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Showing posts from 2017

How to Stand up a Spring Cloud Config Server?

Setup and Configure Spring Cloud Config Server Project

Spring Cloud Config Server is just another Spring Boot application. It provides several infrastructure micro services to centralize access to configuration information backed by a version controlled (well at least in the case of default GIT storage) repository.

Step 1 - Create a Spring Boot project in STS with the dependencies shown in Figure 2.

Click on 'Finish' to complete the creation of the Spring Boot project in STS.
The build.gradle file is shown in listing below. There is only one dependency to the Spring Cloud Config Server. Also Spring Cloud release train 'Dalston.SR1'.
Step 2 - Annotate the class containing main method
The next step is to annotate the ConfigServerInfraApplication class with @EnableConfigServer
That's all is needed on the Java side to start the configuration server.

Step 3 - Final step, create the configuration file.
Finally, create a file named bootstrap.yml and configure it as shown in …

Upgrading Lead Microservice - Use MariaDB and Flyway with Spring Boot

So far I have been using an in-memory H2 database or Mockito for testing the lead microservice. To make the transition towards using the Spring Cloud Config server, I need to upgrade the micro-application to use MariaDB. I will be adding the configuration in the application.yml  the file which in the subsequent post will move over to the config server store. I will also be using Flyway to make it easy to maintain the database schema changes in future. I will use this post to introduce Flyway in the mix. Spring Boot also provides first class integration with Flyway. I am using Flyway as its really quick and easy to get started, minimal learning curve (no DSL) and I am comfortable with it having used it in the past.


MariaDB 10 is installedBasic familiarity with FlywayHeidi SQL client is installed.
Step 1 - Update build.gradle to include the MariaDB JDBC and Flyway dependencies.
Do not forget to do a Gradle refresh on your IDE (I am using STS 3.8.4 on Java 8)

Step 2 - Rename the…

Why do you need Spring Cloud Config server?

Last month I wrote a primer on concepts around 12 factor app. Before getting into the details of the Spring Cloud Config Server, I must refresh on the principle #3 from the list presented in that post.

3 – ConfigurationStore config in the environments
Configuration information must be separate from the source code. This may seem so obvious, but often we are guilty of leaving critical configuration parameters in the scattered in the code. Instead, applications should have environment specific configuration files. The sensitive information like database password or API key should be stored in these environment configuration files in encrypted format.
 The key takeaways from this postulate for a cloud-native microservices application are:
Do not store configuration as part of the deployable unit (in the case of lead microservice - inside the jar or war if you are still deploying war like the good old days). Instead, store it in an external location and make it easily accessible during run-…

Unit Test - Microservices - Business Layer

In this post, I am going to show how to unit test the business layer of the lead microservice that I am developing. A couple of things to keep in mind to write the unit test for the business layer.

These tests run must very fast for quick feedback.Only the business layer is involved and hence the web layer and repository layer should not be started. In other words, the Spring web tier beans should not be created and neither any database connections should be used. (This helps to achieve #1). The repository layer will be mocked using Mockito.The fluent assert from AssertJ library will be used.  The source code of the lead business unit test is shown in listing below.
Most of the test methods are straight forward. However, the testDelete the method needs some explanation. Here the findOne method is mocked/stubbed. This ensures that correct lead object is returned by the stub method. The other thing to note is that the verify the method for saving method captures the internal Lead objec…

Complete Unit tests - Microservices - Repository Layer

In the previous post, I introduced the unit tests for the repository layer of the lead microservice. In this short post, I will do some cleanup, add all the unit tests. Finally, I replaced all the JUNIT asserts with AssertJ asserts. AssserJ is also recommended by the Spring champions over at Pivotal.

AssertJ - provides fluent assertions for Java. Testing improvements in Spring Boot

Ok thats it for now. In the next post I will show how to unit test the business / service layer of the lead microservice.

Microservice - Unit Test - Repository Layer

Now that we have completed the first round of development of our lead microservice, it is time to focus on some testing. I will follow a bottom-up approach and start by writing unit tests for the repository layer.

In order to write unit tests, I will make use of the Spring Test Framework and Spring Boot Test support. Spring Boot makes it extremely easy to unit test slices of the application. We can use @DataJpaTest and just unit test the database layer with an embedded database like H2. However, there are some gotchas (I do not know exactly what at this moment), the @DataJpaTest does not work if you have extended the Spring Data JPA to add a custom method for all the repositories. The problem I found was that the when running the Spring Boot application, everything works fine and the custom method works fine and the query returns the correct results. However, when the unit test is run, Spring Data JPA fails, complaining that it is not able to find an attribute for the entity/type.


Lead Microservice - Add the service and controller

This post continues from the last one. I will try to complete the lead microservice in this post. I will be focusing primarily on the CRUD operation. In CRM applications, that is the primary set of operations.
I will start by creating the exception class. Later I would show how to use this exception class and Spring Rest exception handling and build a robust error handling around the API calls.
Listing 1 -

Next step would be to introduce the service class. Since this is CRUD most of the functionality can be encapsulated in an abstract parent service class. Any specific feature like convert lead to opportunity can be implemented in the LeadService class.

Listing 2 -
And then finally the LeadService implementation class is shown in Listing 3.

Listing 3 -
Note that this code will not compile. In order to get this to compile, you will need to add 2 new dependencies for the Jodd libraries. Jodd is a popular mi…

First Microservice - Lead Service

This is a continuation of my previous post where I listed the key domain components of CRM. For sake of simplicity, I will focus on just two key components - Lead and Opportunity respectively. These two modules will help me explore end to microservice implementation. I will be primarily using Spring framework's support to deliver the microservices. I am deliberating on a nice interesting Javascript framework for the front end. More on this later.


For the time being, I am just going to focus on building the backend and cloud enable it. Then slowly I am going to add the front end and security to the backend and front end. I will also explore the complete Sping Cloud gamut of projects and beyond. I will then deliberate on cloud-native applications, transactions and actually making this application suitable to run on virtually any cloud. I will also explore cloud and microservices application design patterns. Last but not the least we also need to check where this application fit…

Breaking down the CRM monolith

In my previous posts, I have shared some theory regarding microservices. But it's time to start some implementation. I love to write code and see and feel things working. So I will start a series to refactor a monolithic CRM system and transform it into microservices based flexible software.

Big ball of mud.

Customer Relationship Management(CRM) is that giant software which existed since time immemorial and is used by all companies in some form or shape. Big enterprises will buy CRM software (also known as packages) from top CRM vendors like Oracle, SAP, Salesforce etc and then employ an army of consultants to try and implement it. Most of the classic CRM systems in the market today, even if deployed on the cloud are the big monolithic ball of mud. They are the gigantic piece of software with the huge feature set. Most often those requirements are surplus to the requirement or they will not fit into the processes of the company. So the company has to hire these certified consultant…

Primer on 12-factor app

The 12-factor app guideline was published by Heroku the platform as a service (PaaS) provider (now a part of These were a set of principles/best practices that one needed to follow to build applications on the Heroku PaaS. Over time, this has become the de-facto standard for building web applications on the cloud or more precisely cloud-native applications. The original 12-factor app guideline is available at and was not really meant for microservices. In this post, I will try to go over the 12-factor app guidelines and check how they fit into microservices architecture.

1 – CodebaseOne codebase tracked in revision control, many deploys
The application codebase should be maintained in a version control system (VCS).All developers should have easy access to VCS.There is only one codebase per application in the VCS, but there can be multiple deployment copies of this application codebase. For example, an application can be deployed in different environments…

So whats wrong with Classic Applications a.k.a Monoliths?

A real life story In my previous post introducing microservices, I wrote about this insurance product I was working on at the beginning of my IT career. It started off very simple as a layered application. Well it was not simple, the learning curve with J2EE of that time was indeed high. Just like microservices, it was all shiny new thing. The application started with just a couple of us. Then we started adding features. The product was sold. I was happy, I went to install and implement it at customer sites. It was fun.

Then customers demanded more and more features. New features were also required to address new business challenges and compete with established players. So we kept adding more bricks and mortar on that same structure. 2+ years flew by and I realized that we have about 20 odd modules, 500+ tables, and nearly a team of 100+. We had several customers in the US and elsewhere using this product. It was really a big success in such a short span of time.

But I also realized …

Microservices – Vertical Slicing

The whole idea of microservices revolves around building a large application from a set of small modules which are composed around business functions.Let me share one concrete example to understand this better. Figure 1, shows the classic layered architecture that I was introduced to back in 2001 when I was building a large product for the insurance providers.

Only three key modules from the product are shown here for simplicity. This was a very large product with several other modules. The UI was developed using JSPs (HTML, Stylesheets, Javascript). The UI was packed in a war file. The business logic was written using stateless session beans. The data access layer was all entity beans. The EJBs and the war file was then packaged inside an ear file and finally deployed in a Java application server.

This application was also modular, but horizontally.So that ear file contained everything – the UI, business logic, the data access logic for all the insurance business functions – underwr…

What are Microservices?

Microservices is still a new and evolving subject. Hence, there is a lot of confusion regarding the term and concepts around it. A lot of clarity is starting to emerge of late, as teams try to embrace this new architectural style.I know people tend to think and preach that since the application that they have developed recently expose few REST web services, they are doing microservices. Some have even installed API Gateway in front of the Rest web services layer. Trust me this is still a layered cake classic architecture which is just opposite of microservices. The naysayers call this a monolith. I have some reservations against that word. Later I will explain the reason for the same.
Microservices is an architectural style. In this style, an application (generally large and complex one) is built using a small set of loosely coupled services which implement specific business capabilities. Well, we have been doing this for years, haven't we? What is the difference?  The difference…

Spring 4: Unit Testing Classic Controller

Spring Boot is a great gift for all Spring developers. The productivity boost is enormous. It also makes it extremely easy to unit tests slices of your layered application. This feature is available from Spring Boot 1.4.x onwards. In this post, I am going to focus only on unit testing of Spring MVC classic controller i.e non-REST controller.

Spring Boot test slice support for MVC controller is enabled by the following annotation

This tells Spring MVC test framework that we only intend to test EmployeeController So it will only make the web MVC components (controllers, interceptors etc) available with mocking support. For more details of this annotation please refer to the Javadoc here.

In the example above, we are testing the request to copy the Employee. Mockito is used to create and inject the mock objects. Spring takes care of the mock objects, dependencies for us. This makes it extremely easy to write unit tests for classic Spring MVC controllers. Note that for quick feedback…