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106 lines
4.3 KiB
106 lines
4.3 KiB
// serverHandler.java
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// -------------------------------------------
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// (C) by Michael Peter Christen; mc@yacy.net
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// first published on http://www.anomic.de
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// Frankfurt, Germany, 2004
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// last major change: 05.04.2004
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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/*
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serverHandler:
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A Generic Server becomes a server for s specific protocol by impementation of
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a corresponding handler class. The handler class provides methods for each
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command of the protocol that is implemented.
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The Handler class is assigned to the serverCore by passing the handlers
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name to the serverCore upon initialization.
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Example:
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serverCore server = new serverCore(port, 1000, 0, false, "ftpdProtocol", null, 0);
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In this example the protocol handler "ftpdProtocol" is assigned. There a class
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named ftpdProtocol.java must be implemented, that implements this interface,
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a serverHandler.
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Any protocol command can be implemented in either way:
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public String COMMAND(String arg) throws IOException;
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public InputStream COMMAND(String arg) throws IOException;
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public void COMMAND(String arg) throws IOException;
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..where COMMAND is the command that had been passed to the server
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on the terminal connection. The 'arg' argument is the remaining part of
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the command on the terminal connection.
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If the handler method returns a NULL value, which is especially
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the case if the method implements a 'void' return-value method,
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then the server disconnects the connection.
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Any other return value (String or an InputStream) is returned to
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the client on it's own line through the terminal connection.
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If it is wanted that the server terminates right after submitting
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a last line, then this can be indicated by prefixing the return
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value by a '!'-character.
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If one of the command methods throws a IOException, then the
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server asks the error - method for a return value on the terminal
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connection.
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The greeting-method is used to request a string that is transmitted
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to the client as terminal output at the beginning of a connection
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session.
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*/
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package net.yacy.server;
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import java.io.IOException;
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import net.yacy.server.serverCore.Session;
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public interface serverHandler {
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// a response line upon connection is send to client
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// if no response line is wanted, return "" or null
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public String greeting();
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// return string in case of any error that occurs during communication
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// is always (but not only) called if an IO-dependent exception occurs.
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public String error(Throwable e);
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// clone method for the handler prototype
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// each time a server makes a new connection it clones the hanlder prototype
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// the clone method does not need to clone every detail of a handler connection,
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// but only the necessary one for a newly initialized instance
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public serverHandler clone();
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/**
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* Instead of using clone this function can be used to reset an existing
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* handler prototype so that it can e reused
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*/
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public void reset();
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/**
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* Tthis function will be called by the {@link serverCore}.listen() function
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* if the whole request line is empty and therefore no function of this
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* serverHandlerClass can be called because of the missing command name
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*/
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public Boolean EMPTY(String arg, Session session) throws IOException;
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/**
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* This function will be called by the {@link serverCore}.listen() function
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* if no corresponding funktion of the serverHandler class can be
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* found for the received command.
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*/
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public Boolean UNKNOWN(String requestLine, Session session) throws IOException;
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}
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