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/*
* Channel.java February 2007
*
* Copyright (C) 2007, Niall Gallagher
*
* 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.simpleframework.transport;
import java.nio.channels.SocketChannel;
import java.util.Map;
import javax.net.ssl.SSLEngine;
import org.simpleframework.transport.trace.Trace;
/**
* The Channel interface represents a connected channel
* through which data can be sent and received. Typically a channel
* will have a connected TCP socket, which can be used to determine
* when the channel is read ready, and write ready. A channel can
* also contain a bag of attributes used to describe the connection.
*
* Reading and writing to a channel is performed using two special
* interfaces. The first is the Cursor object which is
* used to read data from the channel in a non-blocking manner. This
* can also be used to reset data if it has read too much. To write
* the Sender can be used, this provides a blocking
* interface much like a conventional output stream.
*
* @author Niall Gallagher
*/
public interface Channel {
/**
* This is used to determine if the channel is secure and that
* data read from and data written to the request is encrypted.
* Channels transferred over SSL are considered secure and will
* have this return true, otherwise it will return false.
*
* @return true if this is secure for reading and writing
*/
boolean isSecure();
/**
* This is the connected socket channel associated with this. In
* order to determine if content can be read or written to or
* from the channel this socket can be used with a selector. This
* provides a means to react to I/O events as they occur rather
* than polling the channel which is generally less performant.
*
* @return this returns the connected socket channel
*/
SocketChannel getSocket();
/**
* This is used to acquire the SSL engine used for security. If
* the socket is connected to an SSL transport this returns an
* SSL engine which can be used to establish the secure connection
* and send and receive content over that connection. If this is
* null then the socket represents a normal transport.
*
* @return the SSL engine used to establish a secure transport
*/
SSLEngine getEngine();
/**
* This gets the Trace object associated with the
* channel. The trace is used to log various events for the life
* of the transaction such as low level read and write events
* as well as milestone events and errors.
*
* @return this returns the trace associated with the socket
*/
Trace getTrace();
/**
* This provides the Cursor for this channel. The
* cursor provides a resettable view of the input buffer and will
* allow the server kernel to peek into the input buffer without
* having to take the data from the input. This allows overflow
* to be pushed back on to the cursor for subsequent reads.
*
* @return this returns the input cursor for the channel
*/
Cursor getCursor();
/**
* This provides the Sender for the channel. This is
* used to provide a blocking output mechanism for the channel.
* Enabling blocking reads ensures that output buffering can be
* limited to an extent, which ensures that memory remains low at
* high load periods. Writes to the sender may result in the data
* being copied and queued until the socket is write ready.
*
* @return this returns the output sender for this channel
*/
Sender getSender();
/**
* This returns the Map of attributes used to hold
* connection information for the channel. The attributes here
* are taken from the pipeline attributes and may contain details
* such as SSL certificates or other such useful information.
*
* @return returns the attributes associated with the channel
*/
Map getAttributes();
/**
* Because the channel represents a duplex means of communication
* there needs to be a means to close it down. This provides such
* a means. By closing the channel the cursor and sender will no
* longer send or recieve data to or from the network. The client
* will also be signaled that the connection has been severed.
*/
void close();
}