org.dspace.ctask.replicate.ObjectStore Maven / Gradle / Ivy
/**
* The contents of this file are subject to the license and copyright
* detailed in the LICENSE and NOTICE files at the root of the source
* tree and available online at
*
* http://www.dspace.org/license/
*/
package org.dspace.ctask.replicate;
import java.io.File;
import java.io.IOException;
/**
* An ObjectStore provides access to a managed store containing objects
* that possess a set of attributes. ObjectStores allow storage within named
* containers, here called groups.
*
* @author richardrodgers
*/
public interface ObjectStore {
/**
* Initializes the storage service for use.
*/
void init() throws IOException;
/**
* Returns whether an object with the passed id exists in the store.
*
* @param group
* @param id
* @return true if a representation of the object named by ID exists
*/
boolean objectExists(String group, String id) throws IOException;
/**
* Obtains attributes of the representation of the object with passed ID.
*
* @param group
* @param id
* @param attrName - name of the attribute
* @return value of the attribute if it exists, else null
* @throws IOException
*/
String objectAttribute(String group, String id, String attrName) throws IOException;
/**
* Fetches a copy of the object with passed ID, and places it in passed file.
*
* @param group
* @param id
* @return number of bytes the replica used
* @throws IOException
*/
long fetchObject(String group, String id, File file) throws IOException;
/**
* Transfers a copy of this file to the object store
*
* @param group
* @param file the file to transfer to store
* @return number of bytes transferred to store or 0 if transfer failed.
* @throws IOException
*/
long transferObject(String group, File file) throws IOException;
/**
* Removes the passed object from the store.
*
* @param group
* @param id the id of the object to remove
* @return number of bytes the object was using, or 0 if
* object did not exist.
*/
long removeObject(String group, String id) throws IOException;
}