medgai ...

JMS: Java Messaging Service JMS is an example of Messaging Systems based on asynnchronous design pattern which is used by microservices to interact with each other to send data and events. For introductory part, please refer  here . JMS allow applications to create and send, receive and read messages in a shared environment. JMS: Programming Model Basic components to develop client based producer and consumer system are: ConnectionFactory : Use the Java Naming and Directory Interface (JNDI) to find a ConnectionFactory object, or instantiate a ConnectionFactory object directly and set its attributes. Based on delivery model, client has separate instance for connection factory to create a connection to a provider: Point to point :  QueueConnectionFactory Publish/subscribe: TopicConnectionFactory             The following snippet of code demonstrates how to use JNDI to find a connection factory object: Context ctx = new Init...

Why we need messaging system in enterprise applications ? If applications have dependency i.e microservices depends on each other for resources, then we need RPC , hence RPC systems were made. Remote procedure call (RPC) systems, including Java RMI, are synchronous i.e the caller must block and wait until the called method completes execution, and thus offer no potential for developing loosely coupled enterprise applications without the use of multiple threads. In other words, RPC systems require the client and the server to be available at the same time. However, such tight coupling may not be possible or desired in some applications. Message-Oriented Middleware (MOM) systems provide solutions to such problems. They are based on the asynchronous interaction model, and provide the abstraction of a message queue that can be accessed across a network. Note, however, that messaging here refers to asynchronous requests or events that are consumed by enterprise applications and not humans...

Generally, a web application starts with a login portal or registration portal, otherwise we could use simple html pages for rest things out there. Our first web application will be starting with a login portal, interacting with database through a servlet with validation and login error handling . Requirements : An IDE (most preferably Eclipse J2EE)   Server (Apache Tomcat) // link to download is given in previous blog post. Database (most preferably MySql 5.5) Follow the steps below and code to create a login page : 1. Open Eclipse Enterprise edition. File -> New -> Dynamic Web Project . 2. Enter project name and choose a new runtime which is the server itself. 3. Select server name and specify it’s directory in the system. 4. click next, and put build/classes as the output folder (by default it’s same written here) and then next, check the web.xml for deployment description purpose. 5. Click on Fin...