The Techno Journals

In this tutorial we will learn how to create registry/ discovery server using Eureka and Spring boot. We will register our Rest microservice with this registry server which can be discovered by client by connecting to registry server. What is registry/ discovery server We can assume registry or discovery server as a central place where we can find all our microservices using their registered IDs with discovery server. Microservices register themselves in registry server and client applications access them using a single registry or discovery server. It is similar to a phone directory but provides many other useful features. If we don't user registry server then we need host name and endpoint details to access a service. In today's era most of the services are deployed in cloud and using cloud features like auto-scaling where network addresses are updated dynamically and we can't use a simple network address for that. Now when we use registry server, then such microserv...

In this tutorial we are going to learn about mock unit testing. We are using here Mockito with Spring to write unit tests. We will also see how to mock an EJB session bean inside mocked service without constructor/setters injection. What is mocking Mocking is a technique to replace the actual implementation with some dummy or provided code chunk during unit testing. For example if we need to unit test some service which persist data to database then we can mock that persist method to add it to some in-memory collection. Also we can mock data retrieval to get the data from same collection or so. Mockito provide various class and features to implement the mocking seamlessly. Maven dependency We are using Spring (XML base configuration) and mockito for mock testing. Below dependencies are required. <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>4.1.9.RELEASE</ver...

What is CORS CORS is cross origin resource sharing which allows or block the cross domain calls from a web application between different domains. By default you are able to make Ajax calls to other domain. To enable it that provider also need to add certain headers to allow the requester domain. CORS Headers Below are the required headers to implement the CORS. Access-Control-Allow-Origin In this header we specify the domain from which we want to allow the access, for example: example.com. Access-Control-Allow-Credentials This header specifies if it can pass authorization details in cross domain request. for example: true/false. Access-Control-Max-Age We can use this header to specify how long we want to cache the preflight request details like allowed methods, allowed headers etc. We can specify value in seconds and we can cache them for a long time as such details are not change frequently. Access-Control-Allow-Methods Here we specify the methods we want to allow for requ...

Spring Retry API Spring provides spring-retry API for running business logic with retry options and recovery method or operations. In this tutorial we will learn the usage of all these with example. We are using Spring boot application here for our example code. Maven dependencies To use spring retry we need below dependencies. spring-retry This API provides many annotations which we can use in a declarative manner to implement the same. <dependency> <groupId>org.springframework.retry</groupId> <artifactId>spring-retry</artifactId> <version>1.2.5.RELEASE</version> </dependency> spring-boot-starter-aop Spring AOP is also required for retry implementation. <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-aop</artifactId> </dependency> Retry implementation To ...

We are going to validate XML using XSD schema in Java. We will create XML Schema using XSD and then use same schema to create the XML file. Then we will write our code to validate this XML against same schema. XSD Schema creation Below is our schema where we are defining the Schema for XML elements. In this schema we creating two elements, one for request and another for response. We are publishing this schema using targetNamespace which we will use during XML creation. <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:tns="http://services.ttj.com/hello-service" targetNamespace="http://services.ttj.com/hello-service" elementFormDefault="qualified"> <xs:element name="sayHelloRequest"> <xs:complexType> <xs:sequence> <xs:element name="userName" type="xs:string"/> </xs:sequence> </xs:c...

In this tutorial we will learn how to create a react application. Softwares required for ReactJS We need to install below softwares for react development. Visual studio code This software is free and can be downloaded from  https://code.visualstudio.com/download . Once downloaded, extract the zip  and place the binary under "Applications" and allow app access from System Preferences -> Security & privacy. Node.JS and NPM Node.JS provides a java script enabled environment to run on a web server. It eases our development for UI based applications. NPM is a package manager which installs along with Node.jS and helpful in installing packages and libraries. Install Node.JS and NPM using brew. brew install node Check version of Node and NPM using below command. node -v npm -v Create React application To create react application we will first install the required package and latter will use it to create our ReactJS application. Install create-react-app pa...

Soap over JMS comes with several benefits like, asynchronous processing, one time delivery, assured delivery. This paradigm is mainly used internally in an organization (service providers and clients). In this tutorial we are going to use Spring boot and Apache CXF to develop a Soap service and then use Active MQ to make it work as "Soap Over JMS". Creating Soap service using Spring boot and Apache CXF It is very easy to develop a Soap service with Spring boot. We will follow contract first approach to develop the service. We will create a XML schema & use jaxb2 plugin to generate necessary schema classes and then implement the service using them. Please refer below post where it explains in detail, how to develop a Soap service using Spring boot and CXF. https://www.thetechnojournals.com/2020/01/soap-services-with-spring-boot-and.html Implementing Soap over JMS To implement the Soap over JMS we need to integrate JMS with soap service where our service listens to...