/*
* RHQ Management Platform
* Copyright (C) 2005-2008 Red Hat, Inc.
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
package org.rhq.enterprise.communications.command.client;
import java.util.Map;
import org.rhq.enterprise.communications.command.Command;
import org.rhq.enterprise.communications.command.CommandResponse;
import org.rhq.enterprise.communications.command.param.ParameterDefinition;
/**
* Interface to all clients of commands. This interface defines the operations one can make as a client to a remote
* command server.
*
* @author John Mazzitelli
*/
public interface CommandClient {
/**
* Gets the object that encapsulates the underlying remote framework implementation. This is the object that
* performs the actual sending of commands and receiving of command responses over the underlying remote framework
* transport.
*
* @return the remote communicator object that is specific to a particular underlying remote framework.
*/
RemoteCommunicator getRemoteCommunicator();
/**
* Sets the object that encapsulates the underlying remote framework implementation. This is the object that
* performs the actual sending of commands and receiving of command responses over the underlying remote framework
* transport.
*
* @param remoteCommunicator the remote communicator object that is specific to a particular underlying remote
* framework.
*/
void setRemoteCommunicator(RemoteCommunicator remoteCommunicator);
/**
* Provides a mechanism by which users can notify this object that the user is about to issue commands and that a
* remoting communicator should be created and should connect to the remote server.
*
* @throws Exception if failed to connect to the remote server for any reason
*
* @see #disconnectRemoteCommunicator()
*/
void connectRemoteCommunicator() throws Exception;
/**
* Provides a mechanism by which users can notify this object that the user is no longer interested in issuing
* commands to the remote server. The effect of this is the remoting communicator will now disconnect from the
* remote server.
*
* <p>Note that the user may later on change its mind and reconnect simply by calling
* {@link #connectRemoteCommunicator()}. Calling that method will reconnect the remoting communicator.</p>
*/
void disconnectRemoteCommunicator();
/**
* Invokes the actual command by utilizing the remoting communicator to transport the command to the server. This is
* the method in which subclasses make the command-specific client calls necessary to invoke the command on the
* remote server.
*
* <p>This method is typically used in conjunction with {@link CmdlineClient} to invoke commands that are unknown at
* compile-time. In this case, <code>params</code> typically contain values of type <code>String</code> - these are
* text-based parameters that were entered via a script or cmdline. That text-based data will be
* {@link ParameterDefinition#convertObject(Object) converted} to meaningful Java types in order to be able to build
* the proper {@link Command} objects.</p>
*
* @param params a set of command parameters that are to be used to execute the proper command (may be <code>
* null</code>)
*
* @return the command response
*
* @throws Throwable on any error (either during the sending or execution of the command)
*
* @see #createNewCommand(Map)
*/
CommandResponse invoke(Map<String, Object> params) throws Throwable;
/**
* Invokes the actual command by utilizing the remoting communicator to transport the command to the server. This is
* the method in which subclasses make the command-specific client calls necessary to invoke the command on the
* remote server.
*
* <p>This is the prefered method for clients to call when it needs to invoke commands since each {@link Command} is
* strongly typed and provides compile-time error checking. However, in order to be able to invoke this method on
* subclasses, concrete implementations must be used and hence the actual command that is to be issued must be known
* at compile time. Should a dynamic runtime client be needed to invoke commands unknown at compile time (see
* {@link CmdlineClient}), the use of {@link #invoke(Map)} will be required.</p>
*
* @param command encapsulates the command that is to be executed (must not be <code>null</code>)
*
* @return the command response
*
* @throws Throwable on any error (either during the sending or execution of the command)
*/
CommandResponse invoke(Command command) throws Throwable;
/**
* Creates a new {@link Command} object that can be used by this client. The client can take this new command
* instance, fill it in with parameter values and execute it. The given map of parameters is optional; if non-
* <code>null</code>, all parameters found in the map will be added to the command.
*
* @param params contains parameter values keyed on the parameter names (may be <code>null</code>)
*
* @return a new {@link Command} instance
*/
Command createNewCommand(Map<String, Object> params);
}