2018 Java Recommended library for easily creating microservices

Overview

I would like to introduce a recommended library to use when implementing microservices in Java. This time, I selected the library based on the following three points.

• Targets RESTful API microservices that send and receive via HTTP
• Make it a simple library that can be used easily to reduce installation costs and learning costs (full stack is not applicable)
• De facto standard and library with a lot of usage records

Spark Framework

• Easy microservices with Spark Framework!

Gson / Jackson

Since microservices operate in cooperation with multiple services, messages are exchanged. In that case, format conversion is important. I think that there are many conversions between Java (object) and Json, but Gson is often used (supported) in other libraries. gson) and Jackson. Whichever you like, please. However, for example, a library uses Jackson as a stack (it has a dependency), but using Gson includes two types of libraries for the same purpose (format conversion). It is not preferable because it becomes. Looking at the stack as a whole, you should select Jackson in this case.

Bean Validation

Bean Validation (JSR-303) that checks the input by adding a special annotation is easy. Since Bean Validation is a specification, an implementation library is required to use it. Hibernate-validator is a well-known implementation library, so we recommend that you use it.

**(Caution) When running on a Java EE server, you have the option of not using hibernate-validator because the implementation of Bean Validation is also on the server. This time, we are introducing hibernate-validator in consideration of microservices that can be operated even in a normal Java process. ** **

(Added 6/10/2018)

• Easy input check with Bean Validation!

Sql2o

• Easy database access with Java Sql2o

Feign

• Feign, which implements an API client with just an interface, is very convenient!

Jedis

I think that the number of cases where KVS (Key Value Store) is used as a cache has increased. The most commonly used of KVS is Redis, and the famous Java client is Jedis.

Paho

Paho is a well-known client of MQTT. We provide libraries for various programming languages such as Java, .net (C #, VB.net), Python, etc. (I also use Paho when using MQTT in programming languages other than Java)