Category Archives: Architecture

Microservice, enterprise system, design partern

What is the behavior of the annotation @Autowired with regards to field injection, constructor injection, and method injection?

The following are the types of dependency injections (DI) that could be injected into your application: Constructor-based dependency injection Setter-based dependency injection Field-based dependency injection The constructor injection pattern It is more suitable for mandatory dependencies, and it makes a strong dependency contract It provides a more compact code structure than others It supports testing… Read More »

Get Client IP Address in HttpServletRequest

1. Problem. This note is to improve How to get client Ip Address in Java post to friendly display to clients and related issues. The display could be shown like a figure below: Client also want to see IP address in details as Google IP Address example: 2. Solution. In order to get a real… Read More »

Singleton Pattern

1. Definition. Singleton Pattern makes sure that a class only have one instance and provide a global point of access to it. It also belongs to Creation Pattern Group. Singleton Pattern should be used where we only need one of: Thread pools, caches, dialog boxes, object that handle preferences and registry settings, objects used of… Read More »

Observer Pattern

Observer Pattern defines a one-to-many relationship between a set of objects. When the state of one object changes, all of its dependents are notified/updated automatically. It also belongs to Behavior pattern group. 1. A customized notification system. Several newspaper agencies like CNN, NYTime, BBC are subscribed to a feed of new tweets and may want… Read More »

Advantages and Disadvantages of Microservices

To begin with an interesting question, is a microservice architecture a good choice for the system you’re working on? Basically, micro-service often deals with large team, multi-tenancy, supporting many user interaction models, allowing different business functions to evolve independently, and scaling. However, the best answer is it depends on complexity and productivity. If a system… Read More »

Factory Pattern

Factory Pattern is to create object through a common interface/ abstract class. It belongs to Creational Pattern group. 1. Real-life example Suppose that we have two different types of instruments in capital market – one with an Equities and another with a Dept. A company want to use an instrument to raise capital, and represents… Read More »