[[CLI_extensibility_for_layered_products]]
= CLI extensibility for layered products

In addition to supporting the ServiceLoader extension mechanism to load
command handlers coming from outside of the CLI codebase, starting from
the wildfly-core-1.0.0.Beta1 release the CLI running in a modular
classloading environment can be extended with commands exposed in server
extension modules. The CLI will look for and register extension commands
when it (re-)connects to the controller by iterating through the
registered by that time extensions and using the ServiceLoader mechanism
on the extension modules. (Note, that this mechanism will work only for
extensions available in the server installation the CLI is launched
from.)

Here is an example of a simple command handler and its integration.

[source,java,options="nowrap"]
----
package org.jboss.as.test.cli.extensions;public class ExtCommandHandler extends org.jboss.as.cli.handlers.CommandHandlerWithHelp {     
 
package org.jboss.as.test.cli.extensions;
public class ExtCommandHandler extends org.jboss.as.cli.handlers.CommandHandlerWithHelp {
 
 
    public static final String NAME = "ext-command";
    public static final String OUTPUT = "hello world!";
 
 
    public CliExtCommandHandler() {
        super(NAME, false);
    }
 
 
    @Override
    protected void doHandle(CommandContext ctx) throws CommandLineException {
        ctx.printLine(OUTPUT);
    }
}
----

The command will simply print a message to the terminal. The next step
is to implement the CLI CommandHandlerProvider interface.

[source,java,options="nowrap"]
----
package org.jboss.as.test.cli.extensions;
public class ExtCommandHandlerProvider implements org.jboss.as.cli.CommandHandlerProvider {
 
 
    @Override
    public CommandHandler createCommandHandler(CommandContext ctx) {
        return new ExtCommandHandler();
    }
 
 
    /**
     * Whether the command should be available in tab-completion.
     */
    @Override
    public boolean isTabComplete() {
        return true;
    }
 
 
    /**
     * Command name(s).
     */
    @Override
    public String[] getNames() {
        return new String[]{ExtCommandHandler.NAME};
    }
}
----

The final step is to include
*META-INF/services/org.jboss.as.cli.CommandHandlerProvider* entry into
the JAR file containing the classes above with value
*org.jboss.as.test.cli.extensions.ExtCommandHandlerProvider*.
