At this point, we have a very simple Java project setup that will be packaged as a WAR file. The next natural step is to add the required dependencies or libraries. Vaadin, like many other Java web applications, requires the Servlet API. Add it as follows to the pom.xml file:

    <dependencies>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>

Notice that the scope of this dependency is set as provided, which means that a server, or more specifically, a Servlet Container, such as Jetty or Tomcat, will provide the implementation.

Let’s continue by adding the required Vaadin dependencies. First, add the vaadin-bom dependency to your pom.xml file:

     <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>com.vaadin</groupId>
                <artifactId>vaadin-bom</artifactId>
                <version>8.3.2</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

A Maven BOM, or bill of materials, frees you from worrying about versions of related dependencies; in this case, the Vaadin dependencies. Let's drop these dependencies next. Add the following to your pom.xml file:

    <dependency>
        <groupId>com.vaadin</groupId>
        <artifactId>vaadin-server</artifactId>
    </dependency>
    <dependency>
        <groupId>com.vaadin</groupId>
        <artifactId>vaadin-client-compiled</artifactId>
    </dependency>
    <dependency>
        <groupId>com.vaadin</groupId>
        <artifactId>vaadin-themes</artifactId>
    </dependency>

There's no need to explicitly set the version for these thanks to the vaadin-bom dependency. We've just added a server-side API (vaadin-server), a client-side engine or widget set (vaadin-client-compiled), and the Valo theme (vaadin-themes).

At this point, you can compile the project by running the following command inside the chapter-01 directory:

mvn clean install

This will download the dependencies to your local Maven repository if you haven't used Vaadin 8.3.2 before.