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The UnboundID LDAP SDK for Java is a fast, comprehensive, and easy-to-use
Java API for communicating with LDAP directory servers and performing
related tasks like reading and writing LDIF, encoding and decoding data
using base64 and ASN.1 BER, and performing secure communication. This
package contains the Standard Edition of the LDAP SDK, which is a
complete, general-purpose library for communicating with LDAPv3 directory
servers.
/*
* Copyright 2007-2018 Ping Identity Corporation
* All Rights Reserved.
*/
/*
* Copyright (C) 2008-2018 Ping Identity Corporation
*
* 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.Debug;
import com.unboundid.util.NotMutable;
import com.unboundid.util.ThreadSafety;
import com.unboundid.util.ThreadSafetyLevel;
import static com.unboundid.ldap.sdk.controls.ControlMessages.*;
/**
* 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)
{
Debug.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)
{
Debug.debugException(ae);
throw new LDAPException(ResultCode.DECODING_ERROR,
ERR_PAGED_RESULTS_FIRST_NOT_INTEGER.get(ae), ae);
}
cookie = ASN1OctetString.decodeAsOctetString(valueElements[1]);
}
/**
* {@inheritDoc}
*/
@Override()
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(')');
}
}