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/*
* Copyright 2007-2017 UnboundID Corp.
* All Rights Reserved.
*/
/*
* Copyright (C) 2008-2017 UnboundID Corp.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License (GPLv2 only)
* or the terms of the GNU Lesser General Public License (LGPLv2.1 only)
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see .
*/
package com.unboundid.ldap.sdk.controls;
import com.unboundid.asn1.ASN1Element;
import com.unboundid.asn1.ASN1Exception;
import com.unboundid.asn1.ASN1Integer;
import com.unboundid.asn1.ASN1OctetString;
import com.unboundid.asn1.ASN1Sequence;
import com.unboundid.ldap.sdk.Control;
import com.unboundid.ldap.sdk.DecodeableControl;
import com.unboundid.ldap.sdk.LDAPException;
import com.unboundid.ldap.sdk.ResultCode;
import com.unboundid.ldap.sdk.SearchResult;
import com.unboundid.util.NotMutable;
import com.unboundid.util.ThreadSafety;
import com.unboundid.util.ThreadSafetyLevel;
import static com.unboundid.ldap.sdk.controls.ControlMessages.*;
import static com.unboundid.util.Debug.*;
/**
* This class provides an implementation of the simple paged results control as
* defined in RFC 2696. It
* allows the client to iterate through a potentially large set of search
* results in subsets of a specified number of entries (i.e., "pages").
*
* The same control encoding is used for both the request control sent by
* clients and the response control returned by the server. It may contain
* two elements:
*
*
Size -- In a request control, this provides the requested page size,
* which is the maximum number of entries that the server should return
* in the next iteration of the search. In a response control, it is an
* estimate of the total number of entries that match the search
* criteria.
*
Cookie -- A token which is used by the server to keep track of its
* position in the set of search results. The first request sent by the
* client should not include a cookie, and the last response sent by the
* server should not include a cookie. For all other intermediate search
* requests and responses, the server will include a cookie value in its
* response that the client should include in its next request.
*
* When the client wishes to use the paged results control, the first search
* request should include a version of the paged results request control that
* was created with a requested page size but no cookie. The corresponding
* response from the server will include a version of the paged results control
* that may include an estimate of the total number of matching entries, and
* may also include a cookie. The client should include this cookie in the
* next request (with the same set of search criteria) to retrieve the next page
* of results. This process should continue until the response control returned
* by the server does not include a cookie, which indicates that the end of the
* result set has been reached.
*
* Note that the simple paged results control is similar to the
* {@link VirtualListViewRequestControl} in that both allow the client to
* request that only a portion of the result set be returned at any one time.
* However, there are significant differences between them, including:
*
*
In order to use the virtual list view request control, it is also
* necessary to use the {@link ServerSideSortRequestControl} to ensure
* that the entries are sorted. This is not a requirement for the
* simple paged results control.
*
The simple paged results control may only be used to iterate
* sequentially through the set of search results. The virtual list view
* control can retrieve pages out of order, can retrieve overlapping
* pages, and can re-request pages that it had already retrieved.
*
*
Example
* The following example demonstrates the use of the simple paged results
* control. It will iterate through all users, retrieving up to 10 entries at a
* time:
*
* // Perform a search to retrieve all users in the server, but only retrieving
* // ten at a time.
* int numSearches = 0;
* int totalEntriesReturned = 0;
* SearchRequest searchRequest = new SearchRequest("dc=example,dc=com",
* SearchScope.SUB, Filter.createEqualityFilter("objectClass", "person"));
* ASN1OctetString resumeCookie = null;
* while (true)
* {
* searchRequest.setControls(
* new SimplePagedResultsControl(10, resumeCookie));
* SearchResult searchResult = connection.search(searchRequest);
* numSearches++;
* totalEntriesReturned += searchResult.getEntryCount();
* for (SearchResultEntry e : searchResult.getSearchEntries())
* {
* // Do something with each entry...
* }
*
* LDAPTestUtils.assertHasControl(searchResult,
* SimplePagedResultsControl.PAGED_RESULTS_OID);
* SimplePagedResultsControl responseControl =
* SimplePagedResultsControl.get(searchResult);
* if (responseControl.moreResultsToReturn())
* {
* // The resume cookie can be included in the simple paged results
* // control included in the next search to get the next page of results.
* resumeCookie = responseControl.getCookie();
* }
* else
* {
* break;
* }
* }
*
*/
@NotMutable()
@ThreadSafety(level=ThreadSafetyLevel.COMPLETELY_THREADSAFE)
public final class SimplePagedResultsControl
extends Control
implements DecodeableControl
{
/**
* The OID (1.2.840.113556.1.4.319) for the paged results control.
*/
public static final String PAGED_RESULTS_OID = "1.2.840.113556.1.4.319";
/**
* The serial version UID for this serializable class.
*/
private static final long serialVersionUID = 2186787148024999291L;
// The encoded cookie returned from the server (for a response control) or
// that should be included in the next request to the server (for a request
// control).
private final ASN1OctetString cookie;
// The maximum requested page size (for a request control), or the estimated
// total result set size (for a response control).
private final int size;
/**
* Creates a new empty control instance that is intended to be used only for
* decoding controls via the {@code DecodeableControl} interface.
*/
SimplePagedResultsControl()
{
size = 0;
cookie = new ASN1OctetString();
}
/**
* Creates a new paged results control with the specified page size. This
* version of the constructor should only be used when creating the first
* search as part of the set of paged results. Subsequent searches to
* retrieve additional pages should use the response control returned by the
* server in their next request, until the response control returned by the
* server does not include a cookie.
*
* @param pageSize The maximum number of entries that the server should
* return in the first page.
*/
public SimplePagedResultsControl(final int pageSize)
{
super(PAGED_RESULTS_OID, false, encodeValue(pageSize, null));
size = pageSize;
cookie = new ASN1OctetString();
}
/**
* Creates a new paged results control with the specified page size. This
* version of the constructor should only be used when creating the first
* search as part of the set of paged results. Subsequent searches to
* retrieve additional pages should use the response control returned by the
* server in their next request, until the response control returned by the
* server does not include a cookie.
*
* @param pageSize The maximum number of entries that the server should
* return in the first page.
* @param isCritical Indicates whether this control should be marked
* critical.
*/
public SimplePagedResultsControl(final int pageSize, final boolean isCritical)
{
super(PAGED_RESULTS_OID, isCritical, encodeValue(pageSize, null));
size = pageSize;
cookie = new ASN1OctetString();
}
/**
* Creates a new paged results control with the specified page size and the
* provided cookie. This version of the constructor should be used to
* continue iterating through an existing set of results, but potentially
* using a different page size.
*
* @param pageSize The maximum number of entries that the server should
* return in the next page of the results.
* @param cookie The cookie provided by the server after returning the
* previous page of results, or {@code null} if this request
* will retrieve the first page of results.
*/
public SimplePagedResultsControl(final int pageSize,
final ASN1OctetString cookie)
{
super(PAGED_RESULTS_OID, false, encodeValue(pageSize, cookie));
size = pageSize;
if (cookie == null)
{
this.cookie = new ASN1OctetString();
}
else
{
this.cookie = cookie;
}
}
/**
* Creates a new paged results control with the specified page size and the
* provided cookie. This version of the constructor should be used to
* continue iterating through an existing set of results, but potentially
* using a different page size.
*
* @param pageSize The maximum number of entries that the server should
* return in the first page.
* @param cookie The cookie provided by the server after returning the
* previous page of results, or {@code null} if this
* request will retrieve the first page of results.
* @param isCritical Indicates whether this control should be marked
* critical.
*/
public SimplePagedResultsControl(final int pageSize,
final ASN1OctetString cookie,
final boolean isCritical)
{
super(PAGED_RESULTS_OID, isCritical, encodeValue(pageSize, cookie));
size = pageSize;
if (cookie == null)
{
this.cookie = new ASN1OctetString();
}
else
{
this.cookie = cookie;
}
}
/**
* Creates a new paged results control from the control with the provided set
* of information. This should be used to decode the paged results response
* control returned by the server with a page of results.
*
* @param oid The OID for the control.
* @param isCritical Indicates whether the control should be marked
* critical.
* @param value The encoded value for the control. This may be
* {@code null} if no value was provided.
*
* @throws LDAPException If the provided control cannot be decoded as a
* simple paged results control.
*/
public SimplePagedResultsControl(final String oid, final boolean isCritical,
final ASN1OctetString value)
throws LDAPException
{
super(oid, isCritical, value);
if (value == null)
{
throw new LDAPException(ResultCode.DECODING_ERROR,
ERR_PAGED_RESULTS_NO_VALUE.get());
}
final ASN1Sequence valueSequence;
try
{
final ASN1Element valueElement = ASN1Element.decode(value.getValue());
valueSequence = ASN1Sequence.decodeAsSequence(valueElement);
}
catch (final ASN1Exception ae)
{
debugException(ae);
throw new LDAPException(ResultCode.DECODING_ERROR,
ERR_PAGED_RESULTS_VALUE_NOT_SEQUENCE.get(ae), ae);
}
final ASN1Element[] valueElements = valueSequence.elements();
if (valueElements.length != 2)
{
throw new LDAPException(ResultCode.DECODING_ERROR,
ERR_PAGED_RESULTS_INVALID_ELEMENT_COUNT.get(
valueElements.length));
}
try
{
size = ASN1Integer.decodeAsInteger(valueElements[0]).intValue();
}
catch (final ASN1Exception ae)
{
debugException(ae);
throw new LDAPException(ResultCode.DECODING_ERROR,
ERR_PAGED_RESULTS_FIRST_NOT_INTEGER.get(ae), ae);
}
cookie = ASN1OctetString.decodeAsOctetString(valueElements[1]);
}
/**
* {@inheritDoc}
*/
public SimplePagedResultsControl
decodeControl(final String oid, final boolean isCritical,
final ASN1OctetString value)
throws LDAPException
{
return new SimplePagedResultsControl(oid, isCritical, value);
}
/**
* Extracts a simple paged results response control from the provided result.
*
* @param result The result from which to retrieve the simple paged results
* response control.
*
* @return The simple paged results response control contained in the
* provided result, or {@code null} if the result did not contain a
* simple paged results response control.
*
* @throws LDAPException If a problem is encountered while attempting to
* decode the simple paged results response control
* contained in the provided result.
*/
public static SimplePagedResultsControl get(final SearchResult result)
throws LDAPException
{
final Control c = result.getResponseControl(PAGED_RESULTS_OID);
if (c == null)
{
return null;
}
if (c instanceof SimplePagedResultsControl)
{
return (SimplePagedResultsControl) c;
}
else
{
return new SimplePagedResultsControl(c.getOID(), c.isCritical(),
c.getValue());
}
}
/**
* Encodes the provided information into an octet string that can be used as
* the value for this control.
*
* @param pageSize The maximum number of entries that the server should
* return in the next page of the results.
* @param cookie The cookie provided by the server after returning the
* previous page of results, or {@code null} if this request
* will retrieve the first page of results.
*
* @return An ASN.1 octet string that can be used as the value for this
* control.
*/
private static ASN1OctetString encodeValue(final int pageSize,
final ASN1OctetString cookie)
{
final ASN1Element[] valueElements;
if (cookie == null)
{
valueElements = new ASN1Element[]
{
new ASN1Integer(pageSize),
new ASN1OctetString()
};
}
else
{
valueElements = new ASN1Element[]
{
new ASN1Integer(pageSize),
cookie
};
}
return new ASN1OctetString(new ASN1Sequence(valueElements).encode());
}
/**
* Retrieves the size for this paged results control. For a request control,
* it may be used to specify the number of entries that should be included in
* the next page of results. For a response control, it may be used to
* specify the estimated number of entries in the complete result set.
*
* @return The size for this paged results control.
*/
public int getSize()
{
return size;
}
/**
* Retrieves the cookie for this control, which may be used in a subsequent
* request to resume reading entries from the next page of results. The
* value should have a length of zero when used to retrieve the first page of
* results for a given search, and also in the response from the server when
* there are no more entries to send. It should be non-empty for all other
* conditions.
*
* @return The cookie for this control, or {@code null} if there is none.
*/
public ASN1OctetString getCookie()
{
return cookie;
}
/**
* Indicates whether there are more results to return as part of this search.
*
* @return {@code true} if there are more results to return, or
* {@code false} if not.
*/
public boolean moreResultsToReturn()
{
return (cookie.getValue().length > 0);
}
/**
* {@inheritDoc}
*/
@Override()
public String getControlName()
{
return INFO_CONTROL_NAME_PAGED_RESULTS.get();
}
/**
* {@inheritDoc}
*/
@Override()
public void toString(final StringBuilder buffer)
{
buffer.append("SimplePagedResultsControl(pageSize=");
buffer.append(size);
buffer.append(", isCritical=");
buffer.append(isCritical());
buffer.append(')');
}
}
