src/org/ungoverned/osgi/service/shell/Command.java

/*
 *   Copyright 2005 The Apache Software Foundation
 *
 *   Licensed under the Apache License, Version 2.0 (the "License");
 *   you may not use this file except in compliance with the License.
 *   You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *   limitations under the License.
 *
 */
package org.ungoverned.osgi.service.shell;

import java.io.PrintStream;

/**
 * This interface is used to define commands for the Felix shell
 * service. Any bundle wishing to create commands for the
 * shell service simply needs to create a service object that
 * implements this interface and then register it with the OSGi
 * framework. The shell service automatically includes any
 * registered command services in its list of available commands.
**/
public interface Command
{
    /**
     * Returns the name of the command that is implemented by the
     * interface. The command name should not contain whitespace
     * and should also be unique.
     * @return the name of the command.
    **/
    public String getName();

    /**
     * Returns the usage string for the command. The usage string is
     * a short string that illustrates how to use the command on the
     * command line. This information is used when generating command
     * help information. An example usage string for the <tt>install</tt>
     * command is:
     * <pre>
     *     install <URL> [<URL> ...]
     * </pre>
     * @return the usage string for the command.
    **/
    public String getUsage();

    /**
     * Returns a short description of the command; this description
     * should be as short as possible. This information is used when
     * generating the command help information.
     * @return a short description of the command.
    **/
    public String getShortDescription();

    /**
     * Executes the command using the supplied command line, output
     * print stream, and error print stream.
     * @param line the complete command line, including the command name.
     * @param out the print stream to use for standard output.
     * @param err the print stream to use for standard error.
    **/
    public void execute(String line, PrintStream out, PrintStream err);
}