Microservices

-

 Microservice Architecture is a Service Oriented Architecture.

The microservice defines an approach to the architecture that divides an application into a pool of loosely coupled services that implements business requirements.

The most important feature of the microservice-based architecture is that it can perform continuous delivery of a large and complex application.

Microservice helps in breaking the application and build a logically independent smaller application.

Principles of Microservices
    There are the following principles of Microservices:
        1) Single Responsibility principle
        2) Modelled around business domain
        3) Isolate Failure
        4) Infrastructure automation
        5) Deploy independently

Microservices Monitoring Tool
    There are three monitoring tools are as follows:
        1) Hystrix dashboard
        2) Eureka admin dashboard
        3) Spring boot admin dashboard

Components of Microservices
    There are the following components of microservices:
        Spring Cloud Config Server
        Netflix Eureka Naming Server
        Hystrix Server
        Netflix ZuulAPI Gateway Server
        Netflix Ribbon
        Zipkin Distributed Tracing Server

Spring Cloud Config Server (port - 8888)
Spring Cloud Config Server provides the HTTP resource-based API for external configuration in the distributed system. 
We can enable the Spring Cloud Config Server by using the annotation @EnableConfigServer.
spring.cloud.config.uri=http://localhost:8888
spring .profile.active=dev 

Netflix Eureka Naming Server (port - 8761)
Netflix Eureka Server is a discovery server. 
It provides the REST interface to the outside for communicating with it. 
A microservice after coming up, register itself as a discovery client. 
The Eureka server also has another software module called Eureka Client. 
Eureka client interacts with the Eureka server for service discovery. 
The Eureka client also balances the client requests.

Hystrix Server
Hystrix server acts as a fault-tolerance robust system. 
It is used to avoid complete failure of an application.
It does this by using the Circuit Breaker mechanism.
If there is an error encountered in the application, the Hystrix Server opens the circuit. 
The Hystrix server stops the further request to calling service.

Netflix Zuul API Gateway Server (port - 8765)
Netflix Zuul Server is a gateway server from where all the client request has passed through. 
It acts as a unified interface to a client. 
It also has an inbuilt load balancer to load the balance of all incoming request from the client.


SOLID Principles Java
    SOLID principles are an object-oriented approach
    It is conceptualized by Robert C. Martin (also known as Uncle Bob)
  1. Single Responsibility Principle (SRP) - every Java class must perform a single functionality
  2. Open-Closed Principle (OCP) - the module should be open for extension but closed for modification.
  3. Liskov Substitution Principle (LSP) - derived classes must be completely substitutable for their base classes.
  4. Interface Segregation Principle (ISP) - the larger interfaces split into smaller ones.
  5. Dependency Inversion Principle (DIP) - use abstraction (abstract classes and interfaces) instead of concrete implementations. 

Load Balancer
    HLB - Hardware Load Balancer
        L4 & L7 (Transport Layer & Application Layer)
        F5 Hardware
        UDP, TCP, SCTP
        HTTP, HTTPS, SMTP, IMAP, FTP, DNS, NNTP
    SLB - Software Load Balancer
        L7 (Application Layer)
        NGINX
        HTTP, HTTPS, SMTP, IMAP, FTP, DNS, NNTP

API Gateway

Service Registry

Service Discovery


Layers Model

The OSI Reference Model:

Application - Layer 7 (HTTP URL, Path, Params)
Presentation - Layer 6
Session Layer - Layer 5
Transport - Layer 4 (IP, Port, Protocol, TLS)(Load Balancer)
Network Layer - Layer 3
Data Link Layer - Layer 2
Physical Layer - Layer 1
^|^|^|^|^|^|^|^|^|^|^
Physical Medium


Comments

Post a Comment

Popular posts from this blog

PL/SQL

-
PL/SQL PL/SQL stands for Procedural Language extensions to the Structured Query Language (SQL). PL/SQL can execute a number of queries in one block using single command. One can create a PL/SQL unit such as procedures, functions, packages, triggers, and types, which are stored in the database for reuse by applications. The PL/SQL engine resides in the Oracle engine. The Oracle engine can process not only single SQL statement but also block of many statements. Structure of PL/SQL Block: DECLARE     declaration statements; BEGIN     executable statements EXCEPTIONS     exception handling statements END; / Example : SET SERVEROUTPUT ON; SQL> DECLARE        var varchar2(40) := 'I love GeeksForGeeks' ;      BEGIN        dbms_output.put_line(var);      END;      / PL/SQL Functions PL/SQL functions are reusable blocks of code that can be used to perform specific tasks. They are...
Read more

JAVA8 Features

-
Java8 Features 1) Lambda Expressions : Concise functional code using ->. Lambda Expression basically expresses an instance of the functional interface, Lambda Expression provides a clear and concise way to represent a method of the functional interface using an expression. 2) Functional Interfaces : Single-method interfaces. An interface that contains only one abstract method is known as a functional interface. There is no restriction, that can have n number of default and static methods inside a functional interface. A functional interface is an interface that contains only one abstract method.  @FunctionalInterface annotation is used to ensure that the functional interface can’t have more than one abstract method. Runnable, ActionListener, and Comparable are some of the examples of functional interfaces.   Runnable –> This interface only contains the run() method.   Comparable –> This interface only contains the compareTo() method.   ActionListener –> ...
Read more

Build Automation

-
ANT: Ant was the first build tool released in 2000. Ant was developed on procedural programming idea. Ant was improved with an ability to accept plug-ins and dependency management over the network, with the help on Apache-IVY. Drawbacks: 1) XML is used as a format to write the build scripts. 2) Being hierarchical is not good for procedural programming, and 3) XML is relatively unmanageable.   MAVEN: Maven was introduced in 2004. Maven relied on the conventions and was able to download the dependencies over the network. Benefits : Life cycle of Maven, while following the same life cycle for multiple projects continuously. Problems: 1) Maven does not handle the conflicts between versions of the same library. 2) Complex customised build scripts are difficult to write in Maven, as compared to writing the build scripts in ANT. GRADLE : Gradle came into picture in 2012 Features  Declarative builds and build-by-convention 1) Gradle is available with separate Domain Specific Language ...
Read more