Configuration Properties
You can change the behavior of Vaadin applications by setting the configuration properties. You can set them either through the system properties, or the servlet initialization parameters. See the full list of properties for details.
See also the Spring-specific instructions for Spring-based applications.
Using System Properties
When using Java system properties to set Vaadin application parameters, the vaadin. prefix must be specified before each parameter name. The following example shows how to set the pnpm.enable system property when executing a Maven goal from the command-line:
mvn jetty:run -Dvaadin.pnpm.enable=trueYou can configure system properties for Maven plugin executions. For instance, the following sets a Vaadin-specific system property when running the Jetty Maven plugin:
<plugin>
<groupId>org.eclipse.jetty</groupId>
<artifactId>jetty-maven-plugin</artifactId>
<configuration>
<systemProperties>
<systemProperty>
<name>vaadin.pushMode</name>
<value>disabled</value>
</systemProperty>
</systemProperties>
</configuration>
</plugin>Servlet Initialization Parameters
Another option for setting configuration properties is to use servlet initialization parameters. Use the Servlet 3.0 @WebServlet annotation. This requires you to configure your servlet, unless you want Vaadin Flow to do it, using default parameter values.
@WebServlet(urlPatterns = "/*", name = "myservlet", asyncSupported = true, loadOnStartup = 1,
initParams = { @WebInitParam(name = "pnpm.enable", value = "true") })
public class MyServlet extends VaadinServlet {
}Yet another approach is to use the web.xml file. Below is an example of one:
<?xml version="1.0" encoding="UTF-8"?>
<web-app
id="WebApp_ID" version="3.0"
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
<servlet>
<servlet-name>myservlet</servlet-name>
<servlet-class>
com.vaadin.flow.server.VaadinServlet
</servlet-class>
<load-on-startup>1</load-on-startup>
<init-param>
<param-name>pnpm.enable</param-name>
<param-value>true</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>myservlet</servlet-name>
<url-pattern>/*</url-pattern>
</servlet-mapping>
</web-app>|
Note
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System Properties Override Servlet Parameters
When a system property and a servlet parameter have the same name, the system property is used and the servlet parameter is ignored.
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Configuration Properties
The following table contains the properties that are defined in the com.vaadin.server.DeploymentConfiguration and com.vaadin.server.Constants classes. They’re listed in alphabetical order. If you use Spring Boot, you should add the vaadin. prefix to them (e.g., change brotli to vaadin.brotli).
| Property Name | Default Value | Description |
|---|---|---|
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| Determines whether pre-compressed Brotli files should be used if accepted by the browser. Brotli files are created during a production build. The property is used only in production mode. Set to |
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| Closes the Vaadin session if no UI is active. A UI is considered active if it’s open on the client-side and has any activity — besides heartbeat requests. By default, heartbeat requests keep the Vaadin session open even when there is no user interaction. Set to |
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| Defines the hosts allowed to access Vaadin development tools. A comma-separated list of allowed hosts should be provided as the value. The |
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| Enables live reload. When using a server-side live reload tool, the browser is refreshed after code is rebuilt on the server. Set to |
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| Optimizes frontend resource bundles. All frontend resources in the classpath are included by default in the generated bundle in development mode. When set to |
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| Enables session serialization. When session serialization is enabled, |
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| Enables the Component Locator tracker utility. Set to |
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| Enables Vaadin to collect usage statistics that can guide further development. Statistics are collected based on features that are used in the application. No data is collected in production mode. Some usage statistics are collected through the web browser. See the client-side collector repository for instructions on how to opt out. This applies only to development mode. |
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| Disables automatic servlet registration that’s required by Vaadin applications. You must register Vaadin servlets if set to |
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| Disables cross-site request forgery protection. The protection is enabled by default. You should keep it enabled — except for certain types of testing. |
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| Enables the client-side bootstrap page to include the initial JSON data fragment. |
|
| If |
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| Enables development using the frontend development server instead of an application bundle. This applies only to development mode. |
| 300 seconds (i.e., 5 minutes) | Sets the heartbeat interval time. UIs that are open on the client-side send a regular heartbeat to the server indicating that they’re still active even without ongoing user interaction. When the server doesn’t receive a valid heartbeat from a given UI within a certain amount of time, it removes that UI from the session. The interval value is expressed in |
|
| Sets the fully-qualified name for the internationalization provider class. To translate strings for localization, the application should implement the |
| 5000 ms (i.e., 5 seconds) | Sets the maximum time in |
|
| Enables |
|
| Enables |
|
| Sets the application to work in production mode. This disables most of the logged information to improve performance — information that appears on the server and browser console. Development mode JavaScript functions aren’t exported. Any |
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| Sets the timeout in |
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| Enables server push. The permitted values are |
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| Specifies the servlet mapping used for bidirectional (i.e., "push") client-server communication. Some Java application servers require special context. For example, you can specify websockets with this. |
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| Includes basic timing information in responses that can be used for performance testing. |
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| Enables synchronized ID checking. The synchronized ID is used to handle situations in which the client sends a message to a connector that has been removed from the server. It’s set to |
| 300 seconds (i.e., 5 minutes) | Sets the number of |
| assert | When production mode is enabled, the Vaadin session lock check is done according to this setting. By default, the check is done only if assertions are also enabled: this is to avoid the small performance impact of continuously checking the lock status. Alternative values are 'log' to log a warning, or 'throw' to fail with an |
Vaadin Plugin Properties
The following table contains the properties that are used only by the Vaadin Maven and Gradle Plugin, and are not applicable for deployment configuration:
System Property | Plugin Configuration | Description | Default Value |
|
| Determines whether |
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| Forces Vaadin Flow to create a new production bundle, even if there is already a usable pre-compiled bundle. This is required usually when creating an optimized production bundle, and to load component sources to the browser on demand — such as when opening a route where these components are used. |
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| Prevents a frontend development bundle from being re-built, even if Vaadin Flow decides to use an existing compiled development bundle. This is mainly needed when re-bundling checker in Vaadin Flow has problems leading to false re-bundling, and one needs a workaround while it’s being resolved. |
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