Creating V7 and V14+ CDI applications side-by-side

If you have an application developed using Vaadin 7 and CDI, you have the option to keep your legacy code untouched and continue developing new pages with V14+.

You will also be able to use CDI beans, e.g. SessionScoped beans, in both V14+ and Vaadin 7 parts of your application. The following instructions are step-by-step guide on how to adopt this approach with Vaadin 14. The same instructions can be followed to do the same with Vaadin 15+. You just need to use the Vaadin version of your choice.

Add Vaadin 14 to your maven dependencies.

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>com.vaadin</groupId>
            <artifactId>vaadin-bom</artifactId>
            <type>pom</type>
            <scope>import</scope>
            <version>14.12.4</version>
        </dependency>
    </dependencies>
</dependencyManagement>
<dependencies>
    <dependency>
        <groupId>com.vaadin</groupId>
        <artifactId>vaadin-core</artifactId>
    </dependency>
</dependencies>

Exclude conflicted dependencies between Vaadin 7 and Vaadin 14 which are jsoup and atmosphere-runtime from Vaadin 7 in your pom.xml, like shown in the following example:

<dependency>
    <groupId>com.vaadin</groupId>
    <artifactId>vaadin-server</artifactId>
    <version>${framework.7.version}</version>
    <exclusions>
        <exclusion>
            <groupId>com.vaadin.external.atmosphere</groupId>
            <artifactId>atmosphere-runtime</artifactId>
        </exclusion>
        <exclusion>
            <groupId>org.jsoup</groupId>
            <artifactId>jsoup</artifactId>
        </exclusion>
    </exclusions>
</dependency>

Remove dependency of vaadin-cdi 1.* and add a dependency to mpr-cdi-v7 1.0.0.

<dependency>
    <groupId>com.vaadin</groupId>
    <artifactId>mpr-cdi-v7</artifactId>
    <version>1.0.0</version>
</dependency>

Add the vaadin-cdi dependency. The version is not needed as it is defined by the vaadin-bom.

<dependency>
    <groupId>com.vaadin</groupId>
    <artifactId>vaadin-cdi</artifactId>
</dependency>

Since the root path of your application is managed by Vaadin 7, you need to define the Vaadin 14 servlet manually, and set its url pattern to a value that doesn’t collide with any of the V7 servlets.

@WebServlet(name = "Flow Servlet", urlPatterns = {
        MyFlowServlet.FLOW_SERVLET_ROOT + "/*" })
public class MyFlowServlet extends CdiVaadinServlet {
    public static final String FLOW_SERVLET_ROOT = "flow";
}

Now, you can have both Vaadin 7 and Vaadin 14 parts of your application in one project. To navigate from Vaadin 7 part to Vaadin 14 part you can simply use the following line of code.
```
getUI().getPage().setLocation(MyFlowServlet.FLOW_SERVLET_ROOT);
```
And, to navigate from Vaadin 14 part to a Vaadin 7 view you can for example use an Anchor like the below code.
```
Anchor anchor = new Anchor("/#!home", "Home");
add(anchor);
```

To have shared data between Vaadin 14 and Vaadin 7 parts, you can use SessionScoped beans that are shared for both V7 and V14 applications.

@SessionScoped
public class SecurityContext implements Serializable {
    private User currentUser = new User();

    public boolean signIn(String username, String password) {
        if (username == null || username.isEmpty())
            return false;

        currentUser.setUsername(username);

        return true;
    }
}

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Creating V7 and V14+ CDI applications side-by-side