Chapter 21. Development Mode

Weld comes with a special mode for application development. When enabled, certain built-in tools which facilitate the development of CDI applications, are available.

Note

The development mode should not be used in production as it may have negative impact on the performance of the application. Make sure to disable the development mode before deploying to production.

Warning

Not all environments and containers may support the development mode and all tools. Check the tools details and the container documentation.

21.1. How to enable the development mode

21.1.1. Web application

For a web application, set the Servlet initialization parameter org.jboss.weld.development to true:


<web-app version="3.1" xmlns="http://xmlns.jcp.org/xml/ns/javaee/"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd">



    <context-param>

        <param-name>org.jboss.weld.development</param-name>

        <param-value>true</param-value>

    </context-param>



</web-app>

Note

An integrator is allowed to specify an alternative way of enabling the development mode.

21.1.2. Weld SE

For a Java SE application, set the system property org.jboss.weld.development to true:

java -cp myCoolApp.jar -Dorg.jboss.weld.development=true com.foo.MyMain

21.1.3. Is The Development Mode Enabled?

You should see the following log message during initialization of your application:

=====================================
 Weld Development Mode: ENABLED
=====================================

21.2. Development Tools

21.2.1. Probe

This tool allows to inspect the application CDI components at runtime. See also the demo application hosted on OpenShift.

JSON data are available through the REST API, eventually (if JMX support is enabled) through the MXBean of name org.jboss.weld.probe:type=JsonData,context=ID where ID should be replaced with an idenfitier of an application.

However, a default UI - HTML client (single-page application) is only available in a web application at {webappContextPath}/weld-probe, e.g. http://localhost:8080/weld-numberguess/weld-probe.

Right now, the integration is provided for WildFly 10, Tomcat and Jetty (Weld Servlet) and Weld SE.

Tip

There are some configuration properties which allow to tune or disable Probe features, e.g. to restrict the set of components which will be monitored. See also Section 19.1.9, “Development Mode”.