A Minimalist Guide to Building Spring Boot Angular 5 Applications

Over the last year, I have worked with many teams using Spring Boot with Angular/React for developing Java web applications. I consider Spring Boot a pragmatic opinionated way to build Spring applications. Spring Boot makes it easy to build web applications in Java and provides a productive environment for development.
Continue reading “A Minimalist Guide to Building Spring Boot Angular 5 Applications”

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Keeping Spring Boot Powered REST API Request and Response Objects Minimal

I am a big fan of Spring Boot. It is my preferred choice for building REST APIs in Java. It takes less than 5 minutes(given that you have Maven dependencies on your local machine) to get started with Spring Boot thanks to its auto configuration. In this blog, I will talk about a specific aspect of building REST API with Spring Boot. We will look at the request and response objects. The request object that you receive during the HTTP POST request and response object that you send in the response of HTTP GET request. I will discuss how you can keep these request and response objects to the bare minimum so that we can avoid writing and maintaining useless getters and setters.

Continue reading “Keeping Spring Boot Powered REST API Request and Response Objects Minimal”

Spring Test Failing with A ServletContext is required to configure default servlet handling

If you are getting exception shown below in your Spring test

Caused by: java.lang.IllegalArgumentException: A ServletContext is required to configure default servlet handling
at org.springframework.util.Assert.notNull(Assert.java:112)
at org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer.(DefaultServletHandlerConfigurer.java:54)
at org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport.defaultServletHandlerMapping(WebMvcConfigurationSupport.java:330)
at org.springframework.web.servlet.config.annotation.DelegatingWebMvcConfiguration$$EnhancerByCGLIB$$c733f512.CGLIB$defaultServletHandlerMapping$22()
at org.springframework.web.servlet.config.annotation.DelegatingWebMvcConfiguration$$EnhancerByCGLIB$$c733f512$$FastClassByCGLIB$$b76778f9.invoke()
at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228)
at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:285)
at org.springframework.web.servlet.config.annotation.DelegatingWebMvcConfiguration$$EnhancerByCGLIB$$c733f512.defaultServletHandlerMapping()
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:160)

Then to fix this error migrate to Spring 3.2 release. Change the maven dependency as shown below

<dependency>
 <groupId>org.springframework</groupId>
 <artifactId>spring-context</artifactId>
 <version>3.2.0.RELEASE</version>
</dependency>

Spring Roo PGP Exception

Today when I fired Spring Roo shell I started getting exception as shown below and I was not able to execute any command. I uninstalled Spring Roo (thinking that it might have got corrupted) but it didn’t helped after lot of firefighting I figured out the solution to overcome this problem. The problem was that yesterday I trusted some pgp keys and somehow Roo was not able to find them and started throwing exception. The solution is to remove a file name .spring_roo_pgp.bpg and restart Spring Roo. Spring Roo will create a new clean file. Continue reading “Spring Roo PGP Exception”

Fixing Exception — Entity manager has not been injected (is the Spring Aspects JAR configured as an AJC/AJDT aspects library?)

If you are working with Spring Roo and suddenly start getting exception “Entity manager has not been injected (is the Spring Aspects JAR configured as an AJC/AJDT aspects library?)” then make sure you have _Configurable.aj ITD in your project. This ITD makes the sure that your entity classes have all the required dependencies like EntityManager injected in them. Configurable ITD  looks like as shown below

privileged aspect Movie_Roo_Configurable {

    declare @type: Movie: @Configurable;

}

Spring Roo + OpenShift Express == Extreme Productivity In Cloud Part 1

Today, I released the second version of OpenShift Express Spring Roo Add-on. With this release add-on also support creation of domain namespace and changing the domain namespace. Now the only important thing left in the add-on is support for session management so that users does not  have to enter email and password with every command. From today, I am starting a series of short blog posts which will cover the features of this add-on. In this post I will be  talking about creating and changing domain namespace. Before I get into details lets me first tell you what is Spring Roo and OpenShift Express in case you don’t know about them.

Note :You can also refer to my Spring Roo series on IBM DeveloperWorks for more details.

What is Spring Roo?

Spring Roo is a lightweight productivity tool for Java™ technology that makes it fast and easy to develop Spring-based applications. Applications created using Spring Roo follow Spring best practices and are based on standards such as JPA, Bean Validation (JSR-303), and Dependency Injection (JSR-330). Roo offers a usable, context-aware, tab-completing shell for building applications. Spring Roo is extensible and allows add-ons, enhancing its capability.

What is OpenShift Express?

OpenShift Express is a Platform as a Service offering from RedHat. OpenShift Express allows you to create and deploy applications to the cloud. The OpenShift Express client is a command line tool that allows you to manage your applications in the cloud. It is currently free and runs on Amazon EC2. Currently it supports Java, Ruby, PHP, Python run times. You can refer to OpenShift Express documentation for more details.

OpenShift Express Client Tools

OpenShift Express has three client tools for creating and deploying applications to cloud. These are RHC Ruby Gem., OpenShift Express Eclipse Plugin, and SeamForge RHC Plugin. I have mainly used RHC Ruby Gem and it is very easy to use and work. There were two problems why I decided to write Roo add-on. One is that you need Ruby Runtime and second is I use Spring Roo a lot so it allows me to perform full lifecycle of the application from within Roo shell. Because I am writing add-on I can also do lot of interesting stuff like session management, making some changes to the code to avoid repetitive work. One such thing that I have already added is adding OpenShift profile in the pom.xml. This will help me automate repetitive work.

Lets Get Started

Getting started with the add-on is very easy. First you need to download Spring Roo and fire the Roo shell. Once inside the Roo shell we have to install the add-on. To do this execute the following command as shown below.

osgi start --url http://spring-roo-openshift-express-addon.googlecode.com/files/org.xebia.roo.addon.openshift-0.2.RELEASE.jar

It will take couple of seconds to install the add-on. You can view that a new OSGI process has started using osgi ps command.

Creating Domain

Before you can create domain please signup at https://openshift.redhat.com/app/express.  The email and password with which you signup will be the credentials for accessing the cloud. After you have signed up the next step is to create a domain. You can’t create the applications before creating a domain. The domain is a logical name within which all your applications will reside. It forms the part of your application url. For example if you created a domain with name “paas” and application with name “openshift” your application url will be http://openshift-paas.rhcloud.com . We can create the domain using rhc-create-domain command but in this blog I will show you how to create using Spring Roo add-on. To create domain using Spring Roo execute the command shown below.

rhc create domain --namespace openpaas --rhLogin <rhlogin> --password <password> --passPhrase <passphrase>

This command does the following things :

  1. It will create the ssh keys under user.home/.ssh folder if they does not exist. The passphrase is required for creating the sshkeys.
  2. If ssh keys already exists it loads the ssh keys from user.home/.ssh location and reuse them.
  3. finally it creates the domain with namespace openpaas.
  4. In case your credentials are wrong it will show a log line saying that credentials are wrong.

Changing Domain Namespace

Although you can’t delete a domain after you have created but you can change the domain name. To do that you can use the command shown below.

rhc change domain --namespace xyz --rhLogin <rhlogin> --password <password>

This will change the domain name to xyz.

Thats it for this blog. In the next blog we will look at how to create Spring JPA application using Spring Roo and deploy it to OpenShift Express.