Infinispan Embedded Tutorial: Weather App

Overview

This is a tutorial which explains how to use Infinispan embedded in your own application. The application will retrieve the current weather conditions for some cities and store them in a cache, for quicker retrieval. It will also show how to configure the cache for expiration, so that entries get removed as they age. It will then demonstrate how to cluster multiple nodes together and reacting to events in the cluster. Finally, a computation of average temperatures per country will show the power of the map/reduce functionality.

Each tagged commit is a separate lesson teaching a single aspect of Infinispan.

The tutorial instructions are at http://infinispan.org/tutorials/embedded/

N.B. The tutorial connects to OpenWeatherMap (http://openweathermap.org) to retrieve current weather data. The service requires obtaining a free API key. Before launching the application, ensure you've set the OWMAPIKEY environment variable to your API key. If you don't want to register for the service, if you don't have an Internet connection or you are having trouble connecting to the service, just don't set the environment variable, and it will use the RandomWeatherService.

Prerequisites

Git

• A good place to learn about setting up git is here
• Git home (download, documentation)

JDK

• Get a JDK. You will need version 1.8 or higher

Maven

• Get Maven. You will need version 3.2 or higher

Commits / Tutorial Outline

You can check out any point of the tutorial using git checkout step-?

To see the changes between any two lessons use the git diff command. git diff step-?..step-?

step-0/setup

• The initial implementation of the Weather application

step-1/cache-manager

• Adding Infinispan to the project and initializing a cache manager

step-2/cache-put-get

• Add caching to the weather service

step-3/expiration

• Store the entries in the cache with an expiration time

step-4/cachemanager-configuration

• Configure the features of the default cache

step-5/clustering

• Add a transport to the CacheManager so that it supports clustering

step-6/cachemanager-listener

• Use CacheManager events to detect changes in the cluster

step-7/cache-listener

• Detect changes to the cache with a clustered listener

step-8/grouping

• Group related entries on the same nodes for efficiency

step-9/externalizer

• Implement a custom externalizer for our value class

step-10/streams

• Use Distributed Streams to compute temperature averages per country

step-11/declarative-configuration

• Use the XML configuration instead of the programmatic API

Building and running the tutorial

• Run mvn clean package to rebuild the application
• Run mvn exec:exec to execute the application. In case you're running a clustered step, run this from multiple terminals, where each instance will represent a node
• Run mvn clean package docker:build to build docker image, and then run docker run infinispan-embedded-tutorial/infinispan-embedded-tutorial in 2 different terminals to simulate multiple nodes of distributed cache

Application Directory Layout

docker/             -->
src/                -->
  main/             -->
    java/           -->
    resources/      -->

Contact

For more information on Infinispan please check out http://infinispan.org/