The Weather App

Tutorials The Weather App

Tutorial Steps

The Weather App

Let's begin by checking out the project. Fire up your terminal and enter:

      
        git clone https://github.com/infinispan/infinispan-embedded-tutorial.git && cd infinispan-embedded-tutorial

The above commands will create a local copy (clone) of the git repository and change the current directory so that all subsequent commands will run from the project root directory. We now want to move to "Step 0" in the project:

      
        git checkout -f step-0

The initial step is just a plain Maven Java project with an implementation of our Weather Application. The application connects to the OpenWeatherMap API to retrieve current weather data for a variety of cities. Usage of the OpenWeatherMap API requires registering for a free API key. Before launching the application, ensure you've set the OWMAPIKEY environment variable to your API key:

        
          export OWMAPIKEY=111111

In Windows you'd use:

        
          C:\> set OWMAPIKEY=111111

If you'd rather not register, if you don't have an Internet connection or you are having trouble connecting to the service, don't worry: the application will use a random weather service. This initial step has no dependencies and uses JDK logging. The following image shows the layout of the project:

Let's compile and run it:

      
        mvn clean package

Maven will run both goals specified on the command-line in order. The first goal (clean) just cleans any previously generated files and the second one (package) compiles the project, runs any unit tests and packages the resulting code into a Jar file. At this point we can also run the code. The main() method of the WeatherApp class initializes the WeatherService and retrieves the current temperature for the list of cities twice and prints the elapsed time after each retrieval. Since no caching is being done at this stage, the application is quite slow on both runs, since it always has to retrieve the information.

      
        mvn exec:exec

Output

          
            ---- Fetching weather information ----
            Rome, Italy - Temperature: 12.9° C, Conditions: light rain
            Como, Italy - Temperature: 6.3° C, Conditions: Sky is Clear
            Basel, Switzerland - Temperature: 0.8° C, Conditions: overcast clouds
            Bern, Switzerland - Temperature: -1.6° C, Conditions: broken clouds
            London, UK - Temperature: 1.8° C, Conditions: light rain
            Newcastle, UK - Temperature: 2.6° C, Conditions: scattered clouds
            Bucharest, Romania - Temperature: 9.3° C, Conditions: scattered clouds
            Cluj-Napoca, Romania - Temperature: 6.4° C, Conditions: scattered clouds
            Ottawa, Canada - Temperature: -7.0° C, Conditions: overcast clouds
            Toronto, Canada - Temperature: -7.0° C, Conditions: broken clouds
            Lisbon, Portugal - Temperature: 14.6° C, Conditions: overcast clouds
            Porto, Portugal - Temperature: 12.2° C, Conditions: moderate rain
            Raleigh, USA - Temperature: 3.9° C, Conditions: Sky is Clear
            Washington, USA - Temperature: 3.4° C, Conditions: light rain
            ---- Fetched in 2210ms ----
            ---- Fetching weather information ----
            Rome, Italy - Temperature: 12.9° C, Conditions: light rain
            Como, Italy - Temperature: 6.3° C, Conditions: Sky is Clear
            Basel, Switzerland - Temperature: 0.8° C, Conditions: overcast clouds
            Bern, Switzerland - Temperature: -1.6° C, Conditions: broken clouds
            London, UK - Temperature: 1.8° C, Conditions: light rain
            Newcastle, UK - Temperature: 2.6° C, Conditions: scattered clouds
            Bucharest, Romania - Temperature: 9.3° C, Conditions: scattered clouds
            Cluj-Napoca, Romania - Temperature: 6.4° C, Conditions: scattered clouds
            Ottawa, Canada - Temperature: -7.0° C, Conditions: overcast clouds
            Toronto, Canada - Temperature: -7.0° C, Conditions: broken clouds
            Lisbon, Portugal - Temperature: 14.6° C, Conditions: overcast clouds
            Porto, Portugal - Temperature: 12.2° C, Conditions: moderate rain
            Raleigh, USA - Temperature: 3.9° C, Conditions: Sky is Clear
            Washington, USA - Temperature: 3.4° C, Conditions: light rain
            ---- Fetched in 1820ms ----

Things will get more interesting in the next step.