Is Spring Boot just for Microservices or can I use Spring Boot for Monolithic architecture?
Spring Boot in itself has nothing to do with microservices. It's a Spring module which simply makes the configuration of your app easier. As such, it absolutely can be used in a monolithic app.
From the official docs:
Spring Boot makes it easy to create stand-alone, production-grade Spring based Applications that you can "just run".
We take an opinionated view of the Spring platform and third-party libraries so you can get started with minimum fuss. Most Spring Boot applications need very little Spring configuration.
Features
Create stand-alone Spring applications
Embed Tomcat, Jetty or Undertow directly (no need to deploy WAR files)
Provide opinionated 'starter' dependencies to simplify your build configuration
Automatically configure Spring and 3rd party libraries whenever possible
Provide production-ready features such as metrics, health checks and externalized configuration
Absolutely no code generation and no requirement for XML configuration
Related
I am new to spring framework. I have a confusion regarding spring boot and spring cloud.
I used https://start.spring.io/ to initialize a spring boot application. I think I am using the spring boot framework. However, I would like to use some spring cloud dependencies such as spring-cloud-stream-binder-kafka.
Question 1: If I added this dependency above to my spring boot application, I am wondering if I still can go with the spring boot framework, or I have to change to spring cloud framework.
Question 2: I am wondering if there is any difference when deploying the spring boot or spring cloud application. Or, they just have the different frameworks, and we could deploy them in the same way.
Thank you so much!
You can use together Spring Boot and Spring Cloud packages.
Spring Boot is just a preconfigured Spring Framework with some extra functionalities. It also uses library versions compatibile with each other. Spring Cloud is also the part of the Spring ecosystem, contains libraries that mostly used in cloud applications.
In the background, these packages will pull all necessary Spring (and other) libraries into your project, as transitive dependencies.
So you can use the generated pom/gradle, and add other dependencies. In this case Spring boot will be your core and cloud add extras.
I know that Spring Boot, in contrast to Spring Framework, does not support WAR deployment for Spring WebFlux applications. My question is simple: will it ever in the future?
My use case is this: we have a lot of customers that still live in the traditional "we deploy everything on application server X" world. So although we would like to push standalone JARs, they are not ready (yet). We heavily use Spring Boot, and would really like to continue to do so, so abandoning that is not an option.
We are building reactive applications and would like to use Spring WebFlux for that, but we still need to deploy to application servers, so that is not an option. In the meantime we avoid Spring WebFlux and simply use Controllers, which works, but is not as elegant. Hence my question.
There are no plans to support Spring WebFlux with war deployments. However, you can use reactive return types, Reactor's Mono and Flux and those from RxJava, with Spring MVC packaged and deployed as war. That will allow you to build an entire reactive pipeline as you would with WebFlux, but deployed to an application server. It doesn't give you all of the benefits of full-blown reactive (no event loop-based concurrency, for example), but it can be a good middle ground for those in your situation.
I have a Spring web application - which doesn't use Spring-based GUI, but Wicket - and I would like to build contract-first REST services.
I already have a contract defined in Swagger and I generate model and API artifacts. Swagger codegen generates either Spring Boot artifacts, or Spring MVC ones.
My intention is to use ideally just a model, and maybe API (controllers) from this generated code. But up to my knowledge/research, there is no simple way to have just simple REST service without MVC/Boot boilerplate.
Therefore my questions are:
Is it possible to build lightweight Spring-based REST service, without having "heavy" dependency of full Spring MVC/Spring Boot?
If not, which approach is more lightweight? Spring Boot, or Spring MVC?
You are misinterpreting the Spring ecosystem.
Spring MVC is THE rest web and web service library within Spring portfolio.
The same way as Spring-WS is THE soap web service library.
They are very similar in architecture and style of use.
The fact that Spring MVC is bundled with Spring Framework does not change the situation.
Spring Boot does not bring any new REST offering. It is just a bootstrap mechanism to start Java web server with web app already deployed from a plain main() method. Therefore if you see "Building REST web services with Spring Boot", it just means that it is Spring MVC bootstrapped by Spring Boot.
Therefore, the question to what is more lightweight is straightforward: Spring MVC.
To answer the question #2:
The usage of Spring MVC is more lighweight, then usage of Spring Boot:
Size of the WAR archive:
6,1 MB for Spring MVC
9,2 MB for Spring Boot
Number of libraries in WAR archive:
12 for Spring MVC
28 for Spring Boot
I have just built a RESTful web service with Spring Boot.
I now want to utilise the RESTful web service and start making calls to it by building a java console application (eventually adding GUI and security).
I was wondering if I can use any of the Spring functionality outside of the Spring (Boot) environment and use it in my java console application? For example, can I use Spring's RestTemplate in my non-Spring java application to make the REST api calls? I am new to Spring and I want to stick as close to Spring as possible. I think you can't, but I just want to make sure.
If not possible, I know you can create non-web application with Spring. Is it possible to integrate a GUI? Might not be best practice, just exploring what is possible and conventional.
Spring Boot is not coupled, in any way, to an application type. You can run command-line only apps, batch apps, web apps or any other kind of apps with it. You can even benefit from Spring Boot's auto-configuration.
In the case of the RestTemplate you may want to import spring-web directly rather than spring-boot-starter-web. Or you could add the starter and exclude the embedded container (spring-boot-starter-tomcat). Spring Boot will auto-adapt and not start an embedded web server in that case.
Everything I found on the internet about Spring Cloud Netflix is about running microservices from Boot applications using #EnableEurekaClients and so on.
Now I'm trying to connect my logging microservice within a traditional war application (springmvc, jaxws etc) - piece of legacy which can not be converted to Boot or modified in any way (by technical task).
I've created a new maven module "log-server-client" that knows nothing about upper web layer and intended to be used as a simple dependency in any maven project.
How should I configure access to Spring Cloud Netflix for this simple dependency? At least, how to configure Eureka and Ribbon?
I just extracted some lines of code from RestTemplate and created my custom JmsTemplate (microservice works with jms remoting with apache camel and activemq), exactly how it is done in RestTemplate, but this code stil lacks connection to infrastructure
afaik, we can create a global singleton bean, run a separate thread from this bean, and run Boot app from this thread, but don't you think that it is very ugly and can lead to problems? How it really should be used?
Great question!
One approach is to use a "sidecar". This seems to be a companion Spring Boot application that registers with the Eureka Server on behalf of your traditional web app.
See e.g.:
http://www.java-allandsundry.com/2015/09/spring-cloud-sidecar.html
http://cloud.spring.io/spring-cloud-netflix/spring-cloud-netflix.html#_polyglot_support_with_sidecar
Another approach is to use the following library:
"A small lib to allow registration of legacy applications in Eureka service discovery."
https://github.com/sawano/eureka-legacy-registrar
This library can be used outside of Spring Boot.