I am somewhat new to java and spring.
We have the requirement of reading the file of some thousand records and calling micro service developed in spring boot deployed on PCF.
I have two approaches in my mind. One is we have simple spring boot application where it reads the file and call required micro service. The other is to develop spring batch with dummy item writer which calls micro service.
Confused which one to choose. Any advise here will be appreciated.
Related
and if not what are more things that we can do with spring boot?
i know that we can build a whole web app(frontend and backend) in one spring boot application in the folder resource/template and resource/static but in the real world does somebody uses this method to create web application with the resource/template and resource/static?
and one more question what is used in the real world hibernate(with the SessionFactory or EntityManager) or JpaRepository in the spring data jpa?
No Spring Boot isn't just for REST APIs.
Spring Boot is "just" a mechanism for autoconfiguring a Spring Framework based application.
Therefore you can use and it does get used for all kinds of stuff.
REST APIs for webservices
Full web application using Spring MVC
SOAP services (or are they called SOAP dispensers?)
Reactive web applications
Command line tools
Batch jobs
Swing / JavaFX applications
...
Of course there are many more people writing web applications than Swing applications with or without Spring.
The kind of web application you describe and which I put under "Full web application using Spring MVC" is a very well established model and when done right way better aligned with the principles of REST than the average so called REST service. My very personal guess is: They will still be around when nobody remembers what Angular is.
For your additional question:
Your question sounds a little like the relation between JPA and Spring Data JPA might not be completely clear.
(see Spring Data JDBC / Spring Data JPA vs Hibernate)
Both are certainly used in real world projects. By definition more projects use JPA than Spring Data JPA since the first is a superset of the later.
This involves complete Spring history,
Actual motive of Spring was to enable loose coupling , so that unit tests can be easily performed . Spring MVC was for developing web applications with Model View Controller having their proper boundaries.
Then Spring Boot which enabled developer to focus on business logic then configurations. That's why spring boot is a good choice for microservices.
For JPA or hibernate query , many people prefer using JPARepositoy as again you just have to define entity for the repository and Spring boot automatically provides you queries like findById and so on.
In short Spring boot have made it really easy to run the applications with different configurations and environment smoothly.
I have been working for a while with Spring micro-services and have no come across Apache Camel as a tool for building micro-services. I'm unclear -- is Apache Camel a replacement for creating micro-sevices with Spring Boot or does it add functionality / short-cuts to developing such services with Spring Boot? It's already fairly simple to create microservices with Spring Boot so it's hard to imagine what Apache Camel would add but that is the essence of my question.
Apache Camel has nothing to do with microservices.
It's an implementation of the Enterprise Integration Patterns: https://www.enterpriseintegrationpatterns.com/
Apache Camel provides an implementation for most of the patterns from the book from Gregor Hohpe and Bobby Woolf. Plus a variety of inbound and outbound endpoints to integrate with systems like the file system, FTP, HTTP, Messaging, Facebook etc.
Find more information on the website: https://camel.apache.org/
There is a Spring Boot Starter project to run Camel in a Spring Boot application:
https://camel.apache.org/spring-boot.html
what Apache Camel would add, that is the essence of my question
In service of declaring REST based microservices, Camel's REST DSL provides a fluent API for declaring microservices. Take for example:
rest("/books").produces("application/json")
.get().outType(Book[].class)
.to("bean:bookService?method=getBooks(${header.bookCategory})")
Should tell you at a glance that requests to the path /books will get you a List of Book, as long as you send a request parameter named bookCategory. This is mapped to a POJO bean called bookService.
Spring Boot is a framework which simplifies application packing and startup while Spring is the actual framework which has libraries for performing various tasks.
Technically, we can use Camel for building micro-services as well and many aspects of camel depend on Spring. If you foresee many integration related functionality like sending email or communicating with other system, you can use also use Hexagonal architecture.
I'm trying to learn SI (Spring Integration) but i'm a bit confused on the real usage of this.
As first example i would like to interact with a WebService but i dont understand what could be the difference from
Invoke a WebService Using SI
Invoke a Webservice using RestTemplate
So, what is the benefit of using SI (in Webservice context, or in other context)?
Looking the web, i havent find an article that explain:
Usually you will do in this way....
With SI you can do better - in this another way - and the benefit are....
To be more explicit on what i have to realize, this is an example:
1) I have to write an application (Standalone application) that have to collect some data in the system periodically and then invoke a Web Service that will store it.
2) The Web Service receive the call from the "clients" and store in the database.
My webservice will use REST.
The reason because i've think to use SI is that the Standalone Application should interact with different system
Webservice in first instance
A Web Mail, if the webservice is not achievable
File system if Web mail is not achievable too
If you only need to pull some data in a simple way and push it onwards to a REST service this does not "justify" the use of Spring Integration. A simple Spring (Boot) application combined with a scheduler will be sufficient.
But if you want to use a more complex data source for which an endpoint is available, you need transformations, complex and flexible routing is a high priority or even Enterprise Integration Patterns (EIP) then Spring Integration is for you. Have a look at the Overview and decide if it mentions something you consider as valuable to you.
Perhaps you will create additional value by mixing in Spring Batch if you need to process a lot of data.
But as I understand your current demand starting with just a RESTTemplate should do for the moment. Starting small will not prevent you from switching to Spring Integration later on.
Have a look at the various tutorials and guides provided by the Spring Boot project. There is even an example for Spring Integration.
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.
I have an existing stand-alone Spring Boot (CommandLineRunner) application that generates JSON payloads, currently written to the local file system. Though I could tail that file easily in Spring XD, I'd rather have the entire Spring Boot application run as either a source or job module in Spring XD, but I'm having some difficulties making the conversion. Does anyone know of a Spring XD sample where the XD module (source or job) is the creator/originator of outgoing messages, instead of using some sort of inbound adapter from another external system? (Maybe my entire premise is misguided, but I want the application to be managed by Spring XD so that I don't have to manage another out-of-band orchestration tool to start and stop the JSON-generating process.)