Temperature Server application

A simple Spring Boot service for storing, retrieving and viewing temperature measurements. The idea is that for a certain name (e.g. location) a number of temperature measurements will be added over time.

Requirements:

• Java 8
• maven (tested with 3.3.9 and 3.5.3)

Java 9 is currently not supported - the application will neither run nor build. All the necessary hoops that need jumping through to get this working (see e.g. here) with no real benefit were the deciding factors. Once Spring Boot, Maven and Hibernate have fully committed to Java9, my opinion may change.

Building

A simple mvn clean install will do.

Running

From the root of the project, switch to the target subdirectory. Run

java -jar temperature-server-<version>.jar

The default port used is 8080 - to change it, add the VM option -Dserver.port=<port number> to the command line, e.g.

java -Dserver.port=8081 -jar temperature-server-<version>.jar

Usage

Browsing to http://localhost:8080/ (or whichever port you chose) will open the Vaadin-based UI showing the current temperature readings available.

To add a new measurement point:

HTTP POST /temperature/<name>?value=<value>

Where <name> is a string label such as "Kitchen" and <value> a floating-point temperature such as 23.456. By default the unit will be Celsius. To change it (in other words: if you're American) to Fahrenheit, do

HTTP POST /temperature/<name>?value=<value>&unit=FAHRENHEIT

To retrieve the the most recent temperature measurement for every name, simply use

HTTP GET /temperature/current

which will return a JSON like this:

[
  {"id":2,"timestamp":"2018-03-11T13:33:26.774Z","name":"Kitchen","value":20.319,"unit":"CELSIUS"},
  {"id":3,"timestamp":"2018-03-11T14:02:16.775Z","name":"Living room","value":20.319,"unit":"CELSIUS"}
]

You can view all stored measurements using HTTP GET /temperature which will return the same JSON structure.

Data Storage Options

By default, the server will use an in-memory database provider (H2) that will run out-of-the-box. Of course that means any saved data will not survive a server restart.

There are options, however. Please refer to the Spring Boot documentation for ways to change any configuration properties to suit your specific setup.

Note that all the relational storage options below use Flyway to set up the database tables on application startup. Refer to the specific section for other requirements.

Postgresql

If you have a Postgres DB server running, you can use that. Start the server application with the spring.profiles.active=postgres option to do so.

The default configuration is:

spring:
  datasource:
    url: jdbc:postgresql://localhost:5432/temperature
    username: postgres
    password: postgres

You will need to create the temperature database before running the server, since Postgres does not support automatic creation upon connection.

MariaDB

An existing MariaDB 10 can be used as the data store with the spring.profiles.active=mariadb option. By default a database named temperature is used, which are also the default user and password.