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106 lines
3.3 KiB
106 lines
3.3 KiB
// Dao.java
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// (C) 2009 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
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// first published 25.05.2009 on http://yacy.net
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//
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// $LastChangedDate: 2006-04-02 22:40:07 +0200 (So, 02 Apr 2006) $
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// $LastChangedRevision: 1986 $
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// $LastChangedBy: orbiter $
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//
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// LICENSE
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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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package de.anomic.content.dao;
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import java.io.File;
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import java.sql.SQLException;
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import java.util.Date;
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import java.util.concurrent.BlockingQueue;
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import de.anomic.content.DCEntry;
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/*
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* Database Access Objects are used to get a normalized view on database objects with java objects
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*/
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public interface Dao {
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// item-oriented retrieval
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/**
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* get the maximum number of possible DCEntry items in the database
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* @throws SQLException
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*/
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public int size() throws SQLException;
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/**
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* retrieve a single item from the database
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* @param item
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* @return a single result entry in Dublin Core format
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*/
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public DCEntry get(int item);
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/**
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* retrieve a set of entries in the database;
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* the object denoted with until is not contained in the result set
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* all retrieved objects are pushed concurrently to a blocking queue
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* @param from the first id
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* @param until the limit of the last id (the id is not included)
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* @param queueSize the maximum number of entries in the blocing queue
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* @return a quere where the results are written in concurrently
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*/
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public BlockingQueue<DCEntry> query(int from, int until, int queueSize);
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// date-oriented retrieval
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/**
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* return the date of the first entry
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*/
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public Date first();
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/**
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* return the date of the latest entry
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* @return the date of the latest entry
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*/
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public Date latest();
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/**
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* retrieve a set of entries in the database;
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* the result set contains all entries up to the most recent
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* all retrieved objects are pushed to the blocking queue
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* @param from
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* @return a quere where the results are written in concurrently
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*/
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public BlockingQueue<DCEntry> query(Date from, int queueSize);
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// export methods
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public int writeSurrogates(
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BlockingQueue<DCEntry> queue,
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File targetdir,
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String versioninfo,
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int maxEntriesInFile
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);
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// workflow
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/**
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* close the connection to the database
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*/
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public void close();
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}
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