Book Image

Building Microservices with Spring

By : Dinesh Rajput, Rajesh R V
Book Image

Building Microservices with Spring

By: Dinesh Rajput, Rajesh R V

Overview of this book

Getting Started with Spring Microservices begins with an overview of the Spring Framework 5.0, its design patterns, and its guidelines that enable you to implement responsive microservices at scale. You will learn how to use GoF patterns in application design. You will understand the dependency injection pattern, which is the main principle behind the decoupling process of the Spring Framework and makes it easier to manage your code. Then, you will learn how to use proxy patterns in aspect-oriented programming and remoting. Moving on, you will understand the JDBC template patterns and their use in abstracting database access. After understanding the basics, you will move on to more advanced topics, such as reactive streams and concurrency. Written to the latest specifications of Spring that focuses on Reactive Programming, the Learning Path teaches you how to build modern, internet-scale Java applications in no time. Next, you will understand how Spring Boot is used to deploying serverless autonomous services by removing the need to have a heavyweight application server. You’ll also explore ways to deploy your microservices to Docker and managing them with Mesos. By the end of this Learning Path, you will have the clarity and confidence for implementing microservices using Spring Framework. This Learning Path includes content from the following Packt products: • Spring 5 Microservices by Rajesh R V • Spring 5 Design Patterns by Dinesh Rajput
Table of Contents (22 chapters)
Title Page
Copyright
About Packt
Contributors
Preface
Index

Implementing Advice


As you know that, Spring provides five types of advices, let's see work flow of one by one.

Advice type - Before

Let's see the following figure for before advice. This advice executes the before the target method:

As you can see in figure, before advice is executed first and then it calls the Target method. As we know that Spring AOP is proxy-based. So a Proxy object is created of target class. It is based on Proxy design pattern and Decorator Design Pattern.

Before Advice example

Let's see the use of @Before annotation:

    //Before transfer service 
    @Before("execution(* com.packt.patterninspring.chapter6.
    bankapp.service.TransferService.transfer(..))")  
    public void validate(){ 
      System.out.println("bank validate your credentials before amount 
      transferring"); 
    } 
 
    //Before transfer service 
    @Before("execution(* com.packt.patterninspring.chapter6.
    bankapp.service.TransferService.transfer(..))")  
    public void transferInstantiate...