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java/org/apache/catalina/tribes/ChannelInterceptor.java
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java/org/apache/catalina/tribes/ChannelInterceptor.java
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/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.catalina.tribes;
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import org.apache.catalina.tribes.group.InterceptorPayload;
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/**
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* A ChannelInterceptor is an interceptor that intercepts
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* messages and membership messages in the channel stack.
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* This allows interceptors to modify the message or perform
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* other actions when a message is sent or received.<br>
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* Interceptors are tied together in a linked list.
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* @see org.apache.catalina.tribes.group.ChannelInterceptorBase
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*/
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public interface ChannelInterceptor extends MembershipListener, Heartbeat {
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/**
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* An interceptor can react to a message based on a set bit on the
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* message options. <br>
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* When a message is sent, the options can be retrieved from ChannelMessage.getOptions()
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* and if the bit is set, this interceptor will react to it.<br>
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* A simple evaluation if an interceptor should react to the message would be:<br>
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* <code>boolean react = (getOptionFlag() == (getOptionFlag() & ChannelMessage.getOptions()));</code><br>
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* The default option is 0, meaning there is no way for the application to trigger the
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* interceptor. The interceptor itself will decide.<br>
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* @return int
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* @see ChannelMessage#getOptions()
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*/
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public int getOptionFlag();
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/**
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* Sets the option flag
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* @param flag int
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* @see #getOptionFlag()
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*/
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public void setOptionFlag(int flag);
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/**
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* Set the next interceptor in the list of interceptors
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* @param next ChannelInterceptor
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*/
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public void setNext(ChannelInterceptor next) ;
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/**
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* Retrieve the next interceptor in the list
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* @return ChannelInterceptor - returns the next interceptor in the list or null if no more interceptors exist
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*/
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public ChannelInterceptor getNext();
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/**
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* Set the previous interceptor in the list
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* @param previous ChannelInterceptor
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*/
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public void setPrevious(ChannelInterceptor previous);
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/**
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* Retrieve the previous interceptor in the list
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* @return ChannelInterceptor - returns the previous interceptor in the list or null if no more interceptors exist
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*/
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public ChannelInterceptor getPrevious();
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/**
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* The <code>sendMessage</code> method is called when a message is being sent to one more destinations.
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* The interceptor can modify any of the parameters and then pass on the message down the stack by
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* invoking <code>getNext().sendMessage(destination,msg,payload)</code><br>
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* Alternatively the interceptor can stop the message from being sent by not invoking
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* <code>getNext().sendMessage(destination,msg,payload)</code><br>
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* If the message is to be sent asynchronous the application can be notified of completion and
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* errors by passing in an error handler attached to a payload object.<br>
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* The ChannelMessage.getAddress contains Channel.getLocalMember, and can be overwritten
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* to simulate a message sent from another node.<br>
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* @param destination Member[] - the destination for this message
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* @param msg ChannelMessage - the message to be sent
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* @param payload InterceptorPayload - the payload, carrying an error handler and future useful data, can be null
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* @throws ChannelException if a serialization error happens.
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* @see ErrorHandler
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* @see InterceptorPayload
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*/
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public void sendMessage(Member[] destination, ChannelMessage msg, InterceptorPayload payload) throws ChannelException;
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/**
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* the <code>messageReceived</code> is invoked when a message is received.
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* <code>ChannelMessage.getAddress()</code> is the sender, or the reply-to address
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* if it has been overwritten.
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* @param data ChannelMessage
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*/
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public void messageReceived(ChannelMessage data);
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/**
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* The <code>heartbeat()</code> method gets invoked periodically
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* to allow interceptors to clean up resources, time out object and
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* perform actions that are unrelated to sending/receiving data.
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*/
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@Override
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public void heartbeat();
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/**
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* Intercepts the <code>Channel.hasMembers()</code> method
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* @return boolean - if the channel has members in its membership group
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* @see Channel#hasMembers()
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*/
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public boolean hasMembers() ;
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/**
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* Intercepts the <code>Channel.getMembers()</code> method
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* @return Member[]
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* @see Channel#getMembers()
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*/
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public Member[] getMembers() ;
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/**
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* Intercepts the <code>Channel.getLocalMember(boolean)</code> method
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* @param incAliveTime boolean
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* @return Member
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* @see Channel#getLocalMember(boolean)
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*/
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public Member getLocalMember(boolean incAliveTime) ;
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/**
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* Intercepts the <code>Channel.getMember(Member)</code> method
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* @param mbr Member
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* @return Member - the actual member information, including stay alive
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* @see Channel#getMember(Member)
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*/
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public Member getMember(Member mbr);
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/**
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* Starts up the channel. This can be called multiple times for individual services to start
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* The svc parameter can be the logical or value of any constants
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* @param svc int value of <BR>
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* Channel.DEFAULT - will start all services <BR>
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* Channel.MBR_RX_SEQ - starts the membership receiver <BR>
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* Channel.MBR_TX_SEQ - starts the membership broadcaster <BR>
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* Channel.SND_TX_SEQ - starts the replication transmitter<BR>
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* Channel.SND_RX_SEQ - starts the replication receiver<BR>
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* @throws ChannelException if a startup error occurs or the service is already started.
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* @see Channel
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*/
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public void start(int svc) throws ChannelException;
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/**
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* Shuts down the channel. This can be called multiple times for individual services to shutdown
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* The svc parameter can be the logical or value of any constants
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* @param svc int value of <BR>
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* Channel.DEFAULT - will shutdown all services <BR>
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* Channel.MBR_RX_SEQ - stops the membership receiver <BR>
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* Channel.MBR_TX_SEQ - stops the membership broadcaster <BR>
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* Channel.SND_TX_SEQ - stops the replication transmitter<BR>
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* Channel.SND_RX_SEQ - stops the replication receiver<BR>
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* @throws ChannelException if a startup error occurs or the service is already started.
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* @see Channel
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*/
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public void stop(int svc) throws ChannelException;
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public void fireInterceptorEvent(InterceptorEvent event);
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/**
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* Return the channel that is related to this interceptor
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* @return Channel
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*/
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public Channel getChannel();
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/**
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* Set the channel that is related to this interceptor
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* @param channel The channel
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*/
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public void setChannel(Channel channel);
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interface InterceptorEvent {
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int getEventType();
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String getEventTypeDesc();
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ChannelInterceptor getInterceptor();
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}
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}
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