/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.catalina.tribes;
import org.apache.catalina.tribes.group.InterceptorPayload;
/**
* A ChannelInterceptor is an interceptor that intercepts
* messages and membership messages in the channel stack.
* This allows interceptors to modify the message or perform
* other actions when a message is sent or received.<br>
* Interceptors are tied together in a linked list.
* @see org.apache.catalina.tribes.group.ChannelInterceptorBase
* @author Filip Hanik
*
*/
public interface ChannelInterceptor extends MembershipListener, Heartbeat {
/**
* An interceptor can react to a message based on a set bit on the
* message options. <br>
* When a message is sent, the options can be retrieved from ChannelMessage.getOptions()
* and if the bit is set, this interceptor will react to it.<br>
* A simple evaluation if an interceptor should react to the message would be:<br>
* <code>boolean react = (getOptionFlag() == (getOptionFlag() & ChannelMessage.getOptions()));</code><br>
* The default option is 0, meaning there is no way for the application to trigger the
* interceptor. The interceptor itself will decide.<br>
* @return int
* @see ChannelMessage#getOptions()
*/
public int getOptionFlag();
/**
* Sets the option flag
* @param flag int
* @see #getOptionFlag()
*/
public void setOptionFlag(int flag);
/**
* Set the next interceptor in the list of interceptors
* @param next ChannelInterceptor
*/
public void setNext(ChannelInterceptor next) ;
/**
* Retrieve the next interceptor in the list
* @return ChannelInterceptor - returns the next interceptor in the list or null if no more interceptors exist
*/
public ChannelInterceptor getNext();
/**
* Set the previous interceptor in the list
* @param previous ChannelInterceptor
*/
public void setPrevious(ChannelInterceptor previous);
/**
* Retrieve the previous interceptor in the list
* @return ChannelInterceptor - returns the previous interceptor in the list or null if no more interceptors exist
*/
public ChannelInterceptor getPrevious();
/**
* The <code>sendMessage</code> method is called when a message is being sent to one more destinations.
* The interceptor can modify any of the parameters and then pass on the message down the stack by
* invoking <code>getNext().sendMessage(destination,msg,payload)</code><br>
* Alternatively the interceptor can stop the message from being sent by not invoking
* <code>getNext().sendMessage(destination,msg,payload)</code><br>
* If the message is to be sent asynchronous the application can be notified of completion and
* errors by passing in an error handler attached to a payload object.<br>
* The ChannelMessage.getAddress contains Channel.getLocalMember, and can be overwritten
* to simulate a message sent from another node.<br>
* @param destination Member[] - the destination for this message
* @param msg ChannelMessage - the message to be sent
* @param payload InterceptorPayload - the payload, carrying an error handler and future useful data, can be null
* @throws ChannelException
* @see ErrorHandler
* @see InterceptorPayload
*/
public void sendMessage(Member[] destination, ChannelMessage msg, InterceptorPayload payload) throws ChannelException;
/**
* the <code>messageReceived</code> is invoked when a message is received.
* <code>ChannelMessage.getAddress()</code> is the sender, or the reply-to address
* if it has been overwritten.
* @param data ChannelMessage
*/
public void messageReceived(ChannelMessage data);
/**
* The <code>heartbeat()</code> method gets invoked periodically
* to allow interceptors to clean up resources, time out object and
* perform actions that are unrelated to sending/receiving data.
*/
public void heartbeat();
/**
* Intercepts the <code>Channel.hasMembers()</code> method
* @return boolean - if the channel has members in its membership group
* @see Channel#hasMembers()
*/
public boolean hasMembers() ;
/**
* Intercepts the code>Channel.getMembers()</code> method
* @return Member[]
* @see Channel#getMembers()
*/
public Member[] getMembers() ;
/**
* Intercepts the code>Channel.getLocalMember(boolean)</code> method
* @param incAliveTime boolean
* @return Member
* @see Channel#getLocalMember(boolean)
*/
public Member getLocalMember(boolean incAliveTime) ;
/**
* Intercepts the code>Channel.getMember(Member)</code> method
* @param mbr Member
* @return Member - the actual member information, including stay alive
* @see Channel#getMember(Member)
*/
public Member getMember(Member mbr);
/**
* Starts up the channel. This can be called multiple times for individual services to start
* The svc parameter can be the logical or value of any constants
* @param svc int value of <BR>
* Channel.DEFAULT - will start all services <BR>
* Channel.MBR_RX_SEQ - starts the membership receiver <BR>
* Channel.MBR_TX_SEQ - starts the membership broadcaster <BR>
* Channel.SND_TX_SEQ - starts the replication transmitter<BR>
* Channel.SND_RX_SEQ - starts the replication receiver<BR>
* @throws ChannelException if a startup error occurs or the service is already started.
* @see Channel
*/
public void start(int svc) throws ChannelException;
/**
* Shuts down the channel. This can be called multiple times for individual services to shutdown
* The svc parameter can be the logical or value of any constants
* @param svc int value of <BR>
* Channel.DEFAULT - will shutdown all services <BR>
* Channel.MBR_RX_SEQ - stops the membership receiver <BR>
* Channel.MBR_TX_SEQ - stops the membership broadcaster <BR>
* Channel.SND_TX_SEQ - stops the replication transmitter<BR>
* Channel.SND_RX_SEQ - stops the replication receiver<BR>
* @throws ChannelException if a startup error occurs or the service is already started.
* @see Channel
*/
public void stop(int svc) throws ChannelException;
public void fireInterceptorEvent(InterceptorEvent event);
interface InterceptorEvent {
int getEventType();
String getEventTypeDesc();
ChannelInterceptor getInterceptor();
}
}