Spring Cloud Bus

• All micro services register themselves with cloud bus.
• The cloud bus is in touch with the config server.
• If a particular instance of a micro-service updates The config server and We refresh the config server via “actuator/bus-refresh”. The cloud bus will tell the micro services for a bus refresh via message broker.
• The message could be rabbit, MQ or Kafka or any else. By default, it is Rabbit MQ.
• 
  

• Helps in Service registry and discovery
• Each micro SS will have to register register itself With a centralised server. Other micro services will be able to discover that micro SS And communicate with dynamically.
• Helps in decoupling microservices
• Load balancing
• As the load on our micro service enquiries, we will have to have different instances of the server and load should be balanced.
• Ribbon is used for load balancing.
• Fault Tolerance
• If something goes down In one of the micro services, the entire system should not go down.
• Easy integration
• They should be able to easily communicate with each other.
• Feign client
• Zool Proxy Gateway
• Cross Cutting concerns
• Common requirements across all micro services like authentication, authorisation, , Logging.
• Distributed tracing
• We should be able to twist, how request are going and how response are coming back. Where request went wrong.
• Sluth Is used for distributed tracing.
• Spring cloud configuration server
• We have configuration as a separate micro service.
• Our configuration system should be
• Externalised 
• Environment specific
• Consistent
• Version history
• Real time management
• All instances of a micro service should be consistent and reliable. They should be having same configuration. 
• We have one service for providing configuration.
• All other services connect with the same service to get configuration.
• Options for config as a service
• Apache zookeeper
• ETCD-Distributed key value store
• Hashicorp Consul
• Spring cloud configuration server
• Spring cloud configuration, server directly connects with git repository to get updated files.