// Copyright (C) 2010 Google Inc.
//
// 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 com.google.enterprise.connector.instantiator;
/**
* Checks for changes in a persistent store. Intended to be run both
* manually to handle local servlet changes, and periodically to check
* for remote connector manager changes.
*
* @see com.google.enterprise.connector.persist.PersistentStore
* @see ChangeListener
*/
interface ChangeDetector {
/**
* Compares the version stamps for the in-memory objects and
* persisted objects, and notifies the {@link ChangeListener} of the
* needed updates.
*
* <p>
* The in-memory objects should reflect the persistent store, even
* if the store contains older objects. If the version stamp for a
* persisted object is older, then the in-memory object should be
* reverted.
*/
void detect();
}